templar

README

Templar

A command line utility for rendering Go template files.

Overview

Templar allows you to quickly render one or more Go template files to disk injecting environment variables or command line arguments.

Installation

At present, templar only supports Linux and macOS due to the fact that we allow file system permission manipulation in an operating system specific way.

Binaries

Release binaries are available for templar from the release page here. Download the appropriate binary for your operating system and either invoke it explicitly (e.g., ./templar.linux) or copy it to your PATH.

Note, it's likely that you'll want to rename it templar for ease of use and the following instructions make this assumption.

Docker

Docker images of templar are available as well and can be found in DockerHub.

Usage

Templar uses Cobra so all commands support a help option (e.g., templar -h or templar --help). As a result, the following usage instructions only cover the top level use cases and do not attempt to provide descriptions of all options available.

Version

To print the current version and commit for the templar binary run the following command:

templar version 

Render

Rendering a template to disk is performed by running the following syntax:

templar render TEMPLATE_PATH:RENDERED_PATH[:RENDERED_MODE]

Where:

• TEMPLATE_PATH is the path of the template file
• RENDERED_PATH is the path of to which the template file is rendered
• RENDERED_MODE is the Unix permission in numeric notation (i.e., 0700) of the rendered file

For example, the following command will render the template at /etc/example/example.json.tpl to /etc/example/example.json and ensure that it only can only be read by the owner.

templar render /etc/example/example.json.tpl:/etc/example/example.json:0400

Also note that it is also possible to render multiple templates in a single command:

templar render /etc/example/example.json.tpl:/etc/example/example.json /etc/example/example.yaml.tpl:/etc/example/example.yaml

User Variables

Templar supports injecting variables into rendered templates with command line arguments using the -v or -variable option. The following command sets a variable named AUTHOR to Joan Wilder.

templar render -v "AUTHOR=Joan Wilder" /var/lib/rts.json.tpl:/var/lib/rts.json

Using a command line variable within the template is done with the variable function exposed to the template:

{{ variable "AUTHOR" }}

Environment Variables

Templar supports injecting environment variables into rendered templates with command line arguments using the -e or --environment option.

templar render -e AUTHOR /var/lib/rts.json.tpl:/var/lib/rts.json

Using an environment variable within the template is done with the variable function exposed to the template:

{{ variable "AUTHOR" }}

Note that only environment variables explicitly passed via the -e or --environment option will be availble to prevent accidentally leaking sensitive material.

Available Functions

Templar also supports a number of additional functions that can be used to inject and manipulate common values in templates.

Function	Example	Description
variable	{{ var "NAME" }}	Returns the value of a command line or environment variable if set; otherwise, an empty string.

Note that all other functions supported within Go templates are also available.

Building

Dependencies

In order to build templar the following dependencies are required.

• Go (1.13.7)
• Make (3.81 or greater)

Build

To build a binary for the current operating system run the following command:

make build

Additionally, build targets are provided for macOS, Linux and Docker (i.e., make build.docker, make build.linux, and make build.macos).

Testing

To test templar run the following command:

make test