Applications

For api docs, see juju.application.Application.

Deploying

To deploy a new application, connect a model and then call its deploy() method. An Application instance is returned.

from juju.model import Model

model = Model()
await model.connect_current()

mysql_app = await model.deploy(
    # If a revision number is not included in the charm url,
    # the latest revision from the Charm Store will be used.
    'cs:mysql-55',
    application_name='mysql',
    series='trusty',
    channel='stable',
    config={
        'tuning-level': 'safest',
    },
    constraints={
        'mem': 256 * MB,
    },
)

Deploying a Local Charm

To deploy a local charm, pass the charm directory path to Model.deploy().

from juju.model import Model

model = Model()
await model.connect_current()

# Deploy a local charm using a path to the charm directory
await model.deploy(
    '/home/tvansteenburgh/src/charms/ubuntu',
    application_name='ubuntu',
    series='trusty',
)

Adding Units

To add units to a deployed application, use the juju.application.Application.add_units() method. A list of the newly added units (Unit objects) is returned.

ubuntu_app = await model.deploy(
    'ubuntu',
    application_name='ubuntu',
    series='trusty',
    channel='stable',
)

unit_a, unit_b = await ubuntu_app.add_units(count=2)

Updating Config and Constraints

Example showing how to update configuration and constraints on a deployed application. The mysql_app object is an instance of juju.application.Application.

MB = 1024 * 1024

# Update and check app config
await mysql_app.set_config({'tuning-level': 'fast'})
config = await mysql_app.get_config()

assert(config['tuning-level']['value'] == 'fast')

# update and check app constraints
await mysql_app.set_constraints({'mem': 512 * MB})
constraints = await mysql_app.get_constraints()

assert(constraints['mem'] == 512 * MB)

Adding and Removing Relations

The juju.application.Application.add_relation() method returns a juju.relation.Relation instance.

from juju.model import Model

model = Model()
await model.connect_current()

# Deploy mysql-master application
mysql_master = await model.deploy(
    'cs:mysql-55',
    application_name='mysql-master',
    series='trusty',
    channel='stable',
)

# Deploy mysql-slave application
mysql_slave = await model.deploy(
    'cs:mysql-55',
    application_name='mysql-slave',
    series='trusty',
    channel='stable',
)

# Add the master-slave relation
relation = await mysql_master.add_relation(
    # Name of the relation on the local (mysql-master) side
    'master',
    # Name of the app:relation on the remote side
    'mysql-slave:slave',
)

# Remove the relation
await mysql_master.remove_relation(
    'master',
    'mysql-slave:slave',
)