How to Determine the Entrypoint for a Docker Image

You can use docker inspect to determine the entrypoint of a docker image.

The command looks like this:

docker inspect --type=image --format='{{json .Config.Entrypoint}}' <image-name> 

And here’s a real-world example (assuming you have the hashicorp/terraform image downloaded):

docker inspect --type=image --format='{{json .Config.Entrypoint}}' hashicorp/terraform

["/bin/terraform"]

There are some examples on the official docs but none of the examples covered my use cases, so here are some additional useful docker inspect examples using the busybox image.

List environment variables:

docker inspect --type=image --format='{{json .Config.Env}}' busybox

["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"]

List the CMD:

docker inspect --type=image --format='{{json .Config.Cmd}}' busybox

["sh"]

Print out the architecture:

docker inspect --type=image --format='{{json .Architecture}}' busybox

"amd64"

The docker inspect command can also be used to inspect other docker resources too, not just images. Check out the documentation for more information.

References:

• https://docs.docker.com/engine/reference/commandline/inspect/