xslt-lab: chart 0.4.2 (backend resources) and a second backend replica

The chart now declares resources for the backend container, which runs three
JVMs adding up to 512 MB of heap: it had been living on a manual kubectl patch
of 256Mi and was OOMKilled five times a day. minReplicas goes to 2 for the same
reason the frontend did — a restarting pod should not be the whole service.

apps/xslt-lab/values.yaml

@@ -26,7 +26,10 @@ replicaCount:
 hpa:
   backend:
     enabled: true
-    minReplicas: 1
+    # Same reasoning as the frontend below: one backend pod is a SPOF, and this
+    # one was being OOMKilled several times a day, so "the only replica is
+    # restarting" was not hypothetical.
+    minReplicas: 2
     maxReplicas: 5
     targetCPUUtilizationPercentage: 80
   frontend:

argocd/applications/xslt-lab.yaml

@@ -8,7 +8,7 @@ spec:
   sources:
   - repoURL: https://xsltplayground.com/blog
     chart: xslt-playground
-    targetRevision: 0.4.1
+    targetRevision: 0.4.2
     helm:
       releaseName: lab
       valueFiles: