Prebid Server - New Bid Adapter (Go)

Thank you for contributing a bid adapter to the open source Prebid Server project. Each new adapter gives publishers more options for monetizing their inventory and strengthens the header bidding community.

This document guides you through the process of developing a new bid adapter for your bidding server. We encourage you to look at existing bid adapters for working examples and practical guidance. You can also ask us questions by submitting a GitHub issue.

There are two implementations of Prebid Server, PBS-Go and PBS-Java. We recommend you build new adapters for PBS-Go and allow us to port it to PBS-Java within a couple of months. If you’d like to build both yourself, please also follow these instructions for building an adapter in PBS-Java.

Overview

Bid adapters are responsible for translating an OpenRTB 2.5 Bid Request to your bidding server’s protocol and mapping your server’s response to an OpenRTB 2.5 Bid Response.

An OpenRTB 2.5 Bid Request contains one or more Impressions, each representing a single ad placement. An Impression may define multiple sizes and/or multiple ad formats. If your bidding server limits requests to a single ad placement, size, or format, then your adapter will need to split the Impression into multiple calls and merge the responses.

Plan Your Bid Adapter

Choose A Name

You will need to choose a unique name for your bid adapter. Names should be written in lower case and may not contain special characters or emoji. If you already have a Prebid.js bid adapter, we encourage you to use the same name with the same bidder parameters. You may not name your adapter all, context, data, general, prebid, skadn or tid as those have special meaning in various contexts. Existing bid adapter names are maintained here.

We ask that the first 6 letters of the name you choose be unique among the existing bid adapters. This consideration helps with generating targeting keys for use by some ad exchanges, such as Google Ad Manager. There’s no need to manually check, as this constraint is enforced by the TestBidderUniquenessGatekeeping test.

Throughout the rest of this document, substitute {bidder} with the name you’ve chosen.

Respect The Rules

We are proud to run the Prebid Server project as a transparent and trustworthy header bidding solution. You are expected to follow our community’s code of conduct and module rules when creating your adapter and when interacting with others through issues, code reviews, and discussions.

Please take the time to read our rules in full. Below is a summary of some of the rules which apply to your Prebid Server bid adapter:

  • Adapters must not modify bids from demand partners, except to either change the bid from gross to net or from one currency to another.
  • Adapters must use the functions provided by the core framework for all external communication. Initiation of any form of network connection outside of what is provided by the core framework is strictly prohibited. No exceptions will be made for this rule.
  • Adapters must support the creation of multiple concurrent instances. This means adapters may not mutate global or package scoped variables.
  • Bidding server endpoints should prefer secure HTTPS to protect user privacy and should allow keep alive connections (preferably with HTTP/2 support) to increase host performance.
  • Adapters must include maintainer information with a group email address for Prebid.org to contact for ongoing support and maintenance.
  • Adapters must annotate the bid response with the proper media type, ideally based on the response from the bidding server.

Failure to follow the rules will lead to delays in approving your adapter. If you’d like to discuss an exception to a rule, please make your request by submitting a GitHub issue.

Support and Maintenance

You are expected to provide support and maintenance for the code you contribute to Prebid Server as part of your bid adapter. We ask that you proactively update your adapter when your bidding server introduces new features or breaking changes.

Occasionally, we’ll introduce changes to the core framework as part of our ongoing maintenance and enhancement of the project. If this causes a compilation error or a performance impact to your adapter, we will update the affected portion of your bid adapter code and provide full unit test coverage of our changes. We will notify you via email if this happens and give you at least one week to review the PR and provide comments. Please understand that we will not wait for your explicit approval for these kinds of changes unless you respond to our email or comment on the PR.

Please be attentive in reading and responding to emails and GitHub issues from publishers, hosts, and Prebid.org project maintainers. If we receive complaints about your bid adapter and you do not respond to our communications, we may disable your adapter by default or remove it from the project entirely.

Create Your Adapter

Prebid Server bid adapters consist of several components: bidder info, bidder parameters, adapter code, registration with the core framework, and default configuration values. This document will guide you though each component.

Please refer to existing bid adapters for working examples and practical guidance, but understand that our adapter interfaces and coding style evolve over time. The examples in this document have precedence over differences you may find in an existing bid adapter.

Our project is written in the Go programming language. We understand not everyone has prior experience writing Go code. Please try your best and we’ll respectfully steer you in the right direction during the review process.

Please do not ignore errors from method calls made in your bid adapter code. Even if it’s seemingly impossible for an error to occur, such as from json.Marshal, it’s still possible under the high throughput multi-threaded nature of Prebid Server.

Bidder Info

Let’s begin with your adapter’s bidder information YAML file. This file is required and contains your bid adapter’s maintainer email address, GDPR Global Vendor List (GVL) ID, supported ad formats, user sync endpoints, and allows you to opt-out of video impression tracking.

Create a file with the path static/bidder-info/{bidder}.yaml and begin with the following template:

maintainer:
  email: prebid-maintainer@example.com
gvlVendorID: 42
modifyingVastXmlAllowed: true
capabilities:
  app:
    mediaTypes:
      - banner
      - video
      - audio
      - native
  site:
    mediaTypes:
      - banner
      - video
      - audio
      - native
userSync:
  redirect:
    url: https://foo.com/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID

Modify this template for your bid adapter:

  • Change the maintainer email address to a group distribution list on your ad server’s domain. A distribution list is preferred over an individual mailbox to allow for robustness, as roles and team members naturally change.
  • Change the gvlVendorID from the sample value of 42 to the id of your bidding server as registered with the GDPR Global Vendor List (GVL), or remove this line entirely if your bidding server is not registered with IAB Europe.
  • Change the modifyingVastXmlAllowed value to false if you’d like to opt-out of video impression tracking, or remove this line entirely if your adapter doesn’t support VAST video ads.
  • Remove the capabilities (app/site) and mediaTypes (banner/video/audio/native) combinations which your adapter does not support.
  • Follow the User Sync Configuration documentation below to configure the endpoints for your bid adapter, or remove the userSync section if not supported.
Example: Website with banner ads only.
maintainer:
  email: foo@foo.com
gvlVendorID: 42
capabilities:
  site:
    mediaTypes:
      - banner
userSync:
  redirect:
    url: https://foo.com/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID
Example: Website with banner ads only and not registered with IAB Europe.
maintainer:
  email: foo@foo.com
capabilities:
  site:
    mediaTypes:
      - banner
userSync:
  redirect:
    url: https://foo.com/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID
Example: Website or app with banner or video ads and video impression tracking.
maintainer:
  email: foo@foo.com
gvlVendorID: 42
modifyingVastXmlAllowed: true
capabilities:
  app:
    mediaTypes:
      - banner
      - video
  site:
    mediaTypes:
      - banner
      - video
userSync:
  redirect:
    url: https://foo.com/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID

User Sync Configuration

Prebid Server offers a federated user sync process to store user ids from multiple bidders in a single cookie under the host’s domain. You may add support for your bid adapter by configuring iframe and/or redirect endpoints.

The Bidder Info template above demonstrates configuration of a redirect user sync. The url points to an endpoint on your bidding server which will honor the privacy policies, replace the userMacro in the redirect url with the user’s tracking id, and respond with an HTTP 302 redirect to that url. You may also specify an iframe endpoint which will return an HTML document to be rendered in an iframe on the user’s device and use JavaScript to perform the redirect. You may omit the {{.GDPR}}, {{.GDPRConsent}}, and/or {{.USPrivacy}} macros if they are not applicable to your legal situation.

If both iframe and redirect endpoints are provided, the iframe endpoint will be used by default.

userSync:
  iframe:
    url: https://foo.com/iframe/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID
  redirect:
    url: https://foo.com/redirect/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID

If your bid adapter supports user sync and doesn’t have a good default endpoint, you may optionally specify a supports array with the items iframe and/or redirect to inform Prebid Server hosts. Hosts will receive a warning on startup if a bid adapter supports user sync and isn’t configured. Expect hosts to contact you at the maintainer email address for instructions.

userSync:
  # foo supports user syncing, but requires configuration by the host. contact this
  # bidder directly at the email address in this file to ask about enabling user sync.
  supports:
    - iframe
    - redirect

Each user sync is assigned a case-sensitive key, defaulting to your bidder name. You may use a different key value, but we discourage doing so except for when multiple bidders share the same bidding server. You might encounter this use case for built-in aliases or for multiple bidders implementing different protocols for the same bidding server. Only one bid adapter may specify endpoints when using a shared key, or Prebid Server will fail to startup due to the ambiguity.

foo.yaml
--------
userSync:
  redirect:
    url: https://foo.com/sync?gdpr={{.GDPR}}&consent={{.GDPRConsent}}&us_privacy={{.USPrivacy}}&redirect={{.RedirectURL}}
    userMacro: $UID

bar.yaml
--------
userSync:
  key: foo

Bidder Parameters

Your bid adapter might require extra information from the publisher to form a request to your bidding server. The bidder parameters JSON Schema codifies this information to allow Prebid Server to verify requests and to provide an API for configuration systems.

Publishers will provide extra information using an OpenRTB 2.5 Bid Request Extension, preferably at request.imp[].ext.prebid.bidder.{bidder} but also supported at request.imp[].ext.{bidder}. Prebid Server will validate the publisher information based on your schema and relocate the data to request.imp[].ext.bidder, regardless of your bidder name or the publisher’s chosen location.

We request you do not duplicate information already present in the OpenRTB 2.5 Bid Request specification or already part of an established Prebid convention. For example, your bidder parameters should not include first party data, bid floors, schain, video parameters, referrer information, or privacy consent including COPPA, CCPA, and GDPR TCF. For video parameters in particular, you must prefer the OpenRTB 2.5 Bid Request standard of request.imp[].video.

You may not use an endpoint domain as a bidder parameter. Prebid Server is not an open proxy. If absolutely necessary, you may specify a portion of the domain as a parameter to support geo regions or account specific servers. However, this is discouraged and may degrade the performance of your adapter since the server needs to maintain more outgoing connections. Host companies may choose to disable your adapter if it uses a dynamically configured domain.

Create a file with the path static/bidder-params/{bidder}.json and use JSON Schema to define your bidder parameters. Prebid Server requires this file for every adapter, even if yours doesn’t require bidder parameters (see the ‘no parameters’ example at the end of this section).

Let’s start with this example which defines one required placementId string parameter:

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {
    "placementId": {
      "type": "string",
      "description": "Placement ID"
    }
  },

  "required": ["placementId"]
}

We encourage you to utilize the full features of JSON Schema to narrowly define your bidder parameter data types. If you copy and paste these examples, please remember to change the title and description to refer to your bidder name instead of our fictional Foo example.

When choosing your parameter names, please consider aligning with the OpenRTB 2.5 standard by using lower case letters without camel casing or special characters.

Properties in JSON Schema are case sensitive. If you choose to specify multiple properties differing only by case for compatibility, we ask that you include the word ‘preferred’ in one of the descriptions to give a hint to third party configuration systems.

In addition to the examples listed below, please refer to existing bidder parameter files for guidance.

Example: No parameters.
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {}
}
Example: Required integer placement id.
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {
    "placementId": {
      "type": "integer",
      "minimum": 1,
      "description": "Placement ID"
    }
  },

  "required": ["placementId"]
}
Example: Required access token and an optional hexadecimal account.
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {
    "token": {
      "type": "string",
      "description": "Token"
    },
    "account": {
      "type": "string",
      "description": "Account",
      "pattern": "^([a-fA-F\\d]+)$"
    }
  },

  "required": ["token"]
}
Example: Required access token or secret.
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {
    "token": {
      "type": "string",
      "description": "Token"
    },
    "secret": {
      "secret": "string",
      "description": "Secret"
    }
  },

  "oneOf": [
    { "required": ["token"] },
    { "required": ["secret"] }
  ]
}
Example: Multiple properties differing only by case.
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Foo Adapter Params",
  "description": "A schema which validates params accepted by the Foo adapter",
  "type": "object",

  "properties": {
    "partnerid": {
      "type": "string",
      "description": "Partner ID, preferred."
    },
    "partnerID": {
      "secret": "string",
      "description": "Partner ID"
    }
  },

  "oneOf": [
    { "required": ["partnerid"] },
    { "required": ["partnerID"] }
  ]
}

Bidder Parameters Code

You can skip this section if your adapter has no bidder parameters.

If you defined bidder parameters for your adapter, you also need to represent your bidder parameters in code. The core framework uses the JSON Schema file for validation, but your adapter code needs a data structure to support JSON unmarshalling / deserialization. These data structures are organized in a shared path using a standard naming convention, which also serves as documentation of all adapter parameters.

Create a file with the path openrtb_ext/imp_{bidder}.go containing an exported (must start with an upper case letter) data structure named ImpExt{Bidder}. All required and optional bidder parameters from the JSON Schema should be represented as fields.

For example, this is what the bidder parameter code looks like for the Foo example we used in the previous section:

package openrtb_ext

type ImpExtFoo struct {
  PlacementID string `json:"placementId"`
}

Please follow Go’s standard naming convention for the field names (particularly for acronyms) and use `json:...` attributes to specify the JSON name, matching exactly what you defined in the bidder parameters JSON Schema.

Adapter Code

Now it’s time to write the bulk of your bid adapter code.

Each adapter has its own directory (a ‘package’ in Go parlance) for all code and tests associated with translating an OpenRTB 2.5 Bid Request to your bidding server’s protocol and mapping your server’s response to an OpenRTB 2.5 Bid Response. The use of separate packages provide each adapter with its own naming scope to avoid conflicts and gives the freedom to organize files as you best see fit (although we make suggestions in this guide).

Create a file with the path adapters/{bidder}/{bidder}.go. Your bid adapter code will need to implement and export:

  • The adapters.Builder method to create a new instance of the adapter based on the host configuration.
  • The adapters.Bidder interface consisting of the MakeRequests method to create outgoing requests to your bidding server and the MakeBids method to create bid responses.

ACCESS MODIFIERS: Go has only two kinds of access modifiers, exported and private, which are scoped at the package level. The access modifier is encoded into the name of the type or method. Names starting with an upper case letter are exported whereas names starting with a lower case letter are private. Please only export the three required methods and keep everything else private.

Here is a reference implementation for a bidding server which uses the OpenRTB 2.5 protocol:

package foo

import (
  "encoding/json"
  "fmt"
  "net/http"

  "github.com/mxmCherry/openrtb/v15/openrtb2"
  "github.com/prebid/prebid-server/adapters"
  "github.com/prebid/prebid-server/config"
  "github.com/prebid/prebid-server/errortypes"
  "github.com/prebid/prebid-server/openrtb_ext"
)

type adapter struct {
  endpoint string
}

// Builder builds a new instance of the Foo adapter for the given bidder with the given config.
func Builder(bidderName openrtb_ext.BidderName, config config.Adapter) (adapters.Bidder, error) {
  bidder := &adapter{
    endpoint: config.Endpoint,
  }
  return bidder, nil
}

func (a *adapter) MakeRequests(request *openrtb2.BidRequest, requestInfo *adapters.ExtraRequestInfo) ([]*adapters.RequestData, []error) {
  requestJSON, err := json.Marshal(request)
  if err != nil {
    return nil, []error{err}
  }

  requestData := &adapters.RequestData{
    Method:  "POST",
    Uri:     a.endpoint,
    Body:    requestJSON,
  }

  return []*adapters.RequestData{requestData}, nil
}

func (a *adapter) MakeBids(request *openrtb2.BidRequest, requestData *adapters.RequestData, responseData *adapters.ResponseData) (*adapters.BidderResponse, []error) {
  if responseData.StatusCode == http.StatusNoContent {
    return nil, nil
  }

  if responseData.StatusCode == http.StatusBadRequest {
    err := &errortypes.BadInput{
      Message: "Unexpected status code: 400. Bad request from publisher. Run with request.debug = 1 for more info.",
    }
    return nil, []error{err}
  }

  if responseData.StatusCode != http.StatusOK {
    err := &errortypes.BadServerResponse{
      Message: fmt.Sprintf("Unexpected status code: %d. Run with request.debug = 1 for more info.", responseData.StatusCode),
    }
    return nil, []error{err}
  }

  var response openrtb2.BidResponse
  if err := json.Unmarshal(responseData.Body, &response); err != nil {
    return nil, []error{err}
  }

  bidResponse := adapters.NewBidderResponseWithBidsCapacity(len(request.Imp))
  bidResponse.Currency = response.Cur
  for _, seatBid := range response.SeatBid {
    for i, bid := range seatBid.Bid {
      b := &adapters.TypedBid{
        Bid:     &seatBid.Bid[i],
        BidType: getMediaTypeForBid(bid),
      }
      bidResponse.Bids = append(bidResponse.Bids, b)
  }
  return bidResponse, nil
}

Builder

The Builder method is responsible for validating the adapter configuration, performing any necessary pre-processing steps (such as macro parsing), and storing the configuration values in a new instance of the adapter struct.

This method may be called multiple times if the host has configured aliases of your adapter. On the other hand, it will never be called if your bid adapter is disabled by the host. Please be aware the same instance of the adapter will be used to process all bid requests for each bidder or alias. To ensure thread safety, all runtime state must be stored in the adapter instance and the adapter may not mutate any global or package scoped variables.

The first argument, bidderName, is the name of the bidder being built. This may be the bidder name you’ve chosen or it may be an alias. Most adapters don’t make use of the bidderName, but its provided by the core framework for situations where the adapter might need to do something special for aliases.

The second argument, config, is all the configuration values set for your adapter. However, not all of this information is intended for use by the Builder method. The only two fields relevant here are config.Endpoint and config.ExtraAdapterInfo:

  • config.Endpoint is the base url of your bidding server and may be interpreted as either a literal address or as a templated macro to support dynamic paths.
  • config.ExtraAdapterInfo is an optional setting may be used for any other values your adapter may need, such as an application token or publisher allow/deny list. You may interpret this string however you like, although JSON is a common choice.

The Builder method is expected to return an error if either the config.Endpoint or the config.ExtraAdapterInfo values are invalid or cannot be parsed. Errors will be surfaced to the host during application startup as a fatal error.

Example: Builder using endpoint macros.
type adapter struct {
  endpointTemplate *template.Template
}

// Builder builds a new instance of the Foo adapter for the given bidder with the given config.
func Builder(bidderName openrtb_ext.BidderName, config config.Adapter) (adapters.Bidder, error) {
  template, err := template.New("endpointTemplate").Parse(config.Endpoint)
  if err != nil {
    return nil, fmt.Errorf("unable to parse endpoint url template: %v", err)
  }

  bidder := &adapter{
    endpointTemplate: template,
  }
  return bidder, nil
}
Example: Builder using extra adapter info.
type extraInfo struct {
  token string
}

// Builder builds a new instance of the Foo adapter for the given bidder with the given config.
func Builder(bidderName openrtb_ext.BidderName, config config.Adapter) (adapters.Bidder, error) {
  info, err := parseExtraInfo(config.ExtraAdapterInfo)
  if err != nil {
    return nil, err
  }

  bidder := &adapter{
    endpoint: config.Endpoint,
    token:    info.token,
  }
  return bidder, nil
}

func parseExtraInfo(v string) (extraInfo, error) {
  if len(v) == 0 {
    return buildDefaultExtraInfo(), nil
  }

  var info extraInfo
  if err := json.Unmarshal([]byte(v), &info); err != nil {
    return nil, fmt.Errorf("invalid extra info: %v", err)
  }

  return info, nil
}

func buildDefaultExtraInfo() extraInfo {
  return extraInfo{
    token: "all your base are belong to us",
  }
}

MakeRequests

The MakeRequests method is responsible for returning none, one, or many HTTP requests to be sent to your bidding server. Bid adapters are forbidden from directly initiating any form of network communication and must entirely rely upon the core framework. This allows the core framework to optimize outgoing connections using a managed pool and record networking metrics. The return type adapters.RequestData allows your adapter to specify the HTTP method, url, body, and headers.

This method is called once by the core framework for bid requests which have at least one valid Impression for your adapter. Impressions not configured for your adapter are not accessible.

The first argument, request, is the OpenRTB 2.5 Bid Request object. Extension information is stored as json.RawMessage byte arrays and must be unmarshalled and/or marshalled to be read and/or mutated. It is critical to understand that the request object contains pointers to shared memory. If your adapter needs to alter any data referenced by a pointer then you must first make a shallow copy. The only exception is for request.Imp and its elements, as these are already shallow copies. The exact same instance of the request object is also passed to the MakeBids method, so please be careful when mutating. It’s safe to assume that request.Imp[] always contains at least one element and that the request.Imp[].ext.bidder was successfully validated per your bidder parameter JSON Schema.

Example: Mutating banner shared memory (make a copy).
// Populate the top level width and height of a banner request if it's not set by the publisher.

if request.Imp[i].W == nil && request.Imp[i].H == nil && len(request.Imp[i].Format) > 0 {
  bannerCopy := *request.Imp[i].Banner
  bannerCopy.W = &(request.Imp[i].Banner.Format[0].W)
  bannerCopy.H = &(request.Imp[i].Banner.Format[0].H)
  request.Imp[i].Banner = &bannerCopy
}

The second argument, requestInfo, is for extra information and helper methods provided by the core framework. This includes:

  • requestInfo.PbsEntryPoint to access the entry point of the bid request, commonly used to determine if the request is for AMP or for a Long Form Video Ad Pod.
  • requestInfo.GlobalPrivacyControlHeader to read the value of the Sec-GPC Global Privacy Control (GPC) header of the bid request.
  • requestInfo.ConvertCurrency a method to perform currency conversions.

The MakeRequests method is expected to return a slice (similar to a C# List or a Java ArrayList) of adapters.RequestData objects representing the HTTP calls to be sent to your bidding server and a slice of type error for any issues encountered creating them. If there are no HTTP calls or if there are no errors, please return nil for both return values. Please do not add nil items in the slices.

HTTP calls to your bidding server will automatically prefer GZIP compression. You should not specify it yourself using headers. You don’t have to worry about decompressing the response in MakeBids either, as that will be taken care of automatically.

Impression Splitting

An Impression may define multiple sizes and/or multiple ad formats. If your bidding server limits requests to a single ad placement, size, or format, then your adapter will need to split the Impression into multiple calls and merge the responses.

func (a *adapter) MakeRequests(request *openrtb2.BidRequest, requestInfo *adapters.ExtraRequestInfo) (*adapters.RequestData, []error) {
  var requests []*adapters.RequestData
  var errors []error

  requestCopy := *request
  for _, imp := range request.Imp {
    requestCopy.Imp = []openrtb2.Imp{imp}

    requestJSON, err := json.Marshal(request)
    if err != nil {
      errors = append(errors, err)
      continue
    }

    requestData := &adapters.RequestData{
      Method: "POST",
      Uri:    a.endpoint,
      Body:   requestJSON,
    }
    requests = append(requests, requestData)
  }
  return requests, errors
}
Currency

Prebid Server is a global product that is currency agnostic. Publishers may ask for bids in any currency. It’s totally fine if your bidding endpoint only supports a single currency, but your adapter needs to deal with it. This section will describe how to do so.

Here are 3 key points to consider:

  1. If your endpoint only bids in a particular currency, then your adapter must not blindly forward the openrtb to your endpoint. You should instead set $.cur to your server’s required currency.
  2. Your adapter must label bid responses properly with the response currency. i.e. if you only bid in USD, then your adapter must set USD as the response currency. PBS will convert to the publisher’s requested currency as needed. See the currency feature for more info.
  3. You should be aware that floors can be defined in any currency. If your bidding service supports floors, but only in a particular currency, then you must read use the requestInfo.ConvertCurrency function before sending $.imp[].bidfloor and $.imp[].bidfloorcur to your endpoint.
Example: Currency conversion needed for bid floor values in impressions.
func (a *adapter) MakeRequests(request *openrtb2.BidRequest, requestInfo *adapters.ExtraRequestInfo) (*adapters.RequestData, []error) {

  for _, imp := range request.Imp {
    // Check if imp comes with bid floor amount defined in a foreign currency
    if imp.BidFloor > 0 && imp.BidFloorCur != "" && strings.ToUpper(imp.BidFloorCur) != "USD" {

      // Convert to US dollars
      convertedValue, err := reqInfo.ConvertCurrency(imp.BidFloor, imp.BidFloorCur, "USD")
      if err != nil {
        return nil, []error{err}
      }

      // Update after conversion. All imp elements inside request.Imp are shallow copies
      // therefore, their non-pointer values are not shared memory and are safe to modify.
      imp.BidFloorCur = "USD"
      imp.BidFloor = convertedValue
    }
  }

  requestJSON, err := json.Marshal(request)
  if err != nil {
    return nil, []error{err}
  }

  requestData := &adapters.RequestData{
    Method:  "POST",
    Uri:     a.endpoint,
    Body:    requestJSON,
  }

  return []*adapters.RequestData{requestData}, nil
}

Common Data

There are a several values of a bid that publishers expect to be populated. Some are defined by the OpenRTB 2.5 specification and some are defined by Prebid conventions.

Parameter Definer Path & Description
CCPA OpenRTB request.regs.ext.us_privacy
The publisher is specifying the California Consumer Privacy Act consent string.
COPPA OpenRTB request.regs.ext.us_privacy
The publisher is specifying the Children’s Online Privacy Protection flag.
Currency OpenRTB request.cur
The publisher is specifying the desired bid currency. The Prebid Server default is USD.
Debug Prebid request.ext.prebid.debug
The publisher is requesting verbose debugging information from Prebid Server.
Request-Defined currency conversion rates Prebid request.ext.prebid.currency
The publisher decides to prioritize its own custom currency conversion rates over Prebid Server’s currency conversion rates. If a currency rate is not found in request.ext.prebid.currency, Prebid Server’s rates will be used unless usepbsrates is set to false. If missing, usepbsrates defaults to true.
First Party Data (FPD) Prebid request.imp[].ext.context.data.*, request.app.ext.data.*, request.site.ext.data.*, request.user.ext.data.*
The publisher may provide first party data (e.g. keywords).
GDPR OpenRTB request.regs.ext.gdpr, request.user.ext.consent
The publisher is specifying the European General Data Protection Regulation flag and TCF consent string.
Site or App OpenRTB request.site, request.app
The publisher will provide either the site or app, but not both, representing the client’s device.
Supply Chain OpenRTB request.source.ext.schain
The publisher’s declaration of all parties who are selling or reselling the bid request.
Test OpenRTB request.test
The publisher is sending non-production traffic which also enables verbose debugging information from Prebid Server.
Video OpenRTB request.imp[].video
The publisher is specifying video ad requirements or preferences.

For simplicity, adapters are expected to make net-price bids (e.g. “If this ad wins, what will the publisher make?”), not gross-price bids. Publishers can correct for gross-price bids by setting Bid Adjustments to account for fees.

Response

The MakeBids method is responsible for parsing the bidding server’s response and mapping it to the OpenRTB 2.5 Bid Response object model.

This method is called for each response received from your bidding server within the bidding time window (request.tmax). If there are no requests or if all requests time out, the MakeBids method will not be called.

It’s imperative to include all required information in the response for your bid to be accepted. Please avoid common mistakes, such as not specifying the bid currency and not properly detecting the media type from the bidding server response.

The first argument, request, is the exact same OpenRTB 2.5 Bid Request object provided to (and potentially mutated by) the MakeRequests method. The information in the request may be useful when detecting the media type.

The second argument, requestData, is the exact same adapters.RequestData object returned by the MakeRequests method. It’s rare for adapters to make use of this information, but it’s provided for potential edge cases.

The third argument, responseData, is the HTTP response received from your bidding server and contains the status code, body, and headers. If your bidding server replies with a GZIP encoded body, it will be automatically decompressed.

The MakeBids method is expected to return an adapters.BidderResponse object with one or more bids mapped from your bidding server’s response. This may be as simple as decorating an OpenRTB 2.5 Bid Response with some Prebid Server metadata (such as the media type) or more complicated mapping logic depending on your server’s response format.

Object Model

Please review the entire OpenRTB 2.5 Bid Response documentation to fully understand the response object model and expectations. We’ve summarized some common fields below. Data which is listed as required is enforced by the core framework and cannot be omitted.

BidderResponse Path Scope Description
.Currency Required 3-letter ISO 4217 code defining the currency of the bid. The Prebid Server default is USD.
.Bids[].BidType Required Prebid Server defined value identifying the media type as banner, video, audio, or native. Should be mapped from the bidding server response.
.Bids[].Bid.CrID Required Unique id of the creative.
.Bids[].Bid.ID Required Bidder generated id to assist with logging and tracking.
.Bids[].Bid.ImpID Required ID of the corresponding bid request Impression. Prebid Server validates the id is actually found in the bid request.
.Bids[].Bid.Price Required Net price CPM of the bid, not gross price. Publishers can correct for gross price bids by setting Bid Adjustments to account for fees. We recommend the most granular price a bidder can provide.
.Bids[].Bid.ADomain Optional Advertiser domain for block list checking.
.Bids[].Bid.AdM Optional Ad markup to serve if the bid wins. May be HTML, Native, or VAST/VMAP formats. You should resolve any AUCTION_PRICE macros.
.Bids[].Bid.W Optional Width of the creative in pixels.
.Bids[].Bid.H Optional Height of the creative in pixels.
.Bids[].Bid.Ext Optional Embedded JSON containing Prebid metadata (see below) or custom information.

We recommend resolving creative OpenRTB macros in your adapter. Otherwise, AUCTION_PRICE will eventually get resolved by the Prebid Universal Creative, but by then the bid price will be in the ad server currency and quantized by the price granularity.

If you’d like to support Long Form Video Ad Podss, then you’ll need to provide the followings information:

BidderResponse Path Description
.Bids[].BidVideo.PrimaryCategory Category for the bid in the taxonomy used by the ad server. Will be passed through without translation.
.Bids[].Bid.Cat IAB category for the bid which may be translated to the taxonomy used by the ad server.
.Bids[].BidVideo.Duration Length of the video in integer seconds.
.Bids[].DealPriority Deal tier integer value. Defaults to 0.

Either .Bids[].BidVideo.PrimaryCategory or .Bids[].Bid.Cat should be provided.

Metadata

Prebid has introduced a standard object model for sharing granular bid response data with publishers, analytics, and reporting systems. We encourage adapters to provide as much information as possible in the bid response.

Bid metadata will be required in Prebid.js 5.X+ release, specifically for bid.ADomain and MediaType. We recommend making sure your adapter sets these values or Prebid.js may throw out the bid.

Path Description
.NetworkID Bidder-specific network/DSP id.
.NetworkName Bidder-specific network/DSP name.
.AgencyID Bidder-specific agency id.
.AgencyName Bidder-specific agency name.
.AdvertiserID Bidder-specific advertiser id.
.AdvertiserName Bidder-specific advertiser name.
.BrandID Bidder-specific brand id for advertisers with multiple brands.
.BrandName Bidder-specific brand name.
.DemandSource Bidder-specific demand source. Some adapters may functionally serve multiple SSPs or exchanges, and this specifies which.
.DChain Demand chain object.
.PrimaryCategoryID Primary IAB category id.
.SecondaryCategoryIDs Secondary IAB category ids.
.MediaType Either banner, audio, video, or native. This is used in the scenario where a bidder responds with a mediatype different than the stated type. e.g. native when the impression is for a banner. One use case is to help publishers determine whether the creative should be wrapped in a safeframe.

Example: Setting metadata.
func (a *adapter) MakeBids(request *openrtb2.BidRequest, requestData *adapters.RequestData, responseData *adapters.ResponseData) (*adapters.BidderResponse, []error) {
  ...
  for _, seatBid := range response.SeatBid {
    for i, bid := range seatBid.Bid {
      b := &adapters.TypedBid{
        Bid:     &seatBid.Bid[i],
        BidType: getMediaTypeForBid(bid),
        BidMeta: getBidMeta(bid),
      }
  }
  ...
}

func getBidMeta(bid *adapters.TypedBid) *openrtb_ext.ExtBidPrebidMeta {
  // Not all fields are required. This example includes all fields for
  // demonstration purposes.
  return &openrtb_ext.ExtBidPrebidMeta {
    NetworkID:            1,
    NetworkName:          "Some Network Name",
    AgencyID:             2,
    AgencyName:           "Some Agency Name",
    AdvertiserID:         3,
    AdvertiserName:       "Some Advertiser Name",
    AdvertiserDomains:    []string{"Some Domain"},
    DemandSource:         "Some Demand Source",
    DChain:               json.RawMessage(`{Some Demand Chain JSON}`),
    BrandID:              4,
    BrandName:            "Some Brand Name",
    PrimaryCategoryID:    "IAB-1",
    SecondaryCategoryIDs: []string{"IAB-2", "IAB-3"},
    MediaType:            "banner",
  }
}

Register With The Core

Prebid Server does not use reflection or any other automated technology to recognize your new bid adapter. You must manually register it with the core framework.

You will need to add an import statement for your bid adapter package in these files. Modern code editors such as Visual Studio Code and JetBrain’s GoLand will automatically do that for you.

Edit the file openrtb_ext/bidders.go to add your bidder name constant and include it alphabetically in the CoreBidderNames list:

// Names of core bidders. These names *must* match the bidder code in Prebid.js if an adapter also exists in that
// project. You may *not* use the name 'general' as that is reserved for general error messages nor 'context' as
// that is reserved for first party data.
//
// Please keep this list alphabetized to minimize merge conflicts.
const (
  ...
  Bidder{Bidder} BidderName = "{bidder}"
  ...
)
// CoreBidderNames returns a slice of all core bidders.
func CoreBidderNames() []BidderName {
  return []BidderName{
    ...
    Bidder{Bidder},
    ...
  }
}

Edit the file exchange/adapter_builders.go to register your builder method:

func newAdapterBuilders() map[openrtb_ext.BidderName]adapters.Builder {
  return map[openrtb_ext.BidderName]adapters.Builder{
    ...
    openrtb_ext.Bidder{Bidder}: {bidder}.Builder,
    ...
  }
}

Set Adapter Defaults

You need to provide default settings for your bid adapter. You can decide if you’d like your bid adapter to be enabled out of the box, and if so, you’ll need to provide a default endpoint and default extra adapter info (if applicable). If your bid adapter requires host specific information to function properly, such as a security token or host account, then it’s best to leave the adapter disabled.

HOST SPECIFIC INFO: The default endpoint must not be specific to any particular host, such as Xandr/AppNexus. We may ask you about suspicious looking ids during the review process. Please reach out to individual hosts if you need to set specialized configuration.

Enabled By Default

Edit the file config/config.go to register your default endpoint within the SetupViper method. If your bid adapter makes use of extra adapter info and you’d like to provide a good default value, you can do that here too.

func SetupViper(v *viper.Viper, filename string) {
  ...
  v.SetDefault("adapters.{bidder}.endpoint", "https://your.url/any/path")
  v.SetDefault("adapters.{bidder}.extra_info", `{"your": "extra info"}`)
  ...
}

Disabled By Default

Edit the file config/config.go to register your default endpoint within the SetupViper method. You may still provide a default endpoint or extra adapter info.

func SetupViper(v *viper.Viper, filename string) {
  ...
  v.SetDefault("adapters.{bidder}.disabled", "true")
  ...
}

Test Your Adapter

This section will guide you through the creation of automated unit tests to cover your bid adapter code and bidder parameters JSON Schema. We use GitHub Action Workflows to ensure the code you submit passes validation. You can run the same validation locally with this command:

./validate.sh --nofmt --cov --race 10

Adapter Code Tests

Bid requests and server responses can be quite verbose. To avoid large blobs of text embedded within test code, we’ve created a framework for bid adapters which use a JSON body and/or a url to send a bid request. We require the use of our test framework as it includes checks to ensure no changes are made to shared memory.

We strive for as much test coverage as possible, but recognize that some code paths are impractical to simulate and rarely occur. You do not need to test the error conditions for json.Marshal calls, for template parse errors within MakeRequests or MakeBids, or for url.Parse calls. Following this guidance usually results in a coverage rate of around 90% - 95%, although we don’t enforce a specific threshold.

To use the test framework, create a file with the path adapters/{bidder}/{bidder}_test.go with the following template:

package {bidder}

import (
  "testing"

  "github.com/prebid/prebid-server/adapters/adapterstest"
  "github.com/prebid/prebid-server/config"
  "github.com/prebid/prebid-server/openrtb_ext"
)

func TestJsonSamples(t *testing.T) {
  bidder, buildErr := Builder(openrtb_ext.Bidder{Bidder}, config.Adapter{
    Endpoint: "http://whatever.url"})

  if buildErr != nil {
    t.Fatalf("Builder returned unexpected error %v", buildErr)
  }

  adapterstest.RunJSONBidderTest(t, "{bidder}test", bidder)
}

You should use an obviously fake endpoint for your tests. There’s no reason to use a real endpoint value. Please also note the _test.go file suffix is a required Go idiom. The Go test runner will look in these files for tests and the Go compiler will exclude test code from production binaries.

Each test case should be written in its own JSON file with a succinct, yet descriptive, name of what’s being tested. The files should be located in either:

  • adapters/{bidder}/{bidder}test/exemplary/ for straight forward “happy path” tests. We expect to see tests here for each supported media type.
  • adapters/{bidder}/{bidder}test/supplemental for tests which produce errors or cover more complicated scenarios.

The format of a JSON test is as follows:

{
  "mockBidRequest": {
    «OpenRTB 2.5 Bid Request»
  },
  "httpCalls": [{
    "expectedRequest": {
      "uri": "«Bidding Server Endpoint»",
      "headers": {
        "«Name»": ["«Value»"],
      },
      "body": {
         «Bidding Server Request Body»
      }
    },
    "mockResponse": {
      "status": «Mock HTTP Status Code (e.g. 200,
      "headers": {
        "«Name»": ["«Value»"],
      },
      "body": {
         «Bidding Server Response Body»
      },
    },
  }],
  "expectedBidResponses": [{
    "bids": [{
       «Prebid Server Bid Response»
    }]
  }],
  "expectedMakeRequestsErrors": [{
    "value": "«Value»",
    "comparison": "«literal or regex»"
  }],
  "expectedMakeBidsErrors": [{
    "value": "«Value»",
    "comparison": "«literal or regex»"
  }]
}

The mockBidRequest, httpCalls, and expectedBidResponses fields are required. The expectedMakeRequestsErrors and expectedMakeBidsErrors may be omitted if there are no expected errors. We provide a literal and regex mode for testing error values. We often use the regex mode to handle error messages produced by the core Go framework which changed between recent releases.

Please use a JSON ‘prettifier’ to apply standard formatting to your test files. We recommend the use of Visual Studio Code’s Beautify extension.

Builder Tests

The TestJsonSamples tests provide adequate test coverage of your bid adapter’s Builder method if it remains simple. If you’ve added custom logic, macro support, or make use of extra adapter info, you’ll need additional tests.

If your adapter supports template parsing, we recommend adding this failure test to the adapters/{bidder}/{bidder}_test.go file:

func TestEndpointTemplateMalformed(t *testing.T) {
  _, buildErr := Builder(openrtb_ext.Bidder{Bidder}, config.Adapter{
    Endpoint: "{{Malformed}}"})

  assert.Error(t, buildErr)
}

If your adapter supports extra adapter info, we recommend adding these tests to the adapters/{bidder}/{bidder}_test.go file. You should customize the TestEmptyConfig test to assert your adapter’s default extra info values.

func TestBadConfig(t *testing.T) {
  _, buildErr := Builder(openrtb_ext.Bidder{Bidder}, config.Adapter{
    Endpoint:         `http://it.doesnt.matter/bid`,
    ExtraAdapterInfo: `{foo:42}`,
  })

  assert.Error(t, buildErr)
}

func TestEmptyConfig(t *testing.T) {
  bidder, buildErr := Builder(openrtb_ext.Bidder{Bidder}, config.Adapter{
    Endpoint:         `http://it.doesnt.matter/bid`,
    ExtraAdapterInfo: ``,
  })

  bidder{Bidder} := bidder.(*adapter)

  assert.NoError(t, buildErr)
  assert.Empty(t, bidder{Bidder}.extraInfo.SomeInfo)
}

Bidder Parameter Tests

The bidder parameter JSON Schema files are considered a form of code and must be tested. Create a file with the path adapters/{bidder}/params_test.go using the following template:

package {bidder}

import (
  "encoding/json"
  "testing"

  "github.com/prebid/prebid-server/openrtb_ext"
)

func TestValidParams(t *testing.T) {
  validator, err := openrtb_ext.NewBidderParamsValidator("../../static/bidder-params")
  if err != nil {
    t.Fatalf("Failed to fetch the json schema. %v", err)
  }

  for _, p := range validParams {
    if err := validator.Validate(openrtb_ext.Bidder{Bidder}, json.RawMessage(p)); err != nil {
      t.Errorf("Schema rejected valid params: %s", p)
    }
  }
}

func TestInvalidParams(t *testing.T) {
  validator, err := openrtb_ext.NewBidderParamsValidator("../../static/bidder-params")
  if err != nil {
    t.Fatalf("Failed to fetch the json schema. %v", err)
  }

  for _, p := range invalidParams {
    if err := validator.Validate(openrtb_ext.Bidder{Bidder}, json.RawMessage(p)); err == nil {
      t.Errorf("Schema allowed invalid params: %s", p)
    }
  }
}

var validParams = []string{
  `{"placementId": ""}`,
  `{"placementId": "Some Placement ID}`,
}

var invalidParams = []string{
  `{"placementId": 42}`,
}

Please include tests for required fields, optional fields, conditional fields such as oneOf, regex filters, and data type mismatches. For example, if the field is defined as a string please include one invalid case for the wrong data type such as an integer in this example.

There is no need to provide a combinatorial for every edge case possibility. We’re looking for just enough test cases to build confidence.

Manual End To End Tests

We’ll verify your adapter works correctly on a technical level during the code review, but you’ll need to perform manual end-to-end testing:

  1. Build the project and start your server:
    go build .
    ./prebid-server
    
  2. POST an OpenRTB 2.5 Bid Request with at least one Impression defined for your bid adapter with a supported media type. This is an example template for a banner ad.
    curl --request POST \
     --url 'https://localhost:8000/openrtb2/auction' \
     --header 'Content-Type: application/json' \
     --data '{
       "id": "some-request-id",
       "test": 1,
       "site": {
         "page": "prebid.org"
       },
       "imp": [{
         "id": "some-impression-id",
         "banner": {
           "format": [{
             "w": 600,
             "h": 500
           }, {
             "w": 300,
             "h": 600
           }]
         },
         "ext": {
           "prebid": {
             "bidder": {
               "{bidder}": {
                 <Your Bid Adapter Parameters>
               }
             }
           }
         }
       }],
       "tmax": 1000
     }'
    

User Sync Testing

If your bid adapter defines one or more user sync endpoints, you’ll need to perform manual end-to-end testing of each endpoint using the following process:

  1. Save a User ID using the key of your user sync endpoint. This should default to your bidder name and is case sensitive.

  2. Run a test auction (see the curl example above) and verify in the debug response that the outgoing request.ext.debug.httpcalls calls includes the User ID you saved in step 1.

If you are having issues finding the root cause of user sync errors, please submit a GitHub issue and we’ll provide guidance.

User Documentation

Human readable documentation for bid adapters is required in the separate prebid.github.io repository. We will not merge your bid adapter until you’ve at least opened a documentation PR and comment with a link to it.

  1. If you already have a Prebid.js bid adapter, update your existing bidder file in https://github.com/prebid/prebid.github.io/tree/master/dev-docs/bidders to add the pbs: true variable in the header section. If your Prebid Server bidding parameters are different from your Prebid.js parameters, please include the differences in this document for publishers to be aware.
  2. If you don’t have a Prebid.js bid adapter, create a new file in https://github.com/prebid/prebid.github.io/tree/master/dev-docs/bidders using this template:
---
layout: bidder
title: {bidder}
description: Prebid {Bidder} Bidder Adapter
biddercode: {bidder}
gdpr_supported: true/false
gvl_id: 111
usp_supported: true/false
coppa_supported: true/false
schain_supported: true/false
dchain_supported: true/false
userId: <list of supported vendors>
media_types: banner, video, audio, native
safeframes_ok: true/false
deals_supported: true/false
floors_supported: true/false
fpd_supported: true/false
pbjs: true/false
pbs: true/false
pbs_app_supported: true/false
prebid_member: true/false
multiformat_supported: will-bid-on-any, will-bid-on-one, will-not-bid
ortb_blocking_supported: true/partial/false
---

### Note:

The Example Bidding adapter requires setup before beginning. Please contact us at setup@example.com

### Bid Params

{: .table .table-bordered .table-striped }
| Name          | Scope    | Description  | Example   | Type     |
|---------------|----------|--------------|-----------|----------|
| `placementId` | required | Placement ID | `'11111'` | `string` |

Notes on the metadata fields:

  • Add pbs: true. If you also have a Prebid.js bid adapter, add pbjs: true. Default is false for both.
  • If you’re on the IAB’s Global Vendor List, place your ID in gvl_id. No default.
  • If you support the GDPR and have a GVL ID, you may add gdpr_supported: true. Default is false.
  • If you support the US Privacy consentManagementUsp module, add usp_supported: true. Default is false.
  • If you support one or more userId modules, add userId: (list of supported vendors). Default is none.
  • If you support video and/or native mediaTypes add media_types: video, native. Note that display is added by default. If you don’t support display, add “no-display” as the first entry, e.g. media_types: no-display, native. No defaults.
  • If you support COPPA, add coppa_supported: true. Default is false.
  • If you support the supply chain feature, add schain_supported: true. Default is false.
  • If you support adding a demand chain on the bid response, add dchain_supported: true. Default is false.
  • If your bidder doesn’t work well with safeframed creatives, add safeframes_ok: false. This will alert publishers to not use safeframed creatives when creating the ad server entries for your bidder. No default.
  • If your bidder supports mobile apps, set pbs_app_supported: true. No default value.
  • If your bidder supports deals, set deals_supported: true. No default value.
  • If your bidder supports floors, set floors_supported: true. No default value.
  • If you support first party data, you must document what exactly is supported and then you may set fpd_supported: true. No default value.
  • If you support any OpenRTB blocking parameters, you must document what exactly is supported and then you may set ortb_blocking_supported to ‘true’,’partial’, or ‘false’. No default value. In order to set ‘true’, you must support: bcat, badv, battr, and bapp.
  • If you’re a member of Prebid.org, add prebid_member: true. Default is false.

File Checklist

  • Bidder Info
    • static/bidder-info/{bidder}.yaml
  • Bidder Parameters
    • static/bidder-params/{bidder}.json
    • openrtb_ext/imp_{bidder}.go
    • adapters/{bidder}/params_test.go
  • Adapter Code
    • adapters/{bidder}/{bidder}.go
    • adapters/{bidder}/{bidder}_test.go
    • adapters/{bidder}/{bidder}test/exemplary/*.json
    • adapters/{bidder}/{bidder}test/supplemental/*.json
  • Register With The Core
    • openrtb_ext/bidders.go
    • exchange/adapter_builders.go
  • Defaults
    • config/config.go

Contribute

Thank you for taking the time to develop a Prebid Server bid adapter. When you’re ready, contribute your new bid adapter by opening a PR to the PBS-Go GitHub repository with the name “New Adapter: {Bidder}”.

You don’t need to ask permission or open a GitHub issue before submitting an adapter.