Helm

Contents[+]

Helm[+]

https://codersociety.com/blog/articles/helm-best-practices

Commands

Env

helm env
# ...
# HELM_NAMESPACE

repo

https://helm.sh/docs/helm/helm_repo/

# --- список "добавленных" репозиториев
helm repo list

# --- добавить репозиторий
helm repo add \
  nexus https://repo.corp.tander.ru/repository/cross-docking-charts \
  --ca-file ./certs/TanderCorpCA.crt

# --- обновление репозитория
#     выполняется всегда, после helm add
helm repo update

search

https://helm.sh/docs/helm/helm_search/

Helm Hub

# --- search for charts in Helm Hub
helm search hub loki
# --- search for carts without output truncate
helm search hub loki --max-col-width=0

Repo

# --- поиск крайней версии схемы в репозиториях, которые добавляются через helm repo addи (всех добавленных репозиториях?)
helm search repo kdk-standalone
# --- поиск крайней версии схемы для мажорной версии 0
#     подходят версии: 0.0.1, 0.1.0, 0.1.1, 0.123.123
#     не подходят версии: 1.0.0, 2.х.y
helm search repo kdk-standalone --version 0
# --- поиск крайней версии для мажорной и минорной версии
#     подходят версии: 1.2.0, 1.2.1, 1.2.123
#     не подходят версии: 1.1.0, 1.3.0, 2.x.y
helm search repo kdk-standalone --version 1.2

# --- поиск всех версий схемы
helm search repo kdk-cluster --versions
# NAME                    CHART VERSION   APP VERSION     DESCRIPTION
# nexus/kdk-cluster       2.5.7           2               cross-docking cluster
# nexus/kdk-cluster       2.5.6           2               cross-docking cluster
# nexus/kdk-cluster       2.5.5           2               cross-docking cluster
# nexus/kdk-cluster       2.5.3           2               cross-docking cluster
# nexus/kdk-cluster       2.5.2           2               cross-docking cluster

show chart info

# --- show the chart definition
helm show chart bitnami/wordpress
# --- show chart README
helm show readme bitnami/wordpress
# --- show chart values
helm show values bitnami/wordpress
# --- show all information about chart
helm show all bitnami/wordpress

inspecting release

helm get hooks RELEASE_NAME --namespace NAMESPACE
helm get manifest RELEASE_NAME --namespace NAMESPACE
helm get notes RELEASE_NAME --namespace NAMESPACE
helm get values RELEASE_NAME --namespace NAMESPACE
# --- history
helm history RELEASE_NAME

install / upgrade

helm install --debug --dry-run test .

# --set    - values from command line
# --values - values from YAML file or URL

# --- install wordpress
helm install wordpress bitnami/wordpress \
  --values=wordpress-values.yaml \
  --namespace chapter3 \
  --version 8.1.0
# --- upgrade wordpress
helm upgrade ...

rollback / uninstall

helm rollback RELEASE_NAME [REVISION] [flags]
helm uninstall RELEASE_NAME

Creating chart

Scaffolding the initial file scructure

helm create guestbook
cd guestbook

Modifying values

# values.yaml
redis:
  fullnameOverride: redis
  auth.enabled: false
  commonConfiguration: |-
    appendonly no

Install chart

helm install my-guestbook .

Access to application

k get po
export NODE_PORT=$(kubectl get --namespace chapter5 -o jsonpath="{.spec.ports[0].nodePort}" services my-guestbook)
export NODE_IP=$(kubectl get nodes --namespace chapter5 -o jsonpath="{.items[0].status.addresses[0].address}")
echo http://$NODE_IP:$NODE_PORT

Dependencies

See p. 120 in Learn Helm Packt https://trello.com/c/FmnGbXCi

Find char dependency

helm search hub redis
helm add repo bitnami https://charts.bitnami.com
helm search repo redis --versions | head

Adding dependency and downloading it

# Chart.yaml
dependencies:
  - name: redis
    version: 16.8.9
    repository: https://charts.bitnami.com/bitnami

helm dependency update

Show dependency values

helm show values charts/redis-VERSION.tgz

Templates

if / else

readinessProbe:
{{- if .Values.probeType.httpGet }}
  httpGet:
    path: /healthz
    port: 8080
    scheme: HTTP
{{- else }}
  tcpSocket:
    port: 8080
{{- end }}
  initialDelaySeconds: 30
  periodSeconds: 10

with

# --- NO with
cpu: {{ .Values.application.resources.limits.cpu }}
memory: {{ .Values.application.resources.limits.memory }}

# --- YES with
{{- with .Values.application.resources.limits }}
cpu: {{ .cpu }}
memory: {{ .memory }}
{{- end }}

range

# values.yaml
servicePorts:
  - name: http
    port: 8080
  - name: https
    port: 8443
  - name: jolokia
    port: 8778

# templates/foo.yaml
spec:
  ports:
{{- range .Values.servicePorts }}
    - name: {{ - name }}
      port: {{ .port }}
{{- end }}
# --- or
{{- range .Values.servicePorts }}
  - name: {{ $.Release.Name }}-{{ .name }}
    port: {{ .port }}
{{- end }}

Variables

{{ $myvar := 'Hello World!' }}
{{ $myvar := .Values.greeting }}
# ...
data:
  greeting.txt: |
    {{ $myvar }}

Using variables in a range block with index

data:
  greetings.txt: |
{{- range $index, $value := .Values.greetings }}
    Greeting {{ $index }}: {{ $value }}
{{- end }}
# --- same as
data:
  greetings.txt: |
    Greeting 0: Hello
    Greeting 1: Hola
    Greeting 2: Hallo

Using variables in a range block with key (???)

data:
  greetings.txt: |
{{- range $key, $val := .Values.greetings }}
    Greeting in {{ $key }}: {{ $val }}
{{- end }}
# --- same as
data:
  greetings.txt: |
    Greeting in English: Hello
    Greeting in Spain: Hola
    Greeting in German: Hallo

Using variables to refer to a value outside of the current scope

# --- FAIL
#     .Release.Name is not under scope of .Values.application.configuration
{{- with .Values.application.configuration }}
My application is called {{ .Release.Name }}
{{- end }}

# --- OK
{{ $appName := .Release.Name }}
{{- with .Values.application.configuration }}
My application is called {{ $appName }}
{{- end }}

Template functions

See https://helm.sh/docs/chart_template_guide/function_list/

Named Templates

# templates/_helper.tpl
{{- define 'mychart.labels' }}
labels:
  'app.kubernetes.io/instance': {{ .Release.Name }}
  'app.kubernetes.io/managed-by': {{ .Release.Service }}
{{- end }}

Using named template by include [TEMPLATE_NAME] [SCOPE]

# templates/some-resource.yaml
metadata:
  name: {{ .Release.Name }}
{{- include 'mycharts.labels' . | indent 2 }}

We can use template action instead include, but we can't use pipelines in this case.

Hooks

apiVersion: batch/v1
kind: Job
metadata:
  name: helm-auditing
  annotations:
    'helm.sh/hook': pre-install,post-install
spec:
  template:
    metadata:
      name: helm-auditing
    spec:
      restartPolicy: Never
      containers:
        - name: helm-auditing
          command: ["/bin/sh", "-c", "echo Hook executed at $(date)"]
          image: alpine

Troubleshooting

Error: directory charts/redis not found

Для новых зависимостей команда обновления выдает ошибку

helm dependency update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "bitnami" chart repository
Update Complete. ⎈Happy Helming!⎈
Error: directory charts/redis not found

Ошибка выдавалась по причине ошибки в слове repository в описании зависимости в Chart.yaml.install

helm install --debug --dry-run test .

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