ChangeSymlink updates symlink paths to match current version.

CleanMarker removes a marker from disk.

Cleanup removes all artifacts and files related to a specified version.

InvokeWatcher invokes an agent instance using watcher argument for watching behavior of agent during upgrade period.

IsUpgradeable when agent is installed and running as a service or flag was provided.

LoadMarker loads the update marker.

NewCrashChecker creates a new crash checker.

NewErrorChecker creates a new error checker.

NewUpgrader creates an upgrader which is capable of performing upgrade operation.

Rollback rollbacks to previous version which was functioning before upgrade.

UpdateActiveCommit updates active.commit file to point to active version.

ErrAgentStatusFailed is returned when agent reports FAILED status.

CrashChecker checks agent for crash pattern in Elastic Agent lifecycle.

ErrorChecker checks agent for status change and sends an error to a channel if found.

UpdateMarker is a marker holding necessary information about ongoing upgrade.

Upgrader performs an upgrade.

Action is the upgrade action state.