SDN check: Ignore node's canonical name

When verifying that a node's preferred host name or address resolves to its
internal IP address, ignore the canonical name returned by name resolution.
In some valid configurations, the node's preferred name or address differs
from the canonical name.

This change makes the check more consistent with the behavior of the
debug.sh script on which the check was based:
https://github.com/openshift/openshift-sdn/blob/d55c72b668018492059a862bee06f11745de1f97/hack/debug.sh#L126

This commit also fixes a problem with string encodings and comparisons that
shows up on Python 3.

This commit fixes bug 1614261.

https://bugzilla.redhat.com/show_bug.cgi?id=1614261

* roles/openshift_health_checker/openshift_checks/sdn.py
(SDNCheck.read_command_output): Add an optional parameter for UTF-8
encoding (default True).
(SDNCheck.resolve_address): Use read_command_output's new parameter to
disable UTF-8 encoding.  Ignore canonical name in result.
* roles/openshift_health_checker/test/sdn_tests.py (test_resolve_address):
New test.

roles/openshift_health_checker/openshift_checks/sdn.py

@@ -119,7 +119,7 @@ class SDNCheck(OpenShiftCheck):
         """
         self.register_file(path, self.read_command_output(command))
 
-    def read_command_output(self, command):
+    def read_command_output(self, command, utf8=True):
         """Execute the provided command using the command module
         and return its output.
 
@@ -141,7 +141,9 @@ class SDNCheck(OpenShiftCheck):
                 'RemoteCommandFailure',
                 'Failed to execute command on remote host: %s' % command)
 
-        return result['stdout'].encode('utf-8')
+        if utf8:
+            return result['stdout'].encode('utf-8')
+        return result['stdout']
 
     def check_master(self):
         """Gather diagnostic information on a master and ensure it can connect
@@ -425,7 +427,7 @@ class SDNCheck(OpenShiftCheck):
         """Look up the given IPv4 address using getent."""
         command = ' '.join(['/bin/getent', 'ahostsv4', addr])
         try:
-            out = self.read_command_output(command)
+            out = self.read_command_output(command, False)
         except OpenShiftCheckException as exc:
             raise OpenShiftCheckException(
                 'NameResolutionError',
@@ -433,7 +435,7 @@ class SDNCheck(OpenShiftCheck):
 
         for line in out.splitlines():
             record = line.split()
-            if record[1:3] == ['STREAM', addr]:
+            if record[1] == 'STREAM':
                 return record[0]
 
         return None

roles/openshift_health_checker/test/sdn_tests.py

@@ -1,5 +1,6 @@
 import pytest
 from openshift_checks.sdn import SDNCheck
+from openshift_checks import OpenShiftCheckException
 
 
 def fake_execute_module(*args):
@@ -170,6 +171,33 @@ def test_check_nodes():
     SDNCheck(execute_module, task_vars).run()
 
 
+def test_resolve_address():
+    def execute_module(module_name, args, *_):
+        if module_name != 'command':
+            raise ValueError('not expecting module %s' % module_name)
+
+        command_args = args['_raw_params'].split()
+        if command_args[0] != '/bin/getent':
+            raise ValueError('not expecting command: %s' % args.raw_params)
+
+        # The expected command_args is ['/bin/getent', 'ahostsv4', 'foo'].
+        if command_args[2] == 'foo':
+            return {
+                'rc': 0,
+                'stdout': '''1.2.3.4         STREAM bar
+1.2.3.4         DGRAM
+1.2.3.4         RAW
+'''
+            }
+
+        return {'rc': 2}
+
+    check = SDNCheck(execute_module, None)
+    assert check.resolve_address('foo') == '1.2.3.4'
+    with pytest.raises(OpenShiftCheckException):
+        check.resolve_address('baz')
+
+
 def test_no_nodes():
     task_vars = dict(
         group_names=['oo_masters_to_config'],