- added timestamp-based JSON caching of configuration for faster loading

[invirt/packages/invirt-base.git] / files / usr / sbin / invirt-getconf

diff --git a/files/usr/sbin/invirt-getconf b/files/usr/sbin/invirt-getconf
old mode 100644 (file)
new mode 100755 (executable)
index cbb0a85..d503dea
--- a/files/usr/sbin/invirt-getconf
+++ b/files/usr/sbin/invirt-getconf
@@ -1,18 +1,67 @@
 #!/usr/bin/env python
 
+"""
+invirt-getconf [-f FILE] KEY prints the configuration the option named KEY from
+the invirt configuration file FILE.  Keys are dot-separated paths into the YAML
+configuration tree.  List indexes (0-based) are also treated as path
+components.
+
+(Due to this path language, certain restrictions are placed on the keys used in
+the YAML configuration, e.g. they cannot contain dots.)
+
+Examples:
+
+  invirt-getconf db.uri
+  invirt-getconf authn.0.type
+"""
+
 from invirt.config import load
-from sys import argv, stderr
+from sys import argv, exit, stderr
+from optparse import OptionParser
+
+class invirt_exception(Exception): pass
+
+def main(argv):
+    try:
+        parser = OptionParser(usage = '%prog [options] key',
+                description = __doc__.strip().split('\n\n')[0])
+        parser.add_option('-s', '--src',
+                default = '/etc/invirt/master.yaml',
+                help = 'the source YAML configuration file to read from')
+        parser.add_option('-c', '--cache',
+                default = '/var/lib/invirt/invirt.json',
+                help = 'path to the JSON cache')
+        parser.add_option('-r', '--refresh',
+                action = 'store_true',
+                help = 'force the cache to be regenerated')
+        opts, args = parser.parse_args()
+
+        try: [key] = args
+        except: raise invirt_exception(__doc__.strip())
 
-def main( argv ):
-    try: command, key = argv
-    except: print >> stderr, 'invirt-getconf KEY'
-    conf = load()
-    for component in key.split('.')[:-1]:
-        if component.isdigit(): component = int( component )
-        conf = conf[ component ]
-    print conf[key]
+        conf = load(opts.src, opts.cache, opts.refresh)
+        components = key.split('.')
+        for i, component in enumerate(components):
+            progress = '.'.join(components[:i])
+            if type(conf) not in [dict, list]:
+                raise invirt_exception(
+                        '%s: node has no children (atomic datum)' % progress)
+            if type(conf) == list:
+                try: component = int(component)
+                except: raise invirt_exception(
+                        '%s: node a list; integer path component required, '
+                        'but got "%s"' % (progress, component))
+            try: conf = conf[component]
+            except KeyError: raise invirt_exception(
+                    '%s: key "%s" not found' % (progress, component))
+            except IndexError: raise invirt_exception(
+                    '%s: index %s out of range' % (progress, component))
+        print conf
+    except (invirt_exception, OSError), ex:
+        print >> stderr, ex
+        return 1
 
 if __name__ == '__main__':
-    main( argv )
+    exit(main(argv))
 
 # vim:et:sw=4:ts=4