mesos git commit: Updated the way we bring up loopback for a container on a CNI network.

[ji...@apache.org]

Repository: mesos
Updated Branches:
  refs/heads/master e7a5e3db0 -> a3b968153


Updated the way we bring up loopback for a container on a CNI network.

Earlier we were setting up the `pre_exec_command` for the executor
with `ifconfig lo up`. This had a drawback that it assumes that PATH
set for the executor would have `ifconfig`. Unfortunately, it turns
out in most cases the executors PATH is a subset of the agents path
and hence there is a high probability that the executors shell will
not be able to find `ifconfig`.

Instead we bring up the loopback during the setup of network files in
the `NetworkCniIsolatorSetup` subcommand. The subcommand is run with
the agents PATH variable so chances that ifconfig is not present in
the path are much less.

Review: https://reviews.apache.org/r/52622/


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/a3b96815
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/a3b96815
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/a3b96815

Branch: refs/heads/master
Commit: a3b968153cfb1bb54bf9ec888735786a2095d57f
Parents: e7a5e3d
Author: Avinash sridharan <av...@mesosphere.io>
Authored: Fri Oct 7 16:23:42 2016 -0700
Committer: Jie Yu <yu...@gmail.com>
Committed: Fri Oct 7 16:23:42 2016 -0700

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 .../mesos/isolators/network/cni/cni.cpp         | 22 ++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/a3b96815/src/slave/containerizer/mesos/isolators/network/cni/cni.cpp
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diff --git a/src/slave/containerizer/mesos/isolators/network/cni/cni.cpp b/src/slave/containerizer/mesos/isolators/network/cni/cni.cpp
index d530a36..1b22b28 100644
--- a/src/slave/containerizer/mesos/isolators/network/cni/cni.cpp
+++ b/src/slave/containerizer/mesos/isolators/network/cni/cni.cpp
@@ -699,11 +699,6 @@ Future<Option<ContainerLaunchInfo>> NetworkCniIsolatorProcess::prepare(
         launchInfo.set_namespaces(CLONE_NEWNS | CLONE_NEWUTS);
       } else {
         launchInfo.set_namespaces(CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWUTS);
-
-        // This is a top-level container joining a new network
-        // namespace. Hence, set up `pre_exec_command` to bring up the
-        // loopback interface.
-        launchInfo.add_pre_exec_commands()->set_value("ifconfig lo up");
       }
     } else {
       // This is a nested container. This shares the parent's network
@@ -1813,7 +1808,22 @@ int NetworkCniIsolatorSetup::execute()
       return EXIT_FAILURE;
     }
 
-    LOG(INFO) << "Set hostname to '" << flags.hostname.get() << "'" << endl;
+    // Since, the hostname is set, this is a top-level container in a
+    // new network namespace. This implies that we have to bring up
+    // the loopback interface as well.
+    setns = ns::setns(flags.pid.get(), "net");
+    if (setns.isError()) {
+      cerr << "Failed to enter the network namespace of pid "
+           << flags.pid.get() << ": " << setns.error() << endl;
+      return EXIT_FAILURE;
+    }
+
+    if (os::system("ifconfig lo up") != 0) {
+      cerr << "Failed to bring up the loopback interface in the new "
+           << "network namespace of pid " << flags.pid.get()
+           << ": " << os::strerror(errno) << endl;
+      return EXIT_FAILURE;
+    }
   }
 
   return EXIT_SUCCESS;