Workload-Feinschliff in OpenShift

# seit OCP 4.14 legt oc new-app ein Deployment an - hier zum Vergleich beide anlegen:
oc create deployment demo-deploy -n library --image=registry.access.redhat.com/ubi9/httpd-24
oc rollout status deployment/demo-deploy -n library
oc rollout undo deployment/demo-deploy -n library
oc rollout restart deployment/demo-deploy -n library

# ein DeploymentConfig existiert nur noch als Altlast - sichtbar mit:
oc get dc -A
oc explain deploymentconfig.spec.strategy.type

cat <<'YAML' | oc apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-schedule
  namespace: library
spec:
  replicas: 1
  selector: { matchLabels: { app: demo-schedule } }
  template:
    metadata: { labels: { app: demo-schedule } }
    spec:
      nodeSelector:
        kubernetes.io/hostname: nonexistent-node
      containers:
        - name: web
          image: registry.access.redhat.com/ubi9/httpd-24
YAML

oc get pod -n library -l app=demo-schedule
# -> Pending

oc describe pod -n library -l app=demo-schedule | grep -A3 Events
# -> 0/1 nodes are available: 1 node(s) didn't match Pod's node affinity/selector

# reparieren - Selector entfernen, damit der Pod wirklich startet:
oc patch deployment demo-schedule -n library --type=json \
  -p '[{"op":"remove","path":"/spec/template/spec/nodeSelector"}]'
oc get pod -n library -l app=demo-schedule -w

oc create quota demo-quota -n library --hard=requests.cpu=1,requests.memory=512Mi,pods=5

# ohne Requests im Deploy - scheitert an der Quota:
oc create deployment demo-quota-test -n library --image=registry.access.redhat.com/ubi9/httpd-24
oc get events -n library --field-selector involvedObject.name=demo-quota-test | grep -i quota
# -> failed quota: demo-quota: must specify requests.cpu,requests.memory

# jetzt eine LimitRange mit Default-Requests nachruesten:
cat <<'YAML' | oc apply -f -
apiVersion: v1
kind: LimitRange
metadata:
  name: demo-limits
  namespace: library
spec:
  limits:
    - type: Container
      defaultRequest: { cpu: 100m, memory: 128Mi }
      default: { cpu: 300m, memory: 256Mi }
YAML

# derselbe Deploy funktioniert jetzt, weil die LimitRange die Requests ergaenzt:
oc rollout restart deployment/demo-quota-test -n library
oc describe quota demo-quota -n library

oc create configmap demo-cfg -n library --from-literal=GREETING=hallo

cat <<'YAML' | oc apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-config-consumer
  namespace: library
spec:
  replicas: 1
  selector: { matchLabels: { app: demo-config-consumer } }
  template:
    metadata: { labels: { app: demo-config-consumer } }
    spec:
      containers:
        - name: web
          image: registry.access.redhat.com/ubi9/ubi-minimal
          command: ["sleep", "3600"]
          envFrom:
            - configMapRef: { name: demo-cfg }
          volumeMounts:
            - name: cfg
              mountPath: /etc/demo-cfg
      volumes:
        - name: cfg
          configMap: { name: demo-cfg }
YAML

POD=$(oc get pod -n library -l app=demo-config-consumer -o jsonpath='{.items[0].metadata.name}')
oc exec -n library "$POD" -- sh -c 'echo ENV=$GREETING; cat /etc/demo-cfg/GREETING'

# jetzt die ConfigMap aendern, OHNE den Pod neu zu starten:
oc set data configmap/demo-cfg -n library --from-literal=GREETING=servus
sleep 70
oc exec -n library "$POD" -- sh -c 'echo ENV=$GREETING; echo MOUNT=$(cat /etc/demo-cfg/GREETING)'
# ENV zeigt noch "hallo" (eingefroren), MOUNT zeigt "servus" (aktualisiert)