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Summary - Network

Combine create, connect and publish to set up multi-container.

Summary: networking

In this group:

  • Drivers: bridge (default), host, none, overlay.
  • docker network ls/inspect/create/rm/prune manage networks.
  • On user-defined bridge networks the container name is the DNS name; on the default bridge it isn't.
  • network connect/disconnect attach a running container to networks; --network-alias gives an extra name.
  • In-network traffic uses the container port; only entry points like a reverse proxy publish ports.
docker network create arka
docker run -d --name db --network arka postgres:16
docker run -d --name api --network arka -p 8000:8000 api:1.0

Practice A two-tier network

Write three commands: create the arka network; start a container named db from postgres:16 in the background on arka with POSTGRES_PASSWORD=gizli; start a container named api from api:1.0 in the background on arka, mapping 8000 to 8000 and with DATABASE_URL=postgresql://postgres:gizli@db:5432/postgres.

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker network create arka
docker run -d --name db --network arka -e POSTGRES_PASSWORD=gizli postgres:16
docker run -d --name api --network arka -p 8000:8000 -e DATABASE_URL=postgresql://postgres:gizli@db:5432/postgres api:1.0

Expected output

6f708192a3b4…
2b3c4d5e6f70
3c4d5e6f7081

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the simplest way for two containers to find each other by name?

  • Publishing both their ports
  • Using --network host
  • Writing their IPs into /etc/hosts by hand
  • Putting both on the same user-defined network Correct answer

Explanation: Docker's built-in DNS works on user-defined networks.

2 Start the container on a specific network.

Question 
docker run -d --name db ____ arka postgres:16
Answer 
docker run -d --name db --network arka postgres:16

Explanation: --network takes the network name; --link is deprecated.

3 Match.

Term Meaning
bridge Default
DNS On user-defined networks
connect Attach later
-p Open to the outside

All lessons in Beginner

1 What is Docker?

  1. What is Docker?
  2. Containers and virtual machines
  3. Images and containers
  4. Docker architecture
  5. Use cases
  6. Summary - What is Docker

2 Installation and first commands

  1. Installing Docker
  2. docker version
  3. docker info
  4. The hello-world container
  5. Docker Desktop
  6. Summary - Installation

3 First container

  1. docker run basics
  2. Running in the background
  3. docker ps
  4. docker stop and rm
  5. docker logs
  6. Summary - First container

4 Dockerfile basics

  1. What is a Dockerfile?
  2. The FROM instruction
  3. The RUN instruction
  4. COPY and ADD
  5. CMD and ENTRYPOINT
  6. Summary - Dockerfile

5 Build and images

  1. docker build
  2. Tagging images
  3. Build context
  4. Layers and cache
  5. .dockerignore
  6. Summary - Build

6 docker run options

  1. Interactive mode
  2. Naming containers
  3. Restart policy
  4. Working directory
  5. Switching users
  6. Summary - docker run

7 Image management

  1. docker images
  2. docker rmi
  3. docker pull
  4. docker push
  5. docker tag
  6. Summary - Image management

8 Port mapping

  1. The port concept
  2. The -p flag
  3. Multiple ports
  4. Random ports
  5. IP binding
  6. Summary - Port mapping

9 Volumes and data

  1. Data persistence
  2. Named volumes
  3. The -v flag
  4. Bind mounts
  5. Volume management
  6. Summary - Volumes

10 Environment variables

  1. The -e flag
  2. The ENV instruction
  3. The ARG instruction
  4. env-file
  5. The WORKDIR instruction
  6. Summary - Environment

11 Project: docker-compose

  1. Compose design
  2. Service definition
  3. Database service
  4. Volume and network
  5. Putting it together - compose

12 Docker Hub and registry

  1. What is Docker Hub?
  2. docker login
  3. Searching images
  4. Official images
  5. Private registry
  6. Summary - Registry

13 Network basics

  1. Network drivers
  2. docker network ls
  3. Bridge network
  4. Container connectivity
  5. Publishing ports
  6. Summary - Network

14 Beginner final

  1. Challenge - Dockerfile
  2. Challenge - Build and run
  3. Challenge - Volume
  4. Challenge - Compose
  5. Challenge - Beginner project