How do you create custom Helm plugins and when should you use them?

Helm plugins extend Helm CLI functionality with custom commands. They are written as scripts (bash, Python, Go) and placed in $(helm home)/plugins/.

Basic plugin structure: ~/.local/share/helm/plugins/myplugin/ plugin.yaml # Plugin metadata myplugin.sh # Executable script README.md # Documentation LICENSE

plugin.yaml example: name: "myplugin" version: "0.1.0" usage: "Run custom pre-deployment validation" description: |- This plugin validates Helm charts against custom rules before deployment. command: "$HELM_PLUGIN_DIR/validate.sh" ignoreFlags: false useTunnel: false hooks: install: "echo Installing myplugin" update: "echo Updating myplugin"

Plugin script example (validate.sh): #!/bin/bash set -e CHART_PATH=$1 NAMESPACE=$2 echo "Running custom validations..." # Check for disallowed image registries if grep -r "image:.*docker.io" $CHART_PATH/templates/; then echo "ERROR: Docker Hub images not allowed in production" exit 1 fi # Validate all resources have resource limits if ! grep -r "resources:" $CHART_PATH/templates/; then echo "ERROR: Missing resource limits" exit 1 fi echo "All validations passed" exit 0

Installing and using plugins: helm plugin install https://github.com/myorg/helm-myplugin helm myplugin validate ./mychart production helm plugin list helm plugin update myplugin helm plugin uninstall myplugin

Popular community plugins:

• helm-diff - Show diff between releases
• helm-secrets - Manage encrypted secrets
• helm-unittest - Unit testing for charts
• helm-github - Deploy from GitHub releases
• helm-schema-gen - Generate JSON Schema from values.yaml

When to create plugins: Custom validation rules, integration with internal tooling, complex multi-step workflows, custom templating engines, generating documentation, or auditing deployments.