DOC: cache: configuration and management
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William Lallemand
Willy Tarreau
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@ -108,6 +108,7 @@ Summary
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9.2. HTTP compression
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9.3. Stream Processing Offload Engine (SPOE)
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10. Cache
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1. Quick reminder about HTTP
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----------------------------
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@ -3877,7 +3878,8 @@ http-request { allow | auth [realm <realm>] | redirect <rule> | reject |
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sc-inc-gpc0(<sc-id>) |
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sc-set-gpt0(<sc-id>) <int> |
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silent-drop |
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send-spoe-group
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send-spoe-group |
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cache-use
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}
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[ { if | unless } <condition> ]
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Access control for Layer 7 requests
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@ -4112,6 +4114,9 @@ http-request { allow | auth [realm <realm>] | redirect <rule> | reject |
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If the slot <id> doesn't exist, then HAProxy fails parsing the
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configuration to prevent unexpected behavior at run time.
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- cache-use <name> :
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See section 10.2 about cache setup.
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- { track-sc0 | track-sc1 | track-sc2 } <key> [table <table>] :
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enables tracking of sticky counters from current request. These rules
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do not stop evaluation and do not change default action. Three sets of
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@ -4373,7 +4378,8 @@ http-response { allow | deny | add-header <name> <fmt> | set-nice <nice> |
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sc-inc-gpc0(<sc-id>) |
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sc-set-gpt0(<sc-id>) <int> |
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silent-drop |
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send-spoe-group
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send-spoe-group |
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cache-store
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}
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[ { if | unless } <condition> ]
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Access control for Layer 7 responses
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@ -4550,6 +4556,9 @@ http-response { allow | deny | add-header <name> <fmt> | set-nice <nice> |
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If the slot <id> doesn't exist, then HAProxy fails parsing the
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configuration to prevent unexpected behavior at run time.
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- cache-store <name> :
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See section 10.2 about cache setup.
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- "redirect" : this performs an HTTP redirection based on a redirect rule.
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This supports a format string similarly to "http-request redirect" rules,
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with the exception that only the "location" type of redirect is possible
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@ -16938,6 +16947,101 @@ Important note:
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The SPOE filter is highly experimental for now and was not heavily
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tested. It is really not production ready. So use it carefully.
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10. Cache
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---------
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HAProxy provides a cache, which was designed to perform cache on small objects
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(favicon, css...). This is a minimalist low-maintenance cache which runs in
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RAM.
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The cache is based on a memory which is shared between processes and threads,
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this memory is splitted in blocks of 1k.
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If an object is not used anymore, it can be deleted to store a new object
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independently of its expiration date. The oldest objects are deleted first
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when we try to allocate a new one.
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The cache use a hash of the host header and the URI as the key.
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It's possible to view the status of a cache using the Unix socket command
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"show cache" consult section 9.3 "Unix Socket commands" of Management Guide
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for more details.
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When an object is delivered from the cache, the server name in the log is
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replaced by "<CACHE>".
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10.1 Limitation
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---------------
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The cache won't store and won't deliver objects in these cases:
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- If the response is not a 200
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- If the response contains a Vary header
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- If the response does not contain a Content-Length header or if the
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Content-Length + the headers size is greater than a buffer size - the
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reserve.
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- If the response is not cacheable
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- If the request is not a GET
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- If the HTTP version of the request is smaller than 1.1
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Caution!: Due to the current limitation of the filters, it is not recommended
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to use the cache with other filters. Using them can cause undefined behavior
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if they modify the response (compression for exemple).
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10.2 Setup
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----------
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To setup a cache, you must define a cache section and use it in a proxy with
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the corresponding http-request and response actions.
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10.2.1 Cache section
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--------------------
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cache <name>
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Declare a cache section, allocate a shared cache memory named <name>, the
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size of cache is mandatory.
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total-max-size <megabytes>
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Define the size in RAM of the cache in megabytes. this size is splitted in
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blocks of 1kb which are used by the cache entries.
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max-age <seconds>
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Define the maximum expiration duration. The expiration is set has the lowest
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value between the s-maxage or max-age (in this order) directive in the
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Cache-Control response header and this value. The default value is 60
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seconds, which means that you can't cache an object more than 60 seconds by
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default.
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10.2.2 Proxy section
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--------------------
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http-request cache-use <name>
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Try to deliver a cached object from the cache <name>. This directive is also
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mandatory to store the cache as it calculates the cache hash. If you want to
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use a condition for both storage and delivering that's a good idea to put it
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after this one.
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http-response cache-store <name>
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Store an http-response within the cache. The storage of the response headers
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is done at this step, which means you can use others http-response actions
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to modify headers before or after the storage of the response. This action
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is responsible for the setup of the cache storage filter.
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Example:
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backend bck1
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mode http
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http-request cache-use foobar
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http-response cache-store foobar
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server srv1 127.0.0.1:80
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cache foobar
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total-max-size 4
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max-age 240
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/*
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* Local variables:
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* fill-column: 79
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@ -1754,6 +1754,28 @@ show cli sockets
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127.0.0.2:9969 user 2
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[::1]:9999 operator 2
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show cache
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List the configurated caches and the objects stored in each cache tree.
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$ echo 'show cache' | socat stdio /tmp/sock1
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0x7f6ac6c5b03a: foobar (shctx:0x7f6ac6c5b000, available blocks:3918)
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1 2 3 4
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1. pointer to the cache structure
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2. cache name
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3. pointer to the mmap area (shctx)
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4. number of blocks available for reuse in the shctx
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0x7f6ac6c5b4cc hash:286881868 size:39114 (39 blocks), refcount:9, expire:237
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1 2 3 4 5 6
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1. pointer to the cache entry
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2. first 32 bits of the hash
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3. size of the object in bytes
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4. number of blocks used for the object
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5. number of transactions using the entry
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6. expiration time, can be negative if already expired
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show env [<name>]
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Dump one or all environment variables known by the process. Without any
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argument, all variables are dumped. With an argument, only the specified
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