mtanda / argo-cd-helmfile

Integration between argo-cd and helmfile

Intro

Support for helmfile with argo-cd.

argo-cd already supports helm in 2 distinct ways, why is this useful?

• It helps decouple configuration from chart development
• It's similar to using a repo type of helm but you can still manage configuration with git.
• Because I like the power afforded using helmfile's features such as environments, selectors, templates, and being able to use ENV vars as conditionals AND values.
• https://github.com/roboll/helmfile/blob/master/docs/writing-helmfile.md
• https://github.com/roboll/helmfile/blob/master/docs/shared-configuration-across-teams.md

Security

Please make note that helmfile itself allows execution of arbitrary scripts. Due to this feature, execution of arbitrary scripts are allowed by this plugin, both explicitly (see HELMFILE_INIT_SCRIPT_FILE env below) and implicity.

Consider these implications for your environment and act appropriately.

• https://github.com/roboll/helmfile#templating (exec desciption)
• the execution pod/context is the argocd-repo-server

Installation

    configManagementPlugins: |
      - name: helmfile
        init:                          # Optional command to initialize application source directory
          command: ["argo-cd-helmfile.sh"]
          args: ["init"]
        generate:                      # Command to generate manifests YAML
          command: ["argo-cd-helmfile.sh"]
          args: ["generate"]

  volumes:
  - name: custom-tools
    emptyDir: {}

  initContainers:
  - name: download-tools
    image: alpine:3.8
    command: [sh, -c]
    args:
      - wget -qO /custom-tools/argo-cd-helmfile.sh https://raw.githubusercontent.com/travisghansen/argo-cd-helmfile/master/src/argo-cd-helmfile.sh &&
        chmod +x /custom-tools/argo-cd-helmfile.sh &&
        wget -qO /custom-tools/helmfile https://github.com/roboll/helmfile/releases/download/v0.138.7/helmfile_linux_amd64 &&
        chmod +x /custom-tools/helmfile
    volumeMounts:
      - mountPath: /custom-tools
        name: custom-tools
  volumeMounts:
  - mountPath: /usr/local/bin/argo-cd-helmfile.sh
    name: custom-tools
    subPath: argo-cd-helmfile.sh
  - mountPath: /usr/local/bin/helmfile
    name: custom-tools
    subPath: helmfile

Usage

Configure your argo-cd app to use a repo/directory which holds a valid helmfile configuation. This can be a directory which contains a helmfile.yaml file OR a helmfile.d directory containing any number of *.yaml files. You cannot have both configurations.

There are a number of specially handled ENV variables which can be set (all optional):

• HELM_BINARY - custom path to helm binary
• HELM_TEMPLATE_OPTIONS - pass-through options for the templating operation helm template --help
• HELMFILE_BINARY - custom path to helmfile binary
• HELMFILE_GLOBAL_OPTIONS - pass-through options for all helmfile operations helmfile --help
• HELMFILE_TEMPLATE_OPTIONS - pass-through options for the templating operation helmfile template --help
• HELMFILE_INIT_SCRIPT_FILE - path to script to execute during init phase
• HELMFILE_HELMFILE - a complete helmfile.yaml content
• HELMFILE_HELMFILE_STRATEGY - one of REPLACE or INCLUDE
  • REPLACE - the default option, only the content of HELMFILE_HELMFILE is rendered, if any valid files exist in the repo they are ignored
  • INCLUDE - any valid files in the repo AND the content of HELMFILE_HELMFILE are rendered, precedence is given to HELMFILE_HELMFILE should the same release name be declared in multiple files

Of the above ENV variables, the following do variable expansion on the value:

• HELMFILE_GLOBAL_OPTIONS
• HELMFILE_TEMPLATE_OPTIONS
• HELM_TEMPLATE_OPTIONS
• HELMFILE_INIT_SCRIPT_FILE
• HELM_DATA_HOME

Meaning, you can do things like:

• HELMFILE_GLOBAL_OPTIONS="--environment ${ARGOCD_APP_NAME} --selector cluster=${CLUSTER_ID}

Any of the standard Build Environment variables can be used as well as variables declared in the application spec.

• https://argoproj.github.io/argo-cd/user-guide/config-management-plugins/#environment
• https://argoproj.github.io/argo-cd/user-guide/build-environment/

Helm Plugins

To use the various helm plugins the recommended approach is the install the plugins using the/an initContainers (explicity set the HELM_DATA_HOME env var during the helm plugin add command) and simply set the HELM_DATA_HOME environment variable in your application spec (or globally in the pod). This prevents the plugin(s) from being downloaded over and over each run.

# repo server deployment
  volumes:
  ...
  - name: helm-data-home
    emptyDir: {}

# repo-server container
  volumeMounts:
  ...
  - mountPath: /home/argocd/.local/share/helm
    name: helm-data-home

# init container
  volumeMounts:
  ...
  - mountPath: /helm/data
    name: helm-data-home

    [[ ! -d "${HELM_DATA_HOME}/plugins/helm-secrets" ]] && /custom-tools/helm-v3 plugin install https://github.com/jkroepke/helm-secrets --version ${HELM_SECRETS_VERSION}
    chown -R 999:999 "${HELM_DATA_HOME}"

# lastly, in your app definition
...
plugin:
  env:
  - name: HELM_DATA_HOME
    value: /home/argocd/.local/share/helm

If the above is not possible/desired, the recommended approach would be to use HELMFILE_INIT_SCRIPT_FILE to execute an arbitrary script during the init phase. Within the script it's desireable to run helm plugin list and only install the plugin only if it's not already installed.

Custom Init

You can use the HELMFILE_INIT_SCRIPT_FILE feature to do any kind of init logic required including installing helm plugins, downloading external files, etc. The value can be a relative or absolute path and the file itself can be injected using an initContainers or stored in the application git repository.

Development

# format before commit
shfmt -i 2 -ci -w src/argo-cd-helmfile.sh