Overview

This interface layer handles the communication with MySQL via the mysql-shared interface protocol.

Usage

Requires

The interface layer will set the following states, as appropriate:

• {relation_name}.connected The relation is established, but MySQL has not been provided the database information.
• {relation_name}.available MySQL is ready for use. You can get the base connection information via the following methods:
  • allowed_units()
  • database()
  • db_host()
  • hostname()
  • username()
  • password()
• {relation_name}.available.access_network MySQL access network is ready for use. You can get this optional connection information via the following method:
  • access_network()
• {relation_name}.available.ssl MySQL ssl data is ready for use. You can get this optional connection information via the following methods:
  • ssl_ca()
  • ssl_cert()
  • ssl_key()

For example:

from charmhelpers.core.hookenv import log, status_set, unit_get
from charms.reactive import when, when_not


@when('database.connected')
def setup_database(database):
    database.configure('mydatabase', 'myusername', prefix="first")
    database.configure('mydatabase2', 'myusername2', prefix="second")

@when('database.available')
def use_database(database):
    # base data provided by our charm layer
    log("first_database=%s" % database.database("first"))
    log("first_username=%s" % database.username("first"))
    log("first_hostname=%s" % database.hostname("first"))
    log("second_database=%s" % database.database("second"))
    log("second_username=%s" % database.username("second"))
    log("second_hostname=%s" % database.hostname("second"))

    # base data provided by mysql
    log("db_host=%s" % database.db_host())
    log("first_password=%s" % database.password("first"))
    log("first_allowed_units=%s" % database.allowed_units("first"))
    log("second_password=%s" % database.password("second"))
    log("second_allowed_units=%s" % database.allowed_units("second"))

@when('database.available.access_network')
def use_database_access_network(database):
    # optional data provided by mysql
    log("access-network=%s" % database.access_network())

@when('database.available.ssl')
def use_database_ssl(database):
    # optional data provided by mysql
    log("ssl_ca=%s" % database.ssl_ca())
    log("ssl_cert=%s" % database.ssl_cert())
    log("ssl_key=%s" % database.ssl_key())

@when('database.connected')
@when_not('database.available')
def waiting_mysql(database):
    status_set('waiting', 'Waiting for MySQL')

@when('database.connected', 'database.available')
def unit_ready(database):
    status_set('active', 'Unit is ready')

In Juju 2.0 environments, the interface will automatically determine the network space binding on the local unit to present to the remote mysql-shared service based on the name of the relation. In older Juju versions, the private-address of the unit will be used instead. This can be overridden using the hostname parameter of the configure method.

@when('database.connected')
def setup_database(database):
    database.configure('mydatabase', 'myusername', hostname='hostname.override')

Provides

The interface layer will set the following states, as appropriate:

• {relation_name}.connected The relation is established, but the client has not provided the database information yet.
• {relation_name}.available The requested information is complete. The DB, user and hostname can be created.
• connection information is passed back to the client with the following method:
  • set_db_connection_info()

For example:

@reactive.when('leadership.is_leader')
@reactive.when('leadership.set.cluster-instances-clustered')
@reactive.when('shared-db.available')
def shared_db_respond(shared_db):
    with charm.provide_charm_instance() as instance:
        instance.create_databases_and_users(shared_db)
        instance.assess_status()

The interface will automatically determine the network space binding on the local unit to present to the remote mysql-shared client based on the name of the relation. This can be overridden using the db_host parameter of the set_db_connection_info method.