Merge pull request #232 from bridgetkromhout/rollout-params

Clarify rollout params

slides/kube/rollout.md

@@ -33,6 +33,23 @@
 
 ---
 
+## Checking current rollout parameters
+
+- Recall how we build custom reports with `kubectl` and `jq`:
+
+.exercise[
+
+- Show the rollout plan for our deployments:
+  ```bash
+    kubectl get deploy -o json |
+            jq ".items[] | {name:.metadata.name} + .spec.strategy.rollingUpdate"
+  ```
+
+]
+
+---
+
+
 ## Rolling updates in practice
 
 - As of Kubernetes 1.8, we can do rolling updates with:
@@ -141,6 +158,38 @@ Our rollout is stuck. However, the app is not dead (just 10% slower).
 
 ---
 
+## What's going on with our rollout?
+
+- Why is our app 10% slower?
+
+- Because `MaxUnavailable=1`, so the rollout terminated 1 replica out of 10 available
+
+- Okay, but why do we see 2 new replicas being rolled out?
+
+- Because `MaxSurge=1`, so in addition to replacing the terminated one, the rollout is also starting one more
+
+---
+
+class: extra-details
+
+## The nitty-gritty details
+
+- We start with 10 pods running for the `worker` deployment
+
+- Current settings: MaxUnavailable=1 and MaxSurge=1
+
+- When we start the rollout:
+
+  - one replica is taken down (as per MaxUnavailable=1)
+  - another is created (with the new version) to replace it
+  - another is created (with the new version) per MaxSurge=1
+
+- Now we have 9 replicas up and running, and 2 being deployed
+
+- Our rollout is stuck at this point!
+
+---
+
 ## Recovering from a bad rollout
 
 - We could push some `v0.3` image
@@ -222,6 +271,8 @@ spec:
       minReadySeconds: 10
     "
   kubectl rollout status deployment worker
+  kubectl get deploy -o json worker |
+          jq "{name:.metadata.name} + .spec.strategy.rollingUpdate"
   ```
   ]