From 9057ca2541582fc41eb7cb45edd332247a813bba Mon Sep 17 00:00:00 2001
From: Phil Estes <estesp@linux.vnet.ibm.com>
Date: Thu, 5 Mar 2015 00:22:01 -0500
Subject: [PATCH] Don't test resolv.conf updater on overlay filesystem
The overlay filesystem does not support inotify at this time. The
resolv.conf updater test was passing on overlay-based Jenkins because of
a fluke--because it was DIND, /etc/resolv.conf on the "host" was really
a bind-mounted resolv.conf from the outer container, which means a watch
directly on that file worked as it was not overlay backed. The new test
(from #10703) unmounts the bind-mounted copy to test create and modify
code-paths, which caused us to hit the issue.
This PR also adds a note to the docs about the lack of auto-update when
using the overlay storage driver.
See https://lkml.org/lkml/2012/2/28/223 for more info on inotify and
overlay.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
---
docs/sources/articles/networking.md | 7 +++++++
integration-cli/docker_cli_run_test.go | 4 +++-
integration-cli/requirements.go | 11 +++++++++++
3 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/docs/sources/articles/networking.md b/docs/sources/articles/networking.md
index f8b5d7fc33..e1195e10d1 100644
--- a/docs/sources/articles/networking.md
+++ b/docs/sources/articles/networking.md
@@ -189,6 +189,13 @@ the `/etc/resolv.conf` of the host machine where the `docker` daemon is
running. You might wonder what happens when the host machine's
`/etc/resolv.conf` file changes. The `docker` daemon has a file change
notifier active which will watch for changes to the host DNS configuration.
+
+> **Note**:
+> The file change notifier relies on the Linux kernel's inotify feature.
+> Because this feature is currently incompatible with the overlay filesystem
+> driver, a Docker daemon using "overlay" will not be able to take advantage
+> of the `/etc/resolv.conf` auto-update feature.
+
When the host file changes, all stopped containers which have a matching
`resolv.conf` to the host will be updated immediately to this newest host
configuration. Containers which are running when the host configuration
diff --git a/integration-cli/docker_cli_run_test.go b/integration-cli/docker_cli_run_test.go
index 1ca9c830dd..a94c23f6bb 100644
--- a/integration-cli/docker_cli_run_test.go
+++ b/integration-cli/docker_cli_run_test.go
@@ -1589,7 +1589,9 @@ func TestRunDnsOptionsBasedOnHostResolvConf(t *testing.T) {
// stopped and have an unmodified copy of resolv.conf, as well as
// marking running containers as requiring an update on next restart
func TestRunResolvconfUpdater(t *testing.T) {
- testRequires(t, SameHostDaemon)
+ // Because overlay doesn't support inotify properly, we need to skip
+ // this test if the docker daemon has Storage Driver == overlay
+ testRequires(t, SameHostDaemon, NotOverlay)
tmpResolvConf := []byte("search pommesfrites.fr\nnameserver 12.34.56.78")
tmpLocalhostResolvConf := []byte("nameserver 127.0.0.1")
diff --git a/integration-cli/requirements.go b/integration-cli/requirements.go
index 6289d2bad8..346d0cdf66 100644
--- a/integration-cli/requirements.go
+++ b/integration-cli/requirements.go
@@ -66,6 +66,17 @@ var (
},
"Test requires the native (libcontainer) exec driver.",
}
+
+ NotOverlay = TestRequirement{
+ func() bool {
+ cmd := exec.Command("grep", "^overlay / overlay", "/proc/mounts")
+ if err := cmd.Run(); err != nil {
+ return true
+ }
+ return false
+ },
+ "Test requires underlying root filesystem not be backed by overlay.",
+ }
)
// testRequires checks if the environment satisfies the requirements