This is an automated email from the ASF dual-hosted git repository.
klueska pushed a commit to branch 1.7.x
in repository https://gitbox.apache.org/repos/asf/mesos.git
commit 8e4465a851fb3e5d10cea5f0183c08caef606daf
Author: Kevin Klues <klue...@gmail.com>
AuthorDate: Tue Oct 2 11:41:12 2018 +0200
Removed call to 'setsid()' in command executor if TTY attached.
Previously, we would unconditionally call 'setsid()' in the command
executor whenever we launched a process. This causes the process it
launches to start a new session and NOT inherit the controlling TTY
from it's parent. This obviously causes problems, if the goal of
attaching a TTY to a task is so that we can actually give it control
of that TTY while it is executing.
Interestingly, even if process does not control its TTY, it can still
read and write from the file descriptors associated with it (it just
can't receive any signals associated with it, such as SIGWINCH,
SIGHUP, etc.). This is why things "appeared" to mostly work until this
point because stdin/stdout/stderr were all being redirected properly
to it.
Where we saw problems was with trying to 'attach' to an already
running process launched via the command executor using the
ATTACH_NESTED_CONTAINER_INPUT/OUTPUT calls. If you ran something like
'bash', you would not be able to do job control, and you could not
resize the screen properly when running things like 'vim'.
This commit fixes this issue by checking to see if a TTY has been
attached to a task launched by the command executor, and skipping the
'setsid()' call when forking it. We considered a number of alternative
approaches, but finally settled on this one since it was the least
invasive. I.e. only tasks launched with a TTY (which is a failry new
concept in Mesos) will be affected by this change; the semantics of
all traditional tasks launched via the command executor will go
unchanged.
Note: this problem does not exists for the default executor because
the agent does the job of launching all containers, and there is no
executor sitting between the containerizer and the actual process of a
task intervening to call an extra 'setsid()'. This is why containers
launched via LAUNCH_NESTED_CONTAINER_SESSION have always worked as
expected.
Review: https://reviews.apache.org/r/68810/
---
src/launcher/executor.cpp | 18 +++++++++++++++++-
src/slave/containerizer/mesos/io/switchboard.cpp | 7 +++++++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/src/launcher/executor.cpp b/src/launcher/executor.cpp
index 86fb87d..6b1204d 100644
--- a/src/launcher/executor.cpp
+++ b/src/launcher/executor.cpp
@@ -133,6 +133,7 @@ public:
const Option<Environment>& _taskEnvironment,
const Option<CapabilityInfo>& _effectiveCapabilities,
const Option<CapabilityInfo>& _boundingCapabilities,
+ const Option<string>& _ttySlavePath,
const Option<ContainerLaunchInfo>& _taskLaunchInfo,
const FrameworkID& _frameworkId,
const ExecutorID& _executorId,
@@ -158,6 +159,7 @@ public:
taskEnvironment(_taskEnvironment),
effectiveCapabilities(_effectiveCapabilities),
boundingCapabilities(_boundingCapabilities),
+ ttySlavePath(_ttySlavePath),
taskLaunchInfo(_taskLaunchInfo),
frameworkId(_frameworkId),
executorId(_executorId),
@@ -411,6 +413,7 @@ protected:
const Option<string>& workingDirectory,
const Option<CapabilityInfo>& effectiveCapabilities,
const Option<CapabilityInfo>& boundingCapabilities,
+ const Option<string>& ttySlavePath,
const Option<ContainerLaunchInfo>& taskLaunchInfo)
{
// Prepare the flags to pass to the launch process.
@@ -513,6 +516,11 @@ protected:
[](pid_t pid) { return os::set_job_kill_on_close_limit(pid); }));
#endif // __WINDOWS__
+ vector<process::Subprocess::ChildHook> childHooks;
+ if (ttySlavePath.isNone()) {
+ childHooks.emplace_back(Subprocess::ChildHook::SETSID());
+ }
+
Try<Subprocess> s = subprocess(
path::join(launcherDir, MESOS_CONTAINERIZER),
argv,
@@ -523,7 +531,7 @@ protected:
None(),
None(),
parentHooks,
- {Subprocess::ChildHook::SETSID()});
+ childHooks);
if (s.isError()) {
ABORT("Failed to launch '" + commandString + "': " + s.error());
@@ -688,6 +696,7 @@ protected:
workingDirectory,
effectiveCapabilities,
boundingCapabilities,
+ ttySlavePath,
taskLaunchInfo);
LOG(INFO) << "Forked command at " << pid.get();
@@ -1218,6 +1227,7 @@ private:
Option<Environment> taskEnvironment;
Option<CapabilityInfo> effectiveCapabilities;
Option<CapabilityInfo> boundingCapabilities;
+ Option<string> ttySlavePath;
Option<ContainerLaunchInfo> taskLaunchInfo;
const FrameworkID frameworkId;
const ExecutorID executorId;
@@ -1282,6 +1292,10 @@ public:
"task_launch_info",
"The launch info to run the task.");
+ add(&Flags::tty_slave_path,
+ "tty_slave_path",
+ "A path to the slave end of the attached TTY if there is one.");
+
add(&Flags::launcher_dir,
"launcher_dir",
"Directory path of Mesos binaries.",
@@ -1299,6 +1313,7 @@ public:
Option<Environment> task_environment;
Option<mesos::CapabilityInfo> effective_capabilities;
Option<mesos::CapabilityInfo> bounding_capabilities;
+ Option<string> tty_slave_path;
Option<JSON::Object> task_launch_info;
string launcher_dir;
};
@@ -1390,6 +1405,7 @@ int main(int argc, char** argv)
flags.task_environment,
flags.effective_capabilities,
flags.bounding_capabilities,
+ flags.tty_slave_path,
task_launch_info,
frameworkId,
executorId,
diff --git a/src/slave/containerizer/mesos/io/switchboard.cpp
b/src/slave/containerizer/mesos/io/switchboard.cpp
index 498c008..e96504d 100644
--- a/src/slave/containerizer/mesos/io/switchboard.cpp
+++ b/src/slave/containerizer/mesos/io/switchboard.cpp
@@ -443,6 +443,13 @@ Future<Option<ContainerLaunchInfo>>
IOSwitchboard::_prepare(
containerIO.err = containerIO.in;
launchInfo.set_tty_slave_path(slavePath.get());
+
+ // The command executor requires the `tty_slave_path`
+ // to also be passed as a command line argument.
+ if (containerConfig.has_task_info()) {
+ launchInfo.mutable_command()->add_arguments(
+ "--tty_slave_path=" + slavePath.get());
+ }
} else {
Try<std::array<int_fd, 2>> infds_ = os::pipe();
if (infds_.isError()) {
