standalone: strip ansi codes in logs

This fixes a bug when the program output contain some ansi code, like
the \e[0;31m ansi code to display text in color on the terminal. These
characters are not allowed in XML so if they end up in the XML-RPC
messages this cause the underlying expat library to complain that the
stream is not well-formed (invalid token).

Fortunately, supervisor supports this and has a `strip_ansi` option that
we can set in the config to prevent these problems.

slapos/slap/standalone.py

@@ -147,6 +147,7 @@ class SupervisorConfigWriter(ConfigWriter):
         logfile = {standalone_slapos._supervisor_log}
         pidfile = {standalone_slapos._supervisor_pid}
         childlogdir = {standalone_slapos._log_directory}
+        strip_ansi = true
 
         [rpcinterface:supervisor]
         supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface

slapos/tests/test_standalone.py

@@ -424,6 +424,28 @@ class TestSlapOSStandaloneSoftware(SlapOSStandaloneTestCase):
           str(e.exception))
       self.assertNotIn(r"\n", str(e.exception))
 
+  def test_install_software_failure_log_with_ansi_codes(self):
+    with tempfile.NamedTemporaryFile(suffix="-%s.cfg" % self.id()) as f:
+      f.write(
+          textwrap.dedent(
+              r'''
+              [buildout]
+              parts = error
+              newest = false
+              [error]
+              recipe = plone.recipe.command==1.1
+              command = bash -c "echo -e '\033[0;31mRed\033[0m \033[0;32mGreen\033[0m \033[0;34mBlue\033[0m' ; exit 123"
+              stop-on-error = true
+      ''').encode())
+      f.flush()
+      self.standalone.supply(f.name)
+
+      with self.assertRaises(SlapOSNodeSoftwareError) as e:
+        self.standalone.waitForSoftware()
+
+      self.assertEqual(1, e.exception.args[0]['exitstatus'])
+      self.assertIn("Red Green Blue", e.exception.args[0]['output'])
+
 
 class TestSlapOSStandaloneInstance(SlapOSStandaloneTestCase):
   _auto_stop_standalone = False  # we stop explicitly