ngx_redis2 - Nginx upstream module for the Redis 2.0 protocol
*This module is not distributed with the Nginx source.* See the
installation instructions.
STATUS
This module is still under development and is considered experimental.
SYNOPSIS
location /foo {
set $value 'first';
redis2_query set one $value;
redis2_pass 127.0.0.1:6379;
}
# GET /get?key=some_key
location /get {
set_unescape_uri $key $arg_key; # this requires ngx_set_misc
redis2_query get $key;
redis2_pass foo.com:6379;
}
# GET /set?key=one&val=first%20value
location /set {
set_unescape_uri $key $arg_key; # this requires ngx_set_misc
set_unescape_uri $val $arg_val; # this requires ngx_set_misc
redis2_query set $key $val;
redis2_pass foo.com:6379;
}
# multiple pipelined queries
location /foo {
set $value 'first';
redis2_query set one $value;
redis2_query get one;
redis2_query set one two;
redis2_query get one;
redis2_pass 127.0.0.1:6379;
}
location /bar {
# $ is not special here...
redis2_literal_raw_query '*1\r\n$4\r\nping\r\n';
redis2_pass 127.0.0.1:6379;
}
location /bar {
# variables can be used below and $ is special
redis2_raw_query 'get one\r\n';
redis2_pass 127.0.0.1:6379;
}
# GET /baz?get%20foo%0d%0a
location /baz {
set_unescape_uri $query $query_string; # this requires the ngx_set_misc module
redis2_raw_query $query;
redis2_pass 127.0.0.1:6379;
}
Description
This is an nginx upstream module that makes nginx talk to a redis 2.x
server in a non-blocking way. The full Redis 2.0 unified protocol has
been implemented including the redis pipelining support.
This module returns the raw TCP response from the redis server.
It's recommended to use my lua-redis-parser module (written in
pure C) to parse these responses into lua data structure when combined
with the ngx_lua module:
https://github.com/agentzh/lua-redis-parser
If you only want to use the "get" redis command, you can try out the
ngx_redis module here:
http://wiki.nginx.org/HttpRedis
It returns the parsed content part of the redis response because only
"get" is needed to implement.
Another option is to parse the redis responses on your client side yourself.
Directives
redis2_query arg1 arg2 ...
Specify a redis command by specifying its individual arguments
(including the redis command name itself) in a
similar way to the redis-cli utility.
Multiple instances of this directive are allowd in
a single location and these queries will be pipelined.
For example,
location /pipelined {
redis2_query set hello world;
redis2_query get hello;
redis2_pass 127.0.0.1:$TEST_NGINX_REDIS_PORT;
}
then GET /pipelined will yield two successive raw redis responses
+OK
$5
world
while newlines here are actually CR LF ("\r\n").
redis2_raw_query CMD
Specify raw redis queries and nginx variables are recognized
in the CMD argument.
Only one redis command is allowed in the CMD argument, or
you'll receive an error. If you want to specify multiple
pipelined commands in a single query, use the redis2_raw_queries
directive instead.
redis2_raw_queries N CMDS
Specify N commands in the CMDS argument. Both the N and CMDS
arguments can take nginx variables.
Here's some examples
location /pipelined {
redis2_raw_queries 3 "flushall\r\nget key1\r\nget key2\r\n";
redis2_pass 127.0.0.1:6379;
}
# GET /pipelined2?n=2&cmds=flushall%0D%0Aget%20key%0D%0A
location /pipelined2 {
set_unescape_uri $n $arg_n;
set_unescape_uri $cmds $arg_cmds;
redis2_raw_queries $n $cmds;
redis2_pass 127.0.0.1:6379;
}
Note that in the second sample above, the set_unescape_uri directive
is provided by the ngx_set_misc module.
redis2_literal_raw_query CMD
Specify raw redis queries but nginx variables are *not* recognized,
that is to say, you're free to use the dollar sign characters ($)
in your CMD argument.
Only one redis command is allowed in the CMD argument.
redis2_pass
redis2_connect_timeout
syntax: *redis2_connect_timeout <time>*
default: *60s*
context: *http, server, location*
The timeout for connecting to the redis server, in seconds by
default.
It's wise to always explicitly specify the time unit to avoid confusion.
Time units supported are "s"(seconds), "ms"(milliseconds), "y"(years),
"M"(months), "w"(weeks), "d"(days), "h"(hours), and "m"(minutes).
This time must be less than 597 hours.
redis2_send_timeout
syntax: *redis2_send_timeout <time>*
default: *60s*
context: *http, server, location*
The timeout for sending TCP requests to the redis server, in seconds
by default.
It's wise to always explicitly specify the time unit to avoid confusion.
Time units supported are "s"(seconds), "ms"(milliseconds), "y"(years),
"M"(months), "w"(weeks), "d"(days), "h"(hours), and "m"(minutes).
This time must be less than 597 hours.
redis2_read_timeout
syntax: *redis2_read_timeout <time>*
default: *60s*
context: *http, server, location*
The timeout for reading TCP responses from the redis server, in
seconds by default.
It's wise to always explicitly specify the time unit to avoid confusion.
Time units supported are "s"(seconds), "ms"(milliseconds), "y"(years),
"M"(months), "w"(weeks), "d"(days), "h"(hours), and "m"(minutes).
This time must be less than 597 hours.
redis2_buffer_size
redis2_next_upstream
syntax: redis2_next_upstream [ error | timeout | invalid_response | off ]
default: error timeout
context: http, server, location
Specify which failure conditions should cause the request to be forwarded to another
upstream server. Applies only when the value in redis2_pass is an upstream with two or more
servers.
Here's an artificial example:
upstream redis_cluster {
server 127.0.0.1:6379;
server 127.0.0.1:6380;
}
server {
location /redis {
redis2_next_upstream error timeout invalid_response;
redis2_query get foo;
redis2_pass redis_cluster;
}
}
Connection Pool
You can use Maxim Dounin's excellent ngx_http_upstream_keepalive module
( http://mdounin.ru/hg/ngx_http_upstream_keepalive/ )
with this module to privide TCP connection pool
for Redis.
A sample config snippet looks like this
http {
upstream backend {
server 127.0.0.1:6379;
# a pool with at most 1024 connections
# and do not distinguish the servers:
keepalive 1024 single;
}
server {
...
location /redis {
set_unescape_uri $query $arg_query;
redis2_query $query;
redis2_pass backend;
}
}
}
Lua Interoperability
This module can be served as a non-blocking redis2 client
for ngx_lua ( http://github.com/chaoslawful/lua-nginx-module ).
Here's an example using a GET subrequest:
location /redis {
internal;
# set_unescape_uri is provided by ngx_set_misc
set_unescape_uri $query $arg_query;
redis2_raw_query $query;
redis2_pass 127.0.0.1:6379;
}
location /main {
content_by_lua '
local res = ngx.location.capture("/redis",
{ args = { query = "ping\\r\\n" } }
)
ngx.print("[" .. res.body .. "]")
';
}
Then accessing /main yields
[+PONG\r\n]
where "\r\n" is CRLF. That is, this module returns the *raw* TCP responses
from the remote redis server. For lua-based application developers, they
may want to utilize the lua-redis-parser module (written in pure C) to
parse such raw responses into Lua data structures:
https://github.com/agentzh/lua-redis-parser
When moving the inlined Lua code into an external .lua file, it's important
to use the escape sequence "\r\n" directly. We used "\\r\\n" above just because
the Lua code itself needs quoting when being put into an nginx string literal.
You can also use POST/PUT subrequests to transfer the raw redis
request via request body, which does not require URI escaping
and unescaping, thus saving some CPU cycles. Here's such an example:
location /redis {
internal;
# $echo_request_body is provided by the ngx_echo module
redis2_raw_query $echo_request_body;
redis2_pass 127.0.0.1:6379;
}
location /main {
content_by_lua '
local res = ngx.location.capture("/redis",
{ method = ngx.HTTP_PUT,
body = "ping\\r\\n" }
)
ngx.print("[" .. res.body .. "]")
';
}
This yeilds exactly the same output as the previous (GET) sample.
One can also use Lua to pick up a concrete Redis backend
based on some complicated hashing rules. For
instance,
upstream redis-a {
server foo.bar.com:6379;
}
upstream redis-b {
server bar.baz.com:6379;
}
upstream redis-c {
server blah.blah.org:6379;
}
server {
...
location /redis {
set_unescape_uri $query $arg_query;
redis2_query $query;
redis2_pass $arg_backend;
}
location /foo {
content_by_lua "
-- pick up a server randomly
local servers = {'redis-a', 'redis-b', 'redis-c'}
local i = ngx.time() % #servers + 1;
local srv = servers[i]
local res = ngx.location.capture('/redis',
{ args = {
query = '...',
backend = srv
} }
)
ngx.say(res.body)
";
}
}
Redis Publish/Subscribe Support
This module has limited support for redis publish/subscribe feature.
It cannot be fully supported due to the stateless nature of REST and
HTTP model.
Consider the following example:
location /redis {
redis2_raw_queries 2 "subscribe /foo/bar\r\n";
redis2_pass 127.0.0.1:6379;
}
And then publish a message for the key /foo/bar in the redis-cli
command line. And then you'll receive two multi-bulk replies from the
/redis location.
You can surely parse the replies with the lua-redis-parser library if
you're using Lua to access this module's location.
Some limitations:
1. You cannot use ngx_http_upstream_keepalive with this redis
upstream. Only short redis connections will work.
2. There may be some race conditions that produce the harmless "Redis
server returned extra bytes" warnings in your nginx's error.log. Such
warnings might be rare but just be prepared for it.
3. You should tune the various timeout settings provided by ngx_redis2.
Performance Tuning
When you're using ngx_redis2, please ensure you're using a tcp
connection pool (provided by ngx_http_upstream_keepalive)
and redis pipelining wherever possible. These features will
significantly improve performance. Also, using multiple instance of
redis servers on your multi-core machines also help a lot due to the
sequential processing nature of a single redis server instance.
Also, when you're benchmarking performance using something like ab or
http_load, please ensure that your error log level is high enough (like
"warn") to prevent nginx workers spend too much cycles on flushing the
error.log file, which is always unbuffered and blocking and thus very
expensive.
Installation
1. Grab the nginx source code from nginx.net (<http://nginx.net/>), for
example, the version 0.8.54 (see nginx compatibility),
2. and then build the source with this module:
$ wget 'http://sysoev.ru/nginx/nginx-0.8.54.tar.gz'
$ tar -xzvf nginx-0.8.54.tar.gz
$ cd nginx-0.8.54/
# Here we assume you would install you nginx under /opt/nginx/.
$ ./configure --prefix=/opt/nginx \
--add-module=/path/to/redis2-nginx-module
$ make -j2
$ make install
Download the latest version of the release tarball of this module from
redis2-nginx-module file list
(<http://github.com/agentzh/redis2-nginx-module/downloads>).
Compatibility
Redis 2.0, 2.2, and above should work with this module
without any issues. So is the "Alchemy Database"
(aka redisql).
The following versions of Nginx should work with this module:
* 1.0.x (last tested: 1.0.5)
* 0.9.x (last tested: 0.9.4)
* 0.8.x >= 0.8.31 (last tested: 0.8.54)
Earlier versions of Nginx will *not* work.
If you find that any particular version of Nginx above 0.8.31 does not
work with this module, please consider reporting a bug.
Report Bugs
Although a lot of effort has been put into testing and code tuning,
there must be some serious bugs lurking somewhere in this module. So
whenever you are bitten by any quirks, please don't hesitate to
1. send a bug report or even patches to <agentzh@gmail.com>,
2. or create a ticket on the issue tracking interface
(<http://github.com/agentzh/redis2-nginx-module/issues>)
provided by GitHub.
Source Repository
Available on github at agentzh/redis2-nginx-module
(<http://github.com/agentzh/redis2-nginx-module>).
TODO
* Add the "redis2_as_json" directive to allow emitting JSON directly.
AUTHORS
Yichun "agentzh" Zhang (章亦春) < agentzh@gmail.com >
Getting involved
You'll be very welcomed to submit patches to the author or just ask for
a commit bit to the source repository on GitHub.
Copyright & License
Copyright (c) 2010, 2011 Taobao Inc., Alibaba Group ( http://www.taobao.com
).
Copyright (c) 2010, 2011 Yichun "agentzh" Zhang (章亦春) <agentzh@gmail.com>.
This module is licensed under the terms of the BSD license.
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.
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.
SEE ALSO
* a redis response parser for Lua: https://github.com/agentzh/lua-redis-parser
