.gitignore

backups/
example.conf.d/

README.md

Here's an example how we might generalize file reloading.

gist won't let me upload the example.conf.d as a directory

example.builder

example.conf

[swift-hash]

# swift_hash_path_suffix and swift_hash_path_prefix are used as part of the
# the hashing algorithm when determining data placement in the cluster.
# These values should remain secret and MUST NOT change
# once a cluster has been deployed.

swift_hash_path_suffix = changeme
swift_hash_path_prefix = changeme

# storage policies are defined here and determine various characteristics
# about how objects are stored and treated.  Policies are specified by name on
# a per container basis.  Names are case-insensitive.  The policy index is
# specified in the section header and is used internally.  The policy with
# index 0 is always used for legacy containers and can be given a name for use
# in metadata however the ring file name will always be 'object.ring.gz' for
# backwards compatibility.  If no policies are defined a policy with index 0
# will be automatically created for backwards compatibility and given the name
# Policy-0.  A default policy is used when creating new containers when no
# policy is specified in the request.  If no other policies are defined the
# policy with index 0 will be declared the default.  If multiple policies are
# defined you must define a policy with index 0 and you must specify a
# default.  It is recommended you always define a section for
# storage-policy:0.
[storage-policy:0]
name = Policy-0
default = yes

# the following section would declare a policy called 'silver', the number of
# replicas will be determined by how the ring is built.  In this example the
# 'silver' policy could have a lower or higher # of replicas than the
# 'Policy-0' policy above.  The ring filename will be 'object-1.ring.gz'.  You
# may only specify one storage policy section as the default.  If you changed
# this section to specify 'silver' as the default, when a client created a new
# container w/o a policy specified, it will get the 'silver' policy because
# this config has specified it as the default.  However if a legacy container
# (one created with a pre-policy version of swift) is accessed, it is known
# implicitly to be assigned to the policy with index 0 as opposed to the
# current default.
#[storage-policy:1]
#name = silver

# The swift-constraints section sets the basic constraints on data
# saved in the swift cluster. These constraints are automatically 
# published by the proxy server in responses to /info requests.

[swift-constraints]

# max_file_size is the largest "normal" object that can be saved in
# the cluster. This is also the limit on the size of each segment of
# a "large" object when using the large object manifest support.
# This value is set in bytes. Setting it to lower than 1MiB will cause
# some tests to fail. It is STRONGLY recommended to leave this value at
# the default (5 * 2**30 + 2).

#max_file_size = 5368709122


# max_meta_name_length is the max number of bytes in the utf8 encoding
# of the name portion of a metadata header.

#max_meta_name_length = 128


# max_meta_value_length is the max number of bytes in the utf8 encoding
# of a metadata value

#max_meta_value_length = 256


# max_meta_count is the max number of metadata keys that can be stored
# on a single account, container, or object

#max_meta_count = 90


# max_meta_overall_size is the max number of bytes in the utf8 encoding
# of the metadata (keys + values)

#max_meta_overall_size = 4096

# max_header_size is the max number of bytes in the utf8 encoding of each
# header. Using 8192 as default because eventlet use 8192 as max size of
# header line. This value may need to be increased when using identity
# v3 API tokens including more than 7 catalog entries.
# See also include_service_catalog in proxy-server.conf-sample
# (documented in overview_auth.rst)

#max_header_size = 8192


# max_object_name_length is the max number of bytes in the utf8 encoding
# of an object name

#max_object_name_length = 1024


# container_listing_limit is the default (and max) number of items
# returned for a container listing request

#container_listing_limit = 10000


# account_listing_limit is the default (and max) number of items returned
# for an account listing request
#account_listing_limit = 10000


# max_account_name_length is the max number of bytes in the utf8 encoding
# of an account name

#max_account_name_length = 256


# max_container_name_length is the max number of bytes in the utf8 encoding
# of a container name

#max_container_name_length = 256

example.conf.d.tar.gz

example.json

{"foo": "bar"}

example.pkl

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example.py

#!/usr/bin/env python
import os
import time


class ReloadingFile(object):

    def __init__(self, filename, reload_time=300):
        self.filename = filename
        self.reload_time = reload_time
        self._cached_data = None
        self._last_reload = 0
        self._last_mtime = 0
        self.data = None

    def _get_mtime(self):
        return os.stat(self.filename).st_mtime

    def has_changed(self):
        mtime = self._get_mtime()
        if mtime == self._last_mtime:
            return False
        self._last_mtime = mtime
        return True

    def reload(self):
        with open(self.filename) as f:
            return self.parse(f)

    def parse(self, f):
        return f.read()

    def get_data(self):
        now = time.time()
        if self._last_reload + self.reload_time < now:
            self._last_reload = now
            # skip reload if mtimes are the same
            if self.has_changed():
                self._cached_data = self.reload()
        return self._cached_data

import json


class ReloadingJson(ReloadingFile):

    def parse(self, f):
        return json.load(f)


from swift.common.utils import readconf


class ReloadingConfigFile(ReloadingFile):

    def __init__(self, *args, **kwargs):
        self._section_name = kwargs.pop('section_name', None)
        super(ReloadingConfigFile, self).__init__(*args, **kwargs)

    def reload(self):
        return readconf(self.filename, section_name=self._section_name)


class ReloadingConf(ReloadingConfigFile):

    def _get_mtime(self):
        mtime = 0
        for path, dirs, names in os.walk(self.filename):
            for name in names:
                filename = os.path.join(path, name)
                mtime = max((mtime, os.stat(filename).st_mtime))
        return mtime


import pickle


class ReloadingPickle(ReloadingFile):

    def parse(self, f):
        return pickle.load(f)


from swift.common.ring import RingData


class ReloadingRing(ReloadingFile):

    def reload(self):
        return RingData.load(self.filename)


# command line mode is for testing, not really part of the example

import sys
from argparse import ArgumentParser

parser = ArgumentParser()
parser.add_argument('path', help='path to reloading file')
parser.add_argument('-v', '--verbose', action='store_true', help='more info')


def main():
    args = parser.parse_args()
    path = args.path
    if os.path.isdir(path):
        class_ = ReloadingConf
    elif path.endswith('json'):
        class_ = ReloadingJson
    elif path.endswith('conf'):
        class_ = ReloadingConfigFile
    elif path.endswith('.pkl'):
        class_ = ReloadingPickle
    elif path.endswith('.ring.gz'):
        class_ = ReloadingRing
    else:
        class_ = ReloadingFile
    conf = class_(path, reload_time=10)
    while True:
        data = conf.get_data()
        print '%s (%s)' % (id(data), conf._last_reload)
        if args.verbose:
            print data
        time.sleep(3)


if __name__ == "__main__":
    sys.exit(main())

example.ring.gz