Docker

Package an app once, run it anywhere. Build images that don't double in size every Friday.

beginner22 labs

Recommended first

Git Linux

You can still start this course now. Earlier courses give you the mental model the labs here assume.

By the end you'll be able to

Build images that don't ship your .env file
Debug a running container without rebuilding
Compose multi-service stacks locally
Read a Dockerfile and predict what it'll produce

Labs

01
Container vs virtual machine
Form a mental model of how a container differs from a virtual machine so the rest of the Docker labs make sense.
10 min
Start
02
Image vs container
Pull a small image, start two containers from it, and see one image produce many running instances.
12 min
Start
03
Image layers and copy-on-write
Look inside an image to see the layer stack, then write a file in a running container to see copy-on-write at work.
12 min
Start
04
Dockerfile in one minute
Look at the three instructions every Dockerfile needs and build a one-line image from them.
10 min
Start
05
docker run and the flags that matter
Run containers in foreground, detached, and interactive mode, and learn the half-dozen flags you reach for every day.
15 min
Start
06
docker ps and how to filter it
Read the docker ps table, list stopped containers with -a, and trim the output with --format and --filter.
10 min
Start
07
docker exec into a running container
Run a command inside a container that is already running, and open an interactive shell to look around.
12 min
Start
08
Stop, remove, and prune containers
Stop a running container, remove a stopped one, and reclaim space with docker container prune.
10 min
Start
09
FROM, RUN, CMD in a real Dockerfile
Build an image that installs a package at build time and runs a command at start time.
15 min
Start
10
COPY, ADD, and .dockerignore
Copy files into an image, see what ADD does on top, and trim the build context with .dockerignore.
15 min
Start
11
Multi-stage builds
Compile in a fat builder stage, then copy only the binary into a tiny runtime stage.
18 min
Start
12
Tagging and versioning images
Tag an image with a version, a moving alias, and a registry path so later pushes go to the right place.
12 min
Start
13
Image cleanup and layer inspection
See how dangling images appear, look inside an image with docker history, and reclaim disk with docker image prune.
12 min
Start
14
Publishing container ports
Map a container port to a host port with -p, see the difference vs --expose, and pick a host port at random.
12 min
Start
15
Custom bridge networks and DNS
Create a user-defined bridge network, attach two containers, and let them talk by container name.
14 min
Start
16
Named volumes for persistent data
Create a named volume, write data into it from one container, and read it back from a fresh one.
12 min
Start
17
Bind mounts and host paths
Mount a host directory into a container, see writes show up on both sides, and learn when to pick a bind mount over a named volume.
12 min
Start
18
Compose, a one-file stack
Write a compose.yaml with one service, run docker compose up, and see one file describe a whole stack.
15 min
Start
19
depends_on and healthchecks
Order two services with depends_on, gate startup with a healthcheck, and see the difference between started and healthy.
18 min
Start
20
Compose environment variables and .env
Pass environment variables into a service from inline, from a list, and from a .env file.
15 min
Start
21
Diagnose a container that will not stay up
A container exits the moment it starts. Read its state and its logs to find why, then start it correctly so it stays running and answers.
14 min
Start
22
Capstone, build an image and serve it on a network
An open-ended problem with no prescribed commands. Build your own image that serves a known string, run it under a name on a user-defined network, and prove a second container reaches it by that name.
25 min
Start