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fixup! fixup! fixup! update: typos and sequence diagram
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Signed-off-by: benjamin-j-powell <benjamin_j_powell@apple.com>
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benjamin-j-powell committed Sep 30, 2023
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Expand Up @@ -237,7 +237,9 @@ Below defines a list of `link_type` enums a kind can have

| Name | Description |
|----------|-------------------------------------------------------------------------------------------|
| RELATION | When a link has a relation, it can describe that relation with the `to` and `from` fields |
| START | The starting CDEvent in a chain |
| END | The ending CDEvent in a chain |
| RELATION | When a link has a relation, it can describe that relation with the `to` and `from` fields |
| GROUP | When a link is to be grouped with other events, it will use GROUP to establish a grouping |

Below defines a list of `event_kind` enums a link can have
Expand Down Expand Up @@ -265,71 +267,83 @@ The chain ID header will continue to propagate, unless the user explicitly
starts a new CDEvent chain. If there is no chain ID, the client will generate
one and that will be used for the lifetime of the whole events chain

Further, links are always constructed from the consumer point of view, with the
exception being the start and stop links. Allowing for start and stop to be
sent immediately, as opposed from the consumers point of view, allows for
single node events and/or allowing for UI systems to display as events are
occurring. This means when an event is consumed, the consumer will send a link
connecting itself to the parent event, as the consumer will know its context id
which a parent event would not be aware of. Wneh I care.

```
+-----+ +-----+ +-----+ +--------------+ +-----------+
| Git | | CI | | CD | | Link Service | | Event Bus |
+--+--+ +--+--+ +--+--+ +-------+------+ +-----+-----+
| | | #1 (send change merged event) | |
+----------------------------------------------------------------------------------------------------------------------------->|
| | | #2 (source change links) | |
| | | #2 (source change link to start chain) | |
+----------------------------------------------------------------------------------------------------------------------------->|
| | | | #3 (proxy link #2) |
| | | | #3 (proxy link #1) |
| | | |<-----------------------|
| | | #4 (receive change merged event) | |
| |<----------------------------------------------------------------------------------------------------------------+
| | | #5 (send pipeline queued event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #6 (pipeline queued links w/ parent: #1) | |
| | | #6 (source change links connecting #1 -> #5) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #7 (proxy link #6) |
| | | | #7 (proxy link #6) |
| | | |<-----------------------|
| | | #8 (send pipeline started event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #9 (pipeline started links w/ parent: #5) | |
| | | #9 (pipeline queued links connecting #5 -> #8) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #10 (proxy link #9) |
| | | |<-----------------------|
| | | #11 (send build queued event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #12 (build queued event links w/ parent: #8) | |
| | | #12 (pipeline started links connecting #6 -> #9) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #13 (proxy link #12) |
| | | |<-----------------------|
| | | #14 (send build started event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #15 (build started event links w/ parent: #11) | |
| | | #15 (build queued event links connecting #11 -> #14) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #16 (proxy link #15) |
| | | | #17 (proxy link #16) |
| | | |<-----------------------|
| | | #17 (send build completed event) | |
| | | #18 (send build completed event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #18 (build completed event links w/ parent: #14) | |
| | | #19 (build started event links connecting #14 -> #18) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #19 (proxy link #18) |
| | | | #20 (proxy link #15) |
| | | |<-----------------------|
| | | #20 (send pipeline finished event) | |
| | | #21 (send pipeline finished event) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | #21 (pipeline finished event links w/ parent: #17) | |
| | | #22 (build completed event links connecting #18 -> #21) | |
| +---------------------------------------------------------------------------------------------------------------->|
| | | | #22 (proxy link #21) |
| | | | #23 (proxy link #22) |
| | | |<-----------------------|
| | | #23 (receive pipeline finished event) | |
| | | #24 (receive pipeline finished event) | |
| | |<---------------------------------------------------------------------------------------------------+
| | | #24 (send pipeline queued event) | |
| | | #25 (send pipeline queued event) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | #25 (pipeline queued links w/ parent: #20) | |
| | | #26 (pipeline finished event links connecting #21 -> #25) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | | #26 (proxy link #25) |
| | | | #27 (proxy link #26) |
| | | |<-----------------------|
| | | #27 (send pipeline started event) | |
| | | #28 (send pipeline started event) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | #28 (pipeline started links w/ parent: #24) | |
| | | #29 (pipeline queued links connecting #25 -> #28) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | | #29 (proxy link #28) |
| | | | #30 (proxy link #29) |
| | | |<-----------------------|
| | | #30 (send environment created event) | |
| | | #31 (send environment created event) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | #32 (pipeline started links connecting #28 -> #31) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | #31 (environment created links w/ parent: #27) | |
| | | | #33 (proxy link #32) |
| | | |<-----------------------|
| | | #34 (environment created end link for #31) | |
| | +--------------------------------------------------------------------------------------------------->|
| | | | #32 (proxy link #31) |
| | | |<-----------------------|
Expand All @@ -338,6 +352,120 @@ one and that will be used for the lifetime of the whole events chain
This show's an example of how these different types would be used in a CI/CD
setting, but is not the only architecture.

### Payloads

This section will describe the first few sequences in the sequence diagram to
help explain the overall flow using payloads from CDEvents.

1. This is our very first event to the start of our CI/CD chain. This event
would have been sent from some source management tool like Github, Gitlabs,
etc.

```json
{
"context": {
"version": "0.4.0-draft",
"chain_id": "D0BE0005-CCA7-4175-8FE3-F64D2F27BC01",
"id": "38A09112-A1AB-4C26-94C4-EDFC234EF631",
"source": "/event/source/123",
"type": "dev.cdevents.change.merged.0.1.2",
"timestamp": "2023-03-20T14:27:05.315384Z"
},
"subject": {
"id": "mySubject123",
"source": "/event/source/123",
"type": "change",
"content": {
"repository": {
"id": "cdevents/service",
"source": "https://github.com/cdevents/service/pull/1234"
}
}
}
}
```

Something to call out here is that the `chain_id` may have been `null`, for
whatever reason, prior to this event. This means any parents to this event did
not generate a `chain_id`. When an event is sent, it is important that the
sender generates this id.

2. We send the start link to let the links service know that we are creating a
new chain.

```json
{
"chain_id": "D0BE0005-CCA7-4175-8FE3-F64D2F27BC01",
"link_type": "START",
"timestamp": "2023-03-20T14:27:05.315384Z",
"id": "38A09112-A1AB-4C26-94C4-EDFC234EF631" # context.id of #1
}
```

3. Event bus proxies the link payload from `#2` to the links service.

4. Shows some consumer consuming `#1` to do some action.

5. The CI system will queue a pipeline execution, and will generates a
`context.id` to be sent

```json
{
"context": {
"version": "0.4.0-draft",
"chain_id": "D0BE0005-CCA7-4175-8FE3-F64D2F27BC01",
"id": "AA6945F8-B0F1-48DD-B658-25ACF95BD2F5",
"source": "/event/source/123",
"type": "dev.cdevents.pipelinerun.queued.0.1.1",
"timestamp": "2023-03-20T14:27:05.315384Z"
},
"subject": {
"id": "mySubject123",
"source": "/event/source/123",
"type": "pipelineRun",
"content": {
"pipelineName": "myPipeline",
"url": "https://www.example.com/mySubject123"
}
}
}
```

6. As the send change merge event is sent, the system will follow up with
sending a link associated with the prior event which connects `#1` to `#5`

```json
{
"chain_id": "D0BE0005-CCA7-4175-8FE3-F64D2F27BC01",
"link_type": "RELATION",
"timestamp": "2023-03-20T14:27:05.315384Z",
"from": {
"id": "38A09112-A1AB-4C26-94C4-EDFC234EF631" # context.id of #1
},
"to": {
"id": "AA6945F8-B0F1-48DD-B658-25ACF95BD2F5" # context.id of #5
},
"tags": [
"ci.environment": "prod"
]
}
```

7. The event bus will then forward link `#6` to the links service

34. Paylods from `8-33` are very similar to all prior payloads shown here, but
the last sequence is the ending link.

```json
{
"chain_id": "D0BE0005-CCA7-4175-8FE3-F64D2F27BC01",
"link_type": "END",
"timestamp": "2023-03-20T14:27:05.315384Z",
"id": "7D5E011F-5073-44A7-B4F0-86DD7D4C2C7F" # context.id of #31
}
```


### CDEvents Chain Definition

While most use cases can rely on the CDEvents SDK to dictate what a chain may
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