GCP CloudEvents mapping

This library is designed to work with cloudevents-router package.

We generate a mapping for all Google CloudEvents based on JSON Schema catalog published at googleapis/google-cloudevents

Install

``bash
npm install cloudevents-router-gcp
`

Use just types

`typescript
import type { GoogleEvents } from "cloudevents-router-gcp";

/*
Will be equal to the following code snippet:

import { LogEntryData } from '@google/events/cloud/audit/v1/LogEntryData'
import { MessagePublishedData } from '@google/events/cloud/pubsub/v1/MessagePublishedData'
...

export type GoogleEvents = {
'google.cloud.audit.log.v1.written': LogEntryData
'google.cloud.pubsub.topic.v1.messagePublished': MessagePublishedData
...
}
*/
`

Use with cloudevents-router

`typescript
import type { GoogleEvents } from "cloudevents-router-gcp";
import { CloudEventsRouter, getMiddleware } from "cloudevents-router";
import http from "http";

const router = new CloudEventsRouter();

router.on("google.cloud.pubsub.topic.v1.messagePublished", async (event) => {
console.log("PubSub ordering key", event.data.message?.orderingKey);
});

// See cloudevents-router documentation for more integration examples
const middleware = getMiddleware(router, { path: "/" });
const server = http.createServer(middleware);

server.listen(5000);
`

PubSub instructions

While consuming PubSub events with cloudevents is simple the type definition for PubSub is not very useful.

Payload is passed as string or undefined, and all topics end up in the same handler (as message type is always google.cloud.pubsub.topic.v1.messagePublished).

`typescript
interface MessagePublishedData {
subscription?: string;
message?: {
attributes?: { [key: string]: string };
data?: string;
messageId?: string;
orderingKey?: string;
publishTime?: Date | string;
};
}
`

To make it a bit less painful we ship a PubSubParsedMessage generic type and some helper functions to parse and re-route the PubSub messages.

$3

`typescript
import type { GoogleEvents, PubSubParsedMessage } from "cloudevents-router-gcp";

// Define message payload type
type EventMap = GoogleEvents & {
"pubsub.userAdded": PubSubParsedMessage<{
username: string;
password: string;
age?: number;
}>;
"pubsub.profileChanged": PubSubParsedMessage<{
username: string;
profilePicture: string;
}>;
};
`

This will replace data attribute (data?: string) in the original MessagePublishedData type with a more useful extracted type definition.

$3

`typescript
import { CloudEventsRouter } from "cloudevents-router";

const router = new CloudEventsRouter();

router.on("pubsub.profileChanged", async (event) => {
console.log("Profile picture added", event.data.message?.data.profilePicture);
});
`

$3

To use the above handler we need to parse and republish PubSub messages

`typescript
import { republishPubSubByTopic } from "cloudevents-router-gcp";

// use the router from above
// const router = ...

republishPubSubByTopic(router, {
topics: {
"user-added-topic": "pubsub.userAdded",
"profile-changed-topic": "pubsub.profileChanged",
},
});

// setup server as above
// const server = ...
server.listen(5000);
`

GCP PubSub payloads

GCP is publishing data in some known but not too well documented formats.

| Service | Description | Messages |
| ------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------- |
| container-registry | Every time container registry is updated a message is published to grc topic | pubsub.ArtifactMessage |
| cloud-build | Cloud Build publishes messages on a Google Pub/Sub topic called cloud-builds when your build's state changes | TODO |
| alert-center | Alert Center can push notifications to user defined pubsub topic | TODO |

_There are many more, if you are using one of them and its not implemented, please feel free to create a pull request so others can also benefit._

usage is the same as for manually typed messages.

`typescript
import { messages } from "cloudevents-router-gcp";

const EventMap = {
"artifact.published": messages.ArtifactMessage,
};

// ...
``

Thats it ...

... happy coding :)