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Update manual for the cowboy module

This commit separates the documentation of the functions into
separate manual pages, with at least one example per function
and a lot more details about parameters, return values and
related functions and modules. It also includes a changelog
indicating when the function was added or changed.

The inspiration for this comes mainly from the PHP documentation
and feedback from users.
This commit is contained in:
Loïc Hoguin 2016-09-25 17:32:41 +02:00
parent 31cabe0fb9
commit 0424724062
5 changed files with 455 additions and 53 deletions

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@ -9,80 +9,91 @@ cowboy - HTTP server
The `cowboy` module provides convenience functions for
manipulating Ranch listeners.
== Exports
* link:man:cowboy:start_clear(3)[cowboy:start_clear(3)] - Listen for connections using plain TCP
* link:man:cowboy:start_tls(3)[cowboy:start_tls(3)] - Listen for connections using TLS
* link:man:cowboy:stop_listener(3)[cowboy:stop_listener(3)] - Stop the given listener
* link:man:cowboy:set_env(3)[cowboy:set_env(3)] - Update a listener's environment value
== Types
=== fields() = [Field]
=== fields()
[source,erlang]
----
Field = atom()
| {atom(), cowboy_constraints:constraint() | [cowboy_constraints:constraint()]}
| {atom(), cowboy_constraints:constraint() | [cowboy_constraints:constraint()], any()}]
fields() :: [Name
| {Name, Constraints}
| {Name, Constraints, Default}]
Name :: atom()
Constraints :: Constraint | [Constraint]
Constraint :: cowboy_constraints:constraint()
Default :: any()
----
Fields for match operations. Constraint(s) and default value are optional.
Fields description for match operations.
=== http_headers() = [{binary(), iodata()}]
This type is used in link:man:cowboy_router(3)[cowboy_router]
for matching bindings and in the match functions found in
link:man:cowboy_req(3)[cowboy_req].
HTTP headers as a list of key/values.
=== http_headers()
=== http_status() = non_neg_integer() | binary()
[source,erlang]
----
http_headers() :: #{binary() => iodata()}
----
HTTP status.
HTTP headers.
A binary status can be used to set a custom message.
=== http_status()
=== http_version() = \'HTTP/1.1' | \'HTTP/1.0'
[source,erlang]
----
http_status() :: non_neg_integer() | binary()
----
HTTP response status.
A binary status can be used to set a reason phrase. Note
however that HTTP/2 only sends the status code and drops
the reason phrase entirely.
=== http_version()
[source,erlang]
----
http_version() :: 'HTTP/2' | 'HTTP/1.1' | 'HTTP/1.0'
----
HTTP version.
=== `onresponse_fun() = fun((http_status(), http_headers(), iodata(), cowboy_req:req()) -> cowboy_req:req())`
Note that semantically, HTTP/1.1 and HTTP/2 are equivalent.
Fun called immediately before sending the response.
=== opts()
It can perform any operation on the Req object, including
reading the request body or replying. If a reply is sent, it
overrides the reply initially sent. The callback will not be
called again for the new reply.
[source,erlang]
----
opts() :: map()
----
== Exports
Options for the HTTP/1.1, HTTP/2 and Websocket protocols.
=== start_http(Ref, NbAcceptors, TransOpts, ProtoOpts) -> {ok, pid()}
The protocol options are in a map containing all the options for
the different protocols that may be involved when connecting
to the listener, including HTTP/1.1 and HTTP/2 but also
subprotocols like Websocket.
// @todo For Websocket this might change in the future.
Ref = ranch:ref():: Listener name.
NbAcceptors = non_neg_integer():: Number of acceptor processes.
TransOpts = ranch_tcp:opts():: TCP transport options.
ProtoOpts = cowboy_protocol:opts():: HTTP protocol options.
Start listening for HTTP connections. Returns the pid for this
listener's supervisor.
=== start_https(Ref, NbAcceptors, TransOpts, ProtoOpts) -> {ok, pid()}
Ref = ranch:ref():: Listener name.
NbAcceptors = non_neg_integer():: Number of acceptor processes.
TransOpts = ranch_ssl:opts():: SSL transport options.
ProtoOpts = cowboy_protocol:opts():: HTTP protocol options.
Start listening for HTTPS connections. Returns the pid for this
listener's supervisor.
=== stop_listener(Ref) -> ok | {error, not_found}
Ref = ranch:ref():: Listener name.
Stop a previously started listener.
=== set_env(Ref, Name, Value) -> ok
Ref = ranch:ref():: Listener name.
Name = atom():: Name of environment value.
Value = any():: Environment value.
Set or update an environment value for an already running listener.
This will take effect on all subsequent connections.
The HTTP/1.1 options are documented in the
link:man:cowboy_http(3)[cowboy_http(3)] manual;
the HTTP/2 options in
link:man:cowboy_http2(3)[cowboy_http2(3)];
and the Websocket options in
link:man:cowboy_websocket(3)[cowboy_websocket(3)].
== See also
The http://ninenines.eu/docs/en/ranch/HEAD/guide[Ranch guide]
provides detailed information about how listeners work.
link:man:cowboy(7)[cowboy(7)],
link:man:ranch(3)[ranch(3)]

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@ -0,0 +1,79 @@
= cowboy:set_env(3)
== Name
cowboy:set_env - Update a listener's environment value
== Description
[source,erlang]
----
set_env(Name :: ranch:ref(),
Key :: atom(),
Value :: any())
-> ok
----
Set or update an environment value for a previously started
listener.
This is most useful for updating the routes dynamically,
without having to restart the listener.
The new value will only be available to new connections.
Pre-existing connections will still use the old value.
== Arguments
Name::
The name of the listener to update.
+
The name of the listener is the first argument given to the
link:man:cowboy:start_clear(3)[cowboy:start_clear(3)],
link:man:cowboy:start_tls(3)[cowboy:start_tls(3)] or
link:man:ranch:start_listener(3)[ranch:start_listener(3)] function.
Key::
The key in the environment map. Common keys include `dispatch`
and `middlewares`.
Value::
The new value.
The type of the value differs depending on the key.
== Return value
The atom `ok` is returned on success.
An `exit:badarg` exception is thrown when the listener does
not exist.
== Changelog
* *1.0*: Function introduced.
== Examples
.Update a listener's routes
[source,erlang]
----
Dispatch = cowboy_router:compile([
{'_', [
{"/", toppage_h, []},
{"/ws", websocket_h, []}
]}
]),
cowboy:set_env(example, dispatch, Dispatch).
----
== See also
link:man:cowboy(3)[cowboy(3)],
link:man:cowboy:start_clear(3)[cowboy:start_clear(3)],
link:man:cowboy:start_tls(3)[cowboy:start_tls(3)],
link:man:ranch:set_protocol_options(3)[ranch:set_protocol_options(3)]

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@ -0,0 +1,126 @@
= cowboy:start_clear(3)
== Name
cowboy:start_clear - Listen for connections using plain TCP
== Description
[source,erlang]
----
start_clear(Name :: ranch:ref(),
NumAcceptors :: non_neg_integer(),
TransportOpts :: ranch_tcp:opts(),
ProtocolOpts :: opts())
-> {ok, ListenerPid :: pid()}
| {error, any()}
----
Start listening for connections over a clear TCP channel.
Both HTTP/1.1 and HTTP/2 are supported on this listener.
HTTP/2 has two methods of establishing a connection over
a clear TCP channel. Both the upgrade and the prior knowledge
methods are supported.
== Arguments
Name::
The listener name is used to refer to this listener in
future calls, for example when stopping it or when
updating the routes defined.
+
It can be any Erlang term. An atom is generally good enough,
for example `api`, `my_app_clear` or `my_app_tls`.
NumAcceptors::
The number of acceptors is the number of processes that
will accept connections. Tweak this value to improve the
accept rate for incoming connections.
+
The ideal value is between 10 and 100 on most systems.
Larger values may have the opposite effect and reduce the
accept rate. It's generally safe to start with a value of
100 (or 10 on low memory systems). Then, when accept rates
become a concern, measure the performance and update the
value accordingly.
+
This value is unrelated to the maximum number of concurrent
connections.
TransportOpts::
The transport options are where the TCP options, including
the listener's port number, are defined. Transport options
are provided as a list of keys and values, for example
`[{port, 8080}]`.
+
The available options are documented in the
link:man:ranch_tcp(3)[ranch_tcp(3)] manual.
ProtocolOpts::
The protocol options are in a map containing all the options for
the different protocols that may be involved when connecting
to the listener, including HTTP/1.1 and HTTP/2 but also
subprotocols like Websocket.
// @todo For Websocket this might change in the future.
+
The HTTP/1.1 options are documented in the
link:man:cowboy_http(3)[cowboy_http(3)] manual;
the HTTP/2 options in
link:man:cowboy_http2(3)[cowboy_http2(3)];
and the Websocket options in
link:man:cowboy_websocket(3)[cowboy_websocket(3)].
== Return value
An ok tuple is returned on success. It contains the pid of
the top-level supervisor for the listener.
An error tuple is returned on error. The error reason may
be any Erlang term.
A common error is `eaddrinuse`. It indicates that the port
configured for Cowboy is already in use.
== Changelog
* *2.0*: HTTP/2 support added.
* *2.0*: Function introduced. Replaces `cowboy:start_http/4`.
== Examples
.Start a listener
[source,erlang]
----
Dispatch = cowboy_router:compile([
{'_', [
{"/", toppage_h, []}
]}
]),
{ok, _} = cowboy:start_clear(example, 100, [{port, 8080}], #{
env => #{dispatch => Dispatch}
}).
----
.Start a listener on a random port
[source,erlang]
----
Name = example,
{ok, _} = cowboy:start_clear(Name, 100, [], #{
env => #{dispatch => Dispatch}
}),
Port = ranch:get_port(Name).
----
== See also
link:man:cowboy(3)[cowboy(3)],
link:man:cowboy:start_tls(3)[cowboy:start_tls(3)],
link:man:ranch(3)[ranch(3)]

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@ -0,0 +1,131 @@
= cowboy:start_tls(3)
== Name
cowboy:start_tls - Listen for connections using TLS
== Description
[source,erlang]
----
start_tls(Name :: ranch:ref(),
NumAcceptors :: non_neg_integer(),
TransportOpts :: ranch_ssl:opts(),
ProtocolOpts :: opts())
-> {ok, ListenerPid :: pid()}
| {error, any()}
----
Start listening for connections over a secure TLS channel.
Both HTTP/1.1 and HTTP/2 are supported on this listener.
The ALPN TLS extension must be used to initiate an HTTP/2
connection.
== Arguments
Name::
The listener name is used to refer to this listener in
future calls, for example when stopping it or when
updating the routes defined.
+
It can be any Erlang term. An atom is generally good enough,
for example `api`, `my_app_clear` or `my_app_tls`.
NumAcceptors::
The number of acceptors is the number of processes that
will accept connections. Tweak this value to improve the
accept rate for incoming connections.
+
The ideal value is between 10 and 100 on most systems.
Larger values may have the opposite effect and reduce the
accept rate. It's generally safe to start with a value of
100 (or 10 on low memory systems). Then, when accept rates
become a concern, measure the performance and update the
value accordingly.
+
This value is unrelated to the maximum number of concurrent
connections.
TransportOpts::
The transport options are where the TCP options, including
the listener's port number, are defined. They also contain
the TLS options, like the server's certificate. Transport options
are provided as a list of keys and values, for example
`[{port, 8443}, {certfile, "path/to/cert.pem"}]`.
+
The available options are documented in the
link:man:ranch_ssl(3)[ranch_ssl(3)] manual.
ProtocolOpts::
The protocol options are in a map containing all the options for
the different protocols that may be involved when connecting
to the listener, including HTTP/1.1 and HTTP/2 but also
subprotocols like Websocket.
// @todo For Websocket this might change in the future.
+
The HTTP/1.1 options are documented in the
link:man:cowboy_http(3)[cowboy_http(3)] manual;
the HTTP/2 options in
link:man:cowboy_http2(3)[cowboy_http2(3)];
and the Websocket options in
link:man:cowboy_websocket(3)[cowboy_websocket(3)].
== Return value
An ok tuple is returned on success. It contains the pid of
the top-level supervisor for the listener.
An error tuple is returned on error. The error reason may
be any Erlang term.
A common error is `eaddrinuse`. It indicates that the port
configured for Cowboy is already in use.
== Changelog
* *2.0*: HTTP/2 support added.
* *2.0*: Function introduced. Replaces `cowboy:start_https/4`.
== Examples
.Start a listener
[source,erlang]
----
Dispatch = cowboy_router:compile([
{'_', [
{"/", toppage_h, []}
]}
]),
{ok, _} = cowboy:start_tls(example, 100, [
{port, 8443},
{cert, "path/to/cert.pem"}
], #{
env => #{dispatch => Dispatch}
}).
----
.Start a listener on a random port
[source,erlang]
----
Name = example,
{ok, _} = cowboy:start_tls(Name, 100, [
{cert, "path/to/cert.pem"}
], #{
env => #{dispatch => Dispatch}
}),
Port = ranch:get_port(Name).
----
== See also
link:man:cowboy(3)[cowboy(3)],
link:man:cowboy:start_clear(3)[cowboy:start_clear(3)],
link:man:ranch(3)[ranch(3)]

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@ -0,0 +1,55 @@
= cowboy:stop_listener(3)
== Name
cowboy:stop_listener - Stop the given listener
== Description
[source,erlang]
----
stop_listener(Name :: ranch:ref())
-> ok | {error, not_found}.
----
Stop a previously started listener.
Alias of link:man:ranch:stop_listener(3)[ranch:stop_listener(3)].
== Arguments
Name::
The name of the listener to be stopped.
+
The name of the listener is the first argument given to the
link:man:cowboy:start_clear(3)[cowboy:start_clear(3)],
link:man:cowboy:start_tls(3)[cowboy:start_tls(3)] or
link:man:ranch:start_listener(3)[ranch:start_listener(3)] function.
== Return value
The atom `ok` is returned on success.
The `{error, not_found}` tuple is returned when the listener
does not exist.
== Changelog
* *1.0*: Function introduced.
== Examples
.Stop a listener
[source,erlang]
----
ok = cowboy:stop_listener(example).
----
== See also
link:man:cowboy(3)[cowboy(3)],
link:man:cowboy:start_clear(3)[cowboy:start_clear(3)],
link:man:cowboy:start_tls(3)[cowboy:start_tls(3)],
link:man:ranch(3)[ranch(3)],
link:man:ranch:start_listener(3)[ranch:start_listener(3)]