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Tags

Let's publish a new version of our web server. With Docker, a tag is a label that you can assign to a specific version of an image, similar to a tag in Git.

The latest tag is the default tag that Docker uses when you don't specify one. It's a convention to use latest for the most recent version of an image, but it's also common to include other tags, often semantic versioning tags like 0.1.0, 0.2.0, etc.

Deployment Pipelines

Publishing new versions of Docker images is a very common method of deploying cloud-native back-end servers. Here's a diagram describing the deployment pipeline of many production systems (including the server that powers the Boot.dev site you're on currently).

Assignment

Update the Go code of your server:
- Replace: <p> Hello from Docker! I'm a Go server. </p>
- With: <p> Hi Docker, I pushed a new version. </p>
Compile the new go binary: GOOS=linux GOARCH=amd64 go build
Rebuild the Docker image. Make sure to use the same name as before, but this time, add a new tag to the end of the image name:

docker build . -t USERNAME/goserver:0.2.0

Run the new image:

docker run -p 8991:8991 USERNAME/goserver:0.2.0

Open your browser and navigate to http://localhost:8991. You should see the new version of the server running!
Push the new image up to Docker Hub. This time, you need to specify the tag as well:

docker push USERNAME/goserver:0.2.0

Navigate to your repo on DockerHub, and now you should see 2 images with different tags.
Stop and remove the new container you just started.
Delete the local images so that you have no reference on your local machine. Pull and run the new version from Docker Hub.

docker pull USERNAME/goserver:0.2.0
docker run -p 8991:8991 USERNAME/goserver:0.2.0

With the container running, run and submit the CLI tests.