Varlink


Keywords
ipc varlink rpc, ipc, json, python, varlink
License
Apache-2.0
Install
pip install varlink==30.3.0

Documentation

Varlink Certified Build Status Coverage Status PyPI] PyPI - Python Version PyPI - Status

python-varlink

A varlink implementation for Python.

python varlink installation

From pypi:

$ pip3 install --user varlink

With Fedora 28/rawhide:

$ sudo dnf install python3-varlink

Examples

See the tests directory.

$ python3 -m varlink.tests.test_orgexamplemore --varlink="unix:/tmp/test" &
[1] 6434
$ python -m varlink.cli help unix:/tmp/test/org.example.more
# Example Varlink service
interface org.example.more

# Enum, returning either start, progress or end
# progress: [0-100]
type State (
  start: ?bool,
  progress: ?int,
  end: ?bool
)

# Returns the same string
method Ping(ping: string) -> (pong: string)

# Dummy progress method
# n: number of progress steps
method TestMore(n: int) -> (state: State)

# Stop serving
method StopServing() -> ()

# Something failed in TestMore
error TestMoreError (reason: string)


$ fg
python3 -m varlink.tests.test_orgexamplemore --varlink="unix:/tmp/test"
^C
$ python3 -m varlink.tests.test_orgexamplemore --client -A 'python3 -m varlink.tests.test_orgexamplemore --varlink=$VARLINK_ADDRESS'
Connecting to unix:/tmp/tmppxrbqk9p/4927

Listening on /tmp/tmppxrbqk9p/4927
--- Start ---
Progress: 0
Progress: 10
Progress: 20
Progress: 30
Progress: 40
Progress: 50
Progress: 60
Ping:  Test
Progress: 70
Ping:  Test
Progress: 80
Ping:  Test
Progress: 90
Ping:  Test
Progress: 100
Ping:  Test
--- End ---
$ PYTHONPATH=$(pwd) python3 ./varlink/tests/test_orgexamplemore.py
Connecting to unix:/tmp/tmp7n6zc67d/5257

Listening on /tmp/tmp7n6zc67d/5257
--- Start ---
Progress: 0
Progress: 10
Progress: 20
Progress: 30
Progress: 40
Progress: 50
Progress: 60
Ping:  Test
Progress: 70
Ping:  Test
Progress: 80
Ping:  Test
Progress: 90
Ping:  Test
Progress: 100
Ping:  Test
--- End ---
$ python3 -m varlink.tests.test_orgexamplemore --varlink="unix:/tmp/test" &
Listening on /tmp/test
[1] 6434
python3 -m varlink.tests.test_orgexamplemore --client --varlink="unix:/tmp/test"
Connecting to unix:/tmp/test

Ping:  Test
--- Start ---
Progress: 0
Progress: 10
Progress: 20
Progress: 30
Progress: 40
Progress: 50
Progress: 60
Ping:  Test
Progress: 70
Ping:  Test
Progress: 80
Ping:  Test
Progress: 90
Ping:  Test
Progress: 100
Ping:  Test
--- End ---

$ python3 -m varlink.cli call --more unix:/tmp/test/org.example.more.TestMore '{ "n": 10 }'
{'state': {'start': True}}
{'state': {'progress': 0}}
{'state': {'progress': 10}}
{'state': {'progress': 20}}
{'state': {'progress': 30}}
{'state': {'progress': 40}}
{'state': {'progress': 50}}
{'state': {'progress': 60}}
{'state': {'progress': 70}}
{'state': {'progress': 80}}
{'state': {'progress': 90}}
{'state': {'progress': 100}}
{'state': {'end': True}}

$ fg
python3 -m varlink.tests.test_orgexamplemore --varlink="unix:/tmp/test"
^C

You can also start the clients and server with URLs following the varlink URL standard. E.g.

  • unix:@anonuds
  • unix:/run/myserver/socketfile
  • tcp:127.0.0.1:12345
  • tcp:[::1]:12345

Activation Mode

Activation mode starts the service to connect to and passes the socket via socket activation. The VARLINK_ADDRESS environment variable contains the varlink address URI.

$ python3 -m varlink.cli --activate 'python3 -m varlink.tests.test_orgexamplemore --varlink=$VARLINK_ADDRESS' call org.example.more.Ping '{ "ping": "Ping"}'
Listening on @00352
{'pong': 'Ping'}

Bridge Mode

Bridge mode allows to tunnel to a remote point via stdin/stdout and call a method. Running varlink bridge allows to connect stdio to the host services via org.varlink.resolver interface resolving.

# python3 -m varlink.cli -b "ssh host.example.org varlink bridge" call com.redhat.machine.GetInfo '{}'
{
  "hostname": "host.example.org",
  "system": {
    "id": "fedora",
    "kernel_version": "4.18.0-0.rc5.git1.2.fc29.x86_64",
    "name": "Fedora",
    "version": "29"
  },
  "virtualization": {
    "name": "none"
  }
}

Varlink Certification Server

$ python3 -m varlink.tests.test_certification --varlink=tcp:127.0.0.1:12345

Varlink Certification Client

$ python3 -m varlink.tests.test_certification --varlink=tcp:127.0.0.1:12345 --client