Canary deployment

The flowchart describe the stages in a canary deployment controlled by Flagger. This tool makes it possible to control the rollout in a number of different ways (canary, A/B testing, manually gated, etc). I the chart green text indicates types of webhooks that can be used for manually controlled rollout. Below the chart there is a stepwise description of the canary deployment set in ehealth-service.

If canary is enabled for a service in the helmsman file the default configuration will make a rollout in these steps.

1. Start deployment of canary

2. Set traffic to 10% (stepWeight) if pod health is ok

3. After 1 min (interval) check pod health and check threshold for request-success-rate and request-duration.

4. If the threshold test is ok increase traffic limitation with 10% (stepWeight)

5. If threshold still is ok after 1 min, increase traffic again. This step will repeat until 50% (maxWeight) traffic is reached.

6. If tests are still ok after 1 min, complete rollout.

Specifying:

request-success-rate = 99% of all request to the service must return http code non 5xx in the last 1 min

request-duration = the 99 percentile of the request duration must be below 500 ms in the last 30 sec

Minimum time for full rollout = interval * iterations= 1m * 50/10 = 5 min

Minimum time for rollback = interval * threshold = 1m * 5 = 5 min