ArgoCD ytt Config Management Plugin (CMP)

This project was deprecated and replaced in favor of argocd-lovely-plugin

Please check lovely documentation, and more specifically the lovely-ytt plugin variation doc

Old readme

This repository contains an ArgoCD configuration management plugin (CMP) for ytt which permits using YAML Templating Tookit to template YAML/manifests before they are applied by ArgoCD.

More information on CMP can be read in the ArgoCD documentation.

What's special with this argocd-cmp-ytt configuration management plugin is that it permits chaining ytt and Helm/Kustomize, which makes it possible to use the advanced templating capabilities of ytt in e.g. the values.yaml or in a kustomization.yaml (or any other file for that matter), before then running helm template or kustomize build in the repo.

How to use it?

1. add the sidecar container to your repo-server deployment (this can be achieved with the file in ./packaging/k8s/, which you can apply to your repo-server deployment as a strategic merge patch if you're using kustomize)
2. add a .ytt file (can be empty) at the root repo configured for your application
3. add a plugin: section to your application spec, to add some environment variables

an example Application would look like follows:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: kube-contour
  namespace: kube-argocd-master
spec:
  destination:
    namespace: kube-contour
    server: https://yourcluster.company.local
  project: kube-contour-appset
  source:
    repoURL: git@gitlab.pnet.ch:kubernetes/workloads/kube-contour.git
    path: .
    plugin:
      env:
      - name: ingress_name
        value: ingress.yourcluster.company.local
      - name: HELM_RELEASE_NAME # optional, can be used to specify the Helm Release name
        value: contour
    targetRevision: HEAD

Thanks to the .ytt file in your repository, ArgoCD repository server will know that the repository is to be rendered using the argocd-cmp-ytt plugin, and it will then use the sidecar container to render the end manifests.

As specified above, this plugin not only makes it possible to template using ytt, it also permits rendering manifests with Helm or kustomize afterwards.

templating + Helm or kustomize

when argocd-cmp-ytt is called, it lists all files/folders in the repository and checks whether:

• there is a kustomization.yaml file: in that case, the plugin calls ytt --data-values-env=ARGOCD_ENV in-place on all files before running kustomize build .
• there is a Chart.yaml file: in that case, the plugin calls ytt in-place only on the values.yaml file. it then runs helm dependency build and finally runs helm template ...
• there isn't any of the above, it then simply calls ytt --data-values-env=ARGOCD_ENV --file .

what can be achived with ytt ?

ytt playground and documentation are the places where you'll find examples and ideas to template your manifests.

Here is however a simple example showing what can be attained with ytt and how it solves a concrete manifest rendering pain point we had:

#@ load("@ytt:data", "data")
---
#@yaml/text-templated-strings
ingress_name: "(@= data.values.ingress_name @)" # some simple templating taking place
contour:
  enabled: true
  podAnnotations:
    prometheus.io/scrape: "true"
    prometheus.io/port: "8000"
  #@yaml/text-templated-strings
  args:
    - serve
    - --incluster
    - --xds-address=0.0.0.0
    - --xds-port=8001
    - --ingress-status-address={{ getHostByName "(@= data.values.ingress_name @)" }} # we can make a DNS lookup here!