Tell pack where you want your app image to be saved.

By default, when you build an app with pack build <my-image>, the image will be saved to a daemon, such as Docker or Podman, and you can view the image using a command such as docker image ls.

However, you could also choose to “publish” the app to an OCI registry, such as Docker Hub or Google Artifact Registry, or even to a local registry, by providing the pack build --publish flag.

Or, you could save the image in OCI layout format on disk by prefixing your image name with oci:, as in pack build oci:<my-image>. See here for more information about working with layout images.

FAQ: what am I using the daemon for?

Buildpacks always need to run in a containerized environment. Therefore, even when you publish the app image to a registry, pack is still using a daemon under the hood to create the build containers where buildpacks run.

The relationship between the build container and the app container can be seen in the diagram below:

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