Container Images
Image and Container Management
Glossary.
- Container: package and app into a single unit
- Container Runtime Engine: sw that executes your container (docker engine)
- Container Orchestrator: automates and mages workload (k8s)
- ContainerFile: Instructions to build the container
- Container Image: packages app into a single unit of sw including its runtime, env and config
- Container Registry: where to share your container
Render local images you have in your machine.
docker images
Before pushing a docker container image to a registry we need to conform to the conventions of the registry
For example, for docker registry you need to prepend your container image with your username:
docker tag python-hello-world:1.0.0 jose/python-hello-world:1.0.0
If you want to push your container image, you need to auth first,
docker login --username=jose
And then push it
docker push jose/python-hello-world:1.0.0
You can create a backup of container image into a .tar file
docker save -o python-hello-world.tar jose/python-hello-world:1.0.0
Then list it
$ ls
python-hello-world.tar
We can do the inverse from a file:
docker load --input python-hello-world.tar
Learnings from the Lab
Create the container
cd into the dir with the Dockerfile, then do:
docker build -t some-tag:1.0.0 .
The dot is important
You can double check if you did it right with
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
nodejs-hello-world 1.0.0 3af6d05d3c35 8 minutes ago 180MB
Then to actually run the thing,
docker run -d -p 80:3000 nodejs-hello-world:1.0.0
Keep in mind that all the flags go before the image tag, if not it will trip
To list the running containers you can do
$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c02c36ecbc85 nodejs-hello-world:1.0.0 "docker-entrypoint.sā¦" 3 minutes ago Up 3 minutes 0.0.0.0:80->3000/tcp, :::80->3000/tcp angry_mestorf
To stop it you can do
docker container stop angry_mestorf
Saving to a tar file:
docker save -o nodejs-hello-world-1.0.0.tar nodejs-hello-world:1.0.0