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Stefan Prodan
2018-09-24 19:58:18 +03:00
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# steerer
Istio progressive rollout gated by Prometheus HTTP success rate metric
Steerer is a Kubernetes operator that automates the promotion of canary deployments
using Istio routing for traffic shifting and Prometheus metrics for canary analysis.
Gated rollout stages:
* scan for deployments marked for rollout
* check Istio virtual service routes are mapped to primary and canary ClusterIP services
* check primary and canary deployments status
* halt rollout if a rolling update is underway
* halt rollout if pods are unhealthy
* increase canary traffic weight percentage by 10%
* check canary HTTP success rate
* halt rollout if percentage is under the specified threshold
* increase canary traffic wight by 10% till it reaches 100%
* halt rollout while canary success rate is under the threshold
* halt rollout if the primary or canary deployment becomes unhealthy
* halt rollout while canary deployment is being scaled up/down by HPA
* promote canary to primary
* copy canary deployment spec template over primary
* wait for primary rolling update to finish
* halt rollout if pods are unhealthy
* route all traffic to primary
* scale to zero the canary deployment
* mark rollout as finished
* wait for the canary deployment to be updated (revision bump) and start over
### Usage
@@ -13,10 +37,10 @@ kubectl apply -f ./artifacts/steerer
Create a test namespace:
```bash
kubectl apply -f ./artifacts/namespace/
kubectl apply -f ./artifacts/namespaces/
```
Create GA and canary deployments, services, hpa and Istio virtual service:
Create primary and canary deployments, services, hpa and Istio virtual service:
```bash
kubectl apply -f ./artifacts/workloads/
@@ -30,7 +54,7 @@ kubectl apply -f ./artifacts/rollouts/
Rollout output:
```bash
```
kubectl -n test describe rollout/podinfo
Events:
@@ -60,29 +84,6 @@ Events:
Normal Synced 5s steerer Promotion complete! Scaling down podinfo-canary.test
```
Rollout flow:
* scan for deployments marked for rollout
* check Istio virtual service routes are mapped to primary and canary ClusterIP services
* check primary and canary deployments status
* halt rollout if a rolling update is underway
* halt rollout if pods are unhealthy
* increase canary traffic weight percentage by 10%
* check canary HTTP success rate
* halt rollout if percentage is under the specified threshold
* increase canary traffic wight by 10% till it reaches 100%
* halt rollout while canary success rate is under the threshold
* halt rollout if the primary or canary deployment becomes unhealthy
* halt rollout while canary deployment is being scaled up/down by HPA
* promote canary to primary
* copy canary deployment spec template over primary
* wait for primary rolling update to finish
* halt rollout if pods are unhealthy
* route all traffic to primary
* scale to zero the canary deployment
* mark rollout as finished
* wait for the canary deployment to be updated (revision bump) and start over
HTTP success rate query:
```sql