Made the `flamenco-worker.cfg` file mandatory

This makes debugging configuration issues easier. When the file does not
exist, the absolute path of its expected location is logged.

Also moved from os.path to using pathlib.

CHANGELOG.md

@@ -3,6 +3,13 @@
 This file logs the changes that are actually interesting to users (new features,
 changed functionality, fixed bugs).
 
+## Version 2.0.3 (released 2017-04-07)
+
+- Made the `flamenco-worker.cfg` file mandatory, as this makes debugging configuration
+  issues easier. When the file does not exist, the absolute path of its expected
+  location is logged.
+
+
 
 ## Version 2.0.2 (released 2017-04-07)
 

README.md

@@ -20,24 +20,24 @@ Configuration is read from three locations:
 
 - A hard-coded default in the Python source code.
 - `flamenco-worker.cfg` in the current working directory.
-- `$HOME/.flamenco-worker.cfg`.
+- `$HOME/.flamenco-worker.cfg`; this file is optional.
 
-When those files do not exist, they are skipped (i.e. this is not an error). They
-should be in INI format, as specified by the
+The configuration files should be in INI format, as specified by the
 [configparser documentation](https://docs.python.org/3/library/configparser.html)
 
 
 ### Configuration contents:
 
 All configuration keys should be placed in the `[flamenco-worker]` section of the
-config files.
+config files. At least take a look at:
 
 - `manager_url`: Flamenco Manager URL.
-- `job_types`: Space-separated list of job types this worker may execute.
+- `task_types`: Space-separated list of task types this worker may execute.
 - `task_update_queue_db`: filename of the SQLite3 database holding the queue of task
   updates to be sent to the Master.
-These configuration keys are also required, but are created automatically upon startup
-when they don't exist yet:
+
+These configuration keys are also required, but are created automatically in
+`$HOME/.flamenco-worker.cfg` when they don't exist yet:
 
 - `worker_id`: ID of the worker, handed out by the Manager upon registration (see
   Registration below) and used for authentication with the Manager.

flamenco-worker.cfg

@@ -34,6 +34,7 @@ args = (sys.stderr,)
 class = logging.handlers.TimedRotatingFileHandler
 formatter = flamenco
 # (filename, when, interval, backupCount, encoding, delay, utc, atTime=None)
+# Be aware that tilde expansion is *not* performed on the path.
 args = ('/tmp/flamenco-worker.log', 'midnight', 1, 7, 'utf8', True, True)
 
 [formatters]

flamenco_worker/cli.py

@@ -4,13 +4,14 @@ import argparse
 import asyncio
 import logging
 import logging.config
+import pathlib
 
 import requests
 
 
 def main():
     parser = argparse.ArgumentParser()
-    parser.add_argument('-c', '--config',
+    parser.add_argument('-c', '--config', type=pathlib.Path,
                         help='Load this configuration file instead of the default files.')
     parser.add_argument('-v', '--verbose', action='store_true',
                         help='Show configuration before starting, '

flamenco_worker/config.py

@@ -3,13 +3,13 @@
 import collections
 import configparser
 import datetime
-import os.path
+import pathlib
 import logging
 
 from . import worker
 
-HOME_CONFIG_FILE = os.path.expanduser('~/.flamenco-worker.cfg')
-GLOBAL_CONFIG_FILE = 'flamenco-worker.cfg'
+HOME_CONFIG_FILE = pathlib.Path('~/.flamenco-worker.cfg').expanduser()
+GLOBAL_CONFIG_FILE = pathlib.Path('./flamenco-worker.cfg').absolute()
 CONFIG_SECTION = 'flamenco-worker'
 
 DEFAULT_CONFIG = {
@@ -56,18 +56,18 @@ def merge_with_home_config(new_conf: dict):
     for key, value in new_conf.items():
         confparser.set(CONFIG_SECTION, key, value)
 
-    tmpname = HOME_CONFIG_FILE + '~'
+    tmpname = HOME_CONFIG_FILE.with_name(HOME_CONFIG_FILE.name + '~')
     log.debug('Writing configuration file to %s', tmpname)
     with open(tmpname, mode='wt', encoding='utf8') as outfile:
         confparser.write(outfile)
 
     log.debug('Moving configuration file to %s', HOME_CONFIG_FILE)
-    os.replace(tmpname, HOME_CONFIG_FILE)
+    tmpname.replace(HOME_CONFIG_FILE)
 
     log.info('Updated configuration file %s', HOME_CONFIG_FILE)
 
 
-def load_config(config_file: str = None,
+def load_config(config_file: pathlib.Path = None,
                 show_effective_config: bool = False) -> ConfigParser:
     """Loads one or more configuration files."""
 
@@ -80,11 +80,19 @@ def load_config(config_file: str = None,
 
     if config_file:
         log.info('Loading configuration from %s', config_file)
+        if not config_file.exists():
+            log.fatal('Config file %s does not exist', config_file)
+            raise SystemExit()
         loaded = confparser.read(config_file, encoding='utf8')
     else:
+        if not GLOBAL_CONFIG_FILE.exists():
+            log.fatal('Config file %s does not exist', GLOBAL_CONFIG_FILE)
+            raise SystemExit()
+
         config_files = [GLOBAL_CONFIG_FILE, HOME_CONFIG_FILE]
-        log.info('Loading configuration from %s', ', '.join(config_files))
-        loaded = confparser.read(config_files, encoding='utf8')
+        filenames = [str(f.absolute()) for f in config_files]
+        log.info('Loading configuration from %s', ', '.join(filenames))
+        loaded = confparser.read(filenames, encoding='utf8')
 
     log.info('Succesfully loaded: %s', loaded)