From 4e88d9a9b0b50776f0591ccdb5e6944568d366f1 Mon Sep 17 00:00:00 2001
From: Seth Hoenig <shoenig@duck.com>
Date: Mon, 30 Jan 2023 12:17:56 -0600
Subject: [PATCH] docker: set force=true on remove image to handle images
 referenced by multiple tags

This PR changes our call of docker client RemoveImage() to RemoveImageExtended with
the Force=true option set. This fixes a bug where an image referenced by more than
one tag could never be garbage collected by Nomad. The Force option only applies to
stopped containers; it does not affect running workloads.
---
 .changelog/15962.txt               | 3 +++
 drivers/docker/coordinator.go      | 6 ++++--
 drivers/docker/coordinator_test.go | 2 +-
 3 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 .changelog/15962.txt

diff --git a/.changelog/15962.txt b/.changelog/15962.txt
new file mode 100644
index 000000000000..602aedc969d9
--- /dev/null
+++ b/.changelog/15962.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+docker: Fixed a bug where images referenced by multiple tags would not be GC'd
+```
diff --git a/drivers/docker/coordinator.go b/drivers/docker/coordinator.go
index 7a99acdb3f27..edbaf0f63c62 100644
--- a/drivers/docker/coordinator.go
+++ b/drivers/docker/coordinator.go
@@ -59,7 +59,7 @@ func (p *pullFuture) set(imageID string, err error) {
 type DockerImageClient interface {
 	PullImage(opts docker.PullImageOptions, auth docker.AuthConfiguration) error
 	InspectImage(id string) (*docker.Image, error)
-	RemoveImage(id string) error
+	RemoveImageExtended(id string, opts docker.RemoveImageOptions) error
 }
 
 // LogEventFn is a callback which allows Drivers to emit task events.
@@ -320,7 +320,9 @@ func (d *dockerCoordinator) removeImageImpl(id string, ctx context.Context) {
 	d.imageLock.Unlock()
 
 	for i := 0; i < 3; i++ {
-		err := d.client.RemoveImage(id)
+		err := d.client.RemoveImageExtended(id, docker.RemoveImageOptions{
+			Force: true, // necessary to GC images referenced by multiple tags
+		})
 		if err == nil {
 			break
 		}
diff --git a/drivers/docker/coordinator_test.go b/drivers/docker/coordinator_test.go
index 755c6b99e54e..0e08551e1eaa 100644
--- a/drivers/docker/coordinator_test.go
+++ b/drivers/docker/coordinator_test.go
@@ -48,7 +48,7 @@ func (m *mockImageClient) InspectImage(id string) (*docker.Image, error) {
 	}, nil
 }
 
-func (m *mockImageClient) RemoveImage(id string) error {
+func (m *mockImageClient) RemoveImageExtended(id string, options docker.RemoveImageOptions) error {
 	m.lock.Lock()
 	defer m.lock.Unlock()
 	m.removed[id]++