bugfix: fix fail to resolve real graph path from soft link

[Ace-Tang]

assume that /tmp/link is a soft link to /home/link, if we use
/tmp/link/docker as a graph path, and /tmp/link/docker is not exist,
docker can not get the real path.

$ ls -l /tmp/link
lrwxrwxrwx 1 root root 10 11月 20 16:22 /tmp/link -> /home/link

$ service docker restart

$ docker info | grep Root
Docker Root Dir: /tmp/link/docker

Signed-off-by: Ace-Tang aceapril@126.com

- What I did

make docker get real graph path from a soft link path.

create a directory /home/link, and link /tmp/link to it
$ sudo mkdir /home/link

$ sudo ln -s /home/link /tmp/link

$ ls -l /tmp/link
lrwxrwxrwx 1 root root 10 11月 20 16:22 /tmp/link -> /home/link

set /tmp/link/docker(this directory should not be exist before start docker) as a docker graph, restart docker, check docker info
$ docker info | grep Root
WARNING: No swap limit support
Docker Root Dir: /tmp/link/docker

- How I did it

- How to verify it

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[Ace-Tang]

fail with

09:59:44 --- FAIL: TestServicePlugin (63.02s)
09:59:44     daemon.go:295: [d1c3b42ba0b19] waiting for daemon to start
09:59:44     daemon.go:327: [d1c3b42ba0b19] daemon started
09:59:44     daemon.go:282: [d1c3b42ba0b19] exiting daemon
09:59:44     daemon.go:295: [d9cf2f94196cc] waiting for daemon to start
09:59:44     daemon.go:327: [d9cf2f94196cc] daemon started
09:59:44     daemon.go:295: [d5755b3a57d98] waiting for daemon to start
09:59:44     daemon.go:327: [d5755b3a57d98] daemon started
09:59:44     daemon.go:295: [d74f3cac47f75] waiting for daemon to start
09:59:44     daemon.go:327: [d74f3cac47f75] daemon started
09:59:44     plugin_test.go:103: timeout hit after 30s: plugin "127.0.0.1:5000/swarm/test:v1" exists
09:59:44     daemon.go:282: [d74f3cac47f75] exiting daemon
09:59:44     daemon.go:282: [d5755b3a57d98] exiting daemon
09:59:44     daemon.go:282: [d9cf2f94196cc] exiting daemon

seems not relate with my fix ?

[olljanat]

Experimental failed to:

16:14:51 FAIL: docker_api_swarm_node_test.go:75: DockerSwarmSuite.TestAPISwarmNodeDrainPause
16:14:51 
16:14:51 [db1514d271a46] waiting for daemon to start
16:14:51 [db1514d271a46] daemon started
16:14:51 
16:14:51 [dd7fa542a6537] waiting for daemon to start
16:14:51 [dd7fa542a6537] daemon started
16:14:51 
16:14:51 waited for 1.507141492s (out of 30s)
16:14:51 waited for 43.846245ms (out of 30s)
16:14:51 waited for 511.344104ms (out of 30s)
16:14:51 waited for 2.59320616s (out of 30s)
16:14:51 waited for 10.767551ms (out of 30s)
16:14:51 docker_api_swarm_node_test.go:104:
16:14:51     waitAndAssert(c, defaultReconciliationTimeout*2, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d2.CheckActiveContainerCount), checker.Equals, instances)
16:14:51 docker_utils_test.go:441:
16:14:51     c.Assert(v, checker, args...)
16:14:51 ... obtained int = 3
16:14:51 ... expected int = 1
16:14:51 ... output: "d64dc0fd3936\n77a84148c6d2\n49264463ebce\n"
16:14:51 
16:14:51 waited for 1m0.102658589s (out of 1m0s)
16:14:51 [db1514d271a46] exiting daemon
16:14:51 [dd7fa542a6537] exiting daemon
16:15:26 
16:15:26 ----------------------------------------------------------------------

even on second try but let's try once more...

[codecov]

Codecov Report

Merging #38228 into master will decrease coverage by 0.01%.
The diff coverage is 30%.

@@            Coverage Diff             @@
##           master   #38228      +/-   ##
==========================================
- Coverage    36.1%   36.09%   -0.02%     
==========================================
  Files         610      610              
  Lines       45234    45236       +2     
==========================================
- Hits        16333    16328       -5     
- Misses      26661    26665       +4     
- Partials     2240     2243       +3

[thaJeztah]

ping @dmcgowan @kolyshkin PTAL

[thaJeztah]

ping @dmcgowan @kolyshkin PTAL