docker-tagging.md

Tagging an image

• CLI Command docker tag [-f] old:tag namespace/new:tag2

• https://github.com/jasonamyers/docker/blob/retag_manifest/cli/common.go#L65

• Registered as CmdTag in (https://github.com/jasonamyers/docker/blob/retag_manifest/api/client/tag.go#L15))

• which makes a post to /images/old%3Atag/tag?repo=namespace%2Fnew&tag=tag2&force=1

• DAEMON : This route is defined by https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/local.go#L128

• The route triggers postImagesTag in https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/image.go#L476

• Parses the URL parameters

• Instruction the daemon to tag the image via TagImage in https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/image.go#L476

• The daemon.TagImage uses the repositories attribute which is defined at https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/image.go#L476 to Tag the image

• daemon.repositories is a TagStore as defined at https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/image.go#L476 and the Tag method is defined at https://github.com/docker/docker/blob/v1.9.1/api/server/router/local/image.go#L476 but only makes a call to setLoad on the TagStore

• TagStore.setLoad() is defined at https://github.com/docker/docker/blob/v1.9.1/graph/tags.go#L289

• It finds the image in the tag store (e.g. old:tag)

• Locks the tag store and set a defered unlock to make sure when the setLoad method exits the lock is removed

• If no tag is given it uses "latest"

• It validates that the new reponame is vaiid (e.g. namespace/new) with validateRepoName at https://github.com/docker/docker/blob/v1.9.1/graph/tags.go#L428

• Then it validates that the new tag is valid (e.g. tag2) with ValidateTagName at https://github.com/docker/docker/blob/v1.9.1/graph/tags/tags.go#L24

• Refreshes the tag store from disk to make sure it's valid via TagStore.reload at https://github.com/docker/docker/blob/v1.9.1/graph/tags.go#L124

• It Normalizes the local name for the via registry.NormailzeLocalName at https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L384 by

• split the local and remote parts of the name via loadRepositoryName at https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L248

• this is handled by splitReposName (https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L299)) and

• then validating both the index (https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L207)) and remote names (https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L219)) f

• finally repoName is returned from localNameFromRemote (https://github.com/docker/docker/blob/v1.9.1/registry/config.go#L414)) which is used to return a full name that includes any registry information.

• Next if checks to see if the repoName is already in the TagStore

• If that it finds that repoName in the TagStore, it then checks to see if the tag exists in the store as well

• If the repoName and the tag both exist it overwrites if force is supplied other wise it returns an Error message about not replacing it.

• If the repoName is new it adds the repoName to the TagStore as a hashmap named repo

• it then sets the repo[tag] to the imageID found in the first step of TagStore.setLoad()

• Saves the tagStore with the new repo/tag

• An HTTP 201 is returned to the CLI

• The CLI command having not gotten an error returns the proper exit code