fedmsg requires some configuration before it will work properly.

General configuration


A boolean that, if True, will cause the publishing socket to connect to the relay_inbound socket, rather than binding its own socket.


A string prefixed to the topics of all outgoing messages.

The default value is org.fedoraproject.


A string that must be one of ['prod', 'stg', 'dev']. It signifies the environment in which this fedmsg process is running and can be used to weakly separate different logical buses running in the same infrastructure. It is used by fedmsg.publish() when it is constructing a fully-qualified topic.


A string that is the absolute path to a directory where consumers can save the status of their last processed message. In conjunction with datagrepper_url, allows for automatic retrieval of backlog on daemon startup.


A URL to an instance of the datagrepper web service, such as Can be used in conjunction with status_directory to allow for automatic retrieval of backlog on daemon startup.


dict - A mapping of “service keys” to “zeromq endpoints”; the heart of fedmsg.

endpoints is “a list of possible addresses from which fedmsg can send messages.” Thus, “subscribing to the bus” means subscribing to every address listed in this dictionary.

endpoints is also an index where a fedmsg process can look up what port it should bind to to begin emitting messages.

When fedmsg.init() is invoked, a “name” is determined. It is either passed explicitly, or guessed from the call stack. The name is combined with the hostname of the process and used as a lookup key in the endpoints dict.

When sending, fedmsg will attempt to bind to each of the addresses listed under its service key until it can succeed in acquiring the port. There needs to be as many endpoints listed as there will be processes * threads trying to publish messages for a given service key.

For example, the following config provides for four WSGI processes on bodhi on the machine app01 to send fedmsg messages.

>>> config = dict(
...     endpoints={
...         "bodhi.app01":  [
...               "tcp://",
...               "tcp://",
...               "tcp://",
...               "tcp://",
...         ],
...     },
... )

If apache is configured to start up five WSGI processes, the fifth one will produce tracebacks complaining with IOError("Couldn't find an available endpoint.").

If apache is configured to start up four WSGI processes, but with two threads each, four of those threads will raise exceptions with the same complaints.

A process subscribing to the fedmsg bus will connect a zeromq SUB socket to every endpoint listed in the endpoints dict. Using the above config, it would connect to the four ports on


This is possibly the most complicated and hardest to understand part of fedmsg. It is the black sheep of the design. All of the simplicity enjoyed by the python API is achieved at cost of offloading the complexity here.

Some work could be done to clarify the language used for “name” and “service key”. It is not always consistent in fedmsg.core.


list - A list of domain names for which to query SRV records to get the associated endpoints.

When using fedmsg.config.load_config(), the DNS lookup is done and the resulting endpoints are added to config[‘endpoint’][$DOMAINNAME]

For example, the following would query the endpoints for

>>> config = dict(
...     srv_endpoints=[]


dict - A mapping of service keys, the same as for endpoints to replay endpoints, each key having only one. The replay endpoints are special ZMQ endpoints using a specific protocol to allow the client to request a playback of messages in case some have been dropped, for instance due to network failures.

If the service has a replay endpoint specified, fedmsg will automatically try to detect such failures and properly query the endpoint to get the playback if needed.


str - A special zeromq endpoint where the inbound, passive zmq SUB sockets for instances of fedmsg-relay are listening.

Commands like fedmsg-logger actively connect here and publish their messages.

See Commands for more information.


str - A list of special zeromq endpoints where the outbound sockets for instances of fedmsg-relay should bind.


int - A port number for the special outbound zeromq PUB socket posted by fedmsg.commands.gateway.gateway(). The fedmsg-gateway command is described in more detail in Commands.

Authentication and Authorization

The following settings relate to message authentication and authorization.


bool - If set to true, then fedmsg.core will try to sign every message sent using the machinery from fedmsg.crypto.

It is often useful to set this to False when developing. You may not have X509 certs or the tools to generate them just laying around. If disabled, you will likely want to also disable validate_signatures.


bool - If set to true, then the base class fedmsg.consumers.FedmsgConsumer will try to use fedmsg.crypto.validate() to validate messages before handing them off to the particular consumer for which the message is bound.

This is also used by fedmsg.meta to denote trustworthiness in the natural language representations produced by that module.


str - The name of the fedmsg.crypto backend that should be used to sign outgoing messages. It may be either ‘x509’ or ‘gpg’.


list - A list of names of fedmsg.crypto backends that may be used to validate incoming messages.


str - This should be directory on the filesystem where the certificates used by fedmsg.crypto can be found. Typically /etc/pki/fedmsg/.


str - This should be a URL where the certificate revocation list can be found. This is checked by fedmsg.crypto.validate() and cached on disk.


str - This should be the path to a filename on the filesystem where the CRL downloaded from crl_location can be saved. The python process should have write access there.


int - Number of seconds to keep the CRL cached before checking crl_location for a new one.


str - This should be a URL where the certificate authority cert can be found. This is checked by fedmsg.crypto.validate() and cached on disk.


str - This should be the path to a filename on the filesystem where the CA cert downloaded from ca_cert_location can be saved. The python process should have write access there.


int - Number of seconds to keep the CA cert cached before checking ca_cert_location for a new one.


dict - This should be a mapping of certnames to cert prefixes.

The keys should be of the form <service>.<host>. For example: bodhi.app01.

The values should be the prefixes of cert/key pairs to be found in ssldir. For example, if and are to be found in ssldir, then the value should appear in the certnames dict.

Putting it all together, this value could be specified as follows:

    "bodhi.app01": "",
    # ... other certname mappings may follow here.


This is one of the most cumbersome parts of fedmsg. The reason we have to enumerate all these redundant mappings between “service.hostname” and “service-fqdn” has to do with the limitations of reverse dns lookup. Case in point, try running the following on app01.stg inside Fedora Infrastructure’s environment.

>>> import socket
>>> print socket.getfqdn()

You might expect it to print “”, but it doesn’t. It prints “”. Since we can’t rely on programatically extracting the fully qualified domain names of the host machine during runtime, we need to explicitly list all of the certs in the config.


bool - When set to True, messages whose topics do not appear in routing_policy automatically fail the validation process described in fedmsg.crypto. It defaults to False.


A Python dictionary mapping fully-qualified topic names to lists of cert names. If a message’s topic appears in the routing_policy and the name on its certificate does not appear in the associated list, then that message fails the validation process in fedmsg.crypto.

For example, a routing policy might look like this:

    "": [

The above loosely translates to “messages about bodhi buildroot overrides being untagged may only come from the first four app servers.” If a message with that topic bears a cert signed by any other name, then that message fails the validation process.

Expect that your routing_policy (if you define one) will become quite long.

The default is an empty dictionary.


The following settings are ZeroMQ configuration options.


int - An option to zeromq that specifies a hard limit on the maximum number of outstanding messages to be queued in memory before reaching an exceptional state.

For our pub/sub zeromq sockets, the exceptional state means dropping messages. See the upstream documentation for ZMQ_HWM and ZMQ_PUB.

A value of 0 means “no limit” and is the recommended value for fedmsg. It is referenced when initializing sockets in fedmsg.init().


int - An option that specifies the size of a zeromq thread pool to handle I/O operations. See the upstream documentation for zmq_init.

This value is referenced when initializing the zeromq context in fedmsg.init().


float - A number of seconds to sleep after initializing and before sending any messages. Setting this to a value greater than zero is required so that zeromq doesn’t drop messages that we ask it to send before the pub socket is finished initializing.

Experimentation needs to be done to determine and sufficiently small and safe value for this number. 1 is definitely safe, but annoyingly large.


bool - A value that must be true. It is present solely for compatibility/interoperability with moksha.


int - Number of miliseconds that zeromq will wait to reconnect until it gets a connection if an endpoint is unavailable. This is in miliseconds. See upstream zmq options for more information.


int - Max delay that you can reconfigure to reduce reconnect storm spam. This is in miliseconds. See upstream zmq options for more information.


bool - When false, allow splats (‘*’) in topic names when subscribing. When true, disallow splats and accept only strict matches of topic names.

This is an argument to moksha and arose there to help abstract away differences between the “topics” of zeromq and the “routing_keys” of AMQP.


int - Interpreted as a boolean. If non-zero, then keepalive options will be set. See upstream zmq options and general overview.


int - Number of keepalive packets to send before considering the connection dead. See upstream zmq options and general overview.


int - Number of seconds to wait after last data packet before sending the first keepalive packet. See upstream zmq options and general overview.


int - Number of seconds to wait inbetween sending subsequent keepalive packets. See upstream zmq options and general overview.



list - A list of ircbot configuration dicts. This is the primary way of configuring the fedmsg-irc bot implemented in fedmsg.commands.ircbot.ircbot().

Each dict contains a number of possible options. Take the following example:

>>> config = dict(
...     irc=[
...         dict(
...             network='',
...             port=6667,
...             nickname='fedmsg-dev',
...             channel='fedora-fedmsg',
...             timeout=120,
...             make_pretty=True,
...             make_terse=True,
...             make_short=True,
...             filters=dict(
...                 topic=['koji'],
...                 body=['ralph'],
...             ),
...         ),
...     ],
... )

Here, one bot is configured. It is to connect to the freenode network on port 6667. The bot’s name will be fedmsg-dev and it will join the #fedora-fedmsg channel.

make_pretty specifies that colors should be used, if possible.

make_terse specifies that the “natural language” representations produced by fedmsg.meta should be echoed into the channel instead of raw or dumb representations.

make_short specifies that any url associated with the message should be shortened with a link shortening service. If True, the service will be used. You can alternatively specify a callable to use your own custom url shortener, like this:

make_short=lambda url: requests.get('' % url).text.strip()

The filters dict is not very smart. In the above case, any message that has ‘koji’ anywhere in the topic or ‘ralph’ anywhere in the JSON body will be discarded and not echoed into #fedora-fedmsg. This is an area that could use some improvement.


A dictionary mapping module names to MIRC irc color names. For example:

>>> irc_color_lookup = {
...     "fas": "light blue",
...     "bodhi": "green",
...     "git": "red",
...     "tagger": "brown",
...     "wiki": "purple",
...     "logger": "orange",
...     "pkgdb": "teal",
...     "buildsys": "yellow",
...     "planet": "light green",
... }


the name of the method used to publish the messages on IRC. Valid values are msg and notice.

The default is notice.

STOMP Configuration

When using STOMP, you need to set zmq_enabled to False. Additionally, if you’re using STOMP with TLS (recommended), you do not need fedmsg’s cryptographic signatures to validate messages so you can turn those off by setting validate_signatures to False


A string of comma-separated brokers. For example:


There is no default for this setting.


The STOMP heartbeat interval, in milliseconds.

There is no default for this setting.


The username to use with STOMP when authenticating with the broker.

There is no default for this setting.


The password to use with STOMP when authenticating with the broker.

There is no default for this setting.


The PEM-encoded x509 client certificate to use when authenticating with the broker.

There is no default for this setting.


The PEM-encoded private key for the stomp_ssl_crt.

There is no default for this setting.


If set, this will cause the Moksha hub to only listen to the specified queue for all fedmsg consumers. If it is not specified, the Moksha hub will listen to all topics declared by all fedmsg consumers.

There is no default for this setting.