How to Import a Container in Docker: Simple Steps

To import a container in Docker, use the docker import command followed by the tarball file containing the container filesystem. This command creates a new Docker image from the imported container data.

Syntax

The basic syntax to import a container in Docker is:

• docker import [OPTIONS] file|URL|- [REPOSITORY[:TAG]]

Here:

• file|URL|- is the path to the tarball file or URL containing the container filesystem.
• REPOSITORY[:TAG] is an optional name and tag for the new image.
• OPTIONS can include flags like -c to apply Dockerfile instructions.

bash

docker import [OPTIONS] file|URL|- [REPOSITORY[:TAG]]

Example

This example shows how to import a container filesystem saved as a tarball and create a new Docker image named myimportedimage:latest.

bash

docker import mycontainer.tar myimportedimage:latest

Output

sha256:3a1b2c4d5e6f7890abcdef1234567890abcdef1234567890abcdef1234567890

Common Pitfalls

Common mistakes when importing containers include:

• Using docker import to import a container instead of an image tarball. docker import expects a filesystem archive, not a saved image.
• Confusing docker import with docker load. Use docker load to load images saved with docker save.
• Not specifying a repository name or tag, which results in an image with a random ID and no easy reference.

bash

Wrong way:
docker import myimage.tar

Right way:
docker import mycontainer.tar myimage:latest

Quick Reference

Remember these tips when importing containers:

• Use docker import for filesystem tarballs.
• Use docker load for Docker images saved with docker save.
• Always tag your imported image for easy use.

Key Takeaways

Use docker import to create an image from a container filesystem tarball.

Specify a repository and tag to name your imported image clearly.

Do not confuse docker import with docker load; they serve different purposes.

Imported images do not include Docker history or metadata, only the filesystem.

Always verify the tarball source and contents before importing.