Document rollout steps

README.md

@@ -20,11 +20,25 @@ Rollout:
 
 ![rollout-cli](docs/screens/rollout-cli-output.png)
 
+Rollout flow:
+* scan namespace for deployments marked for rollout 
+* scan namespace for a corresponding canary deployment (`-canary` prefix)
+* check Istio virtual service routes are mapped to GA and canary ClusterIP services
+* check GA and Canary deployments status (halt rollout if a rolling update is underway or if pods are in crash loop)
+* increase canary traffic weight percentage by 10%
+* check canary HTTP success rate (halt rollout if percentage is under the specified threshold)
+* advance canary traffic wight by 10% till it reaches 100% (halt rollout if deployments are unhealthy or success rate is under the threshold)
+* promote canary to GA (copy canary deployment spec template over GA)
+* wait for GA rolling update to finish
+* scale to zero the canary deployment
+* mark rollout deployment as finished
+* wait for canary deployment to be updated (revision bump) and start over
+
 HTTP success rate query:
 
 ```sql
 sum(
-    irate(
+    rate(
         istio_requests_total{
           reporter="destination",
           destination_workload_namespace=~"$namespace",
@@ -35,7 +49,7 @@ sum(
 ) 
 / 
 sum(
-    irate(
+    rate(
         istio_requests_total{
           reporter="destination",
           destination_workload_namespace=~"$namespace",