uWSGI internal routing

Updated to 1.9

As of uWSGI 1.9, a programmable internal routing subsystem is available (older releases after 1.1 have a less featureful version). You can use the internal routing subsystem to dynamically alter the way requests are handled. For example you can use it to trigger a 301 redirect on specific URLs, or to serve content from the cache on specific conditions. The internal routing subsystem is inspired by Apache’s mod_rewrite and Linux’s iptables command. Please, before blasting it for being messy, not-elegant nor Turing-complete, remember that it must be FAST and only FAST. If you need elegance and more complexity, do that in your code.

The routing chains

During the request cycle, various “chains” are traversed. Each chain contains a routing table (see below).

Chains can be “recursive”. A “recursive” chain can be called multiple times in a request cycle.

This is the order of chains:

request it is applied before the request is passed to the plugin

error it is applied as soon as an HTTP status code is generate (recursive chain)

response it is is applied after the last response header has been generated (just before sending the body)

final it is aplied after the response has been sent to the client

The request chain is (for convention) the ‘default’ one, so its options are not prefixed, while the others requires a prefix.

Example:

route-user-agent -> happens in the request chain

while

response-route-uri -> happens in the response chain

The internal routing table

The internal routing table is a sequence of ‘’rules’’ executed one after another (forward jumps are allowed too). Each rule is composed by a ‘’subject’‘, a ‘’condition’’ and an ‘’action’’ The ‘’condition’’ is generally a PCRE regexp applied to the subject, if it matches the action is triggered. Subjects are request’s variables. Currently the following subjects are supported:

  • host (check HTTP_HOST)
  • uri (check REQUEST_URI)
  • qs (check QUERY_STRING)
  • remote-addr (check REMOTE_ADDR)
  • remote-user (check REMOTE_USER)
  • referer (check HTTP_REFERER)
  • user-agent (check HTTP_USER_AGENT)
  • status (check HTTP response status code, not available in the request chain)
  • default (default subject, maps to PATH_INFO)

In addition to this, a pluggable system of lower-level conditions is available. You can access this system using the --route-if option. Currently the following checks are supported:

  • exists (check if the subject exists in the filesystem)
  • isfile (check if the subject is a file)
  • isdir (check if the subject is a directory)
  • isexec (check if the subject is an executable file)
  • equal/isequal/eq/== (check if the subject is equal to the specified pattern)
  • ishigherequal/>=
  • ishigher/>
  • islower/<
  • islowerequal/<=
  • startswith (check if the subject starts with the specified pattern)
  • endswith (check if the subject ends with the specified pattern)
  • regexp/re (check if the subject matches the specified regexp)
  • empty (check if the subject is empty)
  • contains

When a check requires a pattern (like with ‘equal’ or ‘regexp’) you split it from the subject with a semicolon:

; never matches
route-if = equal:FOO;BAR log:never here
; matches
route if = regexp:FOO;^F log:starts with F

Actions are the functions to run if a rule matches. This actions are exported by plugins and have a return value.

Action return values

Each action has a return value which tells the routing engine what to do next. The following return codes are supported:

  • NEXT (continue to the next rule)
  • CONTINUE (stop scanning the internal routing table and run the request)
  • BREAK (stop scanning the internal routing table and close the request)
  • GOTO x (go to rule x)

When a rule does not match, NEXT is assumed.

The first example

[uwsgi]
route-user-agent = .*curl.* redirect:http://uwsgi.it
route-remote-addr = ^127\.0\.0\.1$ break:403 Forbidden
route = ^/test log:someone called /test
route = \.php$ rewrite:/index.php
route = .* addheader:Server: my uWSGI server
route-host = ^localhost$ logvar:local=1
route-uri = ^/foo/(.*)\.jpg$ cache:key=$1.jpg
route-if = equal:${PATH_INFO};/bad break:500 Internal Server Error

The previous rules, build the following table:

  • if the HTTP_USER_AGENT var contains ‘curl’ redirect the request to http://uwsgi.it (code 302, action returns BREAK)
  • if REMOTE_ADDR is ‘127.0.0.1’ returns a 403 Forbidden (action returns BREAK)
  • if PATH_INFO starts with /test print the string ‘someone called /test’ in the logs (action returns NEXT)
  • if PATH_INFO ends with ‘.php’ rewrite it to /index.php (action returns NEXT)
  • for all of the PATH_INFO add the HTTP header ‘Server: my uWSGI server’ to the response (action returns NEXT)
  • if HTTP_HOST is localhost add the logvar ‘local’ setting it to ‘1’
  • if REQUEST_URI starts with /foo and ends with .jpg get it from the uWSGI cache using the supplied key (built over regexp grouping) (action returns BREAK)
  • if the PATH_INFO is equal to /bad throws a 500 error

Accessing request vars

In addition to PCRE placeholders/groups (using $1 to $9) you can access request variables (PATH_INFO, SCRIPT_NAME, REQUEST_METHOD...) using the ${VAR} syntax.

[uwsgi]
route-user-agent = .*curl.* redirect:http://uwsgi.it${REQUEST_URI}

Accessing cookies

You can access a cookie value using the ${cookie[name]} syntax:

[uwsgi]
route = ^/foo log:${cookie[foobar]}

this will log the content of the ‘foobar’ cookie of the current request

Accessing query string items

You can access the value of the HTTP query string using the ${qs[name]} syntax:

[uwsgi]
route = ^/foo log:${qs[foobar]}

this will log the content of the ‘foobar’ item of the current request’s query string

Pluggable routing variables

Both the cookie and qs vars, are so-called “routing vars”. They are pluggable, so external plugins can add new vars to add new features to your application. (Check the The GeoIP plugin plugin for an example of this.) A number of embedded routing variables are also available.

  • mime – returns the mime type of the specified var: ${mime[REQUEST_URI]}

    [uwsgi]
    route = ^/images/(.+) addvar:MYFILE=$1.jpg
    route = ^/images/ addheader:Content-Type: ${mime[MYFILE]}
    
  • time – returns time/date in various form. The only supported (for now) is time[unix] returning the epoch

  • httptime – return http date adding the numeric argument (if specified)to the current time (use empty arg for current server time)

[uwsgi]
; add Date header
route-run = addheader:Date ${httptime[]}
  • math – requires matheval support. Example: math[CONTENT_LENGTH+1]
  • base64 – encode the specified var in base64
  • hex – encode the specified var in hex
  • uwsgi – return internal uWSGI information, uwsgi[wid], uwsgi[pid], uwsgi[uuid] and uwsgi[status] are currently supported

Is –route-if not enough? Why –route-uri and friends?

This is a good question. You just need to always remember that uWSGI is about versatility and performance. Gaining cycles is always good. The --route-if option, while versatile, cannot be optimized as all of its parts have to be recomputed at every request. This is obviously very fast, but --route-uri option (and friends) can be pre-optimized (during startup) to directly map to the request memory areas, so if you can use them, you definitely should. :)

GOTO

Yes, the most controversial construct of the whole information technology industry (and history) is here. You can make forward (only forward!) jumps to specific points of the internal routing table. You can set labels to mark specific point of the table, or if you are brave (or foolish) jump directly to a rule number. Rule numbers are printed on server startup, but please use labels.

[uwsgi]

route-host = ^localhost$ goto:localhost
route-host = ^sid\.local$ goto:sid.local
route = .* last:

route-label = sid.local
route-user-agent = .*curl.* redirect:http://uwsgi.it
route-remote-addr = ^192\.168\..* break:403 Forbidden
route = ^/test log:someone called /test
route = \.php$ rewrite:/index.php
route = .* addheader:Server: my sid.local server
route = .* logvar:local=0
route-uri = ^/foo/(.*)\.jpg$ cache:key=$1.jpg
route = .* last:

route-label = localhost
route-user-agent = .*curl.* redirect:http://uwsgi.it
route-remote-addr = ^127\.0\.0\.1$ break:403 Forbidden
route = ^/test log:someone called /test
route = \.php$ rewrite:/index.php
route = .* addheader:Server: my uWSGI server
route = .* logvar:local=1
route-uri = ^/foo/(.*)\.jpg$ cache:key=$1.jpg
route = .* last:

The example is like the previous one, but we with some differences between domains. Check the use of “last:”, to interrupt the routing table scan. You can rewrite the first 2 rules as one:

[uwsgi]

route-host = (.*) goto:$1

Collecting response headers

As we have already seen, each uWSGI request has a set of variables associated. They are generally the CGI vars passed by the webserver, but you can extend them with other variables too (check the ‘addvar’ action).

uWSGI 1.9.16 added a new feature allowing you to store the content of a response header in a request var. This simplify the write of more advanced rules.

For example you may want to gzip all of the text/html responses:

[uwsgi]
; store Content-Type response header in MY_CONTENT_TYPE var
collect-header = Content-Type MY_CONTENT_TYPE
; if response is text/html, and client supports it, gzip it
response-route-if = equal:${MY_CONTENT_TYPE};text/html goto:gzipme
response-route-run = last:

response-route-label = gzipme
; gzip only if the client support it
response-route-if = contains:${HTTP_ACCEPT_ENCODING};gzip gzip:

The available actions

continue/last

Return value: CONTINUE

Stop the scanning of the internal routing table and continue to the selected request handler.

break

Return value: BREAK

Stop scanning the internal routing table and close the request. Can optionally returns the specified HTTP status code:

[uwsgi]
route = ^/notfound break:404 Not Found
route = ^/bad break:
route = ^/error break:500

Note: break doesn’t support request variables because it’s intended to notify browser about the error, not the end user. That said, we can tell following code will send what it reads to browser (i.e. without ${REMOTE_ADDR} being translated to the remote IP address).

[uwsgi]
route-remote-addr = ^127\.0\.0\.1$ break:403 Forbidden for ip ${REMOTE_ADDR}

If you really do want to do wacky stuff, see clearheaders.

return/break-with-status

Return value: BREAK

return uses uWSGI’s built-in status code and returns both status code and message body. It’s similar to break but as mentioned above break doesn’t have the error message body. return:403 is equivalent to following:

[uwsgi]
 route-run = clearheaders:403 Forbidden
 route-run = addheader:Content-Type: text/plain
 route-run = addheader:Content-Length: 9
 route-run = send:Forbidden
 route-run = break:

log

Return value: NEXT

Print the specified message in the logs.

[uwsgi]
route = ^/logme/(.) log:hey i am printing $1

logvar

Return value: NEXT

Add the specified logvar.

[uwsgi]
route = ^/logme/(.) logvar:item=$1

goto

Return value: NEXT

Make a forward jump to the specified label or rule position

addvar

Return value: NEXT

Add the specified CGI (environment) variable to the request.

[uwsgi]
route = ^/foo/(.) addvar:FOOVAR=prefix$1suffix

addheader

Return value: NEXT

Add the specified HTTP header to the response.

[uwsgi]
route = ^/foo/(.) addheader:Foo: Bar

delheader//remheader

Return value: NEXT

Remove the specified HTTP header from the response.

[uwsgi]
route = ^/foo/(.) delheader:Foo

signal

Return value: NEXT

Raise the specified uwsgi signal.

send

Return value: NEXT

Extremely advanced (and dangerous) function allowing you to add raw data to the response.

[uwsgi]
route = ^/foo/(.) send:destroy the world

send-crnl

Return value: NEXT

Extremely advanced (and dangerous) function allowing you to add raw data to the response, suffixed with rn.

[uwsgi]
route = ^/foo/(.) send-crnl:HTTP/1.0 100 Continue

redirect/redirect-302

Return value: BREAK

Plugin: router_redirect

Return a HTTP 302 Redirect to the specified URL.

redirect-permanent/redirect-301

Return value: BREAK

Plugin: router_redirect

Return a HTTP 301 Permanent Redirect to the specified URL.

rewrite

Return value: NEXT

Plugin: router_rewrite

A rewriting engine inspired by Apache mod_rewrite. Rebuild PATH_INFO and QUERY_STRING according to the specified rules before the request is dispatched to the request handler.

[uwsgi]
route-uri = ^/foo/(.*) rewrite:/index.php?page=$1.php

rewrite-last

Alias for rewrite but with a return value of CONTINUE, directly passing the request to the request handler next.

uwsgi

Return value: BREAK

Plugin: router_uwsgi

Rewrite the modifier1, modifier2 and optionally UWSGI_APPID values of a request or route the request to an external uwsgi server.

[uwsgi]
route = ^/psgi uwsgi:127.0.0.1:3031,5,0

This configuration routes all of the requests starting with /psgi to the uwsgi server running on 127.0.0.1:3031 setting modifier1 to 5 and modifier2 to 0. If you only want to change the modifiers without routing the request to an external server, use the following syntax.

[uwsgi]
route = ^/psgi uwsgi:,5,0

To set a specific UWSGI_APPID value, append it.

[uwsgi]
route = ^/psgi uwsgi:127.0.0.1:3031,5,0,fooapp

The subrequest is async-friendly (engines such as gevent or ugreen are supported) and if offload threads are available they will be used.

http

Return value: BREAK

Plugin: router_http

Route the request to an external HTTP server.

[uwsgi]
route = ^/zope http:127.0.0.1:8181

You can substitute an alternative Host header with the following syntax:

[uwsgi]
route = ^/zope http:127.0.0.1:8181,myzope.uwsgi.it

static

Return value: BREAK

Plugin: router_static

Serve a static file from the specified physical path.

[uwsgi]
route = ^/logo static:/var/www/logo.png

basicauth

Return value: NEXT or BREAK 401 on failed authentication

Plugin: router_basicauth

Four syntaxes are supported.

  • basicauth:realm,user:password – a simple user:password mapping
  • basicauth:realm,user: – only authenticates username
  • basicauth:realm,htpasswd – use a htpasswd-like file. All POSIX crypt() algorithms are supported. This is _not_ the same behavior as Apache’s traditional htpasswd files, so use the -d flag of the htpasswd utility to create compatible files.
  • basicauth:realm, – Useful to cause a HTTP 401 response immediately. As routes are parsed top-bottom, you may want to raise that to avoid bypassing rules.

Example:

[uwsgi]
route = ^/foo basicauth-next:My Realm,foo:bar
route = ^/foo basicauth:My Realm,foo2:bar2
route = ^/bar basicauth:Another Realm,kratos:

Example: using basicauth for Trac

[uwsgi]
; load plugins (if required)
plugins = python,router_basicauth

; bind to port 9090 using http protocol
http-socket = :9090

; set trac instance path
env = TRAC_ENV=myinstance
; load trac
module = trac.web.main:dispatch_request

; trigger authentication on /login
route = ^/login basicauth-next:Trac Realm,pippo:pluto
route = ^/login basicauth:Trac Realm,foo:bar

;high performance file serving
static-map = /chrome/common=/usr/local/lib/python2.7/dist-packages/trac/htdocs

basicauth-next

same as basicauth but returns NEXT on failed authentication.

ldapauth

Return value: NEXT or BREAK 401 on failed authentication

Plugin: ldap

This auth router is part of the LDAP plugin, so it has to be loaded in order for this to be available. It’s like the basicauth router, but uses an LDAP server for authentication, syntax: ldapauth:realm,options Available options:

  • url - LDAP server URI (required)
  • binddn - DN used for binding. Required if the LDAP server does not allow anonymous searches.
  • bindpw - password for the binddn user.
  • basedn - base DN used when searching for users (required)
  • filter - filter used when searching for users (default is “(objectClass=*)”)
  • attr - LDAP attribute that holds user login (default is “uid”)
  • loglevel - 0 - don’t log any binds, 1 - log authentication errors, 2 - log both successful and failed binds

Example:

route = ^/protected ldapauth:LDAP auth realm,url=ldap://ldap.domain.com;basedn=ou=users,dc=domain;binddn=uid=proxy,ou=users,dc=domain;bindpw=password;loglevel=1;filter=(objectClass=posixAccount)

ldapauth-next

Same as ldapauth but returns NEXT on failed authentication.

cache

Return value: BREAK

Plugin: router_cache

cachestore/cache-store

cachevar

cacheset

memcached

rpc

The “rpc” routing instruction allows you to call uWSGI RPC functions directly from the routing subsystem and forward their output to the client.

[uwsgi]
http-socket = :9090
route = ^/foo addheader:Content-Type: text/html
route = ^/foo rpc:hello ${REQUEST_URI} ${HTTP_USER_AGENT}
route = ^/bar/(.+)$ rpc:test $1 ${REMOTE_ADDR} uWSGI %V
route = ^/pippo/(.+)$ rpc:test@127.0.0.1:4141 $1 ${REMOTE_ADDR} uWSGI %V
import = funcs.py

call

Plugin: rpc

rpcret

Plugin: rpc

rpcret calls the specified rpc function and uses its return value as the action return code (next, continue, goto, etc)

rpcblob//rpcnext

Plugin: rpc

rpcnext/rpcblob calls the specified RPC function, sends the response to the client and continues to the next rule.

rpcraw

Plugin: rpc

access

spnego

In development...

radius

In development...

xslt

See also

The XSLT plugin

gridfs

donotlog

chdir

setapp

setuser

sethome

setfile

setscriptname

setprocname

alarm

flush

fixcl

cgi

Plugin: cgi

cgihelper

Plugin: cgi

access

Plugin: router_access

cache-continue

Plugin: router_cache

cachevar

Plugin: router_cache

cacheinc

Plugin: router_cache

cachedec

Plugin: router_cache

cachemul

Plugin: router_cache

cachediv

Plugin: router_cache

proxyhttp

Plugin: router_http

memcached

Plugin: router_memcached

memcached-continue

Plugin: router_memcached

memcachedstore

Plugin: router_memcached

memcached-store

Plugin: router_memcached

redis

Plugin: router_redis

redis-continue

Plugin: router_redis

redisstore

Plugin: router_redis

redis-store

Plugin: router_redis

proxyuwsgi

Plugin: router_uwsgi

harakiri

Set harakiri for the current request.

file

Directly transfer the specified filename without using acceleration (sendfile, offloading, etc.).

[uwsgi]
http-socket = :9090
route-run = file:filename=/var/www/${PATH_INFO}

clearheaders

clear the response headers, setting a new HTTP status code, useful for resetting a response

[uwsgi]
http-socket = :9090
response-route = ^/foo goto:foobar
response-route-run = last:

response-route-label = foobar
response-route-run = clearheaders:404 Not Found
response-route-run = addheader:Content-Type: text/html

resetheaders

alias for clearheaders