Make executor hostname configurable

The executor needs to know its hostname as it embeds it into the
finger url. In some environments it cannot correctly determine its own
hostname so the finger url (and thus live log streaming) would not
work. Making the hostname configurable can solve this easily in such
environments.

Change-Id: Ifeb639b4499d737e9045508c4f66aefa950effa6

doc/source/admin/components.rst

@@ -522,6 +522,15 @@ The following sections of ``zuul.conf`` are used by the executor:
       The executor will observe system load and determine whether
       to accept more jobs every 30 seconds.
 
+   .. attr:: hostname
+      :default: hostname of the server
+
+      The executor needs to know its hostname under which it is reachable by
+      zuul-web. Otherwise live console log streaming doesn't work. In most cases
+      This is automatically detected correctly. But when running in environments
+      where it cannot determine its hostname correctly this can be overridden
+      here.
+
 .. attr:: merger
 
    .. attr:: git_user_email

tests/fixtures/zuul-executor-hostname.conf

@@ -0,0 +1,32 @@
+[gearman]
+server=127.0.0.1
+
+[statsd]
+# note, use 127.0.0.1 rather than localhost to avoid getting ipv6
+# see: https://github.com/jsocol/pystatsd/issues/61
+server=127.0.0.1
+
+[scheduler]
+tenant_config=main.yaml
+
+[merger]
+git_dir=/tmp/zuul-test/merger-git
+git_user_email=zuul@example.com
+git_user_name=zuul
+
+[executor]
+git_dir=/tmp/zuul-test/executor-git
+hostname=test-executor-hostname.openstack.org
+
+[connection gerrit]
+driver=gerrit
+server=review.example.com
+user=jenkins
+sshkey=fake_id_rsa_path
+
+[connection smtp]
+driver=smtp
+server=localhost
+port=25
+default_from=zuul@example.com
+default_to=you@example.com

tests/unit/test_executor.py

@@ -401,3 +401,12 @@ class TestAnsibleJob(ZuulTestCase):
         node['ssh_port'] = 22022
         keys = self.test_job.getHostList({'nodes': [node]})[0]['host_keys']
         self.assertEqual(keys[0], '[localhost]:22022 fake-host-key')
+
+
+class TestExecutorHostname(ZuulTestCase):
+    config_file = 'zuul-executor-hostname.conf'
+    tenant_config_file = 'config/single-tenant/main.yaml'
+
+    def test_executor_hostname(self):
+        self.assertEqual('test-executor-hostname.openstack.org',
+                         self.executor_server.hostname)

zuul/executor/server.py

@@ -1535,7 +1535,8 @@ class ExecutorServer(object):
         self.jobdir_root = jobdir_root
         # TODOv3(mordred): make the executor name more unique --
         # perhaps hostname+pid.
-        self.hostname = socket.gethostname()
+        self.hostname = get_default(self.config, 'executor', 'hostname',
+                                    socket.gethostname())
         self.log_streaming_port = log_streaming_port
         self.merger_lock = threading.Lock()
         self.run_lock = threading.Lock()