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Name
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 already production ready.
Version
This document describes ngx_redis2 v0.09
(<https://github.com/agentzh/redis2-nginx-module/tags>) released on 8
September 2012.
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 $query;
redis2_pass 127.0.0.1:6379;
}
location /init {
redis2_query del key1;
redis2_query lpush key1 C;
redis2_query lpush key1 B;
redis2_query lpush key1 A;
redis2_pass 127.0.0.1:6379;
}
location /get {
redis2_query lrange key1 0 -1;
redis2_pass 127.0.0.1:6379;
}
Description
This is an Nginx upstream module that makes nginx talk to a Redis
(<http://redis.io/>) 2.x server in a non-blocking way. The full Redis
2.0 unified protocol has been implemented including the Redis pipelining
support.
This module returns the raw TCP response from the Redis server. It's
recommended to use my [[LuaRedisParser]] (written in pure C) to parse
these responses into lua data structure when combined with
[[HttpLuaModule]].
If you only want to use the "get" redis command, you can try out the
[[HttpRedisModule]]. It returns the parsed content part of the Redis
response because only "get" is needed to implement.
Another option is to parse the redis responses on your client side
yourself.
Directives
redis2_query
syntax: *redis2_query cmd arg1 arg2 ...*
default: *no*
context: *location, location if*
Specify a Redis command by specifying its individual arguments
(including the Redis command name itself) in a similar way to the
"redis-cli" utility.
Multiple instances of this directive are allowed in a single location
and these queries will be pipelined. For example,
location /pipelined {
redis2_query set hello world;
redis2_query get hello;
redis2_pass 127.0.0.1:$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
syntax: *redis2_raw_query QUERY*
default: *no*
context: *location, location if*
Specify raw Redis queries and nginx variables are recognized in the
"QUERY" argument.
Only *one* Redis command is allowed in the "QUERY" 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
syntax: *redis2_raw_queries N QUERIES*
default: *no*
context: *location, location if*
Specify "N" commands in the "QUERIES" argument. Both the "N" and
"QUERIES" 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 $cmds;
redis2_pass 127.0.0.1:6379;
}
Note that in the second sample above, the L<set_unescape_uri|HttpSetMiscModule/"set_unescape_uri"> directive is provided by the [[HttpSetMiscModule]].
redis2_literal_raw_query
syntax: *redis2_literal_raw_query QUERY*
default: *no*
context: *location, location if*
Specify a raw Redis query but Nginx variables in it will not be *not*
recognized. In other words, you're free to use the dollar sign character
("$") in your "QUERY" argument.
Only One redis command is allowed in the "QUERY" argument.
redis2_pass
syntax: *redis2_pass <upstream_name>*
syntax: *redis2_pass <host>:<port>*
default: *no*
context: *location, location if*
phase: *content*
Specify the Redis server backend.
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).
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).
redis2_buffer_size
syntax: *redis2_buffer_size <size>*
default: *4k/8k*
context: *http, server, location*
This buffer size is used for reading Redis replies, but it's not
required to be as big as the largest possible Redis reply.
This default size is the page size, may be 4k or 8k.
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 the excellent [[HttpUpstreamKeepaliveModule]] 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;
}
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
[[HttpLuaModule]] (but nowadays it is recommended to use the
lua-resty-redis (<http://github.com/agentzh/lua-resty-redis>) library
instead, which is much simpler to use and more efficient most of the
time). 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 [[LuaRedisParser]] library
(written in pure C) to parse such raw responses into Lua data
structures.
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)
";
}
}
Pipelined Redis Requests by Lua
Here's a complete example demonstrating how to use Lua to issue multiple
pipelined Redis requests via this Nginx module.
First of all, we include the following in our "nginx.conf" file:
location = /redis2 {
internal;
redis2_raw_queries $args $echo_request_body;
redis2_pass 127.0.0.1:6379;
}
location = /test {
content_by_lua_file conf/test.lua;
}
Basically we use URI query args to pass the number of Redis requests and
request body to pass the pipelined Redis request string.
And then we create the "conf/test.lua" file (whose path is relative to
the server root of Nginx) to include the following Lua code:
-- conf/test.lua
local parser = require "redis.parser"
local reqs = {
{"set", "foo", "hello world"},
{"get", "foo"}
}
local raw_reqs = {}
for i, req in ipairs(reqs) do
table.insert(raw_reqs, parser.build_query(req))
end
local res = ngx.location.capture("/redis2?" .. #reqs,
{ body = table.concat(raw_reqs, "") })
if res.status ~= 200 or not res.body then
ngx.log(ngx.ERR, "failed to query redis")
ngx.exit(500)
end
local replies = parser.parse_replies(res.body, #reqs)
for i, reply in ipairs(replies) do
ngx.say(reply[1])
end
Here we assume that your Redis server is listening on the default port
(6379) of the localhost. We also make use of the [[LuaRedisParser]]
library to construct raw Redis queries for us and also use it to parse
the replies.
Accessing the "/test" location via HTTP clients like "curl" yields the
following output
OK hello world
A more realistic setting is to use a proper upstream definition for our
Redis backend and enable TCP connection pool via the keepalive directive
in it.
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 [[LuaRedisParser]] library if
you're using Lua to access this module's location.
Publish/Subscribe Limitations
* You cannot use [[HttpUpstreamKeepaliveModule]] with this Redis
upstream. Only short Redis connections will work.
* 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.
* You should tune the various timeout settings provided by this module
like redis2_connect_timeout and redis2_read_timeout.
Performance Tuning
* When you're using this module, please ensure you're using a TCP
connection pool (provided by [[HttpUpstreamKeepaliveModule]]) and
Redis pipelining wherever possible. These features will
significantly improve performance.
* 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.
* 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 non-buffered and
blocking and thus very expensive.
Installation
You are recommended to install this module (as well as the Nginx core
and many many other goodies) via the ngx_openresty bundle
(<http://openresty.org>). Check out the installation instructions
(<http://openresty.org/#Installation>) for setting up ngx_openresty
(<http://openresty.org>).
Alternatively, you can install this module manually by recompiling the
standard Nginx core as follows:
* Grab the nginx source code from nginx.org (<http://nginx.org>), for
example, the version 1.2.3 (see nginx compatibility),
* and then download the latest version of the release tarball of this
module from ngx_redis2's file list
(<http://github.com/agentzh/redis2-nginx-module/tags>).
* and finally build the source with this module:
wget 'http://nginx.org/download/nginx-1.2.3.tar.gz'
tar -xzvf nginx-1.2.3.tar.gz
cd nginx-1.2.3/
# 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
Compatibility
Redis 2.0, 2.2, 2.4, and above should work with this module without any
issues. So is the Alchemy Database
(<http://code.google.com/p/alchemydatabase/>) (aka redisql in its early
days).
The following versions of Nginx should work with this module:
* 1.3.x (last tested: 1.3.4)
* 1.2.x (last tested: 1.2.3)
* 1.1.x (last tested: 1.1.5)
* 1.0.x (last tested: 1.0.10)
* 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.
Community
English Mailing List
The openresty-en (<https://groups.google.com/group/openresty-en>)
mailing list is for English speakers.
Chinese Mailing List
The openresty (<https://groups.google.com/group/openresty>) mailing list
is for Chinese speakers.
Bugs and Patches
Please submit bug reports, wishlists, or patches by
1. creating a ticket on the GitHub Issue Tracker
(<http://github.com/agentzh/redis2-nginx-module/issues>),
2. or posting to the OpenResty community.
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.
Author
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
This module is licenced under the BSD license.
Copyright (C) 2010-2012, by Yichun "agentzh" Zhang (章亦春)
<agentzh@gmail.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.
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
* The Redis (<http://redis.io/>) server homepage.
* The Redis wire protocol: http://redis.io/topics/protocol
* a redis response parser and a request constructor for Lua:
[[LuaRedisParser]].
* [[HttpLuaModule]]
* The ngx_openresty bundle (<http://openresty.org>).
* The lua-resty-redis (<https://github.com/agentzh/lua-resty-redis>)
library based on the [[HttpLuaModule]] cosocket API.
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