Cleanup unneeded images after a successful update.

src/application.coffee

@@ -244,6 +244,10 @@ exports.update = update = ->
 				Promise.all(installingPromises.concat(updatingPromises))
 	.then ->
 		failedUpdates = 0
+		updateDeviceInfo(status: 'Cleaning old images')
+		# We cleanup here as we want a point when we have a consistent apps/images state,
+		# rather than potentially at a point where we might clean up an image we still want.
+		cleanupImages()
 	.catch (err) ->
 		failedUpdates++
 		if currentlyUpdating is 2
@@ -286,3 +290,26 @@ exports.updateDeviceInfo = updateDeviceInfo = (body) ->
 				customOptions:
 					apikey: apiKey
 			)
+
+cleanupImages = ->
+	knex('app').select()
+	.then (apps) ->
+		apps = apps.map((app) -> app.imageId + ':latest')
+		# Make sure not to delete the supervisor image!
+		apps.push(config.localImage + ':latest')
+		apps.push(config.remoteImage + ':latest')
+
+		docker.listImagesAsync()
+		.then (images) ->
+			Promise.all(
+				images.filter (image) ->
+					!_.any image.RepoTags, (imageId) ->
+						_.contains(apps, imageId)
+				.map (image) ->
+					# TODO: Remove old supervisor containers cleanly so we don't have to force remove images.
+					docker.getImage(image.Id).removeAsync(force: true)
+					.then ->
+						console.log('Deleted image:', image.Id, image.RepoTags)
+					.catch (err) ->
+						console.log('Error deleting image:', image.Id, image.RepoTags, err)
+			)

src/config.coffee

@@ -8,6 +8,9 @@ module.exports = config =
 	dockerSocket: process.env.DOCKER_SOCKET ? '/run/docker.sock'
 	localImage: process.env.SUPERVISOR_IMAGE ? 'resin/rpi-supervisor'
 	configMountPoint: process.env.CONFIG_MOUNT_POINT ? '/mnt/mmcblk0p1/config.json'
+
+config.remoteImage = config.registryEndpoint + '/' + config.localImage
+
 config.supervisorContainer =
 		Volumes: 
 			'/boot/config.json': {}

src/supervisor-update.coffee

@@ -9,7 +9,7 @@ Promise.promisifyAll(docker.getImage().__proto__)
 Promise.promisifyAll(docker.getContainer().__proto__)
 
 localImage = config.localImage
-remoteImage = config.registryEndpoint + '/' + localImage
+remoteImage = config.remoteImage
 
 startNewSupervisor = (currentSupervisor) ->
 	console.log('Creating supervisor container:', localImage)