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Docker
Images, layers, and containers — what's actually happening when you run a build.
0 of 30 lessons complete
~349 min total
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Lessons 1–12
Images, Containers & Registries → Health Checks & Restart Policies
0/12 done
1
Images, Containers & Registries
Intermediate
Three nouns get used almost interchangeably in casual conversation — image, container, registry — and interviews specifically probe whether you actually know which is which.
12 min · 0/3 questions correct
2
Dockerfile Instructions & Layer Caching
Intermediate
Every Dockerfile instruction is a layer, every layer is cached, and cache invalidation cascades downward — one line in the wrong order can silently turn a 3-second rebuild into a 3-minute one.
14 min · 0/3 questions correct
3
Multi-Stage Builds & Image Size
Intermediate
A production image doesn't need a compiler, a package manager cache, or dev dependencies — it needs the built output and a way to run it. Multi-stage builds are how you ship only that.
13 min · 0/3 questions correct
4
Compose & Multi-Container Development
Intermediate
A real app is rarely one container — it's a frontend, an API, a database, maybe a cache, all needing to find and talk to each other. Compose is how you describe that whole system in one file instead of a page of docker run commands.
13 min · 0/3 questions correct
5
Volumes & Persistent Data
Intermediate
A container's own writable layer dies with the container. Anything that needs to outlive it — a database's data, an upload, a local source tree for hot reload — has to live somewhere else entirely.
12 min · 0/3 questions correct
6
Config & Secrets in Containers
Intermediate
Environment variables solve where config comes from. This lesson is narrower and sharper: which of Docker's several ways to get a value into a container also leaves that value sitting somewhere readable, permanently, by accident.
13 min · 0/3 questions correct
7
Registries & CI/CD Integration
Intermediate
The general CI/CD lesson in this platform's Practices track covers build-test-deploy as a pipeline shape. This one is narrower: the specific decisions a pipeline has to make once what it's shipping is a Docker image.
12 min · 0/3 questions correct
8
Container Orchestration Basics
Intermediate
Compose runs containers on one machine. Production traffic doesn't fit on one machine forever — orchestration is the layer that decides which of many machines runs what, and what happens the instant one of them dies.
13 min · 0/3 questions correct
9
Docker Networking: Drivers & Isolation
Intermediate
Compose's service-name DNS feels like magic until you know what it's built on — a specific network driver, chosen from a small set of options, each with a genuinely different isolation model.
12 min · 0/3 questions correct
10
Storage Drivers & the Union Filesystem
Intermediate
Layer caching only makes sense once you know what a layer actually IS — a union filesystem is the mechanism that stacks a dozen read-only diffs into one filesystem a running container can read and write like a normal disk.
12 min · 0/3 questions correct
11
The Docker Daemon & Client-Server Architecture
Intermediate
The `docker` command never builds an image or starts a container itself — it asks a background process to, over a socket. Whoever can reach that socket has the same power the CLI does, which is a real, common security footgun.
10 min · 0/3 questions correct
12
Health Checks & Restart Policies
Intermediate
"Running" and "working" are different claims — a health check is what closes that gap, and a restart policy is what decides what happens once you know the difference.
10 min · 0/3 questions correct
Lessons 13–24
Resource Limits & cgroups → Private Registries & Registry Authentication
0/12 done
Lessons 25–30
Multi-Architecture Builds with Buildx → Debugging Running Containers
0/6 done