Manual Gating

[aackerman]

I discussed on slack with @stefanprodan the possibility of manual gating.

He mentioned that the feature could be created with new webhooks, flagger could send out a webhook call for external step approval, pre/during/post, and if the webhook returns a 200, then the step would be approved to move forward otherwise the the canary would be halted

[mumoshu]

I was thinking about this as well.

What seems complicated when implemented with a webhook server, is that you'll likely need a unique webhook endpoint per deployment.

Perhaps we could create a generic webhook server that serves:

1. POST /gates/${gate_id}/ to be used as a unique webook endopint per canary deployment
2. POST /gates to create a new gate. This endpoint would be called from within your CI/CD pipeline or your GitHub/Slack webhook server to trigger manual approvals.

A unique webhook endpoint could be used from Flagger's pre-rollout webhook to postpone/start canary rollout with manual gating, for example.

He mentioned that the feature could be created with new webhooks

Does this mean new webhook types other than listed in https://docs.flagger.app/how-it-works#webhooks need to be added to flagger?

[stefanprodan]

I think we could have dedicated webhook types for manual gating. I see two possible types: confirm-rollout (delay analysis until POST /gates/start/{canary.namespace} returns 200) and confirm-promotion (delay promotion until POST /gates/promote/{canary.namespace} returns 200)

PS. I’m on vacation till 22 July

[mumoshu]

@stefanprodan Thanks for the response!

From Flagger's perspective, you'll be able to use whatever path to send webhooks to(i.e. /gates/start/{canary.namespace} is just an example and not hard-coded), right?

I'd like Flagger to work like that so that we can generate whatever URLs with Helm and integrate it with any http server.

FWIW, I'll be using paths like /gates/start/pr/<PR NUMBER> which starts returning 200 once I comment on the PR with /start, and set the PR number to be included in the webhook url via a helm chart value.

[stefanprodan]

@mumoshu with #251 you can set whatever URL you want for the confirm-rollout webhook. Flagger will do a HTTP POST and if the call returns HTTP 200, will proceed with the analysis.

The HTTP POST body is the same as with every hook:

{
    "name": "podinfo",
    "namespace": "test",
    "phase": "Progressing"
}

[mumoshu]

@stefanprodan Just reviewed #251 - looks AWESOME. That's exactly what I wanted. Thanks a lot for your effort!

[stefanprodan]

@mumoshu if the PR looks ok can you please approve it in the GitHub UI? Thanks

[mumoshu]

@stefanprodan Approved 👍