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Multiple Containers

Running a single container? That's easy. Real^tm engineers control entire fleets of containers. Remember, Docker containers are very lightweight. It's normal to run many containers on a single host machine.

Remember, each container is its own isolated environment and process. Even if we start 10 containers from the same image, the image is just the definition of the container (the code and starting environment). Each container is a separate instance of that image.

Assignment

Start five different instances of the docker/getting-started container, each time on a new port:

docker run -d -p 8965:80 docker/getting-started
docker run -d -p 8966:80 docker/getting-started
docker run -d -p 8967:80 docker/getting-started
docker run -d -p 8968:80 docker/getting-started
docker run -d -p 8969:80 docker/getting-started

We use port 80 within each container because that's the port that the application is binding to inside the container. It's being forwarded to the different ports we specify on the host (our) machine.

We have to use different host ports for different containers because two processes can't bind to the same port on the same operating system.

Load each webpage in your browser to make sure it works:

http://localhost:8965
http://localhost:8966
http://localhost:8967
http://localhost:8968
http://localhost:8969

Keep in mind, even though they all serve the same page, each is served from its own container!

Run the ps command to see each running container:

docker ps

Run and submit the CLI tests.

When you're done running the tests, make sure to stop the containers.