Add code style plugins to enforce use of Python f-strings and prevent single-letter variables.

NEWS

@@ -6,6 +6,8 @@
    in borgmatic's storage configuration.
  * #623: Fix confusing message when an error occurs running actions for a configuration file.
  * #655: Fix error when databases are configured and a source directory doesn't exist.
+ * Add code style plugins to enforce use of Python f-strings and prevent single-letter variables.
+   To join in the pedantry, refresh your test environment with "tox --recreate".
 
 1.7.9
  * #295: Add a SQLite database dump/restore hook.

borgmatic/actions/borg.py

@@ -16,7 +16,7 @@ def run_borg(
     if borg_arguments.repository is None or borgmatic.config.validate.repositories_match(
         repository, borg_arguments.repository
     ):
-        logger.info('{}: Running arbitrary Borg command'.format(repository))
+        logger.info(f'{repository}: Running arbitrary Borg command')
         archive_name = borgmatic.borg.rlist.resolve_archive_name(
             repository,
             borg_arguments.archive,

borgmatic/actions/check.py

@@ -37,7 +37,7 @@ def run_check(
         global_arguments.dry_run,
         **hook_context,
     )
-    logger.info('{}: Running consistency checks'.format(repository))
+    logger.info(f'{repository}: Running consistency checks')
     borgmatic.borg.check.check_archives(
         repository,
         location,

borgmatic/actions/compact.py

@@ -39,7 +39,7 @@ def run_compact(
         **hook_context,
     )
     if borgmatic.borg.feature.available(borgmatic.borg.feature.Feature.COMPACT, local_borg_version):
-        logger.info('{}: Compacting segments{}'.format(repository, dry_run_label))
+        logger.info(f'{repository}: Compacting segments{dry_run_label}')
         borgmatic.borg.compact.compact_segments(
             global_arguments.dry_run,
             repository,
@@ -52,7 +52,7 @@ def run_compact(
             threshold=compact_arguments.threshold,
         )
     else:  # pragma: nocover
-        logger.info('{}: Skipping compact (only available/needed in Borg 1.2+)'.format(repository))
+        logger.info(f'{repository}: Skipping compact (only available/needed in Borg 1.2+)')
     borgmatic.hooks.command.execute_hook(
         hooks.get('after_compact'),
         hooks.get('umask'),

borgmatic/actions/create.py

@@ -42,7 +42,7 @@ def run_create(
         global_arguments.dry_run,
         **hook_context,
     )
-    logger.info('{}: Creating archive{}'.format(repository, dry_run_label))
+    logger.info(f'{repository}: Creating archive{dry_run_label}')
     borgmatic.hooks.dispatch.call_hooks_even_if_unconfigured(
         'remove_database_dumps',
         hooks,

borgmatic/actions/export_tar.py

@@ -22,9 +22,7 @@ def run_export_tar(
     if export_tar_arguments.repository is None or borgmatic.config.validate.repositories_match(
         repository, export_tar_arguments.repository
     ):
-        logger.info(
-            '{}: Exporting archive {} as tar file'.format(repository, export_tar_arguments.archive)
-        )
+        logger.info(f'{repository}: Exporting archive {export_tar_arguments.archive} as tar file')
         borgmatic.borg.export_tar.export_tar_archive(
             global_arguments.dry_run,
             repository,

borgmatic/actions/extract.py

@@ -35,7 +35,7 @@ def run_extract(
     if extract_arguments.repository is None or borgmatic.config.validate.repositories_match(
         repository, extract_arguments.repository
     ):
-        logger.info('{}: Extracting archive {}'.format(repository, extract_arguments.archive))
+        logger.info(f'{repository}: Extracting archive {extract_arguments.archive}')
         borgmatic.borg.extract.extract_archive(
             global_arguments.dry_run,
             repository,

borgmatic/actions/mount.py

@@ -17,9 +17,9 @@ def run_mount(
         repository, mount_arguments.repository
     ):
         if mount_arguments.archive:
-            logger.info('{}: Mounting archive {}'.format(repository, mount_arguments.archive))
+            logger.info(f'{repository}: Mounting archive {mount_arguments.archive}')
         else:  # pragma: nocover
-            logger.info('{}: Mounting repository'.format(repository))
+            logger.info(f'{repository}: Mounting repository')
 
         borgmatic.borg.mount.mount_archive(
             repository,

borgmatic/actions/prune.py

@@ -37,7 +37,7 @@ def run_prune(
         global_arguments.dry_run,
         **hook_context,
     )
-    logger.info('{}: Pruning archives{}'.format(repository, dry_run_label))
+    logger.info(f'{repository}: Pruning archives{dry_run_label}')
     borgmatic.borg.prune.prune_archives(
         global_arguments.dry_run,
         repository,

borgmatic/actions/rcreate.py

@@ -23,7 +23,7 @@ def run_rcreate(
     ):
         return
 
-    logger.info('{}: Creating repository'.format(repository))
+    logger.info(f'{repository}: Creating repository')
     borgmatic.borg.rcreate.create_repository(
         global_arguments.dry_run,
         repository,

borgmatic/actions/restore.py

@@ -255,9 +255,8 @@ def run_restore(
     ):
         return
 
-    logger.info(
-        '{}: Restoring databases from archive {}'.format(repository, restore_arguments.archive)
-    )
+    logger.info(f'{repository}: Restoring databases from archive {restore_arguments.archive}')
+
     borgmatic.hooks.dispatch.call_hooks_even_if_unconfigured(
         'remove_database_dumps',
         hooks,

borgmatic/actions/rinfo.py

@@ -19,7 +19,8 @@ def run_rinfo(
         repository, rinfo_arguments.repository
     ):
         if not rinfo_arguments.json:  # pragma: nocover
-            logger.answer('{}: Displaying repository summary information'.format(repository))
+            logger.answer(f'{repository}: Displaying repository summary information')
+
         json_output = borgmatic.borg.rinfo.display_repository_info(
             repository,
             storage,

borgmatic/actions/rlist.py

@@ -19,7 +19,8 @@ def run_rlist(
         repository, rlist_arguments.repository
     ):
         if not rlist_arguments.json:  # pragma: nocover
-            logger.answer('{}: Listing repository'.format(repository))
+            logger.answer(f'{repository}: Listing repository')
+
         json_output = borgmatic.borg.rlist.list_repository(
             repository,
             storage,

borgmatic/borg/check.py

@@ -12,7 +12,7 @@ DEFAULT_CHECKS = (
     {'name': 'repository', 'frequency': '1 month'},
     {'name': 'archives', 'frequency': '1 month'},
 )
-DEFAULT_PREFIX = '{hostname}-'
+DEFAULT_PREFIX = '{hostname}-'  # noqa: FS003
 
 
 logger = logging.getLogger(__name__)
@@ -196,7 +196,7 @@ def make_check_flags(local_borg_version, checks, check_last=None, prefix=None):
         return common_flags
 
     return (
-        tuple('--{}-only'.format(check) for check in checks if check in ('repository', 'archives'))
+        tuple(f'--{check}-only' for check in checks if check in ('repository', 'archives'))
         + common_flags
     )
 

borgmatic/borg/create.py

@@ -217,7 +217,7 @@ def make_list_filter_flags(local_borg_version, dry_run):
         return f'{base_flags}-'
 
 
-DEFAULT_ARCHIVE_NAME_FORMAT = '{hostname}-{now:%Y-%m-%dT%H:%M:%S.%f}'
+DEFAULT_ARCHIVE_NAME_FORMAT = '{hostname}-{now:%Y-%m-%dT%H:%M:%S.%f}'  # noqa: FS003
 
 
 def collect_borgmatic_source_directories(borgmatic_source_directory):

borgmatic/borg/export_tar.py

@@ -56,7 +56,7 @@ def export_tar_archive(
         output_log_level = logging.INFO
 
     if dry_run:
-        logging.info('{}: Skipping export to tar file (dry run)'.format(repository))
+        logging.info(f'{repository}: Skipping export to tar file (dry run)')
         return
 
     execute_command(

borgmatic/borg/flags.py

@@ -10,7 +10,7 @@ def make_flags(name, value):
     if not value:
         return ()
 
-    flag = '--{}'.format(name.replace('_', '-'))
+    flag = f"--{name.replace('_', '-')}"
 
     if value is True:
         return (flag,)

borgmatic/borg/list.py

@@ -113,7 +113,7 @@ def capture_archive_listing(
                     paths=[f'sh:{list_path}'],
                     find_paths=None,
                     json=None,
-                    format='{path}{NL}',
+                    format='{path}{NL}',  # noqa: FS003
                 ),
                 local_path,
                 remote_path,

borgmatic/borg/prune.py

@@ -24,7 +24,7 @@ def make_prune_flags(retention_config, local_borg_version):
         )
     '''
     config = retention_config.copy()
-    prefix = config.pop('prefix', '{hostname}-')
+    prefix = config.pop('prefix', '{hostname}-')  # noqa: FS003
 
     if prefix:
         if feature.available(feature.Feature.MATCH_ARCHIVES, local_borg_version):

borgmatic/borg/rlist.py

@@ -42,7 +42,7 @@ def resolve_archive_name(
     except IndexError:
         raise ValueError('No archives found in the repository')
 
-    logger.debug('{}: Latest archive is {}'.format(repository, latest_archive))
+    logger.debug(f'{repository}: Latest archive is {latest_archive}')
 
     return latest_archive
 

borgmatic/commands/arguments.py

@@ -131,9 +131,7 @@ def make_parsers():
         nargs='*',
         dest='config_paths',
         default=config_paths,
-        help='Configuration filenames or directories, defaults to: {}'.format(
-            ' '.join(unexpanded_config_paths)
-        ),
+        help=f"Configuration filenames or directories, defaults to: {' '.join(unexpanded_config_paths)}",
     )
     global_group.add_argument(
         '--excludes',

borgmatic/commands/borgmatic.py

@@ -70,9 +70,7 @@ def run_configuration(config_filename, config, arguments):
     try:
         local_borg_version = borg_version.local_borg_version(storage, local_path)
     except (OSError, CalledProcessError, ValueError) as error:
-        yield from log_error_records(
-            '{}: Error getting local Borg version'.format(config_filename), error
-        )
+        yield from log_error_records(f'{config_filename}: Error getting local Borg version', error)
         return
 
     try:
@@ -100,7 +98,7 @@ def run_configuration(config_filename, config, arguments):
             return
 
         encountered_error = error
-        yield from log_error_records('{}: Error pinging monitor'.format(config_filename), error)
+        yield from log_error_records(f'{config_filename}: Error pinging monitor', error)
 
     if not encountered_error:
         repo_queue = Queue()
@@ -132,7 +130,7 @@ def run_configuration(config_filename, config, arguments):
                     repo_queue.put((repository_path, retry_num + 1),)
                     tuple(  # Consume the generator so as to trigger logging.
                         log_error_records(
-                            '{}: Error running actions for repository'.format(repository_path),
+                            f'{repository_path}: Error running actions for repository',
                             error,
                             levelno=logging.WARNING,
                             log_command_error_output=True,
@@ -147,7 +145,7 @@ def run_configuration(config_filename, config, arguments):
                     return
 
                 yield from log_error_records(
-                    '{}: Error running actions for repository'.format(repository_path), error
+                    f'{repository_path}: Error running actions for repository', error
                 )
                 encountered_error = error
                 error_repository = repository_path
@@ -169,7 +167,7 @@ def run_configuration(config_filename, config, arguments):
             return
 
         encountered_error = error
-        yield from log_error_records('{}: Error pinging monitor'.format(config_filename), error)
+        yield from log_error_records(f'{repository_path}: Error pinging monitor', error)
 
     if not encountered_error:
         try:
@@ -196,7 +194,7 @@ def run_configuration(config_filename, config, arguments):
                 return
 
             encountered_error = error
-            yield from log_error_records('{}: Error pinging monitor'.format(config_filename), error)
+            yield from log_error_records(f'{config_filename}: Error pinging monitor', error)
 
     if encountered_error and using_primary_action:
         try:
@@ -231,9 +229,7 @@ def run_configuration(config_filename, config, arguments):
             if command.considered_soft_failure(config_filename, error):
                 return
 
-            yield from log_error_records(
-                '{}: Error running on-error hook'.format(config_filename), error
-            )
+            yield from log_error_records(f'{config_filename}: Error running on-error hook', error)
 
 
 def run_actions(
@@ -472,9 +468,7 @@ def load_configurations(config_filenames, overrides=None, resolve_env=True):
                         dict(
                             levelno=logging.WARNING,
                             levelname='WARNING',
-                            msg='{}: Insufficient permissions to read configuration file'.format(
-                                config_filename
-                            ),
+                            msg=f'{config_filename}: Insufficient permissions to read configuration file',
                         )
                     ),
                 ]
@@ -486,7 +480,7 @@ def load_configurations(config_filenames, overrides=None, resolve_env=True):
                         dict(
                             levelno=logging.CRITICAL,
                             levelname='CRITICAL',
-                            msg='{}: Error parsing configuration file'.format(config_filename),
+                            msg=f'{config_filename}: Error parsing configuration file',
                         )
                     ),
                     logging.makeLogRecord(
@@ -587,9 +581,7 @@ def collect_configuration_run_summary_logs(configs, arguments):
 
     if not configs:
         yield from log_error_records(
-            '{}: No valid configuration files found'.format(
-                ' '.join(arguments['global'].config_paths)
-            )
+            r"{' '.join(arguments['global'].config_paths)}: No valid configuration files found",
         )
         return
 
@@ -615,21 +607,21 @@ def collect_configuration_run_summary_logs(configs, arguments):
         error_logs = tuple(result for result in results if isinstance(result, logging.LogRecord))
 
         if error_logs:
-            yield from log_error_records('{}: An error occurred'.format(config_filename))
+            yield from log_error_records(f'{config_filename}: An error occurred')
             yield from error_logs
         else:
             yield logging.makeLogRecord(
                 dict(
                     levelno=logging.INFO,
                     levelname='INFO',
-                    msg='{}: Successfully ran configuration file'.format(config_filename),
+                    msg=f'{config_filename}: Successfully ran configuration file',
                 )
             )
             if results:
                 json_results.extend(results)
 
     if 'umount' in arguments:
-        logger.info('Unmounting mount point {}'.format(arguments['umount'].mount_point))
+        logger.info(f"Unmounting mount point {arguments['umount'].mount_point}")
         try:
             borg_umount.unmount_archive(
                 mount_point=arguments['umount'].mount_point, local_path=get_local_path(configs),
@@ -677,7 +669,7 @@ def main():  # pragma: no cover
         if error.code == 0:
             raise error
         configure_logging(logging.CRITICAL)
-        logger.critical('Error parsing arguments: {}'.format(' '.join(sys.argv)))
+        logger.critical(f"Error parsing arguments: {' '.join(sys.argv)}")
         exit_with_help_link()
 
     global_arguments = arguments['global']
@@ -710,7 +702,7 @@ def main():  # pragma: no cover
         )
     except (FileNotFoundError, PermissionError) as error:
         configure_logging(logging.CRITICAL)
-        logger.critical('Error configuring logging: {}'.format(error))
+        logger.critical(f'Error configuring logging: {error}')
         exit_with_help_link()
 
     logger.debug('Ensuring legacy configuration is upgraded')

borgmatic/commands/completion.py

@@ -34,7 +34,7 @@ def bash_completion():
             '    local this_script="$(cat "$BASH_SOURCE" 2> /dev/null)"',
             '    local installed_script="$(borgmatic --bash-completion 2> /dev/null)"',
             '    if [ "$this_script" != "$installed_script" ] && [ "$installed_script" != "" ];'
-            '        then cat << EOF\n%s\nEOF' % UPGRADE_MESSAGE,
+            f'        then cat << EOF\n{UPGRADE_MESSAGE}\nEOF',
             '    fi',
             '}',
             'complete_borgmatic() {',
@@ -48,7 +48,7 @@ def bash_completion():
             for action, subparser in subparsers.choices.items()
         )
         + (
-            '    COMPREPLY=($(compgen -W "%s %s" -- "${COMP_WORDS[COMP_CWORD]}"))'
+            '    COMPREPLY=($(compgen -W "%s %s" -- "${COMP_WORDS[COMP_CWORD]}"))'  # noqa: FS003
             % (actions, global_flags),
             '    (check_version &)',
             '}',

borgmatic/commands/convert_config.py

@@ -28,9 +28,7 @@ def parse_arguments(*arguments):
         '--source-config',
         dest='source_config_filename',
         default=DEFAULT_SOURCE_CONFIG_FILENAME,
-        help='Source INI-style configuration filename. Default: {}'.format(
-            DEFAULT_SOURCE_CONFIG_FILENAME
-        ),
+        help=f'Source INI-style configuration filename. Default: {DEFAULT_SOURCE_CONFIG_FILENAME}',
     )
     parser.add_argument(
         '-e',
@@ -46,9 +44,7 @@ def parse_arguments(*arguments):
         '--destination-config',
         dest='destination_config_filename',
         default=DEFAULT_DESTINATION_CONFIG_FILENAME,
-        help='Destination YAML configuration filename. Default: {}'.format(
-            DEFAULT_DESTINATION_CONFIG_FILENAME
-        ),
+        help=f'Destination YAML configuration filename. Default: {DEFAULT_DESTINATION_CONFIG_FILENAME}',
     )
 
     return parser.parse_args(arguments)
@@ -59,19 +55,15 @@ TEXT_WRAP_CHARACTERS = 80
 
 def display_result(args):  # pragma: no cover
     result_lines = textwrap.wrap(
-        'Your borgmatic configuration has been upgraded. Please review the result in {}.'.format(
-            args.destination_config_filename
-        ),
+        f'Your borgmatic configuration has been upgraded. Please review the result in {args.destination_config_filename}.',
         TEXT_WRAP_CHARACTERS,
     )
 
+    excludes_phrase = (
+        f' and {args.source_excludes_filename}' if args.source_excludes_filename else ''
+    )
     delete_lines = textwrap.wrap(
-        'Once you are satisfied, you can safely delete {}{}.'.format(
-            args.source_config_filename,
-            ' and {}'.format(args.source_excludes_filename)
-            if args.source_excludes_filename
-            else '',
-        ),
+        f'Once you are satisfied, you can safely delete {args.source_config_filename}{excludes_phrase}.',
         TEXT_WRAP_CHARACTERS,
     )
 

borgmatic/commands/generate_config.py

@@ -23,9 +23,7 @@ def parse_arguments(*arguments):
         '--destination',
         dest='destination_filename',
         default=DEFAULT_DESTINATION_CONFIG_FILENAME,
-        help='Destination YAML configuration file, default: {}'.format(
-            DEFAULT_DESTINATION_CONFIG_FILENAME
-        ),
+        help=f'Destination YAML configuration file, default: {DEFAULT_DESTINATION_CONFIG_FILENAME}',
     )
     parser.add_argument(
         '--overwrite',
@@ -48,17 +46,13 @@ def main():  # pragma: no cover
             overwrite=args.overwrite,
         )
 
-        print('Generated a sample configuration file at {}.'.format(args.destination_filename))
+        print(f'Generated a sample configuration file at {args.destination_filename}.')
         print()
         if args.source_filename:
-            print(
-                'Merged in the contents of configuration file at {}.'.format(args.source_filename)
-            )
+            print(f'Merged in the contents of configuration file at {args.source_filename}.')
             print('To review the changes made, run:')
             print()
-            print(
-                '    diff --unified {} {}'.format(args.source_filename, args.destination_filename)
-            )
+            print(f'    diff --unified {args.source_filename} {args.destination_filename}')
             print()
         print('This includes all available configuration options with example values. The few')
         print('required options are indicated. Please edit the file to suit your needs.')

borgmatic/commands/validate_config.py

@@ -21,9 +21,7 @@ def parse_arguments(*arguments):
         nargs='+',
         dest='config_paths',
         default=config_paths,
-        help='Configuration filenames or directories, defaults to: {}'.format(
-            ' '.join(config_paths)
-        ),
+        help=f'Configuration filenames or directories, defaults to: {config_paths}',
     )
 
     return parser.parse_args(arguments)
@@ -44,13 +42,11 @@ def main():  # pragma: no cover
         try:
             validate.parse_configuration(config_filename, validate.schema_filename())
         except (ValueError, OSError, validate.Validation_error) as error:
-            logging.critical('{}: Error parsing configuration file'.format(config_filename))
+            logging.critical(f'{config_filename}: Error parsing configuration file')
             logging.critical(error)
             found_issues = True
 
     if found_issues:
         sys.exit(1)
     else:
-        logger.info(
-            'All given configuration files are valid: {}'.format(', '.join(config_filenames))
-        )
+        logger.info(f"All given configuration files are valid: {', '.join(config_filenames)}")

borgmatic/config/collect.py

@@ -16,8 +16,8 @@ def get_default_config_paths(expand_home=True):
     return [
         '/etc/borgmatic/config.yaml',
         '/etc/borgmatic.d',
-        '%s/borgmatic/config.yaml' % user_config_directory,
-        '%s/borgmatic.d' % user_config_directory,
+        os.path.join(user_config_directory, 'borgmatic/config.yaml'),
+        os.path.join(user_config_directory, 'borgmatic.d'),
     ]
 
 

borgmatic/config/environment.py

@@ -14,11 +14,14 @@ def _resolve_string(matcher):
     if matcher.group('escape') is not None:
         # in case of escaped envvar, unescape it
         return matcher.group('variable')
+
     # resolve the env var
     name, default = matcher.group('name'), matcher.group('default')
     out = os.getenv(name, default=default)
+
     if out is None:
-        raise ValueError('Cannot find variable ${name} in environment'.format(name=name))
+        raise ValueError(f'Cannot find variable {name} in environment')
+
     return out
 
 

borgmatic/config/generate.py

@@ -48,7 +48,7 @@ def _schema_to_sample_configuration(schema, level=0, parent_is_sequence=False):
             config, schema, indent=indent, skip_first=parent_is_sequence
         )
     else:
-        raise ValueError('Schema at level {} is unsupported: {}'.format(level, schema))
+        raise ValueError(f'Schema at level {level} is unsupported: {schema}')
 
     return config
 
@@ -84,7 +84,7 @@ def _comment_out_optional_configuration(rendered_config):
     for line in rendered_config.split('\n'):
         # Upon encountering an optional configuration option, comment out lines until the next blank
         # line.
-        if line.strip().startswith('# {}'.format(COMMENTED_OUT_SENTINEL)):
+        if line.strip().startswith(f'# {COMMENTED_OUT_SENTINEL}'):
             optional = True
             continue
 
@@ -117,9 +117,7 @@ def write_configuration(config_filename, rendered_config, mode=0o600, overwrite=
     '''
     if not overwrite and os.path.exists(config_filename):
         raise FileExistsError(
-            '{} already exists. Aborting. Use --overwrite to replace the file.'.format(
-                config_filename
-            )
+            f'{config_filename} already exists. Aborting. Use --overwrite to replace the file.'
         )
 
     try:
@@ -218,7 +216,7 @@ def remove_commented_out_sentinel(config, field_name):
     except KeyError:
         return
 
-    if last_comment_value == '# {}\n'.format(COMMENTED_OUT_SENTINEL):
+    if last_comment_value == f'# {COMMENTED_OUT_SENTINEL}\n':
         config.ca.items[field_name][RUAMEL_YAML_COMMENTS_INDEX].pop()
 
 

borgmatic/config/legacy.py

@@ -70,13 +70,11 @@ def validate_configuration_format(parser, config_format):
         section_format.name for section_format in config_format
     )
     if unknown_section_names:
-        raise ValueError(
-            'Unknown config sections found: {}'.format(', '.join(unknown_section_names))
-        )
+        raise ValueError(f"Unknown config sections found: {', '.join(unknown_section_names)}")
 
     missing_section_names = set(required_section_names) - section_names
     if missing_section_names:
-        raise ValueError('Missing config sections: {}'.format(', '.join(missing_section_names)))
+        raise ValueError(f"Missing config sections: {', '.join(missing_section_names)}")
 
     for section_format in config_format:
         if section_format.name not in section_names:
@@ -91,9 +89,7 @@ def validate_configuration_format(parser, config_format):
 
         if unexpected_option_names:
             raise ValueError(
-                'Unexpected options found in config section {}: {}'.format(
-                    section_format.name, ', '.join(sorted(unexpected_option_names))
-                )
+                f"Unexpected options found in config section {section_format.name}: {', '.join(sorted(unexpected_option_names))}",
             )
 
         missing_option_names = tuple(
@@ -105,9 +101,7 @@ def validate_configuration_format(parser, config_format):
 
         if missing_option_names:
             raise ValueError(
-                'Required options missing from config section {}: {}'.format(
-                    section_format.name, ', '.join(missing_option_names)
-                )
+                f"Required options missing from config section {section_format.name}: {', '.join(missing_option_names)}",
             )
 
 
@@ -137,7 +131,7 @@ def parse_configuration(config_filename, config_format):
     '''
     parser = RawConfigParser()
     if not parser.read(config_filename):
-        raise ValueError('Configuration file cannot be opened: {}'.format(config_filename))
+        raise ValueError(f'Configuration file cannot be opened: {config_filename}')
 
     validate_configuration_format(parser, config_format)
 

borgmatic/config/validate.py

@@ -20,9 +20,9 @@ def format_json_error_path_element(path_element):
     Given a path element into a JSON data structure, format it for display as a string.
     '''
     if isinstance(path_element, int):
-        return str('[{}]'.format(path_element))
+        return str(f'[{path_element}]')
 
-    return str('.{}'.format(path_element))
+    return str(f'.{path_element}')
 
 
 def format_json_error(error):
@@ -30,10 +30,10 @@ def format_json_error(error):
     Given an instance of jsonschema.exceptions.ValidationError, format it for display as a string.
     '''
     if not error.path:
-        return 'At the top level: {}'.format(error.message)
+        return f'At the top level: {error.message}'
 
     formatted_path = ''.join(format_json_error_path_element(element) for element in error.path)
-    return "At '{}': {}".format(formatted_path.lstrip('.'), error.message)
+    return f"At '{formatted_path.lstrip('.')}': {error.message}"
 
 
 class Validation_error(ValueError):
@@ -54,9 +54,10 @@ class Validation_error(ValueError):
         '''
         Render a validation error as a user-facing string.
         '''
-        return 'An error occurred while parsing a configuration file at {}:\n'.format(
-            self.config_filename
-        ) + '\n'.join(error for error in self.errors)
+        return (
+            f'An error occurred while parsing a configuration file at {self.config_filename}:\n'
+            + '\n'.join(error for error in self.errors)
+        )
 
 
 def apply_logical_validation(config_filename, parsed_configuration):
@@ -72,9 +73,7 @@ def apply_logical_validation(config_filename, parsed_configuration):
             raise Validation_error(
                 config_filename,
                 (
-                    'Unknown repository in the "consistency" section\'s "check_repositories": {}'.format(
-                        repository
-                    ),
+                    f'Unknown repository in the "consistency" section\'s "check_repositories": {repository}',
                 ),
             )
 
@@ -165,9 +164,9 @@ def guard_configuration_contains_repository(repository, configurations):
     )
 
     if count == 0:
-        raise ValueError('Repository {} not found in configuration files'.format(repository))
+        raise ValueError(f'Repository {repository} not found in configuration files')
     if count > 1:
-        raise ValueError('Repository {} found in multiple configuration files'.format(repository))
+        raise ValueError(f'Repository {repository} found in multiple configuration files')
 
 
 def guard_single_repository_selected(repository, configurations):

borgmatic/execute.py

@@ -154,8 +154,8 @@ def log_command(full_command, input_file=None, output_file=None):
     '''
     logger.debug(
         ' '.join(full_command)
-        + (' < {}'.format(getattr(input_file, 'name', '')) if input_file else '')
-        + (' > {}'.format(getattr(output_file, 'name', '')) if output_file else '')
+        + (f" < {getattr(input_file, 'name', '')}" if input_file else '')
+        + (f" > {getattr(output_file, 'name', '')}" if output_file else '')
     )
 
 
@@ -235,12 +235,12 @@ def execute_command_and_capture_output(
             env=environment,
             cwd=working_directory,
         )
-        logger.warning('Command output: {}'.format(output))
+        logger.warning(f'Command output: {output}')
     except subprocess.CalledProcessError as error:
         if exit_code_indicates_error(command, error.returncode):
             raise
         output = error.output
-        logger.warning('Command output: {}'.format(output))
+        logger.warning(f'Command output: {output}')
 
     return output.decode() if output is not None else None
 

borgmatic/hooks/command.py

@@ -16,7 +16,7 @@ def interpolate_context(config_filename, hook_description, command, context):
     names/values, interpolate the values by "{name}" into the command and return the result.
     '''
     for name, value in context.items():
-        command = command.replace('{%s}' % name, str(value))
+        command = command.replace(f'{{{name}}}', str(value))
 
     for unsupported_variable in re.findall(r'{\w+}', command):
         logger.warning(
@@ -38,7 +38,7 @@ def execute_hook(commands, umask, config_filename, description, dry_run, **conte
     Raise subprocesses.CalledProcessError if an error occurs in a hook.
     '''
     if not commands:
-        logger.debug('{}: No commands to run for {} hook'.format(config_filename, description))
+        logger.debug(f'{config_filename}: No commands to run for {description} hook')
         return
 
     dry_run_label = ' (dry run; not actually running hooks)' if dry_run else ''
@@ -49,19 +49,15 @@ def execute_hook(commands, umask, config_filename, description, dry_run, **conte
     ]
 
     if len(commands) == 1:
-        logger.info(
-            '{}: Running command for {} hook{}'.format(config_filename, description, dry_run_label)
-        )
+        logger.info(f'{config_filename}: Running command for {description} hook{dry_run_label}')
     else:
         logger.info(
-            '{}: Running {} commands for {} hook{}'.format(
-                config_filename, len(commands), description, dry_run_label
-            )
+            f'{config_filename}: Running {len(commands)} commands for {description} hook{dry_run_label}',
         )
 
     if umask:
         parsed_umask = int(str(umask), 8)
-        logger.debug('{}: Set hook umask to {}'.format(config_filename, oct(parsed_umask)))
+        logger.debug(f'{config_filename}: Set hook umask to {oct(parsed_umask)}')
         original_umask = os.umask(parsed_umask)
     else:
         original_umask = None
@@ -93,9 +89,7 @@ def considered_soft_failure(config_filename, error):
 
     if exit_code == SOFT_FAIL_EXIT_CODE:
         logger.info(
-            '{}: Command hook exited with soft failure exit code ({}); skipping remaining actions'.format(
-                config_filename, SOFT_FAIL_EXIT_CODE
-            )
+            f'{config_filename}: Command hook exited with soft failure exit code ({SOFT_FAIL_EXIT_CODE}); skipping remaining actions',
         )
         return True
 

borgmatic/hooks/cronhub.py

@@ -34,17 +34,15 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
         return
 
     dry_run_label = ' (dry run; not actually pinging)' if dry_run else ''
-    formatted_state = '/{}/'.format(MONITOR_STATE_TO_CRONHUB[state])
+    formatted_state = f'/{MONITOR_STATE_TO_CRONHUB[state]}/'
     ping_url = (
         hook_config['ping_url']
         .replace('/start/', formatted_state)
         .replace('/ping/', formatted_state)
     )
 
-    logger.info(
-        '{}: Pinging Cronhub {}{}'.format(config_filename, state.name.lower(), dry_run_label)
-    )
-    logger.debug('{}: Using Cronhub ping URL {}'.format(config_filename, ping_url))
+    logger.info(f'{config_filename}: Pinging Cronhub {state.name.lower()}{dry_run_label}')
+    logger.debug(f'{config_filename}: Using Cronhub ping URL {ping_url}')
 
     if not dry_run:
         logging.getLogger('urllib3').setLevel(logging.ERROR)

borgmatic/hooks/cronitor.py

@@ -34,12 +34,10 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
         return
 
     dry_run_label = ' (dry run; not actually pinging)' if dry_run else ''
-    ping_url = '{}/{}'.format(hook_config['ping_url'], MONITOR_STATE_TO_CRONITOR[state])
+    ping_url = f"{hook_config['ping_url']}/{MONITOR_STATE_TO_CRONITOR[state]}"
 
-    logger.info(
-        '{}: Pinging Cronitor {}{}'.format(config_filename, state.name.lower(), dry_run_label)
-    )
-    logger.debug('{}: Using Cronitor ping URL {}'.format(config_filename, ping_url))
+    logger.info(f'{config_filename}: Pinging Cronitor {state.name.lower()}{dry_run_label}')
+    logger.debug(f'{config_filename}: Using Cronitor ping URL {ping_url}')
 
     if not dry_run:
         logging.getLogger('urllib3').setLevel(logging.ERROR)

borgmatic/hooks/dispatch.py

@@ -43,9 +43,9 @@ def call_hook(function_name, hooks, log_prefix, hook_name, *args, **kwargs):
     try:
         module = HOOK_NAME_TO_MODULE[hook_name]
     except KeyError:
-        raise ValueError('Unknown hook name: {}'.format(hook_name))
+        raise ValueError(f'Unknown hook name: {hook_name}')
 
-    logger.debug('{}: Calling {} hook function {}'.format(log_prefix, hook_name, function_name))
+    logger.debug(f'{log_prefix}: Calling {hook_name} hook function {function_name}')
     return getattr(module, function_name)(config, log_prefix, *args, **kwargs)
 
 

borgmatic/hooks/dump.py

@@ -33,7 +33,7 @@ def make_database_dump_filename(dump_path, name, hostname=None):
     Raise ValueError if the database name is invalid.
     '''
     if os.path.sep in name:
-        raise ValueError('Invalid database name {}'.format(name))
+        raise ValueError(f'Invalid database name {name}')
 
     return os.path.join(os.path.expanduser(dump_path), hostname or 'localhost', name)
 
@@ -60,9 +60,7 @@ def remove_database_dumps(dump_path, database_type_name, log_prefix, dry_run):
     '''
     dry_run_label = ' (dry run; not actually removing anything)' if dry_run else ''
 
-    logger.debug(
-        '{}: Removing {} database dumps{}'.format(log_prefix, database_type_name, dry_run_label)
-    )
+    logger.debug(f'{log_prefix}: Removing {database_type_name} database dumps{dry_run_label}')
 
     expanded_path = os.path.expanduser(dump_path)
 
@@ -78,4 +76,4 @@ def convert_glob_patterns_to_borg_patterns(patterns):
     Convert a sequence of shell glob patterns like "/etc/*" to the corresponding Borg archive
     patterns like "sh:etc/*".
     '''
-    return ['sh:{}'.format(pattern.lstrip(os.path.sep)) for pattern in patterns]
+    return [f'sh:{pattern.lstrip(os.path.sep)}' for pattern in patterns]

borgmatic/hooks/healthchecks.py

@@ -99,7 +99,7 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
     ping_url = (
         hook_config['ping_url']
         if hook_config['ping_url'].startswith('http')
-        else 'https://hc-ping.com/{}'.format(hook_config['ping_url'])
+        else f"https://hc-ping.com/{hook_config['ping_url']}"
     )
     dry_run_label = ' (dry run; not actually pinging)' if dry_run else ''
 
@@ -111,12 +111,10 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
 
     healthchecks_state = MONITOR_STATE_TO_HEALTHCHECKS.get(state)
     if healthchecks_state:
-        ping_url = '{}/{}'.format(ping_url, healthchecks_state)
+        ping_url = f'{ping_url}/{healthchecks_state}'
 
-    logger.info(
-        '{}: Pinging Healthchecks {}{}'.format(config_filename, state.name.lower(), dry_run_label)
-    )
-    logger.debug('{}: Using Healthchecks ping URL {}'.format(config_filename, ping_url))
+    logger.info(f'{config_filename}: Pinging Healthchecks {state.name.lower()}{dry_run_label}')
+    logger.debug(f'{config_filename}: Using Healthchecks ping URL {ping_url}')
 
     if state in (monitor.State.FINISH, monitor.State.FAIL, monitor.State.LOG):
         payload = format_buffered_logs_for_payload()

borgmatic/hooks/mongodb.py

@@ -27,7 +27,7 @@ def dump_databases(databases, log_prefix, location_config, dry_run):
     '''
     dry_run_label = ' (dry run; not actually dumping anything)' if dry_run else ''
 
-    logger.info('{}: Dumping MongoDB databases{}'.format(log_prefix, dry_run_label))
+    logger.info(f'{log_prefix}: Dumping MongoDB databases{dry_run_label}')
 
     processes = []
     for database in databases:
@@ -38,9 +38,7 @@ def dump_databases(databases, log_prefix, location_config, dry_run):
         dump_format = database.get('format', 'archive')
 
         logger.debug(
-            '{}: Dumping MongoDB database {} to {}{}'.format(
-                log_prefix, name, dump_filename, dry_run_label
-            )
+            f'{log_prefix}: Dumping MongoDB database {name} to {dump_filename}{dry_run_label}',
         )
         if dry_run:
             continue
@@ -126,9 +124,7 @@ def restore_database_dump(database_config, log_prefix, location_config, dry_run,
     )
     restore_command = build_restore_command(extract_process, database, dump_filename)
 
-    logger.debug(
-        '{}: Restoring MongoDB database {}{}'.format(log_prefix, database['name'], dry_run_label)
-    )
+    logger.debug(f"{log_prefix}: Restoring MongoDB database {database['name']}{dry_run_label}")
     if dry_run:
         return
 

borgmatic/hooks/mysql.py

@@ -119,7 +119,7 @@ def dump_databases(databases, log_prefix, location_config, dry_run):
     dry_run_label = ' (dry run; not actually dumping anything)' if dry_run else ''
     processes = []
 
-    logger.info('{}: Dumping MySQL databases{}'.format(log_prefix, dry_run_label))
+    logger.info(f'{log_prefix}: Dumping MySQL databases{dry_run_label}')
 
     for database in databases:
         dump_path = make_dump_path(location_config)
@@ -209,9 +209,7 @@ def restore_database_dump(database_config, log_prefix, location_config, dry_run,
     )
     extra_environment = {'MYSQL_PWD': database['password']} if 'password' in database else None
 
-    logger.debug(
-        '{}: Restoring MySQL database {}{}'.format(log_prefix, database['name'], dry_run_label)
-    )
+    logger.debug(f"{log_prefix}: Restoring MySQL database {database['name']}{dry_run_label}")
     if dry_run:
         return
 

borgmatic/hooks/pagerduty.py

@@ -29,14 +29,12 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
     '''
     if state != monitor.State.FAIL:
         logger.debug(
-            '{}: Ignoring unsupported monitoring {} in PagerDuty hook'.format(
-                config_filename, state.name.lower()
-            )
+            f'{config_filename}: Ignoring unsupported monitoring {state.name.lower()} in PagerDuty hook',
         )
         return
 
     dry_run_label = ' (dry run; not actually sending)' if dry_run else ''
-    logger.info('{}: Sending failure event to PagerDuty {}'.format(config_filename, dry_run_label))
+    logger.info(f'{config_filename}: Sending failure event to PagerDuty {dry_run_label}')
 
     if dry_run:
         return
@@ -50,7 +48,7 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
             'routing_key': hook_config['integration_key'],
             'event_action': 'trigger',
             'payload': {
-                'summary': 'backup failed on {}'.format(hostname),
+                'summary': f'backup failed on {hostname}',
                 'severity': 'error',
                 'source': hostname,
                 'timestamp': local_timestamp,
@@ -65,7 +63,7 @@ def ping_monitor(hook_config, config_filename, state, monitoring_log_level, dry_
             },
         }
     )
-    logger.debug('{}: Using PagerDuty payload: {}'.format(config_filename, payload))
+    logger.debug(f'{config_filename}: Using PagerDuty payload: {payload}')
 
     logging.getLogger('urllib3').setLevel(logging.ERROR)
     try:

borgmatic/hooks/postgresql.py

@@ -93,7 +93,7 @@ def dump_databases(databases, log_prefix, location_config, dry_run):
     dry_run_label = ' (dry run; not actually dumping anything)' if dry_run else ''
     processes = []
 
-    logger.info('{}: Dumping PostgreSQL databases{}'.format(log_prefix, dry_run_label))
+    logger.info(f'{log_prefix}: Dumping PostgreSQL databases{dry_run_label}')
 
     for database in databases:
         extra_environment = make_extra_environment(database)
@@ -228,9 +228,7 @@ def restore_database_dump(database_config, log_prefix, location_config, dry_run,
     )
     extra_environment = make_extra_environment(database)
 
-    logger.debug(
-        '{}: Restoring PostgreSQL database {}{}'.format(log_prefix, database['name'], dry_run_label)
-    )
+    logger.debug(f"{log_prefix}: Restoring PostgreSQL database {database['name']}{dry_run_label}")
     if dry_run:
         return
 

borgmatic/hooks/sqlite.py

@@ -26,7 +26,7 @@ def dump_databases(databases, log_prefix, location_config, dry_run):
     dry_run_label = ' (dry run; not actually dumping anything)' if dry_run else ''
     processes = []
 
-    logger.info('{}: Dumping SQLite databases{}'.format(log_prefix, dry_run_label))
+    logger.info(f'{log_prefix}: Dumping SQLite databases{dry_run_label}')
 
     for database in databases:
         database_path = database['path']

borgmatic/logger.py

@@ -108,7 +108,7 @@ def color_text(color, message):
     if not color:
         return message
 
-    return '{}{}{}'.format(color, message, colorama.Style.RESET_ALL)
+    return f'{color}{message}{colorama.Style.RESET_ALL}'
 
 
 def add_logging_level(level_name, level_number):

test_requirements.txt

@@ -6,6 +6,8 @@ colorama==0.4.4
 coverage==5.3
 flake8==4.0.1
 flake8-quotes==3.3.2
+flake8-use-fstring==1.4
+flake8-variables-names==0.0.5
 flexmock==0.10.4
 isort==5.9.1
 mccabe==0.6.1

tests/end-to-end/test_borgmatic.py

@@ -12,17 +12,15 @@ def generate_configuration(config_path, repository_path):
     to work for testing (including injecting the given repository path and tacking on an encryption
     passphrase).
     '''
-    subprocess.check_call(
-        'generate-borgmatic-config --destination {}'.format(config_path).split(' ')
-    )
+    subprocess.check_call(f'generate-borgmatic-config --destination {config_path}'.split(' '))
     config = (
         open(config_path)
         .read()
         .replace('ssh://user@backupserver/./sourcehostname.borg', repository_path)
-        .replace('- ssh://user@backupserver/./{fqdn}', '')
+        .replace('- ssh://user@backupserver/./{fqdn}', '')  # noqa: FS003
         .replace('- /var/local/backups/local.borg', '')
         .replace('- /home/user/path with spaces', '')
-        .replace('- /home', '- {}'.format(config_path))
+        .replace('- /home', f'- {config_path}')
         .replace('- /etc', '')
         .replace('- /var/log/syslog*', '')
         + 'storage:\n    encryption_passphrase: "test"'
@@ -47,13 +45,13 @@ def test_borgmatic_command():
         generate_configuration(config_path, repository_path)
 
         subprocess.check_call(
-            'borgmatic -v 2 --config {} init --encryption repokey'.format(config_path).split(' ')
+            f'borgmatic -v 2 --config {config_path} init --encryption repokey'.split(' ')
         )
 
         # Run borgmatic to generate a backup archive, and then list it to make sure it exists.
-        subprocess.check_call('borgmatic --config {}'.format(config_path).split(' '))
+        subprocess.check_call(f'borgmatic --config {config_path}'.split(' '))
         output = subprocess.check_output(
-            'borgmatic --config {} list --json'.format(config_path).split(' ')
+            f'borgmatic --config {config_path} list --json'.split(' ')
         ).decode(sys.stdout.encoding)
         parsed_output = json.loads(output)
 
@@ -64,16 +62,14 @@ def test_borgmatic_command():
         # Extract the created archive into the current (temporary) directory, and confirm that the
         # extracted file looks right.
         output = subprocess.check_output(
-            'borgmatic --config {} extract --archive {}'.format(config_path, archive_name).split(
-                ' '
-            )
+            f'borgmatic --config {config_path} extract --archive {archive_name}'.split(' '),
         ).decode(sys.stdout.encoding)
         extracted_config_path = os.path.join(extract_path, config_path)
         assert open(extracted_config_path).read() == open(config_path).read()
 
         # Exercise the info action.
         output = subprocess.check_output(
-            'borgmatic --config {} info --json'.format(config_path).split(' ')