Services Python applications are all WSGI applications based on the same stack of tools:
NGinx <= TCP => Gunicorn <= WSGI => SyncServerApp <=> WebOb
Services provides two base libraries to build WSGI applications:
Most Services applications need to generate CEF logs. A CEF Log is a formatted log that can be used by ArcSight, a central application used by the Infrasec team to manage application security.
The cef module provides a log_cef() function that can be used to emit CEF logs:
log_cef(message, severity, environ, config, [username, [signature]], **kw)
Creates a CEF record, and emits it in syslog or another file.
- message: message to log
- severity: integer from 0 to 10
- environ: the WSGI environ object
- config: configuration dict
- username: user name, defaults to ‘none’
- signature: CEF signature code, defaults to ‘AuthFail’
- extra keywords: extra keys used in the CEF extension
>>> from cef import log_cef >>> log_cef('SecurityAlert!', 5, environ, config, ... msg='Someone has stolen my chocolate')
With environ and config provided by the web environment.
Note that the CEF library is published at PyPI: http://pypi.python.org/pypi/cef
See CEF for more info on this.
The server-core library provides helpers to build Services applications.
In server-core‘s philosophy, a WSGI application is a SyncServerApp instance which will contain a config attribute that’s a mapper containing all the configuration needed by the code. This configuration is loaded from a unique ini-like file.
When a request comes in, Routes is used to dispatch it to a controller method.
Controllers are simple classes whose methods receive the request and need to return a response.
The configuration files we use in Services applications are based on an extended version of Ini files. You can find a description of the file at https://wiki.mozilla.org/Services/Sync/Server/GlobalConfFile.
server-core provides a simple reader:
>>> from services.config import Config >>> cfg = Config('/etc/keyexchange/keyexchange.conf') >>> cfg.sections() ['keyexchange', 'filtering', 'cef'] >>> cfg.items('keyexchange') [('max_gets', 10), ('root_redirect', 'https://services.mozilla.com'), ('use_memory', False), ('ttl', 300), ('cache_servers', ['127.0.0.1:11211']), ('cid_len', 4)] >>> cfg.get('keyexchange', 'cid_len') 4
Note that SyncServerApp will automatically create a Config instance over a central configuration file when it’s used to create a web application.
See Configuration file for more info on this.
The SyncServerApp is a base class that can be used to get a few automation and some useful helpers when you want to create an application for Services.
To create an application using SyncServerApp, see Complete layout.