Introduction

A tiny utility for copying a file from a remote repo into the current one.

Think of it as curl for Github.

• Supports public/private Github as well as Github Enterprise
• Lightweight
• Descriptive error messages

Use case

Every repo has a few boilerplate files that can be recycled in other repos as is. For example:

• .editorconfig
• .gitignore
• .github/issue_template.md
• .github/pull_request_template.md
• .eslintrc
• .eslintignore
• jest.config.js
• ...

Usually these are copy/pasted as needed but then if the source file changes, all these copies need to be updated as well.

Bugs reproduce by copy/paste and take shelter in human errors. So if you have to copy/paste, at least automate it.

• curl does the job for public Github repos, but what about the private/enterprise ones? Besides, if there is more than one file that needs to be copied, that knowledge needs to live somewhere.
• some people use a monorepo to avoid this duplication and deal with lerna or other tools
• some even use git submodules

Say hello to ja: it stands for just add!

Usage

# You can install it globally
$ npm i -g ja

# Then run it in the destination repo
$ ja

# You can also run it with npx
$ npx ja

It reads its config from a text file named .ja in the root of the destination repo.

Each line states the source and optionally the destination.

Example:

# Copy the .gitignore from a remote folder to this one
https://github.com/userpixel/micromustache/blob/master/.gitignore
# Copy the issue template to the .github folder
https://github.com/userpixel/micromustache/blob/master/.github/ISSUE_TEMPLATE.md > .github/ISSUE_TEMPLATE.md

When you run ja:

• It'll look for its config file (.ja) in the same directory (it'll exit with an error if it cannot find it).
• It parses the config, and validates it.
• It tries to figure out the "raw" address for each source URL. For example if the source URL looks like https://github.com/userpixel/ja/blob/master/README.md, it'll try to fetch it from https://raw.githubusercontent.com/userpixel/ja/master/README.md
• If there was no problem fetching the file, it write the file.
  • If the destination folder doesn't exist, it creates it
  • If you already have the destination file, it'll rewrite it. No file permission will be changed. You can see the diff using git diff or git status. If the overwritten file has exactly the same content, git doesn't consider them to be changed
  • Obviously if the fetch step fails, it will not write any files.
  • Currently ja only supports utf-8 format

Commit all your changes before running ja because it'll overwrite the local files.

Config file

The config file is named .ja:

• Each line simply contains a URL and a optionally a relative local file path (separated by >).
• Currently you need to specify each file explicitly. It's not possible to fetch a whole directory like .github.
• The local file path is relative to the current directory where the .ja file is located and cannot point to a parent directory.
• For security reasons no absolute path is allowed.
• For security reasons the local file name cannot point to any directory that is the parent of the directory where the .ja file is located.
• Empty lines and lines beginning with # will be ignored.

Token

If the source is a Github Enterprise or a private repository, you'll need a token. ja expects the token in an environment variable named after the host name of the source URL.

For example the token for fetching a file from a private repo on github.com, should be in the GITHUB_COM_TOKEN environment variable.

If your Github Enterprise is hosted under github.companyname.io, the env var is GITHUB_COMPANYNAME_IO_TOKEN.

There are many ways to pass an environment variable to an application:

• You can put the token in an .env file next to your .ja file (ja reads ./.env). This is the smoothest method, plus is localizes the knowledge about the token to the repo that uses it.
• You can put the token in your ~/.bashrc (Linux) or ~/.bash_profile (Mac)
• You can pass the token directly when running ja like this: GITHUB_COM_TOKEN=328948kksjkafhdskjf ja (note that this will leave a trace in your terminal history. In Bash you can start the command with one space to skip adding it to the history)

Generating a token

This is a one-time process:

1. Click on your github profile and go to Settings > Developer settings > Personal access tokens and click Generate new token
2. Give your token a name and for the scope, only choose public_repo (that's all that is needed)
3. Press the Generate token button. Put this token where ja can find it. Make sure to copy your token to a safe place because it's the last time you see it (don't worry you can always go there and make a new one)

Test

We use Jest.

# Install dependencies and run all tests
$ npm it

Debug

We use Debug.

Run the CLI showing debug info:

$ DEBUG=* node cli/ja.js

License

MIT

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Made in Sweden 🇸🇪 by @alexewerlof