Using Helm Templates in Specifications

You can use Helm templates to configure collectors and analyzers for preflight checks and support bundles for Helm installations.

Helm templates can be useful when you need to:

Run preflight checks based on certain conditions being true or false, such as the customer wants to use an external database.
Pull in user-specific information from the values.yaml file, such as the version a customer is using for an external database.

You can also use Helm templating with the Troubleshoot template functions for the clusterPodStatuses analyzer. For more information, see Helm and Troubleshoot Template Example.

Helm Template Example

In the following example, the mysql collector is included in a preflight check if the customer does not want to use the default MariaDB. This is indicated by the template {{- if eq .Values.global.mariadb.enabled false -}}.

This specification also takes the MySQL connection string information from the values.yaml file, indicated by the template '{{ .Values.global.externalDatabase.user }}:{{ .Values.global.externalDatabase.password }}@tcp({{ .Values.global.externalDatabase.host }}:{{ .Values.global.externalDatabase.port }})/{{ .Values.global.externalDatabase.database }}?tls=false' in the uri field.

Additionally, the specification verifies the maximum number of nodes in the values.yaml file is not exceeded by including the template 'count() > {{ .Values.global.maxNodeCount }}' for the nodeResources analyzer.

{{- define "preflight.spec" }}
apiVersion: troubleshoot.sh/v1beta2
kind: Preflight
metadata:
  name: preflight-sample
spec:
  {{ if eq .Values.global.mariadb.enabled false }}
  collectors:
    - mysql:
        collectorName: mysql
        uri: '{{ .Values.global.externalDatabase.user }}:{{ .Values.global.externalDatabase.password }}@tcp({{ .Values.global.externalDatabase.host }}:{{ .Values.global.externalDatabase.port }})/{{ .Values.global.externalDatabase.database }}?tls=false'
  {{ end }}
  analyzers:
    - nodeResources:
        checkName: Node Count Check
        outcomes:
          - fail:
              when: 'count() > {{ .Values.global.maxNodeCount }}'
              message: "The cluster has more than {{ .Values.global.maxNodeCount }} nodes."
          - pass:
              message: You have the correct number of nodes.
    - clusterVersion:
        outcomes:
          - fail:
              when: "< 1.22.0"
              message: The application requires at least Kubernetes 1.22.0, and recommends 1.23.0.
              uri: https://kubernetes.io
          - warn:
              when: "< 1.23.0"
              message: Your cluster meets the minimum version of Kubernetes, but we recommend you update to 1.23.0 or later.
              uri: https://kubernetes.io
          - pass:
              message: Your cluster meets the recommended and required versions of Kubernetes.
    {{ if eq .Values.global.mariadb.enabled false }}
    - mysql:
        checkName: Must be MySQL 8.x or later
        collectorName: mysql
        outcomes:
          - fail:
              when: connected == false
              message: Cannot connect to MySQL server
          - fail:
              when: version < 8.x
              message: The MySQL server must be at least version 8
          - pass:
              message: The MySQL server is ready
    {{ end }}
{{- end }}
---
apiVersion: v1
kind: Secret
metadata:
  labels:
    app.kubernetes.io/managed-by: {{ .Release.Service | quote }}
    app.kubernetes.io/instance: {{ .Release.Name | quote }}
    app.kubernetes.io/version: {{ .Chart.AppVersion }}
    helm.sh/chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"
    troubleshoot.sh/kind: preflight
  name: "{{ .Release.Name }}-preflight-config"
stringData:
  preflight.yaml: |
{{- include "preflight.spec"  . | indent 4 }}

Helm and Troubleshoot Template Example

You can also use Helm templates with the Troubleshoot template functions to automatically add the Pod name and namespace to a message when a clusterPodStatuses analyzer fails. For more information about the Troubleshoot template function, see Cluster Pod Statuses in the Troubleshoot documentation.

When you add the clusterPodStatuses analyzer template function values (such as {{ .Name }}) to your Helm template, you must encapsulate the Helm template using {{ }} so that Helm does not expand it.

The following example shows an analyzer that uses Troubleshoot templates and the override for Helm:

# This is the support bundle config secret that will be used to generate the support bundle
apiVersion: v1
kind: Secret
metadata:
  labels:
    troubleshoot.sh/kind: support-bundle
  name: {{ .Release.Name }}-support-bundle
  namespace: {{ .Release.Namespace }}
type: Opaque
stringData:
  # This is the support bundle spec that will be used to generate the support bundle
  # Notes: we use {{ .Release.Namespace }} to ensure that the support bundle is scoped to the release namespace
  # We can use any of Helm's templating features here, including {{ .Values.someValue }}
  support-bundle-spec: |
    apiVersion: troubleshoot.sh/v1beta2
    kind: SupportBundle
    metadata:
      name: support-bundle
    spec:
      collectors:
        - clusterInfo: {}
        - clusterResources: {}
        - logs:
            selector:
              - app=someapp
            namespace: {{ .Release.Namespace }}
      analyzers:
        - clusterPodStatuses:
            name: unhealthy
            namespaces:
              - default
              - myapp-namespace
            outcomes:
              - fail:
                  when: "== CrashLoopBackOff"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in a CrashLoopBackOff state.` }}
              - fail:
                  when: "== ImagePullBackOff"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in a ImagePullBackOff state.` }}
              - fail:
                  when: "== Pending"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in a Pending state.` }}
              - fail:
                  when: "== Evicted"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in a Evicted state.` }}
              - fail:
                  when: "== Terminating"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in a Terminating state.` }}
              - fail:
                  when: "== Init:Error"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in an Init:Error state.` }}
              - fail:
                  when: "== Init:CrashLoopBackOff"
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is in an Init:CrashLoopBackOff state.` }}
              - fail:
                  when: "!= Healthy" # Catch all unhealthy pods. A pod is considered healthy if it has a status of Completed, or Running and all of its containers are ready.
                  message: {{ `Pod {{ .Namespace }}/{{ .Name }} is unhealthy with a status of {{ .Status.Reason }}.` }}

Helm Template Example​

Helm and Troubleshoot Template Example​

Helm Template Example

Helm and Troubleshoot Template Example