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Name
ngx_drizzle - an upstream module that talks to
mysql, drizzle, and sqlite3 by libdrizzle
Status
This module is already considered production-ready but it's
required to patch libdrizzle-0.8 using the following
patch in order to fix two serious bug in it:
http://agentzh.org/misc/nginx/libdrizzle-0.8-parsebug_and_mac_fixes.patch
This patch is expected to be included in the next
official release of libdrizzle.
We need your help! If you find this module useful and/or
interesting, please consider joining the development!
Commit bit can be freely delivered at your request ;)
Synopsis
http {
...
upstream cluster {
# simple round-robin
drizzle_server 127.0.0.1:3306 dbname=test
password=some_pass user=monty protocol=mysql;
drizzle_server 127.0.0.1:1234 dbname=test2
password=pass user=bob protocol=drizzle;
}
upstream backend {
drizzle_server 127.0.0.1:3306 dbname=test
password=some_pass user=monty protocol=mysql;
}
server {
location /mysql {
set $my_sql 'select * from cats';
drizzle_query $my_sql;
drizzle_pass backend;
drizzle_connect_timeout 500 ms; # default 60 s
drizzle_send_query_timeout 2 s; # default 60 s
drizzle_recv_cols 1 s; # default 60 s
drizzle_recv_rows 1 s; # default 60 s
}
...
}
}
Description
This is an nginx upstream module integrating libdrizzle
( https://launchpad.net/libdrizzle ) into nginx in an
non-blocking and streamming way.
Essentially it provides a very efficient and flexible way
for nginx internals to access mysql, drizzle, sqlite3,
as well as other RDBMS's that support the drizzle protocol
or mysql protocol. Also it can serve as a direct REST
interface to those RDBMS backends.
It also has a builtin per-worker connection pool
mechanism.
Here's a sample configuration:
upstream backend {
drizzle_server 127.0.0.1:3306 dbname=test
password=some_pass user=monty protocol=mysql;
drizzle_keepalive max=100 mode=single overflow=reject;
}
The drizzle_server directive supports the following options:
* user
mysql user name for login
* password
Specify mysql password for login.
* dbname
Specify default mysql database for the connection.
Note that mysql does allow referecing tables belonging to different
databases by qualifying table names with
database names.
* protocol
Specify which wire protocol to use, "drizzle" or "mysql".
Default to "drizzle".
* charset
Explicitly specify the charset for the mysql connection.
Setting this option to a non-empty value will
make ngx_drizzle send out a "set names 'user_charset'" query
right after the mysql connection is established.
If the default character encoding of the mysql connection
is already what you want, you needn't set this option
because it has extra runtime cost. Here is a small
example:
drizzle_server foo.bar.com:3306 user=monty password=some_pass
dbname=test protocol=mysql
charset=utf8;
Note that for the mysql server, "utf-8" is not a valid
encoding name while "utf8" is ;)
The drizzle_keepalive directive has the following options:
* max=<num>
Specify the capacity of the connection pool for
the current upstream block. The <num> value MUST
be non-zero. If set to 0, it effectively disables
the connection pool. And this is the default
if no "drizzle_keepalive" directive is specified.
* mode=<mode>
This supports two values, "single" and "multi".
"single" mode means the pool does not distinguish
various drizzle servers in the current ustream
block while "multi" means the pool will merely
reuse connections which have identical server
host names and ports. Note that it will igore
differences between dbnames or users.
Default to "single".
* overflow=<action>
This option specifies what to do when the
connection pool is already full while new
database connection is required. Either "reject"
(without quotes) or "ignore" can be specified.
In case of "reject", it will reject the current
request, and returns "503 Service Unavaliable"
error page. For "ignore", this module will
go on creating a new DB connection.
For now, the connection pool uses a simple LIFO algorithm
to assign idle connections in the pool. That is,
most recently (successfully) used connections will be
reused first the next time. And new idle connections
will always replace the oldest idle connections in the
pool even if the pool is already full.
Caveats
* Other usptream modules like "upstream_hash" and
"upstream_keepalive" MUST NOT be used with this module
in a single upstream block.
* Directives like "server" MUST NOT be mixed with
"drizzle_server" either.
* Upstream backends that don't use "drizzle_server" to
define server entries MUST NOT be used in the
"drizzle_pass" directive.
Directives
drizzle_server <host>:<port> dbname=<dbname> password=<password> user=<user> protocol=<protocol>
protocol can be either "mysql" or "drizzle".
drizzle_query <sql>
drizzle_connect_timeout <time>
<time> can be an integer, with an optional time unit, like "s", "ms", "m".
The default time unit is "s", ie, "second".
default setting is "60 s".
drizzle_send_query_timeout <time>
default setting is "60 s".
drizzle_recv_cols_timeout <time>
default setting is "60 s".
drizzle_recv_rows_timeout <time>
default setting is "60 s".
Output
This module generates binary query results in a format
that will be shared among the various nginx database
driver modules like ngx_postgresql and ngx_oracle.
This data format is named "Resty DBD Stream" (RDS).
If you're a web app developer, you may be more interested
in using a source filter module like ngx_rds_json module
( http://github.com/agentzh/rds-json-nginx-module ) to
obtain JSON output.
For the HTTP response header part, the 200 OK status
code should always be returned.
The Content-Type header MUST be set to
"application/x-resty-dbd-stream" (without quotes).
And the driver generating this response is also set a
X-Resty-DBD header. For instance, this
module adds the following output header:
X-Resty-DBD-Module: drizzle 0.0.1
where 0.0.1 is this module's own version number. This
X-Resty-DBD-Module header is optional though.
Below is the HTTP response body format (version 0.0.3):
Header part
uint8_t endian type (1 means big-endian and little
endian otherwise)
uint32_t format version
(v1.2.3 is represented as 1002003 in
decimal)
uint8_t result type
(0 means normal SQL result type,
fixed for now)
uint16_t standard error code
uint16_t driver-specific error code
uint16_t driver-specific error string length
u_char* driver-specific error string data
uint64_t database rows affected
uint64_t insert id (if none, 0)
uint16_t column count
Body part
when the "column count" field in the Header part
is zero, then the whole body part is omitted.
0*Column (number of columns is determined by "column count")
uint16_t non-zero value for standard column type
code and for the column list
terminatoandr otherwise.
uint16_t driver-specific column type code
uint16_t column name length
u_char* column name data
0*Row (terminated by 8-bit zero)
uint8_t valid row (1 means valid, and 0 means
the row list terminator)
0*Field (count is predetermined by column number)
uint32_t field length ((uint32_t) -1 represents NULL)
uint8_t* field data (in textual representation), is empty
if field length == (uint32_t) -1
On the nginx output chain link level, the following
components should be put into a single ngx_buf_t struct:
* the header
* each column and the column list terminator
* each row's valid flag byte and row list terminator
* each field in each row (if any) but the field data
can span multiple bufs
Installation
* You should first install libdrizzle 0.8 which can be
obtained from here:
https://launchpad.net/libdrizzle
* Use the following patch in order to fix two serious bugs in
libdrizzle:
http://agentzh.org/misc/nginx/libdrizzle-0.8-parsebug_and_mac_fixes.patch
* Download the latest version of the release tarball of this module from
drizzle-nginx-module file list
(<http://github.com/agentzh/drizzle-nginx-module/downloads>).
* Grab the nginx source code from nginx.net (<http://nginx.net/>), for
example, the version 0.8.41 (see nginx compatibility), and then build
the source with this module:
$ wget 'http://sysoev.ru/nginx/nginx-0.8.41.tar.gz'
$ tar -xzvf nginx-0.8.41.tar.gz
$ cd nginx-0.8.41/
# Here we assume you would install you nginx under /opt/nginx/.
$ ./configure --prefix=/opt/nginx \
--add-module=/path/to/drizzle-nginx-module
$ make -j2
$ make install
Compatibility
The following versions of Nginx should work with this module:
* 0.8.x (last tested: 0.8.53)
* 0.7.x >= 0.7.44 (last tested version is 0.7.67)
Earlier versions of Nginx like 0.6.x and 0.5.x will *not* work.
If you find that any particular version of Nginx above 0.7.44 does not
work with this module, please consider reporting a bug.
TODO
* implement the "drizzle_max_output_size" directive.
When the RDS data is larger then the size specified,
the module will try to terminate the output as quickly
as possible but will still ensure the resulting
response body is still in valid RDS format.
* implement the "drizzle_upstream_next" mechanism for
failover support.
* add support for multiple "drizzle_query" directives
in a single location.
* implement weighted round-robin algorithm for the
upstream server clusters.
* add the "max_idle_time" option to the "drizzle_server"
directive, so that the connection pool will automatically
release idle connections for the timeout you specify.
* add the "min" option to the "drizzle_server" directive
so that the connection pool will automatically create
that number of connections and put them into the pool.
* Unix domain socket support in the "drizzle_server"
directive.
* Make the "drizzle_query" directive reject variables that
have not been processed by a drizzle_process directive.
This will pretect us from SQL injections. There will
also be an option ("strict=no") to disable such checks.
Known Issues
* This module does not (yet) work with the RTSIG event model.
See Also
* the ngx_rds_json module
( http://github.com/agentzh/rds-json-nginx-module )
Authors
chaoslawful (王晓哲) <chaoslawful at gmail dot com>,
agentzh (章亦春) <agentzh at gmail dot com>,
Piotr Sikora <piotr.sikora at frickle dot com>.
Copyright & License
The implementation of the builtin connection pool has borrowed
a lot of code from Maxim Dounin's upstream_keepalive module.
This part of code is copyrighted by Maxim Dounin.
I also borrowed a lot of code from ngx_http_upstream.c and
ngx_http_memcached_module.c in the nginx 0.8.30 core. This
part of code is copyrighted by Igor Sysoev.
This module is licenced under the BSD license.
Copyright (c) 2009-2010, Taobao Inc., Alibaba Group ( http://www.taobao.com ).
Copyright (c) 2009-2010, Xiaozhe Wang (chaoslawful) <chaoslawful@gmail.com>.
Copyright (C) 2009-2010, Yichun Zhang (agentzh) <agentzh@gmail.com>.
Copyright (C) 2010, FRiCKLE Piotr Sikora <info@frickle.com>.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of the Taobao Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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