This document details how to make a module for PBS-Go.
You will want to be familiar with the following background information:
Check out the PBS-Go contribution guide before introducing any code changes.
The Prebid Server repository contains a package modules located in the root project directory. It includes all available PBS modules. So, in order to add a new module, fork the repository and create a folder with the desired name inside the modules folder with the following structure:
+- prebid-server/
+- modules/ <- package with modules that implement various hooks
+- builder.go <- contains a list of all available modules
+- {YOUR_VENDOR_NAME}/ <- top-level package used to group modules from the same vendor
+- {YOUR_MODULE_NAME}/ <- package with source code of your module
+- module.go <- file with module initialization function
Module directory names ({YOUR_VENDOR_NAME}/YOUR_MODULE_NAME/}) must consist of valid identifiers.
A valid identifier is defined as a sequence of one or more letters, including an underscore character (_), and digits.
All other symbols such as -, ., etc. are not permitted.
Here’s a partial example of your module-specific module.go file:
package your_module_name
import (
"context"
"encoding/json"
"github.com/prebid/prebid-server/hooks/hookstage"
"github.com/prebid/prebid-server/modules/moduledeps"
)
func Builder(config json.RawMessage, deps moduledeps.ModuleDeps) (interface{}, error) {
return Module{}, nil
}
// Module must implement at least 1 hook interface.
type Module struct{}
func (m Module) HandleBidderRequestHook(
ctx context.Context,
invocationCtx hookstage.ModuleInvocationContext,
payload hookstage.BidderRequestPayload,
) (hookstage.HookResult[hookstage.BidderRequestPayload], error) {
result := hookstage.HookResult[hookstage.BidderRequestPayload]{}
// hook handling logic
return result, nil
}
In the example above, our module only implements the bidder-request hook interface.
The module’s Builder function receives 2 arguments:
config json.RawMessage - represents a global config of your module, see Configuration.deps moduledeps.ModuleDeps - contains dependencies that your module might require.and returns 2 values:
interface{} - must implement at least 1 hook interface, see hooks. PBS uses type assertion to find out which hook interfaces implemented by module.error - any error occurred during module initialization.All available modules are exposed through the modules/builder.go file. This file is auto-generated, so you shouldn’t edit it manually.
To register a new module, you just need to run one of the following commands from the PBS root directory:
make build-modulesgo generate modules/modules.goThis command scans the modules/ directory for files matching the pattern modules/*/*/module.go and adds all matching packages to the modules/builder.go file.
The quick start is to take a look in two places:
It is required to add a “README.md” file to the root of your module folder. It’s recommended to specify the description of what the implemented module does, links to external documentation and include maintainer contact info (email, slack, etc).
The documentation must also live on the docs.prebid.org site. Please add a markdown file to https://github.com/prebid/prebid.github.io/tree/master/prebid-server/pbs-modules
The Prebid server processing workflow is divided into several ‘stages’ where module authors can inject a specific function signature called a ‘hook’.
The Prebid Server host company will define which modules to run in which order by setting up a configuration defining which hooks run serially and which can run in parallel.
The supported stages are described in the general module overview and in PBS-Core source code at the “github.com/prebid/prebid-server/hooks” package.
These are the available hooks that can be implemented in a module:
In a module it is not necessary to implement all mentioned interfaces but at least one is required by your functionality.
Notes:
BidderRequest and RawBidderResponse stages are called in parallel for each bidder.BidderRequest or RawBidderResponse stages should also supply an Entrypoint hook that returns a module context with a sync.Map entry. See the example below.To update the request in the BidderRequest, your implementation would return a hook result with a change set:
import (
"context"
"github.com/prebid/prebid-server/hooks/hookstage"
)
type Module struct{}
func (m Module) HandleBidderRequestHook(
ctx context.Context,
invocationCtx hookstage.ModuleInvocationContext,
payload hookstage.BidderRequestPayload,
) (hookstage.HookResult[hookstage.BidderRequestPayload], error) {
changeSet := hookstage.ChangeSet[hookstage.BidderRequestPayload]{}
changeSet.BidderRequest().BAdv().Update([]string{"a.com"})
return hookstage.HookResult[hookstage.BidderRequestPayload]{ChangeSet: changeSet}, nil
}
Please note, the hookstage.ChangeSet has a restricted set of methods, but methods can be easily extended when more use cases come up.
For more complex payload updates, you can choose another method:
func (m Module) HandleBidderRequestHook(
ctx context.Context,
invocationCtx hookstage.ModuleInvocationContext,
payload hookstage.BidderRequestPayload,
) (hookstage.HookResult[hookstage.BidderRequestPayload], error) {
battrByImp := map[string][]adcom1.CreativeAttribute{"imp_ID1": []adcom1.CreativeAttribute{adcom1.AttrAudioAuto}}
changeSet := hookstage.ChangeSet[hookstage.BidderRequestPayload]{}
changeSet.AddMutation(func(payload hookstage.BidderRequestPayload) (hookstage.BidderRequestPayload, error) {
for i, imp := range payload.BidRequest.Imp {
if battr, ok := battrByImp[imp.ID]; ok {
imp.Banner.BAttr = battr
payload.BidRequest.Imp[i] = imp
}
}
return payload, nil
}, hookstage.MutationUpdate, "bidrequest", "imp", "banner", "battr")
return hookstage.HookResult[hookstage.BidderRequestPayload]{ChangeSet: changeSet}, nil
}
To reject the bidder in the BidderRequest, your hook implementation would return a hook result with a reject flag and an NBR code:
func (m Module) HandleBidderRequestHook(
ctx context.Context,
invocationCtx hookstage.ModuleInvocationContext,
payload hookstage.BidderRequestPayload,
) (hookstage.HookResult[hookstage.BidderRequestPayload], error) {
return hookstage.HookResult[hookstage.BidderRequestPayload]{Reject: true, NbrCode: 7}, nil
}
Refer here for a list of available No Bid Response Codes.
To supply analytics tags in the BidderRequest, your hook implementation would return a hook result with analytics tags:
import (
"context"
"github.com/prebid/prebid-server/hooks/hookstage"
"github.com/prebid/prebid-server/hooks/hookanalytics"
)
func (m Module) HandleBidderRequestHook(
ctx context.Context,
invocationCtx hookstage.ModuleInvocationContext,
payload hookstage.BidderRequestPayload,
) (hookstage.HookResult[hookstage.BidderRequestPayload], error) {
return hookstage.HookResult[hookstage.BidderRequestPayload]{
AnalyticsTags: hookanalytics.Analytics{
Activities: []hookanalytics.Activity{
{
Name: "enforce_blocking",
Status: hookanalytics.ActivityStatusSuccess,
Results: []hookanalytics.Result{
{
Status: hookanalytics.ResultStatusBlock,
Values: map[string]interface{}{
"attributes": []string{"bcat"},
"bcat": []string{"IAB-1"},
},
AppliedTo: hookanalytics.AppliedTo{Bidder: "appnexus", ImpIds: []string{"imp_ID1"}},
},
{
Status: hookanalytics.ResultStatusAllow,
AppliedTo: hookanalytics.AppliedTo{Bidder: "appnexus", ImpIds: []string{"imp_ID2"}},
},
},
},
},
},
}, nil
}
Writing to the module context from the BidderRequest or RawBidderResponse stages requires synchronization between parallel instances of a module. The recommended approach is for the module to supply an Entrypoint hook that returns a module context with a sync.Map entry.
In the Entrypoint stage:
return hookstage.HookResult[hookstage.EntrypointPayload]{
ModuleContext: hookstage.ModuleContext{
dealsContextKey: &sync.Map{},
blockingDataParamKey: &sync.Map{},
impsContextKey: &sync.Map{},
},
}
In the BidderRequest or RawBidderResponse stage:
...
miCtx.ModuleContext[dealsContextKey].(*sync.Map)
...
It’s possible to define default module configuration which can be read by the module at PBS startup. An example configuration for hooks might look like this:
{
"hooks": {
"enabled": true,
"modules": {
"vendor1": {
"module1": {
"enabled": true
}
}
},
"host_execution_plan": {
"endpoints": {
"/openrtb2/auction": {
"stages": {
"bidder_request": {
"groups": [
{
"timeout": 10,
"hook_sequence": [
{
"module_code": "vendor1.module1",
"hook_impl_code": "code123"
}
]
}
]
}
}
}
}
}
}
}
Unit tests are required. Each implemented hook must be at least 90% covered by unit tests.
Read about the module building in the building section of the technical specification.
Each module can inject analytics tags into the request as described in the analytics tags section.
Analytics adapters receive these tags through the Auction/AMP analytic object.
To get analytics tags you need to go into:
AuctionObject/AmpObject
-> HookExecutionOutcome (iterate through stages)
-> Groups (iterate through groups)
-> InvocationResults (go through hooks invocation results and find interested one)
-> AnalyticsTags
The AnalyticsTags object has activities with collection of github.com/prebid/prebid-server/hooks/hookanalytics.Result objects inside. Each Result has the Values field which holds arbitrary values set by a module.
It depends on the particular module implementation how to parse their analytics tags, since the internal structure is custom and depends on the module. Therefore, analytics modules that want to report on specific behavior need to be coded to know about that module. See the prebid ortb2blocking module for an example of what analytics tags may be available.