Fix keystone-manage mapping_engine tester

There were several problems with keystone-manage mapping_engine

* It aborts with a backtrace because of wrong number of arguments
  passed to the RuleProcessor, it was missing the mapping_id
  parameter.

* Error messages related to input data were cryptic and inprecise.

* The --engine-debug option did not work.

A fake mapping_id is now generated and passed to the RuleProcessor.

If there was invalid data passed it was nearly impossible to determine
what was causing the error, the command takes 2 input files, but which
file contained the error? At what line? Why? For example I was
consistently getting this error:

Error while parsing line: '{': need more than 1 value to unpack

and had no idea of what was wrong, the JSON looked valid to me. Turns
out the assertion file is not formatted as JSON (yes this is
documented in the help message but given the rules are JSON formatted
and the RuleProcessor expects a dict for the assertion_data it's
reasonsable to assume the data in the assertion file is formatted as a
JSON object).

The documentation in mapping_combinations.rst added a note in the
section suggesting the use of the keystone-manage mapping_engine
tester alerting the reader to the expected file formats.

The MappingEngineTester class was refactored slighly to allow each
method to know what file it was operating on and emit error messages
that identify the file. The error message in addition to the pathname
now includes the offending line number as well. As a bonus it doesn't
fail if there is a blank line. The error message now looks like this:

assertion file input.txt at line 4 expected 'key: value' but found 'foo' see help for file format

The mapping_engine.LOG.logger level is now explictily set to DEBUG
when --engine-debug is passed instead of (mistakenly assuming it
defaulted to DEBUG) otherwise it's set to WARN.

Closes-Bug: 1655182
Signed-off-by: John Dennis <jdennis@redhat.com>
Change-Id: I2dea0f38b127ec185b79bfe06dd6a212da75cbca
(cherry picked from commit f2d0f8c9ab)

doc/source/federation/mapping_combinations.rst

@@ -69,6 +69,12 @@ tested with the ``keystone-manage mapping_engine`` command:
 
     $ keystone-manage mapping_engine --rules <file> --input <file>
 
+.. NOTE::
+    Although the rules file is formated as json the input file of assertion
+    data is formatted as individual lines of key: value pairs,
+    see `keystone-manage mapping_engine --help` for details.
+
+
 Mapping Conditions
 ------------------
 

keystone/cmd/cli.py

@@ -1083,65 +1083,89 @@ class MappingEngineTester(BaseApp):
 
     name = 'mapping_engine'
 
-    @staticmethod
+    def __init__(self):
-    def read_rules(path):
+        super(MappingEngineTester, self).__init__()
+        self.mapping_id = uuid.uuid4().hex
+        self.rules_pathname = None
+        self.rules = None
+        self.assertion_pathname = None
+        self.assertion = None
+
+    def read_rules(self, path):
+        self.rules_pathname = path
         try:
             with open(path) as file:
-                return jsonutils.load(file)
+                self.rules = jsonutils.load(file)
         except ValueError as e:
             raise SystemExit(_('Error while parsing rules '
                                '%(path)s: %(err)s') % {'path': path, 'err': e})
 
-    @staticmethod
+    def read_assertion(self, path):
-    def read_file(path):
+        self.assertion_pathname = path
         try:
             with open(path) as file:
-                return file.read().strip()
+                self.assertion = file.read().strip()
         except IOError as e:
             raise SystemExit(_("Error while opening file "
                                "%(path)s: %(err)s") % {'path': path, 'err': e})
 
-    @staticmethod
+    def normalize_assertion(self):
-    def normalize_assertion(assertion):
+        def split(line, line_num):
-        def split(line):
             try:
                 k, v = line.split(':', 1)
                 return k.strip(), v.strip()
-            except ValueError as e:
+            except ValueError:
-                msg = _("Error while parsing line: '%(line)s': %(err)s")
+                msg = _("assertion file %(pathname)s at line %(line_num)d "
-                raise SystemExit(msg % {'line': line, 'err': e})
+                        "expected 'key: value' but found '%(line)s' "
-        assertion = assertion.split('\n')
+                        "see help for file format")
+                raise SystemExit(msg % {'pathname': self.assertion_pathname,
+                                        'line_num': line_num,
+                                        'line': line})
+        assertion = self.assertion.split('\n')
         assertion_dict = {}
         prefix = CONF.command.prefix
-        for line in assertion:
+        for line_num, line in enumerate(assertion, 1):
-            k, v = split(line)
+            line = line.strip()
+            if line == '':
+                continue
+            k, v = split(line, line_num)
             if prefix:
                 if k.startswith(prefix):
                     assertion_dict[k] = v
             else:
                 assertion_dict[k] = v
-        return assertion_dict
+        self.assertion = assertion_dict
 
-    @staticmethod
+    def normalize_rules(self):
-    def normalize_rules(rules):
+        if isinstance(self.rules, list):
-        if isinstance(rules, list):
+            self.rules = {'rules': self.rules}
-            return {'rules': rules}
-        else:
-            return rules
 
     @classmethod
     def main(cls):
-        if not CONF.command.engine_debug:
+        if CONF.command.engine_debug:
+            mapping_engine.LOG.logger.setLevel('DEBUG')
+        else:
             mapping_engine.LOG.logger.setLevel('WARN')
 
-        rules = MappingEngineTester.read_rules(CONF.command.rules)
+        tester = cls()
-        rules = MappingEngineTester.normalize_rules(rules)
-        mapping_engine.validate_mapping_structure(rules)
 
-        assertion = MappingEngineTester.read_file(CONF.command.input)
+        tester.read_rules(CONF.command.rules)
-        assertion = MappingEngineTester.normalize_assertion(assertion)
+        tester.normalize_rules()
-        rp = mapping_engine.RuleProcessor(rules['rules'])
+        mapping_engine.validate_mapping_structure(tester.rules)
-        print(jsonutils.dumps(rp.process(assertion), indent=2))
+
+        tester.read_assertion(CONF.command.input)
+        tester.normalize_assertion()
+
+        if CONF.command.engine_debug:
+            print("Using Rules:\n%s" % (
+                jsonutils.dumps(tester.rules, indent=2)))
+            print("Using Assertion:\n%s" % (
+                jsonutils.dumps(tester.assertion, indent=2)))
+
+        rp = mapping_engine.RuleProcessor(tester.mapping_id,
+                                          tester.rules['rules'])
+        mapped = rp.process(tester.assertion)
+        print(jsonutils.dumps(mapped, indent=2))
 
     @classmethod
     def add_argument_parser(cls, subparsers):