Improve error handling and output

Nathan Parsons · Nathan Parsons · commit 51475a8f024f · 2018-09-23T13:45:04.000+01:00
- Move 'click.command' to the script rather than the module.
- Use exceptions to handle errors and pass them to the script, rather than calling 'sys.exit' from the module.
- Use 'warnings.warn' to handle warnings and catch these in the script.
- Implement colourised print messages along with the '--nocolour' flag to disable them.
- Move message printing to the script rather than logging function, along with logic for '--quiet'.
- Set flake8 'max-line-length = 100'.
- Bump version number to 0.2 to reflect significant changes.
diff --git a/.flake8 b/.flake8
@@ -0,0 +1,2 @@
+[flake8]
+max-line-length=100
diff --git a/.gitignore b/.gitignore
@@ -102,3 +102,6 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# Ignore personal configuration (contains secrets!)
+config.yaml
diff --git a/README.md b/README.md
@@ -50,6 +50,7 @@ The script can be run manually by calling `godaddy-ddns` with the following opti
 - `--config`: Path to the configuration file (default: `/etc/godaddy-ddns/config.yaml`).
 - `--force`: Update the IP address regardless of the value in the cache.
 - `--quiet`: Don't print messages to `stdout`.
+- `--nocolour`: Don't use colour when printing to `stdout`.
 
 ### Systemd
 
diff --git a/bin/godaddy-ddns b/bin/godaddy-ddns
@@ -1,6 +1,65 @@
 #!/usr/bin/env python3
 
+import sys
+import warnings
+
+import click
+
 import godaddy_ddns
 
 
-godaddy_ddns.update_ip()
+@click.command()
+@click.option(
+    '--config', '-c',
+    default="/etc/godaddy-ddns/config.yaml",
+    help="Path to configuration file (.yaml).",
+    type=click.File('r')
+)
+@click.option('--force', '-f', is_flag=True, help="Update the IP regardless of the cached IP.")
+@click.option('--quiet', '-q', is_flag=True, help="Don't print to stdout.")
+@click.option('--nocolour', is_flag=True, help="Don't colourise messages to stdout.")
+def main(config, force, quiet, nocolour):
+    # Define an echo function to account for 'quiet' and 'nocolour'
+    def echo(msg):
+        if quiet:
+            pass
+        elif nocolour:
+            print(msg)
+        else:
+            godaddy_ddns.print_colourised(msg)
+
+    # Notify if forced
+    if force:
+        echo("Info: Beginning forced update.")
+
+    # Perform the update
+    try:
+        # Catch and record warnings to print later
+        with warnings.catch_warnings(record=True) as caught_warnings:
+            updated, myip, domains = godaddy_ddns.update_ip(config, force)
+    except (godaddy_ddns.ConfigError,
+            godaddy_ddns.BadResponse,
+            PermissionError,
+            ConnectionError) as e:
+        # Echo the message and exit with failure
+        echo(str(e))
+        sys.exit(1)
+    except:
+        echo("Error: An unexpected exception occurred!")
+        raise  # raise the exception for debugging/issue reporting
+
+    # Print any warnings
+    for warning in caught_warnings:
+        echo(str(warning.message))
+
+    # Report the status of the update
+    if updated:
+        forced = "forcefully " if force else ""
+        for domain in domains:
+            echo("Success: IP address {}updated to {} for {}.".format(forced, myip, domain))
+    else:
+        echo("Success: IP address is already up-to-date ({})".format(myip))
+
+
+if __name__ == "__main__":
+    main()
diff --git a/godaddy_ddns/__init__.py b/godaddy_ddns/__init__.py
@@ -1,8 +1,6 @@
 import datetime
-import errno
 import os
-import re
-import sys
+import warnings
 
 import click
 import pif
@@ -12,73 +10,75 @@
 from godaddypy.client import BadResponse
 
 
-@click.command()
-@click.option(
-    '--config',
-    default="/etc/godaddy-ddns/config.yaml",
-    help="Path to configuration file (.yaml).",
-    type=click.File('r')
-)
-@click.option('--force', is_flag=True, help="Update the IP regardless of the cached IP.")
-@click.option('--quiet', is_flag=True, help="Don't print to stdout.")
-def update_ip(config, force, quiet):
+class ConfigError(Exception):
+    pass
+
+
+def update_ip(config_file, force):
+    """Update the IP address for the configured domains/subdomains
+
+    Parameters:
+     - config_file: Open file or file-like object configuration file
+     - force: boolean flag for forcing updates (True => force update)
+
+    Returns:
+     - updated: bool indicating whether the IP address was updated
+     - myip: str containing the current IP address
+     - domains: list of updated domains (eg. ["[sub1,sub2].[example.com]"])
+    """
     # Load the configuration file
     try:
-        conf = yaml.load(config)
-    except yaml.MarkedYAMLError as e:
-        # If the error is marked, give the details
-        print("Error: Malformed configuration file.")
-        print(e)
-        sys.exit(errno.EINVAL)
-    except yaml.YAMLError:
-        # Otherwise just state that it's malformed
-        print("Error: Malformed configuration file")
-        sys.exit(errno.EINVAL)
+        config = yaml.load(config_file)
+    except (yaml.MarkedYAMLError, yaml.YAMLError) as e:
+        raise ConfigError("Error: {}".format(e))
 
     # Check the supplied log path
-    if conf.get("log_path", False):
+    log_path = config.get("log_path")
+    if log_path:
         # Make sure that the log path exists and is writable
         try:
-            touch(conf["log_path"])
+            touch(log_path)
         except PermissionError:
-            print("Error: Insufficient permissions to write log to '{}'.".format(conf['log_path']))
-            sys.exit(errno.EACCES)
+            msg = "Error: Insufficient permissions to write log to '{}'.".format(log_path)
+            raise PermissionError(msg)  # Currently no log, so just raise an exception
 
         # Define the logging function
         def write_log(msg):
             now = datetime.datetime.now().isoformat(' ', timespec='seconds')
-            with open(conf["log_path"], 'a') as f:
+            with open(log_path, 'a') as f:
                 f.write("[{now}]: {msg}\n".format(now=now, msg=msg))
-            if not quiet:
-                click.echo(msg)
     else:
         # No log file specified, so disable logging
         def write_log(msg):
-            if not quiet:
-                click.echo(msg)  # Just print the message, don't log it
+            pass
 
     # Check the supplied cache path
-    if conf.get("cache_path", False):
+    cache_path = config.get("cache_path")
+    if cache_path:
         # Make sure that the log path exists and is writable
         try:
-            touch(conf["cache_path"])  # Create the file if necessary
+            touch(cache_path)  # Create the file if necessary
         except PermissionError:
-            write_log("Error: Insufficient permissions to write to cache ({}).".format(conf['cache_path']))
-            sys.exit(errno.EACCES)
+            msg = "Error: Insufficient permissions to write to cache ({}).".format(cache_path)
+            write_log(msg)
+            raise PermissionError(msg)
 
         # Define the caching functions
         def write_cache(ip_addr):
             now = datetime.datetime.now().isoformat(' ', timespec='seconds')
-            with open(conf["cache_path"], 'w') as f:
+            with open(cache_path, 'w') as f:
                 f.write("[{}]: {}".format(now, ip_addr))
 
         def read_cache():
-            with open(conf["cache_path"], "r") as f:
+            with open(cache_path, "r") as f:
                 cached = f.readline()
             return (cached[1:20], cached[23:])  # date_time, ip_addr
     else:
         # No cache file specified, so disable caching and warn the user!
-        write_log("Warning: No cache file specified, so the IP address will always be submitted as if new - this could be considered abusive!")
+        msg = ("Warning: No cache file specified, so the IP address will always be submitted "
+               "as if new - this could be considered abusive!")
+        write_log(msg)
+        warnings.warn(msg)
 
         # Define the caching functions
         def write_cache(ip_addr):
@@ -88,11 +88,12 @@ def read_cache():
             return (None, None)
 
     # Get IPv4 address
-    myip = pif.get_public_ip("v4.ident.me")
+    myip = pif.get_public_ip("v4.ident.me")  # Enforce IPv4 (for now)
 
     if not myip:
-        write_log("Error: Failed to determine IPv4 address")
-        sys.exit(errno.CONNREFUSED)
+        msg = "Error: Failed to determine IPv4 address"
+        write_log(msg)
+        raise ConnectionError(msg)
 
     # Check whether the current IP is equal to the cached IP address
     date_time, cached_ip = read_cache()
@@ -101,63 +102,125 @@ def read_cache():
     elif myip == cached_ip:
         # Already up-to-date, so log it and exit
         write_log("Success: IP address is already up-to-date ({})".format(myip))
-        sys.exit(0)
+        return (False, myip, None)
     else:
         write_log("Info: New IP address detected ({})".format(myip))
 
     # Get API details
-    account = Account(api_key=conf.get("api_key"), api_secret=conf.get("api_secret"))
-    client = Client(account, api_base_url=conf.get("api_base_url", "https://api.godaddy.com"))
+    api_key = config.get("api_key")
+    api_secret = config.get("api_secret")
+
+    # Check that they have values
+    missing_cred = []
+    if not api_key:
+        missing_cred.append("'api_key'")
+    if not api_secret:
+        missing_cred.append("'api_secret'")
+
+    if missing_cred:
+        msg = "Error: Missing credentials - {} must be specified".format(" and ".join(missing_cred))
+        write_log(msg)
+        raise ConfigError(msg)
+
+    # Initialise the connection classes
+    account = Account(api_key=config.get("api_key"), api_secret=config.get("api_secret"))
+    client = Client(account, api_base_url=config.get("api_base_url", "https://api.godaddy.com"))
 
     # Check that we have a connection and get the set of available domains
     try:
         available_domains = set(client.get_domains())
     except BadResponse as e:
-        write_log("Error: Bad response from GoDaddy ({})".format(e._message))
-        sys.exit(errno.CONNREFUSED)
+        msg = "Error: Bad response from GoDaddy ({})".format(e._message)
+        write_log(msg)
+        raise BadResponse(msg)
 
     # Make the API requests to update the IP address
-    failed_domains = {}  # Stores a set of failed domains - failures will be tolerated but logged
-    for target in conf.get("targets", []):
+    failed_domains = set()  # Stores a set of failed domains - failures will be tolerated but logged
+    succeeded_domains = []
+    forced = "forcefully " if force else ""
+
+    for target in config.get("targets", []):
         try:
             target_domain = target["domain"]
         except KeyError:
-            write_log("Error: Missing 'domain' in confuration file")
-            sys.exit(errno.EINVAL)
+            msg = "Error: Missing 'domain' for target in configuration file"
+            write_log(msg)
+            raise ConfigError(msg)
 
-        if type(target_domain) == str:
-            target_domain = {target_domain}
+        if isinstance(target_domain, str):
+            target_domain = {target_domain}  # set of one element
         else:
-            target_domain = set(target_domain)
+            target_domain = set(target_domain)  # set of supplied targets
 
         unknown_domains = target_domain - available_domains
         failed_domains.update(unknown_domains)
 
         domains = list(target_domain & available_domains)  # Remove unknown domains
+        if not domains:
+            continue  # No known domains, so don't bother contacting GoDaddy
+
         subdomains = target.get("alias", "@")  # Default to no subdomain (GoDaddy uses "@" for this)
 
         try:
             update_succeeded = client.update_ip(myip, domains=domains, subdomains=subdomains)
         except BadResponse as e:
-            write_log("Error: Bad response from GoDaddy ({})".format(e._message))
-            sys.exit(errno.CONNREFUSED)
+            msg = "Error: Bad response from GoDaddy ({})".format(e._message)
+            write_log(msg)
+            raise BadResponse(msg)
 
         if update_succeeded:
-            write_log("Success: Updated IP for {subs}.{doms}".format(subs=subdomains, doms=domains))
+            succeeded_domains.append("{subs}.{doms}".format(subs=subdomains, doms=domains))
+            write_log("Success: IP address {}updated to {} for {}.".format(forced,
+                                                                           myip,
+                                                                           succeeded_domains[-1]))
         else:
-            write_log("Error: Unknown failure for (domain(s): {doms}, alias(es): {subs})".format(doms=target_domain, subs=subdomains))
-            sys.exit(errno.CONNREFUSED)
+            msg = "Error: Unknown failure for (domain(s): {doms}, alias(es): {subs})".format(
+                        doms=target_domain, subs=subdomains)
+            write_log(msg)
+            raise BadResponse(msg)
 
     if failed_domains:
-        write_log("Warning: The following domains were not found {}".format(failed_domains))
+        msg = "Warning: The following domains were not found {}".format(failed_domains)
+        write_log(msg)
+        warnings.warn(msg)
 
-    # Write the new IP address to the cache and exit
+    # Write the new IP address to the cache and return
     write_cache(myip)
-    sys.exit(0)
+    return (True, myip, succeeded_domains)
+
+
+def print_colourised(msg):
+    """Print messages automatically colourised based on initial keywords
+
+    Currently supports: "Success", "Info", "Warning", "Error", None
+    """
+    if msg.startswith("Success"):
+        style = {
+            "fg": "green",
+            "bold": True,
+        }
+    elif msg.startswith("Info"):
+        style = {
+            "fg": "blue",
+        }
+    elif msg.startswith("Warning"):
+        style = {
+            "fg": "yellow",
+        }
+    elif msg.startswith("Error"):
+        style = {
+            "fg": "red",
+            "bold": True,
+        }
+    else:
+        style = {}  # Don't apply a special style
+
+    click.echo(click.style(msg, **style))
 
 
-# Define 'touch' function
 def touch(path):
+    """Touch a path, creating it if necessary
+    """
     # Ensure the path exists
     os.makedirs(os.path.dirname(path), exist_ok=True)
     # Create the file if necessary
diff --git a/setup.py b/setup.py
@@ -2,7 +2,7 @@
 
 
 setup(name='godaddy-ddns',
-      version='0.1',
+      version='0.2',
       description='DDNS-like update service for GoDaddy',
       url='http://github.com/N-Parsons/godaddy-ddns',
       author='Nathan Parsons',
