Traffic mirroring is a pre-stage for canary deployments. When mirroring
is enabled, at the beginning of a canary deployment traffic is mirrored
to the canary instead of shifted for one canary period. The service
mesh should mirror by copying the request and sending one copy to the
primary and one copy to the canary; only the response from the primary
is sent to the user. The response from the canary is only used for
collecting metrics.
Once the mirror period is over, the canary proceeds as usual, shifting
traffic from primary to canary until complete.
Added TestScheduler_Mirroring unit test.
SetupMocks() currently takes a bool switch that tells it to configure
against either a shifting canary or an A-B canary. I'll need a third
canary that has mirroring turned on so I changed this to an interface
that just takes the canary to configure (and configs the default
shifting canary if you pass nil).
The mirror option will be used to tell routers to configure traffic
mirroring. Implement mirror for GetRoutes and SetRoutes for Istio. For
other routers, GetRoutes always returns mirror == false, and SetRoutes
ignores mirror.
After this change there is no behavior change because no code sets
mirror true (yet).
Enhanced TestIstioRouter_SetRoutes and TestIstioRouter_GetRoutes.
After the analysis finishes, Flagger will do the promotion and wait for the primary rollout to finish before routing all the traffic back to it. This ensures a smooth transition to the new version avoiding dropping in-flight requests.
The confirm promotion hooks are executed right before the promotion step. The canary promotion is paused until the hooks return HTTP 200. While the promotion is paused, Flagger will continue to run the metrics checks and load tests.
Blue/Green steps:
- scale up green
- run conformance tests on green
- run load tests and metric checks on green
- route traffic to green
- promote green spec over blue
- wait for blue rollout
- route traffic to blue
