Tagging your container images

Using the :latest tag on Docker images is incredibly convenient, but it can easily lead to confusion as to what exactly is running. If you do use :latest, then it is a very good idea to also tell Kubernetes to always attempt to pull a new image when loading the container. We will see how to set this in Chapter 4, Declarative Infrastructure, when we talk about declaratively defining our applications.

An alternative is to make explicit tags, building with a tag, and also using docker tag to tag the image as latest for the convenience factor, but maintaining specific tags within the declarations that you check in to source control. For this example, the tag chosen is 0.2.0, using semantic versioning to represent a value to use with the container, and matched to a git tag as well.

The steps that were used while making this example were:

git tag 0.2.0
docker build -t quay.io/kubernetes-for-developers/nodejs:0.2.0 .
git push origin master --tags
docker push quay.io/kubernetes-for-developers/nodejs