From 7bf13230d3d572b80505b9bec716ce33817b6015 Mon Sep 17 00:00:00 2001
From: Thilo Fromm <thilofromm@microsoft.com>
Date: Mon, 30 Oct 2023 16:16:57 +0100
Subject: [PATCH] kola/update.go: Add test for docker btrfs storage driver

This change adds an update test for instances using the docker btrfs
storage driver. This storage driver was deprecated in docker release 23
and will be removed in a future release.

Docker 23 and above support backwards compatibility if BTRFS storage
exists and is populated.

Signed-off-by: Thilo Fromm <thilofromm@microsoft.com>
---
 kola/tests/update/update.go | 84 +++++++++++++++++++++++++++++++++----
 1 file changed, 77 insertions(+), 7 deletions(-)

diff --git a/kola/tests/update/update.go b/kola/tests/update/update.go
index 6a2ed4384..1582cc337 100644
--- a/kola/tests/update/update.go
+++ b/kola/tests/update/update.go
@@ -54,6 +54,25 @@ func init() {
 			return kola.UpdatePayloadFile == ""
 		},
 	})
+	register.Register(&register.Test{
+		Name:        "cl.update.docker-btrfs-compat",
+		Run:         btrfs_compat,
+		ClusterSize: 1,
+		NativeFuncs: map[string]func() error{
+			"Omaha": Serve,
+		},
+		// This test is normally not related to the cloud environment
+		Platforms: []string{"qemu", "qemu-unpriv"},
+		// This test verifies preservation of storage driver "btrfs" for docker.
+		// Docker releases before v23 defaulted to btrfs if the docker can only run if the update payload to test is given.
+		// The image passed must also be a release lower than or equal to 3760.0.0
+		// because newer versions ship docker 24.
+		EndVersion: semver.Version{Major: 3760},
+		SkipFunc: func(version semver.Version, channel, arch, platform string) bool {
+			return kola.UpdatePayloadFile == ""
+		},
+		Distros: []string{"cl"},
+	})
 	register.Register(&register.Test{
 		Name:        "cl.update.oem",
 		Run:         oemPayload,
@@ -141,13 +160,13 @@ func Serve() error {
 	return omahawrapper.Serve()
 }
 
-func payload(c cluster.TestCluster) {
+func payloadPrepareMachine(conf *conf.UserData, c cluster.TestCluster) (string, platform.Machine) {
 	addr := configureOmahaServer(c, c.Machines()[0])
 
 	// create the actual test machine, the machine
 	// that is created by the test registration is
 	// used to host the omaha server
-	m, err := c.NewMachine(nil)
+	m, err := c.NewMachine(conf)
 	if err != nil {
 		c.Fatalf("creating test machine: %v", err)
 	}
@@ -156,13 +175,14 @@ func payload(c cluster.TestCluster) {
 	// via SSH to allow for testing versions which predate
 	// Ignition
 	configureMachineForUpdate(c, m, addr)
-
 	tutil.AssertBootedUsr(c, m, "USR-A")
 
-	updateMachine(c, m)
+	return addr, m
+}
 
+func payloadPerformUpdate(addr string, m platform.Machine, c cluster.TestCluster) {
+	updateMachine(c, m)
 	tutil.AssertBootedUsr(c, m, "USR-B")
-
 	tutil.InvalidateUsrPartition(c, m, "USR-A")
 
 	/*
@@ -174,12 +194,62 @@ func payload(c cluster.TestCluster) {
 		We configure again to inject the dev-pub-key to correctly verify the downloaded payload
 	*/
 	configureMachineForUpdate(c, m, addr)
-
 	updateMachine(c, m)
-
 	tutil.AssertBootedUsr(c, m, "USR-A")
 }
 
+func payload(c cluster.TestCluster) {
+	addr, m := payloadPrepareMachine(nil, c)
+	payloadPerformUpdate(addr, m, c)
+}
+
+func btrfs_compat(c cluster.TestCluster) {
+	conf := conf.ContainerLinuxConfig(`
+systemd:
+  units:
+    - name: format-var-lib-docker.service
+      enabled: true
+      contents: |
+        [Unit]
+        Before=docker.service var-lib-docker.mount
+        ConditionPathExists=!/var/lib/docker.btrfs
+        [Service]
+        Type=oneshot
+        ExecStart=/usr/bin/truncate --size=25G /var/lib/docker.btrfs
+        ExecStart=/usr/sbin/mkfs.btrfs /var/lib/docker.btrfs
+        [Install]
+        WantedBy=multi-user.target
+    - name: var-lib-docker.mount
+      enabled: true
+      contents: |
+        [Unit]
+        Before=docker.service
+        After=format-var-lib-docker.service
+        Requires=format-var-lib-docker.service
+        [Install]
+        RequiredBy=docker.service
+        [Mount]
+        What=/var/lib/docker.btrfs
+        Where=/var/lib/docker
+        Type=btrfs
+        Options=loop,discard`)
+
+	addr, m := payloadPrepareMachine(conf, c)
+
+	// We need to populate the docker storage.
+	// If empty, docker 23 and above will silently switch to the 'overlay2' driver.
+	// If populated, docker SHOULD preserve the btrfs driver. That's what we test for later.
+	c.MustSSH(m, `docker info | grep 'Storage Driver: btrfs' || { echo "ERROR: expected BTRFS storage driver"; docker info; exit 1; }`)
+	c.MustSSH(m, `docker run -i --name docker_btrfs_driver_test alpine ls /`)
+
+	payloadPerformUpdate(addr, m, c)
+
+	c.MustSSH(m, `docker info | grep 'Storage Driver: btrfs' || { echo "ERROR: expected BTRFS storage driver"; docker info; exit 1; }`)
+
+	c.MustSSH(m, `docker image ls | grep alpine || { echo "ERROR: Container image 'alpine' disappeared after update"; docker image ls; exit 1; } `)
+	c.MustSSH(m, `docker ps --all | grep docker_btrfs_driver_test || { echo "ERROR: Container 'docker_btrfs_driver_test' disappeared after update"; docker ps --all; exit 1; } `)
+}
+
 func configureOmahaServer(c cluster.TestCluster, srv platform.Machine) string {
 	in, err := os.Open(kola.UpdatePayloadFile)
 	if err != nil {