Difference between revisions of "Helm"

Revision as of 23:40, 8 February 2022

Helm is a package manager for Kubernetes.

Commands

• completion — generate autocompletions script for the specified shell (bash or zsh)
• create — create a new chart with the given name
• delete — given a release name, delete the release from Kubernetes
• dependency — manage a chart's dependencies
• fetch — download a chart from a repository and (optionally) unpack it in local directory
• get — download a named release
• help — help about any command
• history — fetch release history
• home — displays the location of HELM_HOME
• init — initialize Helm on both client and server
• inspect — inspect a chart
• install — install a chart archive
• lint — examines a chart for possible issues
• list — list releases
• package — package a chart directory into a chart archive
• plugin — add, list, or remove Helm plugins
• repo — add, list, remove, update, and index chart repositories
• reset — uninstalls Tiller from a cluster
• rollback — roll back a release to a previous revision
• search — search for a keyword in charts
• serve — start a local http web server
• status — displays the status of the named release
• template — locally render templates
• test — test a release
• upgrade — upgrade a release
• verify — verify that a chart at the given path has been signed and is valid
• version — print the client/server version information

Miscellaneous examples

• Install a Helm Chart with:

$ helm upgrade --install ${MY_CHART_NAME} -f values.yaml --namespace=default .

• Install a Helm Chart with multiple values and variables:

$ helm upgrade \
    --install ${MY_CHART_NAME} \
    --set-string version="1.1.0" \
    --values values.yaml \
    --values values-"${DEPLOY_ENV}".yaml \
    --namespace=${MY_CHART_NAME} .

$ helm3 upgrade \
    --debug \
    --install \
    --atomic --cleanup-on-fail --timeout 1200s \
    --namespace "${PROJECT_NAME}" \
    --create-namespace \
    --set-string version="${GITHUB_SHA:0:7}" \
    --values ./values.yaml \
    --values ./values-"${DEPLOY_ENV}".yaml \
    "${PROJECT_NAME}" \
    .

• Delete this Helm Chart (i.e., destroy what it created) with:

$ helm delete --purge ${MY_CHART_NAME}

Example Helm Charts

ConfigMap

.
├── Chart.yaml
├── templates
│   └── configmap.yaml
└── values.yaml

$ cat values.yaml 
vaultConfigMap:
  name: vault-demo
  namespace: default
  certificateAuthorityPem: |
    -----BEGIN CERTIFICATE-----
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
    CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD==
    -----END CERTIFICATE-----

$ cat templates/configmap.yaml 
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Values.vaultConfigMap.name }}
  namespace: {{ .Values.vaultConfigMap.namespace }}
data:
  ca.pem: |
{{ .Values.vaultConfigMap.certificateAuthorityPem | indent 4 }}

$ helm template .
---
# Source: foobar/templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: vault-demo
  namespace: default
data:
  ca.pem: |
    -----BEGIN CERTIFICATE-----
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
    CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD==
    -----END CERTIFICATE-----

$ helm template . | kubectl create -f -
configmap/vault-demo created

$ kubectl get cm vault-demo -o yaml
apiVersion: v1
data:
  ca.pem: |
    -----BEGIN CERTIFICATE-----
    AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
    BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
    CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD==
    -----END CERTIFICATE-----
kind: ConfigMap

Deployment order

Helm collects all of the resources in a given Chart and its dependencies, groups them by resource type, and then installs them in the following order (as shown here):

1. Namespace
2. ResourceQuota
3. LimitRange
4. PodSecurityPolicy
5. Secret
6. ConfigMap
7. StorageClass
8. PersistentVolume
9. PersistentVolumeClaim
10. ServiceAccount
11. CustomResourceDefinition
12. ClusterRole
13. ClusterRoleBinding
14. Role
15. RoleBinding
16. Service
17. DaemonSet
18. Pod
19. ReplicationController
20. ReplicaSet
21. Deployment
22. StatefulSet
23. Job
24. CronJob
25. Ingress
26. APIService

During uninstallation of a release, the order is reversed (as shown here).

External links

• Official website