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async/await client for the Consul HTTP API

Project description

AIO Consul

Consul has multiple components, but as a whole, it is a tool for discovering and configuring services in your infrastructure, like:

  • Service Discovery
  • Health Checking
  • Key/Value Store
  • Multi Datacenter

This library provides several features to interact with its API. It is build in top of asyncio and aiohttp. It works with Python >= 3.5, and is still a work in progress.

The documentation has more details, but sparsely this is how to work with it.

Installation

pip install aioconsul

Usage

Most of the functions are coroutines, so it must be embedded into asyncio tasks:

from aioconsul import Consul
client = Consul()

async def main():
    node = await client.agent.info()
    print('I am %s!' % node["Name"])

loop = asyncio.get_event_loop()
loop.run_until_complete(main)
loop.run_until_complete(future)

Agent checks

Currently this library can handle simple checks:

from aioconsul import Consul
client = Consul()

# list all checks
checks = await client.checks.items()
for check in checks:
    print(check["ID"])

# register a script check
registered = await client.checks.register({
  "Name": "my-script-check",
  "Script": "~/script.sh",
  "Interval": "5m"})

# register a http check
registered = await client.checks.register({
  "Name": 'my-http-check',
  "HTTP": 'http://example.com',
  "Interval": '10h'})

# register a ttl check
registered = await client.checks.register({
  "Name": 'my-ttl-check',
  "ttl": '10s'})

# mark ttl check passing
await client.checks.passing('my-ttl-check', note='Make it so')

# deregister any check
await client.checks.deregister('my-ttl-check')

Agent services

Currently this library can handle simple services:

from aioconsul import Consul
client = Consul()

# list all services
services = await client.services.items()
for srv in services.value():
    print(srv["ID"])

# disable a service
await client.services.disable(srv, reason='Migrating stuff')

# and reenable it
await client.services.enable(srv, reason='Done')

Catalog

This library can consult catalog:

from aioconsul import Consul
client = Consul()

# listing all nodes from catalog
nodes, _ = await client.catalog.nodes()
for node in nodes:
    print(node["Name"])
    print(node["Address"])

# getting a node with all of its service
node, _ = await client.catalog.node('my-node')
print(node["Services"])

# getting all nodes that belong to a service
nodes, _ = await client.catalog.nodes(service='my-service')
print(nodes)

And register checks, services and nodes:

from aioconsul import Consul
client = Consul()

resp = await client.catalog.register({
  "Node": 'my-local-node',
  "Address": "127.0.0.1",
  "Check": {
    "Node": 'my-local-node',
    'Status': 'passing',
    "ServiceID": 'bar'
  },
  "Service": {'ID': 'bar'}
})
assert resp

resp = await client.catalog.deregister({
  "Node": 'my-local-node'
})
assert resp

Events

from aioconsul import Consul
client = Consul()

# send an event
event = await client.event.fire('my-event', node='.*')

# list all events
events, _ = await client.event.items()
for event in events:
    print(event["Name"])

Health

from aioconsul import Consul
client = Consul()

# checks for a node
checks, _ = await client.health.node('my-local-node')
for check in checks:
    assert check["Status"] == 'passing'

# health of a check id
checks, _ = await client.health.checks('serfHealth')
for check in checks:
    assert check["Status"] == 'passing'

# health of a service
checks, _ = await client.health.service('foo', state='any')
for node in checks:
    for check in node["Checks"]:
        if check["ID"] == 'service:foo':
            assert check["Status"] == 'passing'

# passing checks
checks, _ = await client.health.state('passing')
for check in checks:
    assert check["Status"] == 'passing'

KV and Sessions

Simple example:

from aioconsul import Consul
client = Consul()

# set a k/v
await client.kv.set('my.key', 'my.value')

# fetch a k/v
obj, _ = await client.kv.get('my.key')

# fetched values have a special attribute `consul`
assert obj['Key'] == 'my.key'

# delete a k/v
await client.kv.delete('my.key')

Many k/v:

# list many k/v
results, _ = await client.kv.get_tree('')
async for obj in results:
    print(obj['Key'], obj['Value'])

Ephemeral k/v:

session = await client.sessions.create({'Behavior': 'delete'})
await client.kv.lock('my.key', 'my.key', session=session)
await client.sessions.delete(session)

try:
    # try to fetch previous k/v
    obj = await client.kv.get('my.key')
except client.kv.NotFound:
    # but it was destroyed with the session
    pass

ACL

from aioconsul import Consul, PermissionDenied
client = Consul(token=master_token)

# create a token
token = await client.acl.create({
  'Name': 'my-acl',
  'Rules': [
    ('key', '', 'read'),
    ('key', 'foo/', 'deny'),
  ]
})

# access to kv with the fresh token
node = Consul(token=token)
await node.kv.get('foo')
with pytest.raises(PermissionDenied):
    await node.kv.set('foo', 'baz')
with pytest.raises(node.kv.NotFound):
    await node.kv.get('foo/bar')

Testing

Tests rely on Consul binary and py.test.

  1. Install consul binary, it must be reachable in your $PATH.

  2. Install test requirements:

    pip install -r requirements-tests.txt
    
  3. Then run tests:

    py.test --cov-report html --cov aioconsul tests
    

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