doc about error `Privileged mode is incompatible with user namespaces…

[jjqq2013]

Hi, i have my docker daemon run with user namespace enabled(All users in containers will be mapped to sub user of specified external user, see Starting the daemon with user namespaces enabled),

In this case, cadvisor can not list containers in manage web pages without explicit errors, it's confusing for users.

I know the reason is caused by the docker run Privileged mode is incompatible with user namespaces , so i added a statement in README.md.

hope helpful.

[k8s-ci-robot]

Hi @QianJin2013. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with @k8s-bot ok to test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[dashpole]

@k8s-bot ok to test

[dashpole]

@jjqq2013 would you mind moving this to running.md? This is more specific information than I would like to include in the README. Thanks!

[googlebot]

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[jjqq2013]

@googlebot I signed it!

[jjqq2013]

@dashpole ok, moved to running.cmd

[cmluciano]

minor nits

[cmluciano]

Nits

-the above command will emit the following error ...
-move to avoid it... to a new sentence

[jjqq2013]

cAdvisor command itself does not show error to user, it just failed to list all containers in its web UI, shows an error "Can not connect to docker daemon".

[jjqq2013]

Note: cAdvisor command itself does not show error to user, it just fails to list all containers in its web UI, shows an error "Can not connect to docker daemon".

See screenshot:

And this is how i rua my docker daemon with user namespace enabled.( in docker-machine on Mac OS X)

q@mac$ docker-machine ssh default

docker@default:~$ cat /etc/subuid 
dockremap:165536:65536

docker@default:~$ cat /etc/subgid 
dockremap:165536:65536

docker@default:~$ cat /etc/docker/daemon.json
{
  "userns-remap": "default"
}

docker@default:~$ sudo adduser --system dockremap
adduser: user 'dockremap' in use

docker@default:~$ exit

q@mac$ docker-machine restart default

[dashpole]

@jjqq2013 git doesnt seem to think you authored your commits. The icon next to the commit is not yours: https://help.github.com/articles/why-are-my-commits-linked-to-the-wrong-user/#commits-are-not-linked-to-any-user

[jjqq2013]

@dashpole sorry i used another email to commit, now i have added the email to github account settings. It seems now the author icon in my commit correctly show my avatar.

[googlebot]

CLAs look good, thanks!