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https://github.com/sneakybeaky/mod_redis

An Apache HTTPD module for speaking to redis via HTTP
https://github.com/sneakybeaky/mod_redis

Last synced: 8 months ago
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An Apache HTTPD module for speaking to redis via HTTP

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README 

          
mod_redis

=========



This Apache module uses a rule-based engine (based on regular expression parser) to map URLs to 

REDIS commands on the fly. It supports an unlimited number of rules and can match on the full URL 

and the request method (GET, POST, PUT or DELETE) to provide a very flexible option for defining 

a RESTful interface to REDIS.



By default the module returns an XML representation of the resulting REDIS response. For example

configuring a RedisAlias to support the PING command (`RedisAlias ^ping$ "PING"`), the response 

would be:



    

    

    PONG



This behavior can be altered by appending .json to the url, for example:



    { "status" : "PONG" }



Alternatively, appending .jsonp and adding a query parameter ‘callback’ respond with:



    callback({ "status" : "PONG" });



Installation

------------



1. Download Hiredis, a minimalistic C client library for the Redis database



    `curl https://github.com/antirez/hiredis/zipball/master -L -o hiredis.zip`



2. Unzip the downloaded file



    `unzip hiredis.zip`



3. Extract the contents of the zip file (hiredis.zip) and define the base directory. In the 

example below, the last part of the embedded directory has been obscured so please remember to

use the directory created when unzipping the file



    `HIREDIS_HOME=`pwd`/antirez-hiredis-XXXXXXX`



4. Compile the hiredis library



    `pushd $HIREDIS_HOME ; make ; popd`



5. Compile mod_redis



    `apxs -c -I $HIREDIS_HOME $HIREDIS_HOME/libhiredis.a mod_redis.c`



6. Install the module into the currently installed Apache instance



    `sudo apxs -i -a mod_redis.la`



7. Run the tests. This will create a custom httpd.conf and start a new Apache instance on port 

8081 for the purposes of testing. Temp files for this test instance can be found in the ./testing 

directory. By default, the test script will attempt to connect to local REDIS server on the 

standard REDIS port (6379), this can be modified with command line parameters



    `./test.sh [RedisIPAddress] [RedisPort]`



RedisAlias Directive

--------------------



**Description**: Defines a rule to match a URL to a REDIS command  

**Syntax**:      RedisAlias TestString RedisCommandPattern [Method]  



Rules are matched based on the order in which they are defined. Depending on the expression, care

should be taken not to define less specific expressions before more specific ones. Consider a

configuraton defining two directives in the following order, in the following example the second

expression would never be matched because the first expression would evaluate successfully first.



    RedisAlias ^([^/]+)$ "GET $1"

    RedisAlias ^ping$    "PONG"

    

**TestString**   



A regular expression defining the elements in the URL to match. This excludes the

protocol, hostname, portnumber, module location and query string. Consider an local installation

of Apache with mod_redis handler configured for the location `/redis/*`, in the following 

contrived example, the element of the URL that can be matched against is in square brackets



    http://localhost/redis/[Matchable].json?callback=alert

    

Round brackets can used used to create a backreference for part of the matching string which can be 

later referenced in the RedisCommandPattern. This is essential to extract elements of the URL for 

use in the REDIS command itself.



    ^([^/]+)/count$



This example matches any characters appearing before the first matching forward slash, followed by 

a forward slash, the word count and then the end of the string. The round brackets create a 

backreference, capturing the characters before the forward slash so that it can be used in the 

RedisCommandPattern, i.e. `"ZCARD $1"`. Using this example the URL `//myset/count` 

would result in the REDIS command `ZCARD myset`. 



**RedisCommandsPattern**  



The pattern used to create a REDIS command to be executed. The format of 

this command must confirm to the REDIS command syntax. Additionally the text can contain the 

following:



* TestString backreferences: These backreferences take the form $N (0<=N<=9) which provide to the 

grouped parts (in parentheses) of the TestString.



* Request variables: These are variables from the current request being processed



    %{DATA}         The body content of a PUT or POST request  

    ${FORM:field}   The value of a form field taken from PUT or POST request. The request must have

               include the Content-Type header as application/x-www-form-urlencoded  

    ${QSA:field}   The value of a query string argument taken from the request URL



**Method**  



The HTTP method of the given request, GET, PUT, POST or DELETE. When a method is not

specified, GET is assumed as the default. The Method parameter can be used to increase the 

specificity of the directive. In the following example, the **TestString** is identical, however 

the **Method** determines which directive would successfully match.



    RedisAlias ^([^/]+)$ "GET $1"

    RedisAlias ^([^/]+)$ "SET $1 %{DATA}" PUT

    RedisAlias ^([^/]+)$ "DEL $1" DELETE

    



**Examples**  



To define alias to add, remove and count the number of entries in a sorted set, you would add the 

following directives:



    RedisAlias ^([^/]+)/([^/]+)$ "ZADD $1 %{DATA} $2" PUT  

    RedisAlias ^([^/]+)/([^/]+)$ "ZREM $1 $2" DELETE  

    RedisAlias ^([^/]+)/count$ "ZCARD $1"  

    

To define an alias to retrieve a list of members from a sorted set, you could add the following

directive:



    RedisAlias ^([^/]+)/range/([^/]+)/([^/]+)$ "ZRANGE $1 $2 $3 WITHSCORES"



To define an alias to create a new member to a sorted set from a POSTed form you could add the 

following directive:



    RedisAlias ^zadd$ "ZADD ${FORM:key} ${FORM:score} ${FORM:member}" POST

    

To define an alias to determine the rank of a key in a sorted set based on a query parameter, you

could add the following directive:



    RedisAlias ^([^/]+)/rank$ "ZRANK $1 ${QSA:key}"



RedisIPAddress Directive

------------------------



**Description**: Defines the IP address of the REDIS instance to connect to  

**Syntax**:      RedisIPAddress IPAddress  



The default IPAddress is 127.0.0.1



RedisPort Directive

-------------------



**Description**: Defines the port number of the REDIS instance to connect to  

**Syntax**:      RedisPort PortNumber  



The default PortNumber is 6379



Example httpd.conf

------------------



    

    SetHandler redis

    



    

    RedisIPAddress 127.0.0.1

    RedisPort 6379

    RedisAlias ^ping$ "PING"