About

A very simple web server providing an HTTP interface to Redis. It uses hiredis, jansson, libevent, and http-parser.

Webdis depends on libevent-dev. You can install it on Ubuntu by typing sudo apt-get install libevent-dev or on OS X by typing brew install libevent.

make clean all

./webdis &

curl http://127.0.0.1:7379/SET/hello/world
→ {"SET":[true,"OK"]}

curl http://127.0.0.1:7379/GET/hello
→ {"GET":"world"}

curl -d "GET/hello" http://127.0.0.1:7379/
→ {"GET":"world"}

Features

• GET and POST are supported, as well as PUT for file uploads.
• JSON output by default, optional JSONP parameter (?jsonp=myFunction or ?callback=myFunction).
• Raw Redis 2.0 protocol output with .raw suffix
• MessagePack output with .msg suffix
• HTTP 1.1 pipelining (70,000 http requests per second on a desktop Linux machine.)
• Multi-threaded server, configurable number of worker threads.
• WebSocket support (Currently using the “hixie-76” specification).
• Connects to Redis using a TCP or UNIX socket.
• Restricted commands by IP range (CIDR subnet + mask) or HTTP Basic Auth, returning 403 errors.
• Possible Redis authentication in the config file.
• Pub/Sub using Transfer-Encoding: chunked, works with JSONP as well. Webdis can be used as a Comet server.
• Drop privileges on startup.
• Custom Content-Type using a pre-defined file extension, or with ?type=some/thing.
• URL-encoded parameters for binary data or slashes and question marks. For instance, %2f is decoded as / but not used as a command separator.
• Logs, with a configurable verbosity.
• Cross-origin requests, usable with XMLHttpRequest2 (Cross-Origin Resource Sharing - CORS).
• File upload with PUT.
• With the JSON output, the return value of INFO is parsed and transformed into an object.
• Optional daemonize: set "daemonize": true and "pidfile": "/var/run/webdis.pid" in webdis.json.
• Default root object: Add "default_root": "/GET/index.html" in webdis.json to substitute the request to / with a Redis request.
• HTTP request limit with http_max_request_size (in bytes, set to 128MB by default).
• Database selection in the URL, using e.g. /7/GET/key to run the command on DB 7.

Ideas, TODO...

• Add better support for PUT, DELETE, HEAD, OPTIONS? How? For which commands?
  • This could be done using a “strict mode” with a table of commands and the verbs that can/must be used with each command. Strict mode would be optional, configurable. How would webdis know of new commands remains to be determined.
• MULTI/EXEC/DISCARD/WATCH are disabled at the moment; find a way to use them.
• Support POST of raw Redis protocol data, and execute the whole thing. This could be useful for MULTI/EXEC transactions.
• Enrich config file:
  • Provide timeout (maybe for some commands only?). What should the response be? 504 Gateway Timeout? 503 Service Unavailable?
• Multi-server support, using consistent hashing.
• SSL?
  • Not sure if this is such a good idea.
• SPDY?
  • SPDY is mostly useful for parallel fetches. Not sure if it would make sense for Webdis.
• Send your ideas using the github tracker, on twitter @yowgi or by mail to n.favrefelix@gmail.com.

HTTP error codes

• Unknown HTTP verb: 405 Method Not Allowed.
• Redis is unreachable: 503 Service Unavailable.
• Matching ETag sent using If-None-Match: 304 Not Modified.
• Could also be used:
  • Timeout on the redis side: 503 Service Unavailable.
  • Missing key: 404 Not Found.
  • Unauthorized command (disabled in config file): 403 Forbidden.

Command format

The URI /COMMAND/arg0/arg1/.../argN.ext executes the command on Redis and returns the response to the client. GET, POST, and PUT are supported:

• GET /COMMAND/arg0/.../argN.ext
• POST / with COMMAND/arg0/.../argN in the HTTP body.
• PUT /COMMAND/arg0.../argN-1 with argN in the HTTP body (see section on file uploads.)

.ext is an optional extension; it is not read as part of the last argument but only represents the output format. Several formats are available (see below).

Special characters: / and . have special meanings, / separates arguments and . changes the Content-Type. They can be replaced by %2f and %2e, respectively.

ACL

Access control is configured in webdis.json. Each configuration tries to match a client profile according to two criterias:

• CIDR subnet + mask
• HTTP Basic Auth in the format of "user:password".

Each ACL contains two lists of commands, enabled and disabled. All commands being enabled by default, it is up to the administrator to disable or re-enable them on a per-profile basis. Examples:

{
	"disabled":	["DEBUG", "FLUSHDB", "FLUSHALL"],
},

{
	"http_basic_auth": "user:password",
	"disabled":	["DEBUG", "FLUSHDB", "FLUSHALL"],
	"enabled":	["SET"]
},

{
	"ip": 		"192.168.10.0/24",
	"enabled":	["SET"]
},

{
	"http_basic_auth": "user:password",
	"ip": 		"192.168.10.0/24",
	"enabled":	["SET", "DEL"]
}

ACLs are interpreted in order, later authorizations superseding earlier ones if a client matches several. The special value "*" matches all commands.

JSON output

JSON is the default output format. Each command returns a JSON object with the command as a key and the result as a value.

Examples:

// string
$ curl http://127.0.0.1:7379/GET/y
{"GET":"41"}

// number
$ curl http://127.0.0.1:7379/INCR/y
{"INCR":42}

// list
$ curl http://127.0.0.1:7379/LRANGE/x/0/1
{"LRANGE":["abc","def"]}

// status
$ curl http://127.0.0.1:7379/TYPE/y
{"TYPE":[true,"string"]}

// error, which is basically a status
$ curl http://127.0.0.1:7379/MAKE-ME-COFFEE
{"MAKE-ME-COFFEE":[false,"ERR unknown command 'MAKE-ME-COFFEE'"]}

// JSONP callback:
$ curl  "http://127.0.0.1:7379/TYPE/y?jsonp=myCustomFunction"
myCustomFunction({"TYPE":[true,"string"]})

RAW output

This is the raw output of Redis; enable it with the .raw suffix.

// string
$ curl http://127.0.0.1:7379/GET/z.raw
$5
hello

// number
curl http://127.0.0.1:7379/INCR/a.raw
:2

// list
$ curl http://127.0.0.1:7379/LRANGE/x/0/-1.raw
*2
$3
abc
$3
def

// status
$ curl http://127.0.0.1:7379/TYPE/y.raw
+zset

// error, which is basically a status
$ curl http://127.0.0.1:7379/MAKE-ME-COFFEE.raw
-ERR unknown command 'MAKE-ME-COFFEE'

Custom content-type

Several content-types are available:

• .json for application/json (this is the default Content-Type).
• .msg for application/x-msgpack. See http://msgpack.org/ for the specs.
• .txt for text/plain
• .html for text/html
• xhtml for application/xhtml+xml
• xml for text/xml
• .png for image/png
• jpg or jpeg for image/jpeg
• Any other with the ?type=anything/youwant query string.
• Add a custom separator for list responses with ?sep=, query string.

curl -v "http://127.0.0.1:7379/GET/hello.html"
[...]
< HTTP/1.1 200 OK
< Content-Type: text/html
< Date: Mon, 03 Jan 2011 20:43:36 GMT
< Content-Length: 137
<
<!DOCTYPE html>
<html>
[...]
</html>

curl -v "http://127.0.0.1:7379/GET/hello.txt"
[...]
< HTTP/1.1 200 OK
< Content-Type: text/plain
< Date: Mon, 03 Jan 2011 20:43:36 GMT
< Content-Length: 137
[...]

curl -v "http://127.0.0.1:7379/GET/big-file?type=application/pdf"
[...]
< HTTP/1.1 200 OK
< Content-Type: application/pdf
< Date: Mon, 03 Jan 2011 20:45:12 GMT
[...]

File upload

Webdis supports file upload using HTTP PUT. The command URI is slightly different, as the last argument is taken from the HTTP body. For example: instead of /SET/key/value, the URI becomes /SET/key and the value is the entirety of the body. This works for other commands such as LPUSH, etc.

Uploading a binary file to webdis:

$ file redis-logo.png
redis-logo.png: PNG image, 513 x 197, 8-bit/color RGBA, non-interlaced

$ wc -c redis-logo.png
16744 redis-logo.png

$ curl -v --upload-file redis-logo.png http://127.0.0.1:7379/SET/logo
[...]
> PUT /SET/logo HTTP/1.1
> User-Agent: curl/7.19.7 (x86_64-pc-linux-gnu) libcurl/7.19.7 OpenSSL/0.9.8k zlib/1.2.3.3 libidn/1.15
> Host: 127.0.0.1:7379
> Accept: */*
> Content-Length: 16744
> Expect: 100-continue
>
< HTTP/1.1 100 Continue
< HTTP/1.1 200 OK
< Content-Type: application/json
< ETag: "0db1124cf79ffeb80aff6d199d5822f8"
< Date: Sun, 09 Jan 2011 16:48:19 GMT
< Content-Length: 19
<
{"SET":[true,"OK"]}

$ curl -vs http://127.0.0.1:7379/GET/logo.png -o out.png
> GET /GET/logo.png HTTP/1.1
> User-Agent: curl/7.19.7 (x86_64-pc-linux-gnu) libcurl/7.19.7 OpenSSL/0.9.8k zlib/1.2.3.3 libidn/1.15
> Host: 127.0.0.1:7379
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Type: image/png
< ETag: "1991df597267d70bf9066a7d11969da0"
< Date: Sun, 09 Jan 2011 16:50:51 GMT
< Content-Length: 16744

$ md5sum redis-logo.png out.png
1991df597267d70bf9066a7d11969da0  redis-logo.png
1991df597267d70bf9066a7d11969da0  out.png

The file was uploaded and re-downloaded properly: it has the same hash and the content-type was set properly thanks to the .png extension.

WebSockets

Webdis supports WebSocket clients implementing dixie-76.
Web Sockets are supported with the following formats, selected by the connection URL:

• JSON (on / or /.json)
• Raw Redis wire protocol (on /.raw)

Example:

function testJSON() {
	var jsonSocket = new WebSocket("ws://127.0.0.1:7379/.json");
	jsonSocket.onopen = function() {

		console.log("JSON socket connected!");
		jsonSocket.send(JSON.stringify(["SET", "hello", "world"]));
		jsonSocket.send(JSON.stringify(["GET", "hello"]));
	};
	jsonSocket.onmessage = function(messageEvent) {
		console.log("JSON received:", messageEvent.data);
	};
}
testJSON();

This produces the following output:

JSON socket connected!
JSON received: {"SET":[true,"OK"]}
JSON received: {"GET":"world"}

Pub/Sub with chunked transfer encoding

Webdis exposes Redis PUB/SUB channels to HTTP clients, forwarding messages in the channel as they are published by Redis. This is done using chunked transfer encoding.

Example using XMLHttpRequest:

var previous_response_length = 0
xhr = new XMLHttpRequest()
xhr.open("GET", "http://127.0.0.1:7379/SUBSCRIBE/hello", true);
xhr.onreadystatechange = checkData;
xhr.send(null);

function checkData() {
	if(xhr.readyState == 3)  {
    	response = xhr.responseText;
    	chunk = response.slice(previous_response_length);
    	previous_response_length = response.length;
    	console.log(chunk);
    }
};

Publish messages to redis to see output similar to the following:

{"SUBSCRIBE":["subscribe","hello",1]}
{"SUBSCRIBE":["message","hello","some message"]}
{"SUBSCRIBE":["message","hello","some other message"]}