00-docker-basics

Docker workshop - Basics

This section is separated in:

• Docker Basics
• Start Spring Boot MongoDB aplication

DOCKER Basics

Version

Check you have latest version of docker installed:

docker version
docker -v

• If you don't have docker installed, check here
• If you're not on the latest version, it will prompt you to update
• If you're not on docker group you might need to prefix commands with sudo. See here for details about it.

Commands

Check the available docker commands

docker
docker --help

• Whenever you don't remember a command, just type docker
• For more info, type docker help COMMAND (e.g. docker help run)

RUN a "Hello World" container

docker run alpine echo "Hello World"

• If the Image is not cached, it pulls it automatically
• It prints Hello World and exits

Images

Images are the templates docker uses to create containers from. If you're familiar with Object Oriented Programming you may (sort of) think of images as classes and containers as instances.

Check which images you have in your local repository by doing:

docker images

Let's try and get another image

docker pull mongo

This last command pulled an image named mongo from the public docker repository to your local repository. This is very similar to what you achieve with git pull from a public git repository.

We can try an image search:

docker search -s 10 nginx

• -s: Only displays with at least x stars

RUN a Container and expose a Port

docker run -d -p 4000:80 nginx

Open a BROWSER with URL localhost:4000

• -d: Detached mode: Run container in the background, print new container id
• -p: Publish a container's port to the host (format: hostPort:containerPort)
• For more info about the container, see nginx

RUN a Container with a Volume

NOTE: Make sure to be on Docker Workshop directory since we'll use volume mounts in the containers of directories of the repository.

On Linux and Mac

docker run --name daemon -d -p 4001:80 -v $(pwd)/code/hello-world/src/:/usr/share/nginx/html:ro nginx

Open a BROWSER with URL localhost:docker

• -v: Bind mount a volume (e.g., from the host: -v /host:/container, from docker: -v /container)
• The volume is linked inside the container. Any external changes are visible directly inside the container.
• This example breaks the immutability of the container, good for debuging, not recommended for production (Volumes should be used for data, not code)

SHOW all images

Let’s list our images:

docker image ls

• docker image ls is command to command to list images.

SHOW all containers

Let’s see what containers do we have now:

docker ps -a

• docker ps is command to command to list containers.
• -a show all containers (default shows only running).

SHOW container logs

Let’s see what daemon container is doing right - let’s see the logs of it:

docker logs -f daemon

• docker logs is command to fetch the logs of a container.
• -f flag to follow the log output (works actually like tail -f).

STOP/START/REMOVE container

Now let’s stop daemon container:

docker stop daemon

• docker stop is command to stop Docker container.

docker ps -a

Now container daemon is stopped. We can start it again:

docker start daemon

And ensure that it’s running:

docker ps -a

Now let’s stop it again and remove all the containers manually:

docker stop daemon
docker rm <your first container name>
docker rm daemon

To remove all containers we can use this command:

docker rm -f $(docker ps -aq)

• docker rm is command to remove container.
• -f flag (for rm) is to stop container if it's running (force deletion).
• -q flag (for ps) is to print only container IDs.

Let's run ps again to ensure that we don't have containers:

docker ps -a

Start Spring Boot MongoDB aplication

Let’s start mongoDb container

docker run --name mongo -p 27017:27017 -d mongo

Now we cand start Spring Boot aplication

cd code
git clone https://github.com/springframeworkguru/spring-boot-mongodb.git
cd spring-boot-mongodb/
mvn package install
cd target/
java -jar spring-boot-mongodb-0.0.1-SNAPSHOT.jar

Let’s stop daemon container:

docker stop mongo

Let’s start mongoDb container with volume

docker run -p 27017:27017 -d mongo -v /Users/bogdan/Desktop/mongo:/data/db

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