How to Tag and Push Docker Image to Registry

Use docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG] to add a new tag to your image, then use docker push TARGET_IMAGE[:TAG] to upload it to a registry. The TARGET_IMAGE usually includes the registry URL and repository name.

Syntax

The tagging and pushing process uses two main commands:

• docker tag: Assigns a new name or tag to an existing image.
• docker push: Uploads the tagged image to a remote registry.

Format:

docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
docker push TARGET_IMAGE[:TAG]

SOURCE_IMAGE is your local image name or ID. TARGET_IMAGE includes the registry URL, repository, and tag.

bash

docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
docker push TARGET_IMAGE[:TAG]

Example

This example shows how to tag a local image named myapp:latest to a remote registry docker.io/username/myapp:v1.0 and push it.

bash

docker tag myapp:latest docker.io/username/myapp:v1.0
docker push docker.io/username/myapp:v1.0

Output

The push refers to repository [docker.io/username/myapp]
123456789abc: Pushed
v1.0: digest: sha256:abcdef1234567890 size: 1234

Common Pitfalls

Common mistakes include:

• Forgetting to tag the image with the full registry path before pushing.
• Not logging in to the registry with docker login before pushing.
• Using incorrect tag names or missing tags, which defaults to latest.

Always verify the image tag matches the registry path.

bash

docker push myapp:latest
# Error: repository does not exist or no access

# Correct way:
docker tag myapp:latest docker.io/username/myapp:v1.0
docker push docker.io/username/myapp:v1.0

Quick Reference

Command	Purpose
docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]	Add a new tag to an existing image
docker push TARGET_IMAGE[:TAG]	Upload the tagged image to a remote registry
docker login	Authenticate to a registry before pushing
docker images	List local images and tags

Key Takeaways

Always tag your image with the full registry path before pushing.

Use docker push to upload the tagged image to the remote registry.

Login to the registry using docker login to avoid permission errors.

Tags help identify image versions; avoid pushing untagged images.

Verify image names and tags with docker images before pushing.