Invisible Node.js Setup with Docker

Last year I replaced my system package manager with docker. It was a game-changer, but one challenge stood out: setting up tools to work as if they were installed natively.

This is how I interact with node.

docker run -it --rm \
  -v "${PWD}:/workspace" \
  node:16-alpine

There are a few problems with this approach:

The command is very verbose. Even for basic commands like npm install and npm run dev, I need to type a lot of docker boilerplate
With the --rm flag, a new container is created every time I run this command. I loose access to changes made inside the container for example the repl history.
If I don't use the --rm flag, I need to worry about stopping the containers, otherwise I run out of memory.
Cold start on every command.
Throwing away muscle memory and relearning new command syntax. This would also mean I would struggle with regular setups.
I can also use the shell inside the container directly, but I enjoy looking at my pretty prompt. I also cannot live without zsh tab suggestions.

First I need to figure out how my container should be configured and what it can access.

Start inside the project folder by default using the -w or --workdir
```
-w "/workspace"
```
When creating files inside the container, I need them to have the correct owner so I can also access the them from host. I can supply the user via the -u or --user flag. The node user is predefined in the image.
```
-u "node"
```
I need to preserve my repl history. I can simply mount the history file that would have been created during a regular installation.
```
-v "${HOME}/.node_repl_history:/home/node/.node_repl_history"
```
I might want to publish a package on npm or download private packages. Same story.
```
-v "${HOME}/.npmrc:/home/node/.npmrc"
```
I still can't download packages or make fetch calls from the repl. Easiest way is to reuse the host network.
```
--network host
```

Easy stuff done. Maybe I can run a container in background and individually execute command each command inside the background container?

Have a container running in the background with the project mounted doing nothing. -d flag is for "Detached" mode. We need to give a name to the container to refer to it during exec. The last two lines is just running tail -f /dev/null. It keeps the container running in the background doing nothing. It is equivalent to a while (1) loop without consuming the CPU.
```
docker run -it -d \
  -u "node" \
  -v "/some/awesome/project:/workspace" \
  -v "${HOME}/.npmrc:/home/node/.npmrc" \
  -v "${HOME}/.node_repl_history:/home/node/.node_repl_history" \
  -w "/workspace" \
  --name node \
  --network host \
  --entrypoint tail \
  node:16-alpine -f /dev/null
```

Executing commands inside the container.

alias node='docker exec -it node node' # run the node repl
alias npm='docker exec -it node npm' # npm install, npm publish, etc
alias npx='docker exec -it node npx' # curl bashing with extra steps
alias node:shell='docker exec -it node sh' # sometimes I need to debug

I can't remember the start command. Also lets not hardcode the project path. Also commands to stop / restart the container in a new project

alias node:start='docker run -it -d \
  -u "node" \
  -v "${PWD}:/workspace/$(basename ${PWD})" \
  -v "${HOME}/.npmrc:/home/node/.npmrc" \
  -v "${HOME}/.node_repl_history:/home/node/.node_repl_history" \
  -w "/workspace/$(basename ${PWD})" \
  --name node \
  --network host \
  --entrypoint tail \
  node:16-alpine -f /dev/null'
alias node:stop='docker stop node; docker rm node; true'
alias node:restart='node:stop; node:start'

Limitations:

You can only execute commands from the project's root. If you cd in the host shell, the workdir inside the container will still be on the root path.
You have a global instance of node container. You wont be able to work on two projects simultaneously.

Enhancements:

we can create new containers using node:start. This will create containers with node and their path converted to a slug. we can then define new alias node:attach, that sets $NODE_CONTAINER env variable. running node will exec inside container name stored in $NODE_CONTAINER

Edit: 2024-06-24
nix-shell is a much better solution

P.S. A little horror story: While trying to sell Docker to a friend, I completely forgot I had a container running in the background with a different project directory mounted. I ended up accidentally rm -rfing my project while trying to convince him that Docker keeps you safe from this exact scenario. 😭