added new parser for config

lib/config/parser.py

@@ -0,0 +1,153 @@
+'''
+Created on Jun 9, 2013
+
+@author: Rafael Timmerberg(raffn1+linspector@gmail.com)
+'''
+
+import os, os.path as path
+import json
+from layouts import Layout
+from hostgroups import HostGroup
+
+class ConfigurationException(Exception):
+    def __init__(self, msg, log):
+        log.e(msg)
+        self.msg = msg
+        
+    def __str__(self):
+        return repr(self.msg)
+
+
+KEY_LAYOUTS      = "layouts"
+KEY_HOSTGROUPS   = "hostgroups"
+KEY_MEMBERS      = "members"
+KEY_PERIODS      = "periods"
+KEY_CORE         = "core"
+
+
+
+class ConfigParser:
+    def __init__(self, log):
+        '''
+        initializes a new ConfigParser Object
+        
+        params: 
+            log: pre configured logger Object to post messages while parsing"
+        '''
+        self.log = log
+        self.hostgroups = {}
+        self.members = {}
+        self.periods = {}
+        
+    
+    def _read_json_config(self, configFilename):
+        '''
+        reads the config File and returns a dictionary, while lowering the first keys
+        
+        params:
+            configFilename: the path under which the configuration file should be found
+        '''
+        if not path.isfile(configFilename):
+            msg = "config file not found at " + str(configFilename)
+            raise ConfigurationException(msg, self.log)
+        
+        self.configfilename = configFilename
+        
+        with open(configFilename) as cfgFile:
+            config = cfgFile.read()
+        
+        self.log.i("reading Config: " + configFilename)
+        return json.loads(config)
+
+    
+    
+    def _get_as_list(self, configValue):
+        '''
+        In some cases the config permits to define a list or a single value.
+        
+        returns the value as list
+        '''
+        return configValue if isinstance(configValue, list) else [configValue]
+        
+
+    def create_layouts_from_json(self, jsonLayouts):
+        layouts = []
+        for lName, lValues in jsonLayouts.items():
+            try:
+                layout = Layout(lName, **lValues)
+                layouts.append(layout)
+            except Exception:
+                self.log.w("ignoring Layout " + lName + "! reason:")
+                self.log.w(str(Exception))
+        return layouts
+    
+
+    def create_hostgroups_from_json(self, jsonHostGroups):
+        '''
+        creates Hostgroups from the jsonConfig
+        '''
+        hostgroups = []
+        for hgName, hgValues in jsonHostGroups.items():
+            try:
+                hostgroup = HostGroup(hgName, **hgValues)
+                hostgroups.append(hostgroup)
+            except Exception:
+                self.log.w("ignoring hostgroup: " + hgName + "!")
+                self.log.w("reason: " + str(Exception))
+        return hostgroups
+                
+                
+    
+    
+    def parse_config(self, configFilename):
+        '''
+        parses the json configuration and returns a list of layouts, 
+        which contains all nessesary information of the config file.
+        Parsing will be done in 3 steps:
+        1. get raw Config Objects by just passing the values defined inside the config
+        2. replace references by objects
+        3. do sanity checks
+        
+        params:
+            configFilename: indicates which configuration file to parse
+        '''
+        
+        self.jsonDict = self._read_json_config(configFilename)
+        
+        jsonLayouts = self.jsonDict[KEY_LAYOUTS]
+        layouts = self.create_layouts_from_json(jsonLayouts)
+        
+        hostgroupNames = set()
+        for layout in layouts:
+            for hgName in layout.get_hostgroups():
+                hostgroupNames.add(hgName)
+                
+        
+        jsonHostgroups = {}
+        for hgName in hostgroupNames:
+            if not hgName in self.jsonDict[KEY_HOSTGROUPS]:
+                self.log.w("Hostgroup " + hgName + " not found!")
+                for layout in layouts:
+                    if hgName in layout.hostgroups:
+                        del layout.hostgroups[layout.hostgroups.index(hgName)]
+            jsonHostgroups[hgName] = self.jsonDict[KEY_HOSTGROUPS][hgName]
+        
+        self.hostgroups = self.create_hostgroups_from_json(jsonHostgroups)
+        
+        memberNames = set()
+        for hostgroup in self.hostgroups:
+            for memberName in layout.get_mebers():
+                memberNames.add(memberName)
+                
+                
+        jsonMembernames = {}
+        for memberName in hostgroupNames:
+            if not memberName in self.jsonDict[KEY_MEMBERS]:
+                self.log.w("Member " + memberName + " not found!")
+                for hostgroup in self.hostgroups:
+                    if memberName in hostgroup.members:
+                        del hostgroup.members[hostgroup.members.index(hgName)]
+            jsonHostgroups[hgName] = self.jsonDict[KEY_HOSTGROUPS][hgName]
+        
+        self.hostgroups = self.create_hostgroups_from_json(jsonHostgroups)
+