Chapter 0412 mins • beginner

Mastering `docker run` Flags

Environment Variables, Auto-removal, Restart Policies & Memory Limits

What You Will Master:

Inject configuration using `-e KEY=VALUE`
Configure automatic restarts with `--restart always`
Set container resource boundaries with `--memory` and `--cpus`

1Essential docker run Flags

* `-e / --env`: Passes environment variables into the container runtime. * `--restart`: Defines auto-restart behavior on crash (`always`, `on-failure`, `unless-stopped`). * `--rm`: Automatically deletes container when its process exits (great for one-off CLI tools or tests). * `--memory`: Enforces hard RAM limits (e.g. `--memory=512m`).

Interactive Lab

Configure Environment & Restart Policy

Run a node container with custom environment variable `APP_ENV=production` and restart policy `always`.

0/1 Steps Done

Step 1: Run node container with APP_ENV=production and --restart always

Run `docker run -d --name my-api -e APP_ENV=production --restart always node:22-alpine`

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Interactive CLI

Docker Terminalv27.1

Quick:

$docker version3:07:24 PM

Client: Docker Engine - Community v27.1.1
Server: Docker Engine - Simulated In-Browser Runtime (Safe Sandbox)
Storage Driver: overlay2 (Virtual Layers)
Status: Ready • Zero Docker Desktop Required