Add SSH Agent Primitives and usage

Debugging some issues revealed a problem in the __eq__ method that is
patched here. This produced some red herring backtraces unnecessarily.

It's worth noting that close_fds on this subprocess.Popen call is
critical to the health of any other processes being spawned from Zuul.
Without it, git processes run by the git module went defunct and locked
things up in weird ways.

Change-Id: I6875568f4b7ccf261491c45086727250e58f5ed8

zuul/executor/server.py

@@ -79,6 +79,78 @@ class JobDirPlaybook(object):
         self.path = None
 
 
+class SshAgent(object):
+    log = logging.getLogger("zuul.ExecutorServer")
+
+    def __init__(self):
+        self.env = {}
+        self.ssh_agent = None
+
+    def start(self):
+        if self.ssh_agent:
+            return
+        with open('/dev/null', 'r+') as devnull:
+            ssh_agent = subprocess.Popen(['ssh-agent'], close_fds=True,
+                                         stdout=subprocess.PIPE,
+                                         stderr=devnull,
+                                         stdin=devnull)
+        (output, _) = ssh_agent.communicate()
+        output = output.decode('utf8')
+        for line in output.split("\n"):
+            if '=' in line:
+                line = line.split(";", 1)[0]
+                (key, value) = line.split('=')
+                self.env[key] = value
+        self.log.info('Started SSH Agent, {}'.format(self.env))
+
+    def stop(self):
+        if 'SSH_AGENT_PID' in self.env:
+            try:
+                os.kill(int(self.env['SSH_AGENT_PID']), signal.SIGTERM)
+            except OSError:
+                self.log.exception(
+                    'Problem sending SIGTERM to agent {}'.format(self.env))
+            self.log.info('Sent SIGTERM to SSH Agent, {}'.format(self.env))
+            self.env = {}
+
+    def add(self, key_path):
+        env = os.environ.copy()
+        env.update(self.env)
+        key_path = os.path.expanduser(key_path)
+        self.log.debug('Adding SSH Key {}'.format(key_path))
+        output = ''
+        try:
+            output = subprocess.check_output(['ssh-add', key_path], env=env,
+                                             stderr=subprocess.PIPE)
+        except subprocess.CalledProcessError:
+            self.log.error('ssh-add failed: {}'.format(output))
+            raise
+        self.log.info('Added SSH Key {}'.format(key_path))
+
+    def remove(self, key_path):
+        env = os.environ.copy()
+        env.update(self.env)
+        key_path = os.path.expanduser(key_path)
+        self.log.debug('Removing SSH Key {}'.format(key_path))
+        subprocess.check_output(['ssh-add', '-d', key_path], env=env,
+                                stderr=subprocess.PIPE)
+        self.log.info('Removed SSH Key {}'.format(key_path))
+
+    def list(self):
+        if 'SSH_AUTH_SOCK' not in self.env:
+            return None
+        env = os.environ.copy()
+        env.update(self.env)
+        result = []
+        for line in subprocess.Popen(['ssh-add', '-L'], env=env,
+                                     stdout=subprocess.PIPE).stdout:
+            line = line.decode('utf8')
+            if line.strip() == 'The agent has no identities.':
+                break
+            result.append(line.strip())
+        return result
+
+
 class JobDir(object):
     def __init__(self, root=None, keep=False):
         # root
@@ -168,7 +240,7 @@ class UpdateTask(object):
         self.event = threading.Event()
 
     def __eq__(self, other):
-        if (other.connection_name == self.connection_name and
+        if (other and other.connection_name == self.connection_name and
             other.project_name == self.project_name):
             return True
         return False
@@ -513,6 +585,8 @@ class AnsibleJob(object):
         self.proc_lock = threading.Lock()
         self.running = False
         self.aborted = False
+        self.thread = None
+        self.ssh_agent = None
 
         if self.executor_server.config.has_option(
             'executor', 'private_key_file'):
@@ -520,8 +594,11 @@ class AnsibleJob(object):
                 'executor', 'private_key_file')
         else:
             self.private_key_file = '~/.ssh/id_rsa'
+        self.ssh_agent = SshAgent()
 
     def run(self):
+        self.ssh_agent.start()
+        self.ssh_agent.add(self.private_key_file)
         self.running = True
         self.thread = threading.Thread(target=self.execute)
         self.thread.start()
@@ -529,7 +606,8 @@ class AnsibleJob(object):
     def stop(self):
         self.aborted = True
         self.abortRunningProc()
-        self.thread.join()
+        if self.thread:
+            self.thread.join()
 
     def execute(self):
         try:
@@ -549,6 +627,11 @@ class AnsibleJob(object):
                 self.executor_server.finishJob(self.job.unique)
             except Exception:
                 self.log.exception("Error finalizing job thread:")
+            if self.ssh_agent:
+                try:
+                    self.ssh_agent.stop()
+                except Exception:
+                    self.log.exception("Error stopping SSH agent:")
 
     def _execute(self):
         self.log.debug("Job %s: beginning" % (self.job.unique,))
@@ -1032,6 +1115,7 @@ class AnsibleJob(object):
 
     def runAnsible(self, cmd, timeout, trusted=False):
         env_copy = os.environ.copy()
+        env_copy.update(self.ssh_agent.env)
         env_copy['LOGNAME'] = 'zuul'
 
         if trusted: