proxy-cache

Description

The proxy-cache Plugin provides the capability to cache responses based on a cache key. The Plugin supports both disk-based and memory-based caching options to cache for GET, POST, and HEAD requests.

Responses can be conditionally cached based on request HTTP methods, response status codes, request header values, and more.

Attributes

Name	Type	Required	Default	Valid values	Description
cache_strategy	string	False	disk	["disk","memory"]	Caching strategy. Cache on disk or in memory.
cache_zone	string	False	disk_cache_one		Cache zone used with the caching strategy. The value should match one of the cache zones defined in the configuration files and should correspond to the caching strategy. For example, when using the in-memory caching strategy, you should use an in-memory cache zone.
cache_key	array[string]	False	["$host", "$request_uri"]		Key to use for caching. Support NGINX variables and constant strings in values. Variables should be prefixed with a $ sign.
cache_bypass	array[string]	False			One or more parameters to parse value from, such that if any of the values is not empty and is not equal to 0, response will not be retrieved from cache. Support NGINX variables and constant strings in values. Variables should be prefixed with a $ sign.
cache_method	array[string]	False	["GET", "HEAD"]	["GET", "POST", "HEAD"]	Request methods of which the response should be cached.
cache_http_status	array[integer]	False	[200, 301, 404]	[200, 599]	Response HTTP status codes of which the response should be cached.
hide_cache_headers	boolean	False	false		If true, hide Expires and Cache-Control response headers.
cache_control	boolean	False	false		If true, comply with Cache-Control behavior in the HTTP specification. Only valid for in-memory strategy.
no_cache	array[string]	False			One or more parameters to parse value from, such that if any of the values is not empty and is not equal to 0, response will not be cached. Support NGINX variables and constant strings in values. Variables should be prefixed with a $ sign.
cache_ttl	integer	False	300	>=1	Cache time to live (TTL) in seconds when caching in memory. To adjust the TTL when caching on disk, update cache_ttl in the configuration files. The TTL value is evaluated in conjunction with the values in the response headers Cache-Control and Expires received from the Upstream service.

Static Configurations

By default, values such as cache_ttl when caching on disk and cache zones are pre-configured in the default configuration.

To customize these values, add the corresponding configurations to config.yaml. For example:

apisix:
  proxy_cache:
    cache_ttl: 10s  # default cache TTL used when caching on disk, only if none of the `Expires`
                    # and `Cache-Control` response headers is present, or if APISIX returns
                    # `502 Bad Gateway` or `504 Gateway Timeout` due to unavailable upstreams
    zones:
      - name: disk_cache_one
        memory_size: 50m
        disk_size: 1G
        disk_path: /tmp/disk_cache_one
        cache_levels: 1:2
      # - name: disk_cache_two
      #   memory_size: 50m
      #   disk_size: 1G
      #   disk_path: "/tmp/disk_cache_two"
      #   cache_levels: "1:2"
      - name: memory_cache
        memory_size: 50m

Reload APISIX for changes to take effect.

Examples

The examples below demonstrate how you can configure proxy-cache for different scenarios.

note

You can fetch the admin_key from config.yaml and save to an environment variable with the following command:

admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')

Cache Data on Disk

On-disk caching strategy offers the advantages of data persistency when system restarts and having larger storage capacity compared to in-memory cache. It is suitable for applications that prioritize durability and can tolerate slightly larger cache access latency.

The following example demonstrates how you can use proxy-cache Plugin on a Route to cache data on disk.

When using the on-disk caching strategy, the cache TTL is determined by value from the response header Expires or Cache-Control. If none of these headers is present or if APISIX returns 502 Bad Gateway or 504 Gateway Timeout due to unavailable Upstreams, the cache TTL defaults to the value configured in the configuration files.

Create a Route with the proxy-cache Plugin to cache data on disk:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "proxy-cache-route",
    "uri": "/anything",
    "plugins": {
      "proxy-cache": {
        "cache_strategy": "disk"
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org": 1
      }
    }
  }'

Send a request to the Route:

curl -i "http://127.0.0.1:9080/anything"

You should see an HTTP/1.1 200 OK response with the following header, showing the Plugin is successfully enabled:

Apisix-Cache-Status: MISS

As there is no cache available before the first response, Apisix-Cache-Status: MISS is shown.

Send the same request again within the cache TTL window. You should see an HTTP/1.1 200 OK response with the following headers, showing the cache is hit:

Apisix-Cache-Status: HIT

Wait for the cache to expire after the TTL and send the same request again. You should see an HTTP/1.1 200 OK response with the following headers, showing the cache has expired:

Apisix-Cache-Status: EXPIRED

Cache Data in Memory

In-memory caching strategy offers the advantage of low-latency access to the cached data, as retrieving data from RAM is faster than retrieving data from disk storage. It also works well for storing temporary data that does not need to be persisted long-term, allowing for efficient caching of frequently changing data.

The following example demonstrates how you can use proxy-cache Plugin on a Route to cache data in memory.

Create a Route with proxy-cache and configure it to use memory-based caching:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "proxy-cache-route",
    "uri": "/anything",
    "plugins": {
      "proxy-cache": {
        "cache_strategy": "memory",
        "cache_zone": "memory_cache",
        "cache_ttl": 10
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org": 1
      }
    }
  }'

Send a request to the Route:

curl -i "http://127.0.0.1:9080/anything"

You should see an HTTP/1.1 200 OK response with the following header, showing the Plugin is successfully enabled:

Apisix-Cache-Status: MISS

As there is no cache available before the first response, Apisix-Cache-Status: MISS is shown.

Send the same request again within the cache TTL window. You should see an HTTP/1.1 200 OK response with the following headers, showing the cache is hit:

Apisix-Cache-Status: HIT

Cache Responses Conditionally

The following example demonstrates how you can configure the proxy-cache Plugin to conditionally cache responses.

Create a Route with the proxy-cache Plugin and configure the no_cache attribute, such that if at least one of the values of the URL parameter no_cache and header no_cache is not empty and is not equal to 0, the response will not be cached:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "proxy-cache-route",
    "uri": "/anything",
    "plugins": {
      "proxy-cache": {
        "no_cache": ["$arg_no_cache", "$http_no_cache"]
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org": 1
      }
    }
  }'

Send a few requests to the Route with the URL parameter no_cache value indicating cache bypass:

curl -i "http://127.0.0.1:9080/anything?no_cache=1"

You should receive HTTP/1.1 200 OK responses for all requests and observe the following header every time:

Apisix-Cache-Status: EXPIRED

Send a few other requests to the Route with the URL parameter no_cache value being zero:

curl -i "http://127.0.0.1:9080/anything?no_cache=0"

You should receive HTTP/1.1 200 OK responses for all requests and start seeing the cache being hit:

Apisix-Cache-Status: HIT

You can also specify the value in the no_cache header as such:

curl -i "http://127.0.0.1:9080/anything" -H "no_cache: 1"

The response should not be cached:

Apisix-Cache-Status: EXPIRED

Retrieve Responses from Cache Conditionally

The following example demonstrates how you can configure the proxy-cache Plugin to conditionally retrieve responses from cache.

Create a Route with the proxy-cache Plugin and configure the cache_bypass attribute, such that if at least one of the values of the URL parameter bypass and header bypass is not empty and is not equal to 0, the response will not be retrieved from the cache:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "proxy-cache-route",
    "uri": "/anything",
    "plugins": {
      "proxy-cache": {
        "cache_bypass": ["$arg_bypass", "$http_bypass"]
      }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org": 1
      }
    }
  }'

Send a request to the Route with the URL parameter bypass value indicating cache bypass:

curl -i "http://127.0.0.1:9080/anything?bypass=1"

You should see an HTTP/1.1 200 OK response with the following header:

Apisix-Cache-Status: BYPASS

Send another request to the Route with the URL parameter bypass value being zero:

curl -i "http://127.0.0.1:9080/anything?bypass=0"

You should see an HTTP/1.1 200 OK response with the following header:

Apisix-Cache-Status: MISS

You can also specify the value in the bypass header as such:

curl -i "http://127.0.0.1:9080/anything" -H "bypass: 1"

The cache should be bypassed:

Apisix-Cache-Status: BYPASS

Cache for 502 and 504 Error Response Code

When the Upstream services return server errors in the 500 range, proxy-cache Plugin will cache the responses if and only if the returned status is 502 Bad Gateway or 504 Gateway Timeout.

The following example demonstrates the behavior of proxy-cache Plugin when the Upstream service returns 504 Gateway Timeout.

Create a Route with the proxy-cache Plugin and configure a dummy Upstream service:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "proxy-cache-route",
    "uri": "/timeout",
    "plugins": {
      "proxy-cache": { }
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "12.34.56.78": 1
      }
    }
  }'

Generate a few requests to the Route:

seq 4 | xargs -I{} curl -I "http://127.0.0.1:9080/timeout"

You should see a response similar to the following:

HTTP/1.1 504 Gateway Time-out
...
Apisix-Cache-Status: MISS

HTTP/1.1 504 Gateway Time-out
...
Apisix-Cache-Status: HIT

HTTP/1.1 504 Gateway Time-out
...
Apisix-Cache-Status: HIT

HTTP/1.1 504 Gateway Time-out
...
Apisix-Cache-Status: HIT

However, if the Upstream services returns 503 Service Temporarily Unavailable, the response will not be cached.