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Docker Tutorial with Examples.

Docker tutorial for beginners: containerise applications, build optimised images, configure networking and orchestrate with Docker Compose.

3 Beginner 3 Intermediate 3 Advanced +5 From other topics

Architecture at a glance

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Docker architecture at a glance

Dockerfile → build → image → registry → docker run → container

Docker architecture at a glance A Dockerfile is built into an image through cached layers, a multi-stage build slims it down, and it is pushed to a registry before docker run starts a container whose main process runs as PID 1. A running container uses volumes, a bridge network and environment variables; Compose brings up multiple services together. A bottom strip covers non-root hardening, a CIS benchmark scan, cosign signing, production controls, and deploying real apps with FastAPI and Spring Boot. Dockerfile Build layers · cache Image multi-stage Registry tag · push docker run Container PID 1 · signals What a container uses Volumes bind mounts Networking bridge · DNS Env & config env vars · inspect Multi-service Compose services · health Secure and ship Non-root CIS bench Cosign Production Shell jobs FastAPI → K8s Spring Boot
How it fits together (7 steps)
  1. Write a Dockerfile and build it. Docker reuses a cached layer only while the instruction and everything before it are unchanged, so slow steps that don't depend on your source (dependency installs) go before the COPY of your code.
  2. A multi-stage build compiles in a full toolchain stage, then copies only the finished artifact into a small runtime stage — a Go binary goes from 287MB to 2.3MB this way.
  3. Push the image to a registry and sign its digest with cosign so a puller verifies the digest, not a movable tag.
  4. docker run starts a container that is just a host process: its main command runs as PID 1, so docker stop sends SIGTERM and only falls back to SIGKILL after the grace period.
  5. A running container uses volumes or bind mounts for data that outlives it, a user-defined bridge network for DNS and published ports, and environment variables for config.
  6. Multiple services are defined once in docker-compose.yml and brought up together, with health checks gating dependent services.
  7. Secure and ship it: run as non-root and drop capabilities, pass a CIS Docker Benchmark scan, manage background jobs and signals from the shell, add health checks, limits and a restart policy for production, and deploy real apps with FastAPI on Kubernetes or a Dockerized Spring Boot jar.

Beginner

Start here — no prior experience needed

3 lessons
docker beginner
5 min read

Introduction to Docker

Run your first Docker containers and see what they are: ordinary Linux processes sharing the host kernel, started from an image in well under a second.

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docker beginner
5 min read

Docker Images and Dockerfiles

Write a Dockerfile, build and run your own image, order layers for the build cache, use ENTRYPOINT, CMD, ARG and .dockerignore, and push to a registry.

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docker beginner
5 min read

Managing Docker Containers

Run, inspect, stop and remove containers: the lifecycle, port publishing, exec, logs, docker stop versus SIGKILL, memory limits and docker cp.

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Intermediate

For developers with core concepts down

3 lessons
docker intermediate
5 min read

Docker Networking

Connect containers by name on user-defined bridge networks, see network isolation, aliases, the host and none drivers, and reach the host from a container.

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docker intermediate
5 min read

Docker Volumes and Storage

Keep data beyond a container's life with named volumes, bind mounts and tmpfs: sharing, read-only mounts, backup and restore, and permission fixes.

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docker intermediate
5 min read

Docker Compose

Define and run multi-container applications with Docker Compose. Services, networks, volumes, and environment configuration.

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Advanced

Production-grade patterns for experienced engineers

3 lessons
docker advanced
5 min read

Multi-Stage Builds

Use multi-stage Dockerfiles to produce small, secure production images by separating build and runtime environments.

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docker advanced
5 min read

Docker Security

Harden Docker images and containers: non-root users, read-only filesystems, secrets management, image scanning, and runtime policies.

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docker advanced
5 min read

Docker in Production

Health checks that actually flip unhealthy, a container OOM-killed for real, log rotation you can see on disk, an authenticated private registry, a measured BuildKit cache-mount speedup, and a real zero-downtime swap.

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Also part of Docker

Taught in other topics. Each link opens the lesson in its home topic.

5 lessons
fastapi advanced
5 min read

Deploying FastAPI with Docker and Kubernetes: Images, Signals, and Probes

Ship FastAPI on Docker and Kubernetes: a 171 MB multi-stage image, clean SIGTERM shutdown, and liveness, readiness and startup probes on a live minikube.

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java intermediate
5 min read

Dockerizing Spring Boot Applications

Prepare a Spring Boot 3 app for containers: layered jars, env-var config, JVM memory flags, health probes and graceful shutdown, plus a Dockerfile.

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bash intermediate
5 min read

Bash Process Management

Run background jobs, manage processes with jobs/fg/bg, send signals with kill, use trap for cleanup, and understand subshells.

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cloud-security intermediate
5 min read

CIS Docker Benchmark Checks with docker-bench-security

Run the CIS Docker Benchmark's container checks against a container you start, read each WARN, fix privileged mode and missing limits, and re-run to PASS.

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devsecops advanced
5 min read

Signing Container Images with Cosign: Verify the Digest, Not the Tag

Sign an image in a local registry with a Cosign key pair, verify it, then push different content under the same tag and watch verification refuse it.

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