The Engine API is an HTTP API served by Docker Engine. It is the API the Docker client uses to communicate with the Engine, so everything the Docker client can do can be done with the API.

Most of the client's commands map directly to API endpoints (e.g. docker ps is GET /containers/json). The notable exception is running containers, which consists of several API calls.

Errors

The API uses standard HTTP status codes to indicate the success or failure of the API call. The body of the response will be JSON in the following format:

{
  "message": "page not found"
}

Versioning

The API is usually changed in each release of Docker, so API calls are versioned to ensure that clients don't break.

For Docker Engine 17.09, the API version is 1.32. To lock to this version, you prefix the URL with /v1.32. For example, calling /info is the same as calling /v1.32/info.

Engine releases in the near future should support this version of the API, so your client will continue to work even if it is talking to a newer Engine.

In previous versions of Docker, it was possible to access the API without providing a version. This behaviour is now deprecated will be removed in a future version of Docker.

The API uses an open schema model, which means server may add extra properties to responses. Likewise, the server will ignore any extra query parameters and request body properties. When you write clients, you need to ignore additional properties in responses to ensure they do not break when talking to newer Docker daemons.

This documentation is for version 1.33 of the API. Use this table to find documentation for previous versions of the API:

Docker version	API version	Changes
17.09.x	1.31	API changes
17.07.x	1.31	API changes
17.06.x	1.30	API changes
17.05.x	1.29	API changes
17.04.x	1.28	API changes
17.03.1	1.27	API changes
1.13.1 & 17.03.0	1.26	API changes
1.13.0	1.25	API changes
1.12.x	1.24	API changes
1.11.x	1.23	API changes
1.10.x	1.22	API changes
1.9.x	1.21	API changes
1.8.x	1.20	API changes
1.7.x	1.19	API changes
1.6.x	1.18	API changes

Authentication

Authentication for registries is handled client side. The client has to send authentication details to various endpoints that need to communicate with registries, such as POST /images/(name)/push. These are sent as X-Registry-Auth header as a Base64 encoded (JSON) string with the following structure:

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

The serveraddress is a domain/IP without a protocol. Throughout this structure, double quotes are required.

If you have already got an identity token from the /auth endpoint, you can just pass this instead of credentials:

{
  "identitytoken": "9cbaf023786cd7..."
}