moby/docs/reference/api/docker_remote_api.md

Docker Remote API

Docker's Remote API uses an open schema model. In this model, unknown properties in incoming messages are ignored. Client applications need to take this behavior into account to ensure they do not break when talking to newer Docker daemons.

The API tends to be REST, but for some complex commands, like attach or pull, the HTTP connection is hijacked to transport STDOUT, STDIN, and STDERR.

By default the Docker daemon listens on unix:///var/run/docker.sock and the client must have root access to interact with the daemon. If a group named docker exists on your system, docker applies ownership of the socket to the group.

The current version of the API is v1.21 which means calling /info is the same as calling /v1.21/info. To call an older version of the API use /v1.20/info.

Authentication

Since API version 1.2, the auth configuration is now handled client side, so the client has to send the authConfig as a POST in /images/(name)/push. The authConfig, set as the X-Registry-Auth header, is currently a Base64 encoded (JSON) string with the following structure:

{"username": "string", "password": "string", "email": "string",
   "serveraddress" : "string", "auth": ""}

Callers should leave the auth empty. The serveraddress is a domain/ip without protocol. Throughout this structure, double quotes are required.

Using Docker Machine with the API

If you are using docker-machine, the Docker daemon is on a virtual host that uses an encrypted TCP socket. This means, for Docker Machine users, you need to add extra parameters to curl or wget when making test API requests, for example:

curl --insecure --cert ~/.docker/cert.pem --key ~/.docker/key.pem https://YOUR_VM_IP:2376/images/json

wget --no-check-certificate --certificate=$DOCKER_CERT_PATH/cert.pem --private-key=$DOCKER_CERT_PATH/key.pem https://your_vm_ip:2376/images/json -O - -q

Docker Events

The following diagram depicts the container states accessible through the API.

Some container-related events are not affected by container state, so they are not included in this diagram. These events are:

• export emitted by docker export
• exec_create emitted by docker exec
• exec_start emitted by docker exec after exec_create

Running docker rmi emits an untag event when removing an image name. The rmi command may also emit delete events when images are deleted by ID directly or by deleting the last tag referring to the image.

Acknowledgement: This diagram and the accompanying text were used with the permission of Matt Good and Gilder Labs. See Matt's original blog post Docker Events Explained.

Version history

This section lists each version from latest to oldest. Each listing includes a link to the full documentation set and the changes relevant in that release.

v1.21 API changes

Docker Remote API v1.21 documentation

• GET /volumes lists volumes from all volume drivers.
• POST /volumes to create a volume.
• GET /volumes/(name) get low-level information about a volume.
• DELETE /volumes/(name)remove a volume with the specified name.
• VolumeDriver has been moved from config to hostConfig to make the configuration portable.
• GET /images/(name)/json now returns information about tags of the image.

v1.20 API changes

Docker Remote API v1.20 documentation

• GET /containers/(id)/archive get an archive of filesystem content from a container.
• PUT /containers/(id)/archive upload an archive of content to be extracted to an existing directory inside a container's filesystem.
• POST /containers/(id)/copy is deprecated in favor of the above archive endpoint which can be used to download files and directories from a container.
• The hostConfig option now accepts the field GroupAdd, which specifies a list of additional groups that the container process will run as.

v1.19 API changes

Docker Remote API v1.19 documentation

• When the daemon detects a version mismatch with the client, usually when the client is newer than the daemon, an HTTP 400 is now returned instead of a 404.
• GET /containers/(id)/stats now accepts stream bool to get only one set of stats and disconnect.
• GET /containers/(id)/logs now accepts a since timestamp parameter.
• GET /info The fields Debug, IPv4Forwarding, MemoryLimit, and SwapLimit are now returned as boolean instead of as an int. In addition, the end point now returns the new boolean fields CpuCfsPeriod, CpuCfsQuota, and OomKillDisable.

v1.18 API changes

Docker Remote API v1.18 documentation

• GET /version now returns Os, Arch and KernelVersion.
• POST /containers/create and POST /containers/(id)/startallow you to set ulimit settings for use in the container.
• GET /info now returns SystemTime, HttpProxy,HttpsProxy and NoProxy.
• GET /images/json added a RepoDigests field to include image digest information.
• POST /build can now set resource constraints for all containers created for the build.
• CgroupParent can be passed in the host config to setup container cgroups under a specific cgroup.
• POST /build closing the HTTP request cancels the build
• POST /containers/(id)/exec includes Warnings field to response.

v1.17 API changes

Docker Remote API v1.17 documentation

• The build supports LABEL command. Use this to add metadata to an image. For example you could add data describing the content of an image. LABEL "com.example.vendor"="ACME Incorporated"
• POST /containers/(id)/attach and POST /exec/(id)/start
• The Docker client now hints potential proxies about connection hijacking using HTTP Upgrade headers.
• POST /containers/create sets labels on container create describing the container.
• GET /containers/json returns the labels associated with the containers (Labels).
• GET /containers/(id)/json returns the list current execs associated with the container (ExecIDs). This endpoint now returns the container labels (Config.Labels).
• POST /containers/(id)/rename renames a container id to a new name.*
• POST /containers/create and POST /containers/(id)/start callers can pass ReadonlyRootfs in the host config to mount the container's root filesystem as read only.
• GET /containers/(id)/stats returns a live stream of a container's resource usage statistics.
• GET /images/json returns the labels associated with each image (Labels).

v1.16 API changes

Docker Remote API v1.16

• GET /info returns the number of CPUs available on the machine (NCPU), total memory available (MemTotal), a user-friendly name describing the running Docker daemon (Name), a unique ID identifying the daemon (ID), and a list of daemon labels (Labels).
• POST /containers/create callers can set the new container's MAC address explicitly.
• Volumes are now initialized when the container is created.
• POST /containers/(id)/copy copies data which is contained in a volume.

v1.15 API changes

Docker Remote API v1.15 documentation

POST /containers/create you can set a container's HostConfig when creating a container. Previously this was only available when starting a container.

v1.14 API changes

Docker Remote API v1.14 documentation

• DELETE /containers/(id) when using force, the container will be immediately killed with SIGKILL.
• POST /containers/(id)/start the hostConfig option accepts the field CapAdd, which specifies a list of capabilities to add, and the field CapDrop, which specifies a list of capabilities to drop.
• POST /images/create th fromImage and repo parameters supportthe repo:tag format. Consequently, the tag parameter is now obsolete. Using the new format and the tag parameter at the same time will return an error.