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Auto-Update

How It Is Enabled

Auto-update is controlled via the Docker label image-watch.auto-update on the container.

To enable, add the label to your container or service:

services:
  my-service:
    labels:
      - "image-watch.auto-update=true"

The label is declarative: it survives every recreate (manual or automatic) because recreateContainer() copies existing labels from the old container to the new one during inspect -> stop -> remove -> create -> start.

The web UI displays the current auto-update state (read from the label) but does not allow toggling — the label must be set in the container definition (e.g., docker-compose.yml).

The POST /api/images/{id}/auto-update endpoint still returns the current state, but does not modify it.

Why Labels Instead of a File

Approach Survives recreate? Declarative?
auto-update.json (previous) No — new container ID = lost state No
Docker label image-watch.auto-update (current) Yes — labels are copied on recreate Yes

This makes auto-update a true lifecycle feature rather than a one-shot toggle.

Check Interval

Background refresh loop in main.go:

  • runs one initial checkAll() on startup
  • then runs periodically, default 10 minutes
  • configurable via CHECK_INTERVAL env var

Cooldown

Automatic updates use per-container cooldown:

  • default cooldown window: 5 minutes
  • configurable via AUTO_COOLDOWN env var
  • stored in App.cooldowns
  • checked inside checkAll() before triggering auto-update

This avoids repeated rapid recreate cycles when a container stays reported as outdated.

Trigger Conditions

Auto-update only triggers when all conditions are true:

  • container appears in current running container list
  • container has label image-watch.auto-update=true
  • computed status is outdated
  • no active cooldown (default 5 min, configurable via AUTO_COOLDOWN) blocks that container

Concurrency and State Safety

  • sync.RWMutex protects images and cooldowns
  • sync.Map stores pull progress snapshots
  • route-triggered manual updates run in goroutines
  • cooldown tracking reduces risk of concurrent repeated auto-updates for same container

Manual Update Behavior

Manual updates via POST /api/images/{id}/update:

  • do not check cooldown before starting
  • immediately launch updateContainer() in goroutine
  • expose progress through /api/images/{id}/progress

Update Sequence

auto or manual trigger
-> updateContainer()
-> pullImageStream()
-> recreateContainer()
-> checkAll()