nobodd.config

This module contains the classes and functions used to configure the main nobodd application. These are not likely to be of much use to other applications, but are documented here just in case.

ConfigArgumentParser

class nobodd.config.ConfigArgumentParser(*args, template=None, **kwargs)[source]

A variant of ArgumentParser that links arguments to specified keys in a ConfigParser instance.

Typical usage is to construct an instance of ConfigArgumentParser, define the parameters and parameter groups on it, associating them with configuration section and key names as appropriate, then call read_configs() to parse a set of configuration files. These will be checked against the (optional) template configuration passed to the initializer, which defines the set of valid sections and keys expected.

The resulting ConfigParser forms the “base” configuration, prior to argument parsing. This can be optionally manipulated, before passing it to set_defaults_from() to set the argument defaults. At this point, parse_args() may be called to parse the command line arguments, knowing that defaults in the help will be drawn from the “base” configuration.

The resulting Namespace object is the application’s runtime configuration. For example:

>>> from pathlib import Path
>>> from nobodd.config import *
>>> parser = ConfigArgumentParser()
>>> tftp = parser.add_argument_group('tftp', section='tftp')
>>> tftp.add_argument('--listen', type=str, key='listen',
... help="the address on which to listen for connections "
... "(default: %(default)s)")
>>> Path('defaults.conf').write_text('''
... [tftp]
... listen = 127.0.0.1
... ''')
>>> defaults = parser.read_configs(['defaults.conf'])
>>> parser.set_defaults_from(defaults)
>>> parser.get_default('listen')
'127.0.0.1'
>>> config = parser.parse_args(['--listen', '0.0.0.0'])
>>> config.listen
'0.0.0.0'

Note that, after the call to set_defaults_from(), the parser’s idea of the defaults has been drawn from the file-based configuration (and thus will be reflected in printed --help), but this is still overridden by the arguments passed to the command line.

add_argument(*args, section=None, key=None, **kwargs)[source]

Adds section and key parameters. These link the new argument to the specified configuration entry.

The default for the argument can be specified directly as usual, or can be read from the configuration (see read_configs() and set_defaults_from()). When arguments are parsed, the value assigned to this argument will be copied to the associated configuration entry.

add_argument_group(title=None, description=None, section=None)[source]

Adds a new argument group object and returns it.

The new argument group will likewise accept section and key parameters on its add_argument() method. The section parameter will default to the value of the section parameter passed to this method (but may be explicitly overridden).

of_type(type)[source]

Return a set of (section, key) tuples listing all configuration items which were defined as being of the specified type (with the type keyword passed to add_argument().

read_configs(paths)[source]

Constructs a ConfigParser instance, and reads the configuration files specified by paths, a list of Path-like objects, into it.

The method will check the configuration for valid section and key names, raising ValueError on invalid items. It will also resolve any configuration values that have the type Path relative to the path of the configuration file in which they were defined.

The return value is the configuration parser instance.

set_defaults_from(config)[source]

Sets defaults for all arguments from their associated configuration entries in config.

update_config(config, namespace)[source]

Copy values from namespace (an argparse.Namespace, presumably the result of calling something like parse_args()) to config, a ConfigParser. Note that namespace values will be converted to str implicitly.

Board

class nobodd.config.Board(serial, image, partition, ip)[source]

Represents a known board, recording its serial number, the image (filename) that the board should boot, the partition number within the image that contains the boot partition, and the IP address (if any) that the board should have.

classmethod from_section(config, section)[source]

Construct a new Board from the specified section of the config (a mapping, e.g. a ConfigParser section).

classmethod from_string(s)[source]

Construct a new Board from the string s which is expected to be a comma-separated list of serial number, filename, partition number, and IP address. The last two parts (partition number and IP address) are optional and default to 1 and None respectively.

Conversion Functions

nobodd.config.port(s)[source]

Convert the string s into a port number. The string may either contain an integer representation (in which case the conversion is trivial, or a port name, in which case socket.getservbyname() will be used to convert it to a port number (usually via NSS).

nobodd.config.boolean(s)[source]

Convert the string s to a bool. A typical set of case insensitive strings are accepted: “yes”, “y”, “true”, “t”, and “1” are converted to True, while “no”, “n”, “false”, “f”, and “0” convert to False. Other values will result in ValueError.

nobodd.config.size(s)[source]

Convert the string s, which must contain a number followed by an optional suffix (MB for mega-bytes, GB, for giga-bytes, etc.), and return the absolute integer value (scale the number in the string by the suffix given).

nobodd.config.duration(s)[source]

Convert the string s to a timedelta. The string must consist of white-space and/or comma separated values which are a number followed by a suffix indicating duration. For example:

>>> duration('1s')
timedelta(seconds=1)
>>> duration('5 minutes, 30 seconds')
timedelta(seconds=330)

The set of possible durations, and their recognized suffixes is as follows:

  • Microseconds: microseconds, microsecond, microsec, micros, micro, useconds, usecond, usecs, usec, us, µseconds, µsecond, µsecs, µsec, µs

  • Milliseconds: milliseconds, millisecond, millisec, millis, milli, mseconds, msecond, msecs, msec, ms

  • Seconds: seconds, second, secs, sec, s

  • Minutes: minutes, minute, mins, min, mi, m

  • Hours: hours, hour, hrs, hr, h

If conversion fails, ValueError is raised.