1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
.. _startup_chapter:
Startup
=======
When you cause a :app:`Pyramid` application to start up in a console window,
you'll see something much like this show up on the console:
.. code-block:: text
$ pserve development.ini
Starting server in PID 16601.
serving on 0.0.0.0:6543 view at http://127.0.0.1:6543
This chapter explains what happens between the time you press the "Return" key
on your keyboard after typing ``pserve development.ini`` and the time the line
``serving on 0.0.0.0:6543 ...`` is output to your console.
.. index::
single: startup process
pair: settings; .ini
The Startup Process
-------------------
The easiest and best-documented way to start and serve a :app:`Pyramid`
application is to use the ``pserve`` command against a :term:`PasteDeploy`
``.ini`` file. This uses the ``.ini`` file to infer settings and starts a
server listening on a port. For the purposes of this discussion, we'll assume
that you are using this command to run your :app:`Pyramid` application.
Here's a high-level time-ordered overview of what happens when you press
``return`` after running ``pserve development.ini``.
#. The ``pserve`` command is invoked under your shell with the argument
``development.ini``. As a result, Pyramid recognizes that it is meant to
begin to run and serve an application using the information contained
within the ``development.ini`` file.
#. The framework finds a section named either ``[app:main]``,
``[pipeline:main]``, or ``[composite:main]`` in the ``.ini`` file. This
section represents the configuration of a :term:`WSGI` application that will
be served. If you're using a simple application (e.g., ``[app:main]``), the
application's ``paste.app_factory`` :term:`entry point` will be named on the
``use=`` line within the section's configuration. If instead of a simple
application, you're using a WSGI :term:`pipeline` (e.g., a
``[pipeline:main]`` section), the application named on the "last" element
will refer to your :app:`Pyramid` application. If instead of a simple
application or a pipeline, you're using a "composite" (e.g.,
``[composite:main]``), refer to the documentation for that particular
composite to understand how to make it refer to your :app:`Pyramid`
application. In most cases, a Pyramid application built from a scaffold
will have a single ``[app:main]`` section in it, and this will be the
application served.
#. The framework finds all :mod:`logging` related configuration in the ``.ini``
file and uses it to configure the Python standard library logging system for
this application. See :ref:`logging_config` for more information.
#. The application's *constructor* named by the entry point referenced on the
``use=`` line of the section representing your :app:`Pyramid` application is
passed the key/value parameters mentioned within the section in which it's
defined. The constructor is meant to return a :term:`router` instance,
which is a :term:`WSGI` application.
For :app:`Pyramid` applications, the constructor will be a function named
``main`` in the ``__init__.py`` file within the :term:`package` in which
your application lives. If this function succeeds, it will return a
:app:`Pyramid` :term:`router` instance. Here's the contents of an example
``__init__.py`` module:
.. literalinclude:: MyProject/myproject/__init__.py
:language: python
:linenos:
Note that the constructor function accepts a ``global_config`` argument,
which is a dictionary of key/value pairs mentioned in the ``[DEFAULT]``
section of an ``.ini`` file (if :ref:`[DEFAULT]
<defaults_section_of_pastedeploy_file>` is present). It also accepts a
``**settings`` argument, which collects another set of arbitrary key/value
pairs. The arbitrary key/value pairs received by this function in
``**settings`` will be composed of all the key/value pairs that are present
in the ``[app:main]`` section (except for the ``use=`` setting) when this
function is called when you run ``pserve``.
Our generated ``development.ini`` file looks like so:
.. literalinclude:: MyProject/development.ini
:language: ini
:linenos:
In this case, the ``myproject.__init__:main`` function referred to by the
entry point URI ``egg:MyProject`` (see :ref:`MyProject_ini` for more
information about entry point URIs, and how they relate to callables) will
receive the key/value pairs ``{'pyramid.reload_templates':'true',
'pyramid.debug_authorization':'false', 'pyramid.debug_notfound':'false',
'pyramid.debug_routematch':'false', 'pyramid.debug_templates':'true',
'pyramid.default_locale_name':'en'}``. See :ref:`environment_chapter` for
the meanings of these keys.
#. The ``main`` function first constructs a
:class:`~pyramid.config.Configurator` instance, passing the ``settings``
dictionary captured via the ``**settings`` kwarg as its ``settings``
argument.
The ``settings`` dictionary contains all the options in the ``[app:main]``
section of our .ini file except the ``use`` option (which is internal to
PasteDeploy) such as ``pyramid.reload_templates``,
``pyramid.debug_authorization``, etc.
#. The ``main`` function then calls various methods on the instance of the
class :class:`~pyramid.config.Configurator` created in the previous step.
The intent of calling these methods is to populate an :term:`application
registry`, which represents the :app:`Pyramid` configuration related to the
application.
#. The :meth:`~pyramid.config.Configurator.make_wsgi_app` method is called. The
result is a :term:`router` instance. The router is associated with the
:term:`application registry` implied by the configurator previously
populated by other methods run against the Configurator. The router is a
WSGI application.
#. An :class:`~pyramid.events.ApplicationCreated` event is emitted (see
:ref:`events_chapter` for more information about events).
#. Assuming there were no errors, the ``main`` function in ``myproject``
returns the router instance created by
:meth:`pyramid.config.Configurator.make_wsgi_app` back to ``pserve``. As
far as ``pserve`` is concerned, it is "just another WSGI application".
#. ``pserve`` starts the WSGI *server* defined within the ``[server:main]``
section. In our case, this is the Waitress server (``use =
egg:waitress#main``), and it will listen on all interfaces (``host =
0.0.0.0``), on port number 6543 (``port = 6543``). The server code itself
is what prints ``serving on 0.0.0.0:6543 view at http://127.0.0.1:6543``.
The server serves the application, and the application is running, waiting
to receive requests.
.. seealso::
Logging configuration is described in the :ref:`logging_chapter` chapter.
There, in :ref:`request_logging_with_pastes_translogger`, you will also find
an example of how to configure :term:`middleware` to add pre-packaged
functionality to your application.
.. index::
pair: settings; deployment
single: custom settings
.. _deployment_settings:
Deployment Settings
-------------------
Note that an augmented version of the values passed as ``**settings`` to the
:class:`~pyramid.config.Configurator` constructor will be available in
:app:`Pyramid` :term:`view callable` code as ``request.registry.settings``. You
can create objects you wish to access later from view code, and put them into
the dictionary you pass to the configurator as ``settings``. They will then be
present in the ``request.registry.settings`` dictionary at application runtime.
|
