mirror of https://github.com/hashicorp/consul
36 lines
2.2 KiB
Markdown
36 lines
2.2 KiB
Markdown
|
|
# Adding a new topic to streaming
|
|
|
|
This document is a guide for adding a new streaming topic.
|
|
|
|
1. Add the name of the topic to the [proto/pbsubscribe/subscribe.proto Topic enum][1].
|
|
Run `make proto` to generate the Go code from the protobuf.
|
|
2. Add a `FromChanges` function to the list of change functions in
|
|
[agent/consul/state.processDBChanges][2]. The `FromChanges` function should examine the
|
|
list of `Changes` and return a list of events that subscriptions would need to update
|
|
their view.
|
|
3. Add a snapshot function to [agent/consul/state.newSnapshotHandlers][3]. The snapshot
|
|
function should produce a set of events to create the initial state of the view.
|
|
Generally these are all "create" events.
|
|
4. Add a new `Payload` type, similar to [agent/consul/state.EventPayloadCheckServiceNode][6].
|
|
This type will be used in the `Payload` field of the event.
|
|
5. Create the protobuf for the payload, and add the `Payload` type to the `oneof` in
|
|
[proto/pbsubscrube/subscribe.proto Event.Payload][7]. This may require creating other
|
|
protobuf types as well, to encode anything in the payload. Run `make proto` to generate
|
|
the Go code from the protobuf.
|
|
6. Add another case to [agent/rpc/subscribe.setPayload][8] to convert from the Payload
|
|
type in `state`, to the protobuf type. This may require either writing or generating a
|
|
function to convert between the types.
|
|
7. Add a new cache-type that uses [agent/submatview.Materializer][4] similar to
|
|
[agent/cache-types/streaming_health_services.go][5].
|
|
|
|
|
|
[1]: https://github.com/hashicorp/consul/blob/v1.9.4/proto/pbsubscribe/subscribe.proto#L37-L45
|
|
[2]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/consul/state/memdb.go#L188-L192
|
|
[3]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/consul/state/memdb.go#L205-L209
|
|
[4]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/submatview/materializer.go#L76
|
|
[5]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/cache-types/streaming_health_services.go
|
|
[6]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/consul/state/catalog_events.go#L12-L46
|
|
[7]: https://github.com/hashicorp/consul/blob/v1.9.4/proto/pbsubscribe/subscribe.proto#L95-L117
|
|
[8]: https://github.com/hashicorp/consul/blob/v1.9.4/agent/rpc/subscribe/subscribe.go#L161-L168
|