new safe_ssh backend to avoid bugs related to ssh and or ssh wrappers

testinfra/backend/__init__.py

@@ -25,6 +25,7 @@ def get_backend(backend_type, *args, **kwargs):
         backend_class = {
             "local": local.LocalBackend,
             "ssh": ssh.SshBackend,
+            "safe_ssh": ssh.SafeSshBackend,
             "paramiko": paramiko.ParamikoBakend,
         }[backend_type]
     except KeyError:

testinfra/backend/ssh.py

@@ -15,10 +15,14 @@
 
 from __future__ import unicode_literals
 
+import base64
+
+from testinfra.backend import base
 from testinfra.backend import local
 
 
 class SshBackend(local.LocalBackend):
+    """Run command through ssh command"""
 
     def __init__(self, hostspec, *args, **kwargs):
         self.host, self.user, self.port = self.parse_hostspec(hostspec)
@@ -36,7 +40,42 @@ def run(self, command, *args, **kwargs):
         cmd.append("%s %s")
         cmd_args.extend([
             self.host,
-            self.quote(command, *args)
+            self.quote(command, *args),
         ])
         return super(SshBackend, self).run(
             " ".join(cmd), *cmd_args, **kwargs)
+
+
+class SafeSshBackend(SshBackend):
+    """Run command using ssh command but try to get a more sane output
+
+    When using ssh (or a potentially bugged wrapper) additional output can be
+    added in stdout/stderr and exit status may not be propagate correctly
+
+    To avoid that kind of bugs, we wrap the command to have an output like
+    this:
+
+    TESTINFRA_START;EXIT_STATUS;STDOUT;STDERR;TESTINFRA_END
+
+    where STDOUT/STDERR are base64 encoded, then we parse that magic string to
+    get sanes variables
+    """
+
+    def run(self, command, *args, **kwargs):
+        orig_command = self.quote(command, *args)
+
+        out = super(SafeSshBackend, self).run((
+            '''of=$(mktemp)&&ef=$(mktemp)&&%s >$of 2>$ef; r=$?;'''
+            '''echo "TESTINFRA_START;$r;$(base64 < $of);$(base64 < $ef);'''
+            '''TESTINFRA_END";rm -f $of $ef''') % (orig_command,))
+
+        start = out.stdout.find("TESTINFRA_START;") + len("TESTINFRA_START;")
+        end = out.stdout.find("TESTINFRA_END") - 1
+        rc, stdout, stderr = out.stdout[start:end].split(";")
+
+        return base.CommandResult(
+            rc=int(rc),
+            stdout=base64.b64decode(stdout),
+            stderr=base64.b64decode(stderr),
+            command=orig_command,
+        )

testinfra/plugin.py

@@ -34,7 +34,7 @@ def pytest_addoption(parser):
         "--connection",
         action="store",
         dest="connection",
-        help="Remote connection backend ssh|paramiko",
+        help="Remote connection backend ssh|paramiko|safe_ssh",
     )
     group._addoption(
         "--hosts",