Change in osmo-gsm-tester[master]: osmotrx: Make sure remote process stops after ssh session is closed

[Pau Espin Pedrol]

Pau Espin Pedrol has uploaded this change for review. ( https://gerrit.osmocom.org/11192


Change subject: osmotrx: Make sure remote process stops after ssh session is closed
......................................................................

osmotrx: Make sure remote process stops after ssh session is closed

First of all, it was found that vty allocation must be forced (-t -t)
during ssh session creation to make sure SIGHUP is forwarded when
session is closed.

Second, since osmo-trx ignores SIGHUP (osmo_init_ignore_signals()), we
must add a wrapper script which converts received SIGHUP into a SIGINT
to stop osmo-trx.

Change-Id: Ic334a54b1a1827d74fe0b453ac32bb77b8616147
---
M src/osmo_gsm_tester/bts_osmotrx.py
M src/osmo_gsm_tester/process.py
2 files changed, 37 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-gsm-tester refs/changes/92/11192/1

diff --git a/src/osmo_gsm_tester/bts_osmotrx.py b/src/osmo_gsm_tester/bts_osmotrx.py
index 3ed596a..a1814dc 100644
--- a/src/osmo_gsm_tester/bts_osmotrx.py
+++ b/src/osmo_gsm_tester/bts_osmotrx.py
@@ -18,6 +18,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import stat
 import pprint
 import tempfile
 from abc import ABCMeta, abstractmethod
@@ -142,6 +143,7 @@
 
     CONF_OSMO_TRX = 'osmo-trx.cfg'
     REMOTE_DIR = '/osmo-gsm-tester-trx/last_run'
+    WRAPPER_SCRIPT = 'ssh_sigkiller.sh'
 
 ##############
 # PROTECTED
@@ -207,6 +209,28 @@
         proc.launch()
         return proc
 
+    def generate_wrapper_script(self):
+        wrapper_script = self.run_dir.new_file(OsmoTrx.WRAPPER_SCRIPT)
+        with open(wrapper_script, 'w') as f:
+            r = """#!/bin/bash
+            mypid=0
+            sign_handler() {
+                    sig=$1
+                    echo "received signal handler $sig, killing $mypid"
+                    kill $mypid
+            }
+            trap 'sign_handler SIGINT' SIGINT
+            trap 'sign_handler SIGHUP' SIGHUP
+            "$@" &
+            mypid=$!
+            echo "waiting for $mypid"
+            wait $mypid
+            """
+            f.write(r)
+        st = os.stat(wrapper_script)
+        os.chmod(wrapper_script, st.st_mode | stat.S_IEXEC)
+        return wrapper_script
+
 ##############
 # PUBLIC (test API included)
 ##############
@@ -221,13 +245,21 @@
             self.proc_trx = self.launch_process_local(keepalive, self.binary_name(),
                                             '-C', os.path.abspath(self.config_file))
         else:
+            # Run remotely through ssh. We need to run osmo-trx under a wrapper
+            # script since osmo-trx ignores SIGHUP and will keep running after
+            # we close local ssh session. The wrapper script catches SIGHUP and
+            # sends SIGINT to it.
+            wrapper_script = self.generate_wrapper_script()
             remote_run_dir = util.Dir(OsmoTrx.REMOTE_DIR)
             self.remote_inst = process.copy_inst_ssh(self.run_dir, self.inst, remote_run_dir, self.remote_user,
                                                 self.listen_ip, self.binary_name(), self.config_file)
+            remote_wrapper_script = remote_run_dir.child(OsmoTrx.WRAPPER_SCRIPT)
             remote_config_file = remote_run_dir.child(OsmoTrx.CONF_OSMO_TRX)
             remote_lib = self.remote_inst.child('lib')
             remote_binary = self.remote_inst.child('bin', self.binary_name())
-            args = ('LD_LIBRARY_PATH=%s' % remote_lib, remote_binary, '-C', remote_config_file)
+            process.scp(self.run_dir, self.remote_user, self.listen_ip, 'scp-wrapper-to-remote', wrapper_script, remote_wrapper_script)
+
+            args = ('LD_LIBRARY_PATH=%s' % remote_lib, remote_wrapper_script, remote_binary, '-C', remote_config_file)
             self.proc_trx = self.launch_process_remote(self.binary_name(), args, remote_cwd=remote_run_dir, keepalive=keepalive)
 
     def trx_ready(self):
diff --git a/src/osmo_gsm_tester/process.py b/src/osmo_gsm_tester/process.py
index 9db9241..534cdba 100644
--- a/src/osmo_gsm_tester/process.py
+++ b/src/osmo_gsm_tester/process.py
@@ -228,7 +228,10 @@
             cd = 'cd "%s"; ' % self.remote_cwd
         else:
             cd = ''
-        self.popen_args = ['ssh', self.remote_user+'@'+self.remote_host,
+        # We need double -t to force tty and be able to forward signals to
+        # processes (SIGHUP) when we close ssh on the local side. As a result,
+        # stderr seems to be merged into stdout in ssh client.
+        self.popen_args = ['ssh', '-t', '-t', self.remote_user+'@'+self.remote_host,
                            '%s%s' % (cd,
                                      ' '.join(self.popen_args))]
         self.dbg(self.popen_args, dir=self.run_dir, conf=self.popen_kwargs)

-- 
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Gerrit-Project: osmo-gsm-tester
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ic334a54b1a1827d74fe0b453ac32bb77b8616147
Gerrit-Change-Number: 11192
Gerrit-PatchSet: 1
Gerrit-Owner: Pau Espin Pedrol <pespin at sysmocom.de>
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