urlaubsverwaltung: readiness must see the database, health must not lie (9.0.0+up6.7.0)

MANAGEMENT_ENDPOINT_HEALTH_GROUP_READINESS_INCLUDE=readinessState,db puts the datasource into Spring Boot's readiness group, which shipped with readinessState alone: a total database outage left the pod 1/1 Ready while every request failed. Naming the members replaces the default, so readinessState is repeated. The liveness group stays untouched on purpose, because an outage has to keep traffic away rather than add a crash loop to it.

MANAGEMENT_HEALTH_MAIL_ENABLED=false removes the mail indicator, which pinned the aggregate /actuator/health at 503 for the whole life of a healthy release, because the chart's mail wiring points at localhost:1025 where nothing listens. values.yaml and NOTES.txt document what that costs and when it has to be switched back on.

urlaubsverwaltung/values.yaml

@@ -45,6 +45,39 @@ urlaubsverwaltung:
       capabilities:
         drop:
           - ALL
+  # HEALTH INDICATORS — TWO SETTINGS THE CHART FIXES IN THE TEMPLATE
+  #
+  # The chart sets these two as plain environment variables, not as values,
+  # because urlaubsverwaltung.env below already overrides anything:
+  #
+  #   MANAGEMENT_ENDPOINT_HEALTH_GROUP_READINESS_INCLUDE=readinessState,db
+  #     puts the datasource into the readiness group, so a database outage
+  #     takes the pod out of Ready instead of leaving it serving errors (#218).
+  #     The liveness group stays untouched on purpose — an outage must keep
+  #     traffic away, not restart the pod in a loop.
+  #   MANAGEMENT_HEALTH_MAIL_ENABLED=false
+  #     removes the mail indicator, which otherwise pins the aggregate
+  #     /actuator/health at 503 DOWN forever, because the chart's mail wiring
+  #     points at localhost:1025 where nothing listens (#217).
+  #
+  # THE CONSEQUENCE TO KNOW BEFORE IT BITES: whoever later configures real mail
+  # delivery (SPRING_MAIL_HOST/SPRING_MAIL_PORT via urlaubsverwaltung.env) MUST
+  # switch the indicator back on in the same change:
+  #
+  #   env:
+  #     - name: MANAGEMENT_HEALTH_MAIL_ENABLED
+  #       value: "true"
+  #
+  # Left at false, /actuator/health keeps answering 200 while the configured
+  # mail server is unreachable and no notification mail is delivered. The
+  # setting trades a permanently false alarm for silence, and silence is only
+  # correct as long as there is nothing to report about.
+  #
+  # That override repeats a name the chart already sets, and env is additive:
+  # it renders the variable twice (the later entry wins in the container), and
+  # adding it to an ALREADY INSTALLED release makes the next upgrade fail in
+  # the API server. See the "env IS ADDITIVE ONLY" section of NOTES.txt — the
+  # switch has to go in at install time, not at upgrade time.
   livenessProbe:
     httpGet:
       port: 8080