kubectl-tmplt

A kubectl plugin to expand and apply templated resource files to a cluster.

Features;

• doesn't use 'charts' as intermediate when applying resources to target cluster.
• allows to wait for certain conditions in the target cluster before (continuing) applying resources.
• can fetch values from a "master vault" for use in templating or actions.
• can prune.
• can label all resources.
• can perform actions to:
  • read value from cluster to use in subsequent templating steps.
  • write to HashiVault policy or logical paths

Quick Start

Download kubectl-tmplt from releases and put it in your PATH. Check kubectl tmplt --help

Create a 'job.yaml' file:

steps:
- tmplt: "template.yaml"
  values:
    name: "test"
- wait: --for condition=Ready pod -l app=example

defaults:
  namespace: "default"

Create a template.yaml file:

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Values.name }}"
  namespace: "{{ .Values.namespace }}"
  labels:
    app: example
spec:
  containers:
    - args: [sleep, "3600"]
      image: ubuntu
      name: ubuntu

Create a values.yaml file with value overrides:

#values:
#  name: optionally override values defined in template

See what is going to be applied; kubectl tmplt -m generate --job-file job.yaml -set-file values.yaml

Before continuing make sure kubectl config current-context selects the target cluster.

Apply; kubectl tmplt -m apply --job-file job.yaml -set-file values.yaml

Clean-up; kubectl tmplt -m generate --job-file all.yaml -set-file values.yaml | kubectl delete -f -

More examples in test/e2e/testdata/ and kubectl tmplt --help

Wishlist

• Support templates with other delimiters than {{ }}. Use-case; prometheus config uses {{ }} but needs to be templated as well. Possible delimters: <% %> {~ ~} (or configurable via tmplt step parameter)
• [could have] 'delete' step. Use-case: delete CR and wait for operator to do it's work, then delete(prune?) operator.
• Support annotation deploy.mmlt.nl/create=delete|recreate to specify how immutable objects should be handled. For each object with this annotation kubectl-tmplt will get the object from the cluster and if .spec differs will either deletes/create the object or recreate the object. If the object has no annotation or .spec are equal kubectl-tmplt will apply the object.

Known issues