An image is a packaged, executable artifact containing the application code, libraries, environment variables, and configuration files needed to run a container.

Searching for Images

The docker search command queries Docker Hub for available images.

docker search [OPTIONS] TERM

Useful options:

• -f, --filter apply a filter condition
• --format customize output using Go templates
• --limit set the maximum number of results (default 25)
• --no-trunc disable output truncation

Example: search for images contianing "centos" and restrict results to official ones.

docker search -f is-official=true centos

Pulling Images

Download images from a registry with docker pull.

docker pull [OPTIONS] NAME[:TAG|@DIGEST]

• -a, --all-tags downloads every tag of the given image.

# latest Ubuntu image
docker pull ubuntu

# specific version
docker pull ubuntu:16.04

Listing Local Images

Display locally stored images using docker images.

docker images
# filter by name
docker images ubuntu
# wildcard matching
docker images cent*
# specify tag with a pattern
docker images ubun*:16.04

Removing Images

Delete one or more images from the local store.

docker rmi [OPTIONS] IMAGE [IMAGE...]
# or
docker image rm [OPTIONS] IMAGE [IMAGE...]

• -f, --force force removal when image is referenced.

Delete by repository name:

docker rmi ubuntu

Delete by ID (a unique prefix is sufficient):

docker rmi 9f3

Exporting and Importing Images

Backing Up with docker save

Save images into a tar archive.

docker save [OPTIONS] IMAGE [IMAGE...]

• -o, --output specify the output file (default stdout).

docker save ubuntu:16.04 94e814 -o linux.tar

Loading an Archive with docker load

Import images from a tar file created by save.

docker load [OPTIONS]

• -i, --input read from a file instead of stdin
• -q, --quiet suppress progress information

docker load -i linux.tar

When saving by ID without tags, the loaded image may appear with <none> for name and tag. Prefer saving by repository:tag.

Renaming Images

Create a new repository reference (and tag) to an existing image.

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

docker tag 94e ubuntu:18.04

Inspectinng Image Details

View low-level metadata with docker image inspect (or docker inspect).

docker image inspect [OPTIONS] IMAGE [IMAGE...]

• -f, --format output a specific field using Go templates.

# full JSON details
docker image inspect ubuntu:18.04

# extract the image ID
docker image inspect -f "{{ .Id }}" ubuntu:18.04

# storage driver data
docker image inspect -f "{{ .GraphDriver.Data }}" ubuntu:18.04

Viewing the Layer History

Show the layers and their creation commands with docker history.

docker history [OPTIONS] IMAGE

• -H, --human print sizes and dates in human-readable form (default true)
• -q, --quiet display only IDs
• --no-trunc show full output without truncation

docker history ubuntu:18.04