tvl-depot/README.md

Kontemplate - A simple Kubernetes templater

I made this tool out of frustration with the available ways to template Kubernetes resource files. All I want out of such a tool is a way to specify lots of resources with placeholders that get filled in with specific values, based on which context (i.e. k8s cluster) is specified.

Overview

Kontemplate lets you describe resources as you normally would in a simple folder structure:

.
├── prod-cluster.yaml
└── some-api
    ├── deployment.yaml
    └── service.yaml

This example has all resources belonging to some-api (no file naming conventions enforced at all!) in the some-api folder and the configuration for the cluster prod-cluster in the corresponding file.

Lets take a short look at prod-cluster.yaml:

---
context: k8s.prod.mydomain.com
global:
  globalVar: lizards
include:
  - name: some-api
    values:
      version: 1.0-0e6884d
      importantFeature: true
      apiPort: 4567

Those values are then templated into the resource files of some-api.

Installation

Assuming you have Go configured correctly, you can simply go get github.com/tazjin/kontemplate/....

Usage

You must have kubectl installed to use Kontemplate effectively.

usage: kontemplate [<flags>] <command> [<args> ...]

simple Kubernetes resource templating

Flags:
  -h, --help                 Show context-sensitive help (also try --help-long and --help-man).
  -i, --include=INCLUDE ...  Resource sets to include explicitly
  -e, --exclude=EXCLUDE ...  Resource sets to exclude explicitly

Commands:
  help [<command>...]
    Show help.

  template <file>
    Template resource sets and print them

  apply [<flags>] <file>
    Template resources and pass to 'kubectl apply'

  replace <file>
    Template resources and pass to 'kubectl replace'

  delete <file>
    Template resources and pass to 'kubectl delete'

  create <file>
    Template resources and pass to 'kubectl create'

Examples:

# Look at output for a specific resource set and check to see if it's correct ...
kontemplate template example/prod-cluster.yaml -i some-api

# ... maybe do a dry-run to see what kubectl would do:
kontemplate apply example/prod-cluster.yaml --dry-run

# And actually apply it if you like what you see:
kontemplate apply example/prod-cluster.yaml