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moby--moby/api
Sebastiaan van Stijn 51c7992928
API: add "prune" events
This patch adds a new "prune" event type to indicate that pruning of a resource
type completed.

This event-type can be used on systems that want to perform actions after
resources have been cleaned up. For example, Docker Desktop performs an fstrim
after resources are deleted (https://github.com/linuxkit/linuxkit/tree/v0.7/pkg/trim-after-delete).

While the current (remove, destroy) events can provide information on _most_
resources, there is currently no event triggered after the BuildKit build-cache
is cleaned.

Prune events have a `reclaimed` attribute, indicating the amount of space that
was reclaimed (in bytes). The attribute can be used, for example, to use as a
threshold for performing fstrim actions. Reclaimed space for `network` events
will always be 0, but the field is added to be consistent with prune events for
other resources.

To test this patch:

Create some resources:

    for i in foo bar baz; do \
        docker network create network_$i \
        && docker volume create volume_$i \
        && docker run -d --name container_$i -v volume_$i:/volume busybox sh -c 'truncate -s 5M somefile; truncate -s 5M /volume/file' \
        && docker tag busybox:latest image_$i; \
    done;

    docker pull alpine
    docker pull nginx:alpine

    echo -e "FROM busybox\nRUN truncate -s 50M bigfile" | DOCKER_BUILDKIT=1 docker build -

Start listening for "prune" events in another shell:

    docker events --filter event=prune

Prune containers, networks, volumes, and build-cache:

    docker system prune -af --volumes

See the events that are returned:

    docker events --filter event=prune
    2020-07-25T12:12:09.268491000Z container prune  (reclaimed=15728640)
    2020-07-25T12:12:09.447890400Z network prune  (reclaimed=0)
    2020-07-25T12:12:09.452323000Z volume prune  (reclaimed=15728640)
    2020-07-25T12:12:09.517236200Z image prune  (reclaimed=21568540)
    2020-07-25T12:12:09.566662600Z builder prune  (reclaimed=52428841)

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2020-07-28 12:41:14 +02:00
..
server API: add "prune" events 2020-07-28 12:41:14 +02:00
templates/server swagger: fix "generated code" comment not in correct format 2019-11-05 11:32:37 -08:00
types API: add "prune" events 2020-07-28 12:41:14 +02:00
common.go Bump API version to v1.41 2019-05-13 14:55:20 -07:00
common_unix.go Various code-cleanup 2018-05-23 17:50:54 +02:00
common_windows.go Add canonical import comment 2018-02-05 16:51:57 -05:00
README.md API: minor fixes in the README 2017-10-11 16:12:10 +02:00
swagger-gen.yaml Use a config to generate swagger api types 2016-10-31 11:13:41 -04:00
swagger.yaml API: add "prune" events 2020-07-28 12:41:14 +02:00

Working on the Engine API

The Engine API is an HTTP API used by the command-line client to communicate with the daemon. It can also be used by third-party software to control the daemon.

It consists of various components in this repository:

  • api/swagger.yaml A Swagger definition of the API.
  • api/types/ Types shared by both the client and server, representing various objects, options, responses, etc. Most are written manually, but some are automatically generated from the Swagger definition. See #27919 for progress on this.
  • cli/ The command-line client.
  • client/ The Go client used by the command-line client. It can also be used by third-party Go programs.
  • daemon/ The daemon, which serves the API.

Swagger definition

The API is defined by the Swagger definition in api/swagger.yaml. This definition can be used to:

  1. Automatically generate documentation.
  2. Automatically generate the Go server and client. (A work-in-progress.)
  3. Provide a machine readable version of the API for introspecting what it can do, automatically generating clients for other languages, etc.

Updating the API documentation

The API documentation is generated entirely from api/swagger.yaml. If you make updates to the API, edit this file to represent the change in the documentation.

The file is split into two main sections:

  • definitions, which defines re-usable objects used in requests and responses
  • paths, which defines the API endpoints (and some inline objects which don't need to be reusable)

To make an edit, first look for the endpoint you want to edit under paths, then make the required edits. Endpoints may reference reusable objects with $ref, which can be found in the definitions section.

There is hopefully enough example material in the file for you to copy a similar pattern from elsewhere in the file (e.g. adding new fields or endpoints), but for the full reference, see the Swagger specification.

swagger.yaml is validated by hack/validate/swagger to ensure it is a valid Swagger definition. This is useful when making edits to ensure you are doing the right thing.

Viewing the API documentation

When you make edits to swagger.yaml, you may want to check the generated API documentation to ensure it renders correctly.

Run make swagger-docs and a preview will be running at http://localhost. Some of the styling may be incorrect, but you'll be able to ensure that it is generating the correct documentation.

The production documentation is generated by vendoring swagger.yaml into docker/docker.github.io.