Kojo Configuration Ninja ================================================== [](https://badge.fury.io/rb/kojo) [](https://travis-ci.com/DannyBen/kojo) [](https://codeclimate.com/github/DannyBen/kojo/maintainability) Kojo helps you generate configuration files from templates, using variables and definition files. It is a command line utility, and it works on any text file format.

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Table of Contents

• Installation
• Usage
  • Variables
  • Import
  • Transform an Entire Folder
  • Transform One to Many using Config
  • Transform One to Many using Front Matter
  • Conditions and Loops with ERB
• Interactive Mode
• Using from Ruby Code
• Contributing / Support

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Installation

$ gem install kojo

Usage

If you prefer to learn by example, see the examples folder for several use cases. Each example subfolder contains the command to run, the relevant files, and the expected output.

Variables

Include variables in your configuration templates by using this syntax: %{varname}

• Variables can be provided through the command line, or when using @import.
• When one or more variables are not provided, you will be prompted to provide a value.
• Variables from the top level will be forwarded downstream, and aggregated with any additional variables that are defined in subsequent @imports.

Import

Use the @import filename directive anywhere to include another file in the resulting configuration file.

• The @import directive should be the only thing in the line.
• The indentation will be respected when importing.
• The filename parameter does not have to include an extension - Kojo will use the same extension as the parent file.
• The included file will be searched for relative to the file it is included in.
• Arguments can be passed down to the included template by using this syntax:

@import filename (arg: "value", arg2: "value")

The space after filename is optional.

Transform an Entire Folder

Process a folder containing templates and @imports, and generate a mirror output folder, with all the variables and @imports evaluated.

You may use %{variables} in filenames.

Transform One to Many using Config

Using the kojo config command together with a simple definitions file, you can:

1. Generate multiple output files based on a single template file
2. Generate multiple output directories, based on a single source directory.

To achieve this, you need to:

1. Create the configuration template or directory of templates.
2. Create a configuration YAML file using this syntax:

input: base-template.yml

output:
  outfile1.yml:
    argument1: value
    argument2: value

  outfile2.yml:
    argument1: value
    argument2: value

When using a folder as input, simply provide the folder name in the input property, and instead of providing desired output filenames in the output property, provide desired output directories:

input: base

output:
  app1:
    argument1: value
    argument2: value

  app2:
    argument1: value
    argument2: value

Transform One to Many using Front Matter

Define a template that contains the instructions on how to transform it as a YAML front matter.

The YAML front matter should be structured like this:

filename2:
  arg: value
  another_arg: value

filename2:
  arg: value
  another_arg: value
---
Your template that uses %{arg} goes here
...

Additional arguments provided to the command line, will also be transferred to the template.

Conditions and Loops with ERB

Template files are evaluated using ERB, so you can use any Ruby code for more advanced templates (for conditions, loops etc.).

Use this syntax for ruby code:

<%- ruby code here -%>     # for code that should not be printed
<%= ruby code here -%>     # for code that should be printed

Interactive Mode

When Kojo encounters a variable that was not supplied (either through the command line or through a configuration file), it will prompt for a value.

You can enable or disable interactive mode by setting the environment variable KOJO_INTERACTIVE to yes or no.

By default, interactivity is enabled when running the CLI, and disabled when running from within Ruby code.

When running from within Ruby code, you can also use Kojo.interactive = true and Kojo.interactive? to get the current state.

Using from Ruby Code

Although Kojo was primarily designed as a command line utility, you can also use it as a library from your Ruby code.

These are the primary classes:

Class	Description	CLI equivalent
Kojo::Template	generate from a single template	kojo file
Kojo::FrontMatterTemplate	generate from a template with a front matter	kojo single
Kojo::Config	generate from a config file	kojo config
Kojo::Collection	generate from a directory	kojo dir

Examples

# Template
template = Kojo::Template.new 'examples/variables/main.yml'
result = template.render domain: 'example.com', scale: 2
puts result

# Collection
collection = Kojo::Collection.new 'examples/dir'
collection.import_base = 'examples/dir/imports'

params = { env: 'env', app: 'app' }
result = collection.render params do |path, content|
  # code to handle results here
end

# Config
config = Kojo::Config.new 'examples/config-from-file/config.yml'
config.import_base = "examples/config-from-file/imports"

config.generate do |path, content|
  # code to handle results here
end

# FrontMatterTemplate
template = Kojo::FrontMatterTemplate.new 'examples/single/Dockerfile'
params = { version: '0.1.1' }

result = template.render params do |path, content|
  # code to handle results here
end

In addition, Kojo extends Ruby's File class with the File.deep_write method, which lets you write the file and create the directory structure as needed. You may use it in your code like this:

# Config
config = Kojo::Config.new 'examples/config-from-file/config.yml'
config.import_base = "examples/config-from-file/imports"

config.generate do |path, content|
  File.deep_write path, content
end

Contributing / Support

If you experience any issue, have a question or a suggestion, or if you wish to contribute, feel free to open an issue.

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