The ngx_http_memcached_module module allows to obtain responses from a memcached server. The key is set in the $memcached_key variable. A response should be put in memcached in advance via means that are external to nginx.

server {
    location / {
        set            $memcached_key "$uri?$args";
        memcached_pass host:11211;
        error_page     404 502 504 = @fallback;
    }

    location @fallback {
        proxy_pass     http://backend;
    }
}

Forces outgoing connections to a memcached server to originate from the specified local IP address. Value of the parameter can contain variables (1.3.12). The special value off (1.3.12) cancels the effect of the memcached_bind directive inherited from the previous configuration level, allowing the system to auto-assign local address.

memcached_buffer_size 4k|8k;

Sets size of the buffer used for reading a response received from the memcached server. A response is passed to a client synchronously, immediately as it is received.

memcached_connect_timeout 60s;

Defines a timeout for establishing a connection with the memcached server. It should be noted that this timeout cannot usually exceed 75 seconds.

Enables the test for the flag presence in the memcached server response and sets the request header field “Content-Encoding” to “gzip” if the flag is set.

memcached_next_upstream error timeout;

Specifies in which cases a request should be passed to the next server:

error

an error occurred while establishing a connection with the server, passing it a request, or reading the response header;

timeout

a timeout has occurred while establishing a connection with the server, passing it a request, or reading the response header;

invalid_response

a server returned empty or invalid response;

not_found

a response was not found on the server;

off

disables passing a request to the next server.

It should be understood that passing a request to the next server is only possible if a client was not sent anything yet. That is, if an error or a timeout occurs in the middle of transferring a response, fixing this is impossible.

Sets an address of the memcached server. An address can be specified as a domain name or an address, and a port, for example,

memcached_pass localhost:11211;

or as a UNIX-domain socket path:

memcached_pass unix:/tmp/memcached.socket;

If a domain name resolves to several addresses, all of them will be used in a round-robin fashion. In addition, an address can be specified as a server group.

memcached_read_timeout 60s;

Defines a timeout for reading a response from the memcached server. A timeout is only set between two successive read operations, not for the transmission of the whole response. If a memcached server does not transmit anything within this time, a connection is closed.

memcached_send_timeout 60s;

Sets a timeout for transmitting a request to the memcached server. A timeout is only set between two successive write operations, not for the transmission of the whole request. If a memcached server does not receive anything within this time, a connection is closed.