[prometheus-postgres-exporter] unable to use alert variables in prometheusRule entries

[fredericve]

Describe the bug a clear and concise description of what the bug is.

When using an alert variable in the prometheusRule annotations section, I get this output:

COMBINED OUTPUT:
  Error: Failed to render chart: exit status 1: Error: template: prometheus-postgres-exporter/templates/prometheusrule.yaml:18:16: executing "prometheus-postgres-exporter/templates/prometheusrule.yaml" at <tpl (toYaml .) $>: error calling tpl: cannot parse template "- alert: PostgreSQLDown\n  annotations:\n    description: foobar {{ $labels.instance }}\n    summary: faa\n  expr: pg_up{} != 1\n  for: 1m\n  labels:\n    severity: warning": template: gotpl:3: undefined variable "$labels"

My values.yaml contains this:

prometheusRule:
  enabled: true
  namespace: {{ .Values.stack.namespace }}
  rules:
    - alert: PostgreSQLDown
      annotations:
        description: 'foobar {{`{{ $labels.instance }}`}}'
        summary: faa
      expr: pg_up{} != 1
      for: 1m
      labels:
        severity: warning

I tried multiple known ways to escape variable expansion but have exhausted my knowledge.

What's your helm version?

version.BuildInfo{Version:"v3.15.3", GitCommit:"3bb50bbbdd9c946ba9989fbe4fb4104766302a64", GitTreeState:"clean", GoVersion:"go1.22.5"}

What's your kubectl version?

Client Version: v1.30.3 Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3 Server Version: v1.29.14-eks-bc803b4

Which chart?

prometheus-postgres-exporter

What's the chart version?

6.8.1

What happened?

No response

What you expected to happen?

No response

How to reproduce it?

No response

Enter the changed values of values.yaml?

No response

Enter the command that you execute and failing/misfunctioning.

helm install prometheus-postgres-exporter prometheus-community/prometheus-postgres-exporter --version 6.8.1 --values values.yaml

Anything else we need to know?

A similar thing seems to have happened in the past for the prometheus-blackbox-exporter chart. The solution there was to remove the tpl function: #2450

[zeritti]

I attempted to reproduce the error (with helm and helmfile) but so far have failed. Your rule above (without the namespace field's value as the field does not get templated) gets rendered and installed successfully. The escape characters are correct and so is alternative '{{`{{`}} $labels.instance {{`}}`}}'.

[fredericve]

@zeritti strange. I do get the error outputs and the chart fails to install. We're using similar escaping in other charts where it works fine.

Which versions of helm and helmfile are you using? I just upgraded to the latest versions and still have the issue there.

Using these values:

prometheusRule:
  enabled: true
  rules:
    - alert: PostgreSQLDown
      annotations:
        description: '{{ `{{` }} $labels.instance {{ `}}` }} is rejecting query requests from the exporter. Please verify the exporter credentials.'
        summary: 'PostgreSQL is not processing queries on {{ `{{` }} $labels.instance {{ `}}` }}'
      expr: |
        pg_up{} != 1
      for: 1m
      labels:
        severity: warning

I get this result:

#: helmfile -l "name=prometheus-postgres-exporter" apply
Comparing release=prometheus-postgres-exporter, chart=../charts/prometheus-postgres-exporter-6.8.1.tgz, namespace=development-monitoring
in ./helmfile.yaml: in .helmfiles[0]: in /home/fredericve/git/modkub/stacks/monitoring/helmfiles/helmfile.yaml: command "/usr/bin/helm" exited with non-zero status:

PATH:
  /usr/bin/helm

ARGS:
  0: helm (4 bytes)
  1: diff (4 bytes)
  2: upgrade (7 bytes)
  3: --allow-unreleased (18 bytes)
  4: prometheus-postgres-exporter (28 bytes)
  5: ../charts/prometheus-postgres-exporter-6.8.1.tgz (48 bytes)
  6: --version (9 bytes)
  7: 6.8.1 (5 bytes)
  8: --namespace (11 bytes)
  9: development-monitoring (22 bytes)
  10: --values (8 bytes)
  11: /tmp/helmfile1072248345/development-monitoring-prometheus-postgres-exporter-values-6968655549 (93 bytes)
  12: --detailed-exitcode (19 bytes)
  13: --color (7 bytes)
  14: --reset-values (14 bytes)

ERROR:
  exit status 1

EXIT STATUS
  1

STDERR:
  Error: Failed to render chart: exit status 1: Error: template: prometheus-postgres-exporter/templates/prometheusrule.yaml:18:16: executing "prometheus-postgres-exporter/templates/prometheusrule.yaml" at <tpl (toYaml .) $>: error calling tpl: cannot parse template "- alert: PostgreSQLDown\n  annotations:\n    description: '{{ $labels.instance }} is rejecting query requests from the exporter.\n      Please verify the exporter credentials.'\n    summary: PostgreSQL is not processing queries on {{ $labels.instance }}\n  expr: |\n    pg_up{} != 1\n  for: 1m\n  labels:\n    severity: warning": template: gotpl:3: undefined variable "$labels"
  Use --debug flag to render out invalid YAML
  Error: plugin "diff" exited with error

COMBINED OUTPUT:
  Error: Failed to render chart: exit status 1: Error: template: prometheus-postgres-exporter/templates/prometheusrule.yaml:18:16: executing "prometheus-postgres-exporter/templates/prometheusrule.yaml" at <tpl (toYaml .) $>: error calling tpl: cannot parse template "- alert: PostgreSQLDown\n  annotations:\n    description: '{{ $labels.instance }} is rejecting query requests from the exporter.\n      Please verify the exporter credentials.'\n    summary: PostgreSQL is not processing queries on {{ $labels.instance }}\n  expr: |\n    pg_up{} != 1\n  for: 1m\n  labels:\n    severity: warning": template: gotpl:3: undefined variable "$labels"
  Use --debug flag to render out invalid YAML
  Error: plugin "diff" exited with error

[zeritti]

I used helm 3.15.3 as yours and 3.17.2 and helmfile 0.171.