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Configuration as Code with ECMAScript
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jk.go jk: Silence errors and usage coming from cobra Feb 13, 2019
kubernetes.js Implement module loading Oct 24, 2018
nginx.js all: Use @jkcfg/std instead of std Apr 19, 2019
params_option.go jk: Factor out a vm object from run May 10, 2019 jk: Rename the github org to jkcfg Dec 14, 2018 build: Remove the subshell when pushing Jun 11, 2019 tests: Run eslint on examples May 14, 2019
run.go generate: Introduce a generate command May 11, 2019
rx.js Make module resolution deal with relative paths Oct 28, 2018
version.go version: Add a version command Dec 13, 2018
vm.go vm: Fix help text of the -p option May 13, 2019


Build Status

jk is still in very early stages. The standard library API isn't frozen and will most likely change. Feedback is most definitely welcome!

jk - configuration as code

jk is a data templating tool designed to help writing structured configuration files.

The main idea behind jk is to use a general purpose language for this task. They offer mature tooling, great runtimes, a well established ecosystem and many learning resources. jk uses Javascript and a runtime tailored for configuration.

Quick start

A good way to start with jk is to read our introduction tutorial.

More complex examples

Architecture & design


jk itself is a Javascript runtime written in Go and embedding v8. It uses Ryan Dahl's v8worker2 to embed v8 and flatbuffers for the v8 ⟷ Go communication.


While a general purpose language is great, configuration code can be made more maintainable by restricting what it can do. A nice property jk has to offer is being hermetic: if you clone a git repository and execute a jk script, the resulting files should be the same on any machine. To give concrete examples, this means the jk standard library doesn't support environment variables nor has any networking capability.

Library support

jk provides an unopinionated data templating layer. On top of the jk runtime, libraries provide APIs for users to write configuration.

  • mixins: build and compose configuration objects
  • kubernetes: build Kubernetes objects


This project is still in early stages but future (exciting!) plans include:

  • Reach the state of having Kubernetes examples working and well documented.
  • Work on hermeticity. (eg. #110, #44, topic/hermeticity).
  • Native typescript support (#54).
  • HCL support (#94).


When contributing to this repository, please first discuss the change you wish to make via issue with the owners of this repository before making a change.


The jk executable itself is written in Go, but the JavaScript part of this project requires NodeJS.


  • go 1.11.4 or later (modules support)
  • nodejs, npm
  • make

First off, clone this repository:

$ git clone
# or with hub:
$ hub clone jkcfg/jk

$ cd ./jk

Then pull most of the dependencies using the Makefile:

$ make dep

jk is linked against v8worker2. As building V8 takes ~30 minutes, prebuilt versions are provided for linux/amd64 and darwin/amd64. This also includes flatc from flatbuffers:

# download the prebuilt artifacts from GitHub:
$ git clone
$ cd ./prebuilt

# x64 Linux:
$ make install-linux-amd64

# x64 macOS:
$ make install-darwin-amd64


After setting up the environment, the jk binary can be built:

$ make jk
$ ./jk --help # confirm it works

Additionally, on Linux, it's possible to use a docker container to build the project instead of installing the prebuilt libraries and binaries:

$ ./ make dep jk
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