Syntax: limit_conn_zone key zone=name:size; Default: — Context: http Sets parameters for a shared memory zone that will keep states for various keys. In particular, the state includes the current number of connections. The key can contain text, variables, and their combination. Requests with an empty key value are not accounted. Prior to version 1.7.6, a key could contain exactly one variable. Usage example: limit_conn_zone $binary_remote_addr zone=addr:10m; Here,

Syntax: geo [$address] $variable { ... } Default: — Context: stream Describes the dependency of values of the specified variable on the client IP address. By default, the address is taken from the $remote_addr variable, but it can also be taken from another variable, for example: geo $arg_remote_addr $geo { ...; } Since variables are evaluated only when used, the mere existence of even a large number of declared “geo” variables does not cause any extra costs for connection

Syntax: proxy_next_upstream_timeout time; Default: proxy_next_upstream_timeout 0; Context: http, server, location This directive appeared in version 1.7.5. Limits the time during which a request can be passed to the next server. The 0 value turns off this limitation.

Syntax: ssl_stapling_responder url; Default: — Context: http, server This directive appeared in version 1.3.7. Overrides the URL of the OCSP responder specified in the “Authority Information Access” certificate extension. Only “http://” OCSP responders are supported: ssl_stapling_responder http://ocsp.example.com/;

Syntax: proxy_timeout timeout; Default: proxy_timeout 24h; Context: mail, server Sets the timeout between two successive read or write operations on client or proxied server connections. If no data is transmitted within this time, the connection is closed.

Syntax: scgi_cache_use_stale error | timeout | invalid_header | updating | http_500 | http_503 | http_403 | http_404 | off ...; Default: scgi_cache_use_stale off; Context: http, server, location Determines in which cases a stale cached response can be used when an error occurs during communication with the SCGI server. The directive’s parameters match the parameters of the scgi_next_upstream directive. The error parameter also permits usin

Setting up hashes To quickly process static sets of data such as server names, map directive’s values, MIME types, names of request header strings, nginx uses hash tables. During the start and each re-configuration nginx selects the minimum possible sizes of hash tables such that the bucket size that stores keys with identical hash values does not exceed the configured parameter (hash bucket size). The size of a table is expressed in buckets. The adjustment is continued until the table size ex

Syntax: proxy_read_timeout time; Default: proxy_read_timeout 60s; Context: http, server, location Defines a timeout for reading a response from the proxied server. The timeout is set only between two successive read operations, not for the transmission of the whole response. If the proxied server does not transmit anything within this time, the connection is closed.

Syntax: proxy_set_header field value; Default: proxy_set_header Host $proxy_host;proxy_set_header Connection close; Context: http, server, location Allows redefining or appending fields to the request header passed to the proxied server. The value can contain text, variables, and their combinations. These directives are inherited from the previous level if and only if there are no proxy_set_header directives defined on the current level. By default, only two fields are redefined:

Syntax: resolver address ... [valid=time] [ipv6=on|off]; Default: — Context: http, server, location Configures name servers used to resolve names of upstream servers into addresses, for example: resolver 127.0.0.1 [::1]:5353; An address can be specified as a domain name or IP address, and an optional port (1.3.1, 1.2.2). If port is not specified, the port 53 is used. Name servers are queried in a round-robin fashion. Before version 1.1.7, only a single name serve