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Nuster, a web caching proxy server.

Table of Contents


Nuster is a simple yet powerful web caching proxy server based on HAProxy. It is 100% compatible with HAProxy, and takes full advantage of the ACL functionality of HAProxy to provide fine-grained caching policy based on the content of request, response or server status. Its features include:

  • All features of HAProxy are inherited, 100% compatible with HAProxy
  • Powerful dynamic cache ability
    • Based on HTTP method, URI, path, query, header, cookies, etc
    • Based on HTTP request or response contents, etc
    • Based on environment variables, server state, etc
    • Based on SSL version, SNI, etc
    • Based on connection rate, number, byte, etc
  • Extremely fast
  • Cache purging
  • HTTPS supports on both frontend and backend
  • HTTP compression
  • HTTP rewriting and redirection


Nuster is very fast, some test shows nuster is almost three times faster than nginx when both using single core, and nearly two times faster than nginx and three times faster than varnish when using all cores.

See detailed benchmark



Download stable version from releases page for production use, otherwise git clone the source code.


make TARGET=linux2628 USE_LUA=1 LUA_INC=/usr/include/lua5.3 USE_OPENSSL=1 USE_PCRE=1 USE_ZLIB=1 
make install PREFIX=/usr/local/nuster/bin

use USE_PTHREAD_PSHARED=1 to use pthread lib

omit USE_LUA=1 LUA_INC=/usr/include/lua5.3 USE_OPENSSL=1 USE_PCRE=1 USE_ZLIB=1 if unnecessary

See HAProxy README for details.


Create a config file called nuster.conf like Example, and

/usr/local/nuster/bin/haproxy -f nuster.conf


docker pull nuster/nuster
docker run -d -v /path/to/nuster.cfg:/etc/nuster/nuster.cfg:ro -p 8080:8080 nuster/nuster


Nuster is based on HAProxy, all directives from HAProxy are supported in nuster.

In order to use cache functionality, cache on should be declared in global section and a cache filter along with some cache-rules should be added into backend or listen section.

If cache off is declared or there is no cache on|off directive, nuster acts just like HAProxy, as a TCP and HTTP load balancer.



syntax: cache on|off [share on|off] [data-size size] [dict-size size] [purge-method method] [uri manager-uri]

default: none

context: global

Determines whether to use cache or not.


share on

A memory zone with a size of data-size + dict-size will be created. Except for temporary data created and destroyed within request, all cache related data including http response data, keys and overheads are stored in this memroy zone and shared between all processes.

If no more memory can be allocated from this memory zone, new requests that should be cached according to defined cache rules will not be cached unless some memory are freed.

share off

Cache data are stored in a memory pool which allocates memory dynamically from system in case there is no available memory in the pool.

A global internal counter monitors the memory usage of all http response data across all processes, new requests will not be cached if the counter exceeds data-size.

By default, share is set to on in multiple processes mode, and off in single process mode.


With share on, it determines the size of memory zone along with dict-size.

With share off, it detemines the maximum memory used by cache.

It accepts units like m, M, g and G. By default, the size is 1024 * 1024 bytes, which is also the minimal size.


Determines the size of memory used by hash table in share on mode.

It has no effect in share off mode, the hash table resize itself if full.

It accepts units like m, M, g and G. By default, the size is 1024 * 1024 bytes, which is also the minimal size.

Note that it only decides the memory used by hash table not keys. In fact, keys are stored in memory zone which is limited by data-size.

dict-size is different from number of keys. New keys can still be added to hash table even if the number of keys exceeds dict-size as long as there are enough memory.

Nevertheless it may lead to a performance drop if number of keys is greater than dict-size.

An approximate number of keys multiplied by 8 (normally) as dict-size should work.


Define a customized HTTP method with max length of 14 to purge cache, it is PURGE by default.


Enable cache manager API and define the endpoint.

See Cache Management for details.

filter cache

syntax: filter cache [on|off]

default: on

context: backend, listen

Define a cache filter, additional cache-rule should be defined. It can be turned off separately by including off. If there are multiple filters, make sure that cache filter is put after all other filters.


syntax: cache-rule name [key KEY] [ttl TTL] [code CODE] [if|unless condition]

default: none

context: backend, listen

Define cache rule. It is possible to declare multiple rules in the same section. The order is important because the matching process stops on the first match.

acl pathA path /a.html
filter cache
cache-rule all ttl 3600
cache-rule path01 ttl 60 if pathA

cache-rule path01 will never match because first rule will cache everything.


Define a name for this cache-rule. It will be used in cache manager API, it does not have to be unique, but it might be a good idea to make it unique. cache-rule with same name are treated as one.

key KEY

Define the key for cache, it takes a string combined by following keywords with . separator:

  • method: http method, GET/POST...
  • scheme: http or https
  • host: the host in the request
  • uri: first slash to end of the url
  • path: the URL path of the request
  • delimiter: '?' if query exists otherwise empty
  • query: the whole query string of the request
  • header_NAME: the value of header NAME
  • cookie_NAME: the value of cookie NAME
  • param_NAME: the value of query NAME
  • body: the body of the request

By default the key is



http header:
GET /q?name=X&type=Y HTTP/1.1
Cookie: logged_in=yes; user=nuster;

Should result:

  • method: GET
  • scheme: http
  • host:
  • uri: /q?name=X&type=Y
  • path: /q
  • delimiter: ?
  • query: name=X&type=Y
  • header_ASDF: Z
  • cookie_user: nuster
  • param_type: Y
  • body: (empty)

So default key produces, and key produces

If a request has the same key as a cached http response data, then cached data will be sent to the client.

ttl TTL

Set a TTL on key, after the TTL has expired, the key will be deleted. It accepts units like d, h, m and s. Default ttl is 3600 seconds. Set to 0 if you don't want to expire the key.

code CODE1,CODE2...

Cache only if the response status code is CODE. By default, only 200 response is cached. You can use all to cache all responses.

cache-rule only200
cache-rule 200and404 code 200,404
cache-rule all code all

if|unless condition

Define when to cache using HAProxy ACL. See 7. Using ACLs and fetching samples section in HAProxy configuration

Cache Management

Cache can be managed via a manager API which endpoints is defined by uri and can be accessed by making POST requests along with some headers.

Eanble and define the endpoint

cache on uri /nuster/cache

Basic usage

curl -X POST -H "X: Y"

Enable and disable cache-rule

cache-rule can be disabled at run time through manager uri. Disabled cache-rule will not be processed, nor will the cache created by that.


header value description
state enable enable cache-rule
disable disable cache-rule
name cache-rule NAME the cache-rule to be enabled/disabled
proxy NAME all cache-rules belong to proxy NAME
* all cache-rules

Keep in mind that if name is not unique, all cache-rules with that name will be disabled/enabled.


  • Disable cache-rule r1

    curl -X POST -H "name: r1" -H "state: disable"

  • Disable all cache-rule defined in proxy app1b

    curl -X POST -H "name: app1b" -H "state: disable"

  • Enable all cache-rule

    curl -X POST -H "name: *" -H "state: enable"

Purge Cache

There are several ways to purge cache.

Purge one specific url

This method creates a key of, and delete the cache with that key.

Only works for the specific url that is being requested, like this:

curl -XPURGE

You can define customized http method other than the default PURGE in case you need to forward PURGE

to backend servers. By define cache purge-method MYPURGE in global section, you can purge cache like this


If you define cache-rule imgs if { path_beg /imgs/ }, and requested


There will be two cache objects since the default key contains query part. In order to delete that, you have to use

curl -XPURGE

In case that the query part is irrelevant, you can define a key like cache-rule imgs key, in this way only one cache will be created, and you can purge that without query.

Delete by tag(name in cache-rule) or url will be added later.


How to debug?

Set debug in global section, or start haproxy with -d.

Cache related debug messages start with [CACHE].

How to cache POST request?

Enable option http-buffer-request.

By default, the cache key includes the body of the request, remember to put body in key field if you use a customized key.

Note that the body of the request maybe incomplete, refer to option http-buffer-request section in HAProxy configuration for details.

Also it might be a good idea to put it separately in a dedicated backend as example does.

How to restrict access to PURGE?

You can use the powerful HAProxy acl, something like this

acl network_allowed src
acl purge_method method PURGE
http-request deny if purge_method !network_allowed

Note by default cache key contains Host, if you cache a request like and purge from localhost you need to specify Host header:

curl -XPURGE -H "Host:"


    cache on data-size 100m
    ## to debug cache
    retries 3
    option redispatch
    timeout client  30s
    timeout connect 30s
    timeout server  30s
frontend web1
    bind *:8080
    mode http
    acl pathPost path /search
    use_backend app1a if pathPost
    default_backend app1b
backend app1a
    balance roundrobin
    # mode must be http
    mode http

    # http-buffer-request must be enabled to cache post request
    option http-buffer-request

    acl pathPost path /search

    # enable cache for this proxy
    filter cache

    # cache /search for 120 seconds. Only works when POST/PUT
    cache-rule rpost ttl 120 if pathPost

    server s1
backend app1b
    balance     roundrobin
    mode http

    filter cache on

    # cache /a.jpg, not expire
    acl pathA path /a.jpg
    cache-rule r1 ttl 0 if pathA

    # cache /mypage, key contains cookie[userId], so it will be cached per user
    acl pathB path /mypage
    cache-rule r2 key ttl 60 if pathB

    # cache /a.html if response's header[cache] is yes
    http-request set-var(txn.pathC) path
    acl pathC var(txn.pathC) -m str /a.html
    acl resHdrCache1 res.hdr(cache) yes
    cache-rule r3 if pathC resHdrCache1

    # cache /heavy for 100 seconds if be_conn greater than 10
    acl heavypage path /heavy
    acl tooFast be_conn ge 100
    cache-rule heavy ttl 100 if heavypage tooFast 

    # cache all if response's header[asdf] is fdsa
    acl resHdrCache2 res.hdr(asdf)  fdsa
    cache-rule resCache ttl 0 if resHdrCache1

    server s1

frontend web2
    bind *:8081
    mode http
    default_backend app2
backend app2
    balance     roundrobin
    mode http

    # disable cache on this proxy
    filter cache off
    cache-rule all

    server s2

listen web3
    bind *:8082
    mode http

    filter cache
    cache-rule everything

    server s3


  1. Files with same name: those with .md extension belong to Nuster, otherwise HAProxy


  • Join the development
  • Give feedback
  • Report issues
  • Send pull requests
  • Spread nuster


Copyright (C) 2017, Jiang Wenyuan, < koubunen AT gmail DOT com >

All rights reserved.

Licensed under GPL, the same as HAProxy

HAProxy and other sources license notices: see relevant individual files.

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