Instance States

Every instance has a state that reflects what it is currently doing. You can see the current state in the instance list and on the instance detail view. The state also governs which Actions are available at any given time.

Normal Lifecycle

In normal operation an instance is Healthy. Changing its configuration marks it Pending Update until you apply the change with Update; Update, Restart, and Recover each return it to Healthy when they finish, and Destroy is terminal.

A Destroy with a final Snapshot (the default) first shows Snapshot Creating (Pending Destroy), then Destroying. Running Recover while the final Snapshot runs cancels the destroy. Once the instance is gone, its remaining cloud resources are cleaned up in the background.

stateDiagram-v2
    direction TB
    state "Pending Update" as PendingUpdate
    state "Building Image" as BuildingImage
    state update_choice <<choice>>
    [*] --> Creating: Create
    Creating --> Healthy
    Healthy --> PendingUpdate: on configuration change
    PendingUpdate --> update_choice: Update
    update_choice --> BuildingImage: requires a new image
    update_choice --> Updating
    BuildingImage --> Updating: build succeeds
    BuildingImage --> PendingUpdate: build fails
    Updating --> Healthy
    Healthy --> Restarting: Restart
    Restarting --> Healthy
    Healthy --> Recovering: Recover
    Recovering --> Healthy
    state "Snapshot Creating (Pending Destroy)" as PendingDestroy
    Healthy --> PendingDestroy: Destroy with final Snapshot
    PendingDestroy --> Destroying: Snapshot succeeds
    PendingDestroy --> Healthy: Recover, or the Snapshot fails
    Healthy --> Destroying: Destroy without final Snapshot
    Destroying --> [*]

Cloning

A new clone moves through these states (see Clone an Instance):

State	What is happening
Creating (Waiting for Snapshot)	A Snapshot of the source is being taken; the source shows Snapshot Creating. Destroying the clone now removes it right away.
Creating	The clone's instance is built with an empty database.
Snapshot Restoring	The Snapshot is restored into the clone, and the source's uploaded files are copied.
Healthy	The clone is ready.

A clone from an existing Snapshot starts at Creating, and a clone without data ends after Creating.

Error Handling

If an operation fails, the instance enters Errored. From there you can correct the change and Update to retry, Recover to redeploy the last known-good image, or Destroy the instance.

stateDiagram-v2
    direction LR
    [*] --> Errored: an operation fails
    Errored --> Updating: Update
    Updating --> Healthy
    Errored --> Recovering: Recover
    Recovering --> Healthy
    Errored --> Destroying: Destroy
    Destroying --> [*]