5.4 KiB
Kontemplate - A simple Kubernetes templater
Kontemplate is a simple CLI tool that can take sets of Kubernetes resource files with placeholders and insert values per environment.
This tool was made because in many cases all I want in terms of Kubernetes configuration is simple value interpolation per environment (i.e. Kubernetes cluster), but with the same deployment files.
In my experience this is often enough and more complex solutions such as Helm are not required.
Check out a Kontemplate setup example and the feature list below!
Table of Contents
Features
- Simple, yet powerful templates
- Clean cluster configuration files
- Resources organised as simple resource sets
- Integration with pass
- Integration with kubectl
Example
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. That's it!
You can also set up more complicated folder structures for organisation, for example:
.
├── api
│ ├── image-api
│ │ └── deployment.yaml
│ └── music-api
│ └── deployment.yaml
│ │ └── default.json
├── frontend
│ ├── main-app
│ │ ├── deployment.yaml
│ │ └── service.yaml
│ └── user-page
│ ├── deployment.yaml
│ └── service.yaml
├── prod-cluster.yaml
└── test-cluster.yaml
And selectively template or apply resources with a command such as
kontemplate apply test-cluster.yaml --include api --include frontend/user-page
to only update the api resource sets and the frontend/user-page resource set.
Installation
It is recommended to install Kontemplate from the Nix package set,
where it is available since NixOS 17.09 as kontemplate.
If using Nix is not an option for you, several other methods of installation are available:
Binary releases
Signed binary releases are available on the releases page for Linux, OS X, FreeBSD and Windows.
Releases are signed with the GPG key DCF34CFAC1AC44B87E26333136EE34814F6D294A.
Building from source
You can clone Kontemplate either by cloning the full [depot][https://git.tazj.in/] or by just cloning the kontemplate subtree like so:
git clone -b kontemplate https://git.tazj.in kontemplate
The go tooling can be used as normal with this cloned repository. In
a full clone of the dpeot, Nix can be used to build Kontemplate:
nix-build -A ops.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
Check out the feature list and the individual feature documentation above. Then you should be good to go!
Contributing
Feel free to contribute pull requests, file bugs and open issues with feature suggestions!
Kontemplate is licensed under the GPLv3, a copy of the license and its terms can be found
in the LICENSE file.
Please follow the code of conduct.