Event 'install'

Event > List of events > Lifecycle events > install

Source: ops.InstallEvent

This document describes the install event.

Contents:

Emission sequence

The install event is emitted once per unit at the beginning of a charm’s lifecycle. Associated callbacks should be used to perform one-time initial setup operations and prepare the unit to execute the application. Depending on the charm, this may include installing packages, configuring the underlying machine or provisioning cloud-specific resources.

Therefore, ways to cause install to occur are:

Scenario Example Command Resulting Events
Create unit juju deploy foo
juju add-unit foo 		install -> config-changed

Note:

  • Typically, operations performed on install should also be considered for upgrade-charm.
  • In some cases, config-changed can be used instead of install and upgrade-charm because it is guaranteed to fire after both.

Observing this event in Ops

In ops, you can observe this event like you would any other:

# in MyCharm.__init__
self.framework.observe(self.on.install, self._on_install)

The install event object does not expose any specific attributes.

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