Helm
Helm helps you manage Kubernetes applications using helm charts. Helm Charts help you define, install, and upgrade Kubernetes applications.
Example:
# add chart repository
helm repo add bitnami https://charts.bitnami.com/bitnami
# update charts
helm repo update
# install mysql using helm chart by bitnami
helm install bitnami/mysql --generate-name
Helm plugins
Helm plugins provide a way to extend Helm features without modifying the helm core codebase.
Helm plugins have the following features:
- They can be added and removed from a Helm installation without impacting the core Helm tool.
- They can be written in any programming language.
- They integrate with Helm, and will show up in helm help and other places.
Helm plugins are stored in $HELM_PLUGINS
directory, you can change this using helm env
command.
Install a helm plugin
A Helm plugin can be installed from a git repo, a tar release or from a local directory.
helm plugin install <path|url>
Helm plugin anatomy
A helm plugin constists of a plugin.yaml file, which has the plugin definition and its associated commands.
─ fullenv
├── plugin.yaml
└── run.sh
plugin definition
plugin.yaml defines the name, usage, description and command to run when invoked.
- The
Command
can point to your own script of any programming language. - The
ignoreFlags
switch tells Helm to not pass flags to the plugin.
So if a plugin is called with helm myplugin --foo
and ignoreFlags: true, then --foo is silently discarded.
plugin.yaml
name: fullenv
usage: "show env vars"
description: "show all env vars"
command: "$HELM_PLUGIN_DIR/run.sh"
ignoreFlags: true
run.sh - just prints helm environment variables.
#!/bin/sh
echo $HELM_PLUGIN_NAME
echo $HELM_PLUGIN_DIR
echo $HELM_PLUGINS
echo $HELM_REPOSITORY_CONFIG
echo $HELM_REPOSITORY_CACHE
echo $HELM_BIN
Platform specific commands
Helm plugin commands can be configured to target a os platform and architecture.
name: fullenv
usage: "show env vars"
description: "show all env vars"
command: "$HELM_PLUGIN_DIR/run.sh"
platformCommand:
- os: linux
arch: i386
command: "$HELM_PLUGIN_DIR/run.sh"
- os: linux
arch: amd64
command: "$HELM_PLUGIN_DIR/run.sh"
Helm follows the below rules to choose a command.
- If
platformCommand
is present, it will be searched first. - If both
os
andarch
match the current platform, search will stop and the command will be used. - If
os
matches and there is no more specificarch
match, the command will be used. - If no
platformCommand
match is found, the defaultcommand
will be used. - If no matches are found in
platformCommand
and nocommand
is present, Helm will exit with an error.
Install the plugin
cd into the plugin directory and then run the command below
# install
helm plugin install .
# check if the installation is successful
helm plugin list
Test the plugin
helm fullenv
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