containerd API for Python
containerd API Python package
This repository provides a Python3 API to containerd's
(gRPC) API, directly generated from the original containerd
definitions. As it is
generated from the protocol files, this Python package does not aim to be a
fully Pythonesque package. In consequence, the usual idiosyncrasies of gRPC and
protoc shine through.
Note: with Python2 going end-of-life in January 2020 we don't support Python2 in this package at this very late time in the lifecycle.
The versioning of this package complies with PEP 440.
The version is composed of the version of the supported containerd API (e.g. 1.2 or 1.3) and an incremental number for each pycontainerd release for that specific containerd API version (starting from 0) connected with a '.' (a dot).
Ideally the Python containerd API has to be generated only once per containerd API version, resulting in x.y.0 package versions.
The result is version numbers like:
- 1.2.1 for the second release for API 1.2
- 1.3.0 for the first release for API 1.3
This project is licensed as Apache License, Version 2.0 (SPDX-License-Identifier: Apache-2.0).
You can obtain the full license text from the file
License of this repository.
Install as Python Package
Installation depends on your starting point:
- You have a
pycontainerdPython Wheel package (something like
- You only have the source code (the result of cloning the git repository).
Python3 PIP is needed for Wheel installations (either from a ready Wheel package or from a self-built package). PIP takes care of installing all the Python packages listed as dependencies. Runtime dependencies are nevertheless listed below.
Installation from Wheel package
Go to the directory where the wheel package is available and run:
sudo pip3 install containerd-<x.y.z>-py3-none-any.whl
containerd-<x.y.z>-py3-none-any.whl the filename of the wheel package.
NOTE: a global installation is required (or rather, more convenient) because the
containerdAPI socket is usually only reachable for
Installation from source code
Additionally, if building from source code you'll also need
A Makefile is being provided that takes care of
- Building the Wheel package
- Installing the Wheel package
Get into the directory corresponding the API version of your containerd installation and run following:
The second step is under the hood simply running the installation of the wheel
package explained above. Including the global installation, therefore a
execution is asking for the user's password (assuming the user has that right).
Package Structure and Usage
The resulting Wheel package provides following Python packages (they have to be imported individually), providing multiple modules:
- containerd.protobuf (note: this is not a protobuf alias)
In order to get the modules being provided by a package you can run:
python3 -c 'import <package> ; help(<package>)'
For example, for
python3 -c 'import containerd.events ; help(containerd.events)'
List All Namespaces
The following simple example queries containerd for its list of available containerd namespaces. Make sure you have the necessary privileges to connect to containerd; you may need to run this script as root:
import grpc from containerd.services.namespaces.v1 import namespace_pb2_grpc, namespace_pb2 with grpc.insecure_channel('unix:///run/containerd/containerd.sock') as channel: namespacev1 = namespace_pb2_grpc.NamespacesStub(channel) namespaces = namespacev1.List(namespace_pb2.ListNamespacesRequest()).namespaces for namespace in namespaces: print('namespace:', namespace.name)
Usually, you want to add proper error handling. This is just a very simplistic example to illustrate the principle.
List Containers in a Specific Namespace
Several of containerd's APIs are namespaced. That is, they work only on a single
namespace at a time. The namespace applies on the level of individual service
calls and needs to be specified as an (additional) metadata element to these
calls. If not specified, it the namespace will default to the namespace named
default. The following example lists all containers in the
this is the containerd namespace used by Docker.
import grpc from containerd.services.containers.v1 import containers_pb2_grpc, containers_pb2 with grpc.insecure_channel('unix:///run/containerd/containerd.sock') as channel: containersv1 = containers_pb2_grpc.ContainersStub(channel) containers = containersv1.List( containers_pb2.ListContainersRequest(), metadata=(('containerd-namespace', 'moby'),)).containers for container in containers: print('container ID:', container.id)
Watch containerd Events Flowing
Containerd events can be easily read from the endless event stream via the
containerd.services.events.v1 API, using the
Subscribe service. The
following example subscribes to all events and then prints their type and
contents as the events come:
import grpc from containerd.services.events.v1 import unwrap, events_pb2, events_pb2_grpc from google.protobuf import any_pb2 with grpc.insecure_channel('unix:///run/containerd/containerd.sock') as channel: print("waiting for containerd events...") eventsv1 = events_pb2_grpc.EventsStub(channel) for ev in eventsv1.Subscribe(events_pb2.SubscribeRequest()): print('event type: ', ev.event.type_url) print('value: ', unwrap(ev))
containerd.services.events.v1.unwrap(envelope)is a convenience function which unwraps the event object inside an event envelope returned by
Subscribe(): the unwrapped event object is returned as a Python object of sub class
containerd.events.*(as opposed to the arbitrary "any" binary value inside the event envelope).
To help containerd client developers getting started, we've included two simple
examples which are also made available as the CLI programs
watchctr (source code in
examples/) when cloning the repository.
You first have to install the wheel package for the
lsctrlists all containerd containers in all namespaces. It is basically kind of an all-in-one combination of the
ctrcommands for namespaces, containers, and tasks in a single command.
watchctrwatches containerd events, such as container creation, start, stop, et cetera, and then prints them to the terminal.
To check that it works, run the
lsctr command: this should list all available
containerd containers, across all containerd namespaces (remember to use
in case you don't have the necessary privileges as an ordinary user to talk to
This should spit out something like this, when running on a recent Docker CE installation, which uses containerd under the hood:
moby ⤏ labels (0): ▩ container: 0eeb9e2862e9f68e832a2e2c60a2e44e74d54b05266532cf19b112f4d959e3fb ▷ PID: 3359 ⚐ status: RUNNING ⚙ runtime: io.containerd.runtime.v1.linux ⤏ labels (1): "com.docker/engine.bundle.path": "/var/run/docker/containerd/0eeb9e2862e9f68e832a2e2c60a2e44e74d54b05266532cf19b112f4d959e3fb" ◷ created: 2019-09-04 07:24:32.646856 ◷ updated: 2019-09-04 07:24:32.646856 ▩ container: 1663afd0ddc6e0bba30b7fcc27b26044ece6022d970e32731db5dcb807b168df ▷ PID: 66062 ⚐ status: RUNNING ⚙ runtime: io.containerd.runtime.v1.linux ⤏ labels (1): "com.docker/engine.bundle.path": "/var/run/docker/containerd/1663afd0ddc6e0bba30b7fcc27b26044ece6022d970e32731db5dcb807b168df" ◷ created: 2019-08-16 08:08:21.471493 ◷ updated: 2019-08-16 08:08:21.471493 ...
You can use
lsctr -h to see the few CLI options available.
The following Python packages are required:
grpcio– gRPC for Python; required in order to communicate with containerd. This is a runtime dependency.
protobuf– protobuf for Python; required in order to communicate with containerd. This is a runtime dependency.
grpcio-tools– only required when re-generating the containerd API Python code using
Python ContainerD API
API Package (Re)Generation
In case you need to regenerate or update the Python code for the containerd API, in the top-level directory of this repository, run:
Normally, you should not need to regenerate the grpc/pb2 Python modules unless you are a project contributor or maintainer.
The overall directory structure of the Python containerd API package is as
follows (inside the
containerd/contains the Python modules generated by protoc as well as a very few hand-made modules. In order to avoid polluting the top-level package namespace with proto dependencies,
genpb2.sh"vendorizes" dependencies only for such
.protofiles for which no PyPI packages are available, moving such dependencies inside the
containerdtop-level Python package namespace.
services/contains the containerd service API v1.
events/contains the containerd event definitions.
types/contains containerd type definitions required by services and events.
vendor/contains the "vendorized" dependencies.
gogoproto/modules not available as a PyPI package.
genpb2.shis a script to recreate or update the
_pb2_grpc.pyPython modules from the containerd API
.protofile definitions and dependencies. See
genpb2.shfor more information on its workings.
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