From 57bcc8497c3f9ca4d5d7b1728afe5805c1516cd6 Mon Sep 17 00:00:00 2001
From: ahothan <ahothan@cisco.com>
Date: Thu, 19 Mar 2015 08:50:07 -0700
Subject: [PATCH] Add support for $HOME/.vmtp.yaml

Change-Id: I9bdba6a76491867d05ef4a961a5bd6b191cde309
---
 doc/source/usage.rst | 16 ++++++++++++----
 vmtp.py              | 35 ++++++++++++++++++++++++++++++++---
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/doc/source/usage.rst b/doc/source/usage.rst
index 9cb9d4a..2c6a18b 100644
--- a/doc/source/usage.rst
+++ b/doc/source/usage.rst
@@ -21,7 +21,7 @@ VMTP Usage
                    [--stop-on-error] [--vm_image_url <url_to_image>]
                    [--test_description <test_description>]
     
-    OpenStack VM Throughput V2.0.3
+    OpenStack VM Throughput V2.0.4
     
     optional arguments:
       -h, --help            show this help message and exit
@@ -77,13 +77,21 @@ VMTP Usage
 Configuration File
 ^^^^^^^^^^^^^^^^^^
 
-VMTP configuration files follow the yaml syntax and contain variables used by VMTP to run and collect performance data. The default configuration is stored in the cfg.default.yaml file.
+VMTP configuration files follow the yaml syntax and contain variables used by VMTP to run and collect performance data.
+The default configuration is stored in the cfg.default.yaml file.
 
-Default values should be overwritten for any cloud under test by defining new variable values in a new configuration file that follows the same format. Variables that are not defined in the new configuration file will retain their default values.
+Default values should be overwritten for any cloud under test by defining new variable values in a new configuration file that follows the same format.
+Variables that are not defined in the new configuration file will retain their default values.
 
+The precedence order for configuration files is as follows:
+- the command line argument "-c <file>" has highest precedence
+- $HOME/.vmtp.yaml if the file exists in the user home directory
+- cfg.default.yaml has the lowest precedence (always exists in the VMTP package root directory)
+
+To override a default value set in cfg.default.yaml, simply redefine that value in the configuration file passed in -c or in the $HOME/.vmtp.yaml file.
 Check the content of cfg.default.yaml file as it contains the list of configuration variables and instructions on how to set them.
 
-**Note:** the configuration file is not needed if the VMTP only runs the native host throughput option (*--host*)
+**Note:** the configuration file is not needed if VMTP only runs the native host throughput option (*--host*)
 
 
 OpenStack openrc File
diff --git a/vmtp.py b/vmtp.py
index 6799129..0b72050 100755
--- a/vmtp.py
+++ b/vmtp.py
@@ -40,7 +40,7 @@ from neutronclient.v2_0 import client as neutronclient
 from novaclient.client import Client
 from novaclient.exceptions import ClientException
 
-__version__ = '2.0.3'
+__version__ = '2.0.4'
 
 from perf_instance import PerfInstance as PerfInstance
 
@@ -511,6 +511,30 @@ def extract_user_host_pwd(user_host_pwd):
         sys.exit(4)
     return match.groups()
 
+def _merge_config(file, source_config, required=False):
+    '''
+    returns the merged config or exits if the file does not exist and is required
+    '''
+    dest_config = source_config
+
+    fullname = os.path.expanduser(file)
+    if os.path.isfile(fullname):
+        print('Loading ' + fullname + '...')
+        try:
+            alt_config = configure.Configuration.from_file(fullname).configure()
+            dest_config = source_config.merge(alt_config)
+
+        except configure.ConfigurationError:
+            # this is in most cases when the config file passed is empty
+            # configure.ConfigurationError: unconfigured
+            # in case of syntax error, another exception is thrown:
+            # TypeError: string indices must be integers, not str
+            pass
+    elif required:
+        print('Error: configration file %s does not exist' % (fullname))
+        sys.exit(1)
+    return dest_config
+
 if __name__ == '__main__':
 
     fpr = FlowPrinter()
@@ -655,10 +679,15 @@ if __name__ == '__main__':
     default_cfg_file = get_absolute_path_for_file("cfg.default.yaml")
 
     # read the default configuration file and possibly an override config file
+    # the precedence order is as follows:
+    # $HOME/.vmtp.yaml if exists
+    # -c <file> from command line if provided
+    # cfg.default.yaml
     config = configure.Configuration.from_file(default_cfg_file).configure()
+    config = _merge_config('~/.vmtp.yaml', config)
+
     if opts.config:
-        alt_config = configure.Configuration.from_file(opts.config).configure()
-        config = config.merge(alt_config)
+        config = _merge_config(opts.config, config, required=True)
 
     if opts.version:
         print('Version ' + __version__)