proxy-cache

Description

The proxy-cache Plugin can be used to cache the response from the Upstream. It can be used with other Plugins and currently supports disk-based caching.

The data to be cached can be filtered with response codes, request modes, or more complex methods using the no_cache and cache_bypass attributes.

Attributes

Name	Type	Required	Default	Valid values	Description
cache_strategy	string	False	disk	[“disk”,”memory”]	Specifies where the cached data should be stored.
cache_zone	string	False	disk_cache_one		Specifies which cache area to use. Each cache area can be configured with different paths. Cache areas can be predefined in your configuration file (conf/config.yaml). If the specified cache area is inconsistent with the pre-defined cache area in your configuration file, the cache is invalid.
cache_key	array[string]	False	[“$host”, “$request_uri”]		Key to use for caching. For example, `[“$host”, “$uri”, “-cache-id”]`.
cache_bypass	array[string]	False			Conditions in which response from cache is bypassed. Whether to skip cache retrieval. If at least one value of the string parameters is not empty and is not equal to “0” then the response will not be taken from the cache. For example, `[“$arg_bypass”]`.
cache_method	array[string]	False	[“GET”, “HEAD”]	[“GET”, “POST”, “HEAD”]	Request methods for which the response will be cached.
cache_http_status	array[integer]	False	[200, 301, 404]	[200, 599]	HTTP status codes of the Upstream response for which the response will be cached.
hide_cache_headers	boolean	False	false		When set to true adds the `Expires` and `Cache-Control` headers to the client response.
cache_control	boolean	False	false		When set to true, complies with Cache-Control behavior in the HTTP specification. Used only for memory strategy.
no_cache	array[string]	False			Conditions in which the response will not be cached. If at least one value of the string parameters is not empty and is not equal to “0” then the response will not be saved.
cache_ttl	integer	False	300 seconds		Time that a response is cached until it is deleted or refreshed. Comes in to effect when the `cache_control` attribute is not enabled or the proxied server does not return cache header. Used only for memory strategy.

note

The cache expiration time cannot be configured dynamically. It can only be set by the Upstream response header Expires or Cache-Control. The default expiration time is 10s if there is no Expires or Cache-Control in the Upstream response header.

If the Upstream service is not available and APISIX returns a 502 or 504 status code, it will be cached for 10s.

Enabling the Plugin

You can add your cache configuration in you APISIX configuration file (conf/config.yaml) as shown below:

conf/config.yaml

proxy_cache:
    cache_ttl: 10s                 # default caching time if the upstream doesn't specify the caching time
    zones:
    - name: disk_cache_one         # name of the cache. Admin can specify which cache to use in the Admin API by name
      memory_size: 50m             # size of shared memory, used to store the cache index
      disk_size: 1G                # size of disk, used to store the cache data
      disk_path: "/tmp/disk_cache_one" # path to store the cache data
      cache_levels: "1:2"          # hierarchy levels of the cache

You can enable the Plugin on a specific Route as shown below:

curl http://127.0.0.1:9080/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "proxy-cache": {
            "cache_key":  ["$uri", "-cache-id"],
            "cache_bypass": ["$arg_bypass"],
            "cache_method": ["GET"],
            "cache_http_status": [200],
            "hide_cache_headers": true,
            "no_cache": ["$arg_test"]
        }
    },
    "upstream": {
        "nodes": {
            "127.0.0.1:1999": 1
        },
        "type": "roundrobin"
    },
    "uri": "/hello"
}'

In the above configuration, the cache_zone attribute defaults to disk_cache_one.

Example usage

Once you have configured the Plugin as shown above, you can make an initial request:

curl http://127.0.0.1:9080/hello -i

HTTP/1.1 200 OK
Content-Type: application/octet-stream
Content-Length: 6
Connection: keep-alive
Server: APISIX web server
Date: Tue, 03 Mar 2020 10:45:36 GMT
Last-Modified: Tue, 03 Mar 2020 10:36:38 GMT
Apisix-Cache-Status: MISS
hello

The Apisix-Cache-Status in the response shows MISS meaning that the response is not cached, as expected. Now, if you make another request, you will see that you get a cached response:

curl http://127.0.0.1:9080/hello -i

HTTP/1.1 200 OK
Content-Type: application/octet-stream
Content-Length: 6
Connection: keep-alive
Server: APISIX web server
Date: Tue, 03 Mar 2020 11:14:46 GMT
Last-Modified: Thu, 20 Feb 2020 14:21:41 GMT
Apisix-Cache-Status: HIT
hello

If you set "cache_zone": "invalid_disk_cache" attribute to an invalid value (cache not configured in the your configuration file), then it will return a 404 response.

tip

To clear the cached data, you can send a request with PURGE method:

curl -i http://127.0.0.1:9080/hello -X PURGE

HTTP/1.1 200 OK
Date: Tue, 03 Mar 2020 11:17:35 GMT
Content-Type: text/plain
Transfer-Encoding: chunked
Connection: keep-alive
Server: APISIX web server

If the response code is 200, the deletion is successful. If the cached data is not found, a 404 response code will be returned.

Disable Plugin

To disable the proxy-cache Plugin, you can delete the corresponding JSON configuration from the Plugin configuration. APISIX will automatically reload and you do not have to restart for this to take effect.

curl http://127.0.0.1:9080/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/hello",
    "plugins": {},
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1999": 1
        }
    }
}'