npx for Docker

npxd <command> is like npx <command> but runs command inside Docker container defined in docker-compose.yml.

The main benefit: seamless command invocation from either host machine or inside container:

• if invoked from host machine - ensures container is running via docker compose up and runs command via docker compose exec
• if invoked from inside container - just runs command ¯\_(ツ)_/¯

1. Ensure you have docker-compose.yml file in your project
2. Install npxd (details):

   npm i -D npxd
   

3. Prepend package.json scripts with npxd:

   "scripts": {
   -  "test": "mocha test/*.js",
   +  "test": "npxd mocha test/*.js",
   },

4. Run as usual from your host machine:

   npm test
   

5. Check results of command executed in container:

   $ npm test
   
   > npxd mocha test/*.js
   
   Recreating example_app_1 ... done
   
     ✓ should add numbers
   
     1 passing (36ms)
   

See full example code in example directory.

There are to installation options:

Installing from npm will add npxd executable to node_modules/.bin of your project. You will be able to use npxd command in package.json scripts.

npm i -D npxd

Alternatively you can download script directly from GitHub and store it in your project. It allows you to adopt script for your needs (as it's a few lines of code). But in that case you should invoke it as ./npxd.sh not npxd in package.json scripts.

wget -O npxd.sh https://raw.githubusercontent.com/vitalets/npxd/main/npxd.sh
chmod +x npxd.sh

This will NOT work:

"scripts": {
  "lint": "FOO=42 npxd eslint ./src"
},

But this will work:

"scripts": {
  "lint": "npxd env FOO=42 eslint ./src"
},

• if there is single service in docker-compose.yml, commands will automatically run inside it
• if there are several services in docker-compose.yml, you should create .npxdrc file containing target service name

Example of .npxdrc that runs commands in my_app service:

my_app

Note: when you install npxd directly from GitHub you may just edit ./npxd.sh to set particular service name.

When invoked not from package.json scripts section you need to use npx in front of npxd (as it is usual executable inside node_modules/.bin):

$ npx npxd eslint ./src

Or if you installed from GitHub, just run script:

$ ./npxd.sh eslint ./src

MIT @ Vitaliy Potapov