Module ngx_http_proxy_module

The ngx_http_proxy_module module allows passing requests to another server.

location / {
    proxy_pass       http://localhost:8000;
    proxy_set_header Host      $host;
    proxy_set_header X-Real-IP $remote_addr;
}

Makes outgoing connections to a proxied server originate from the specified local IP address with an optional port (1.11.2). Parameter value can contain variables (1.3.12). The special value off (1.3.12) cancels the effect of the proxy_bind directive inherited from the previous configuration level, which allows the system to auto-assign the local IP address and port.

The transparent parameter (1.11.0) allows outgoing connections to a proxied server originate from a non-local IP address, for example, from a real IP address of a client:

proxy_bind $remote_addr transparent;

In order for this parameter to work, it is usually necessary to run nginx worker processes with the superuser privileges. On Linux it is not required (1.13.8) as if the transparent parameter is specified, worker processes inherit the CAP_NET_RAW capability from the master process. It is also necessary to configure kernel routing table to intercept network traffic from the proxied server.

proxy_buffer_size 4k|8k;

Sets the size of the buffer used for reading the first part of the response received from the proxied server. This part usually contains a small response header. By default, the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform. It can be made smaller, however.

proxy_buffering on;

Enables or disables buffering of responses from the proxied server.

When buffering is enabled, nginx receives a response from the proxied server as soon as possible, saving it into the buffers set by the proxy_buffer_size and proxy_buffers directives. If the whole response does not fit into memory, a part of it can be saved to a temporary file on the disk. Writing to temporary files is controlled by the proxy_max_temp_file_size and proxy_temp_file_write_size directives.

When buffering is disabled, the response is passed to a client synchronously, immediately as it is received. nginx will not try to read the whole response from the proxied server. The maximum size of the data that nginx can receive from the server at a time is set by the proxy_buffer_size directive.

Buffering can also be enabled or disabled by passing “yes” or “no” in the “X-Accel-Buffering” response header field. This capability can be disabled using the proxy_ignore_headers directive.

proxy_buffers 8 4k|8k;

Sets the number and size of the buffers used for reading a response from the proxied server, for a single connection. By default, the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform.

proxy_busy_buffers_size 8k|16k;

When buffering of responses from the proxied server is enabled, limits the total size of buffers that can be busy sending a response to the client while the response is not yet fully read. In the meantime, the rest of the buffers can be used for reading the response and, if needed, buffering part of the response to a temporary file. By default, size is limited by the size of two buffers set by the proxy_buffer_size and proxy_buffers directives.

proxy_cache off;

Defines a shared memory zone used for caching. The same zone can be used in several places. Parameter value can contain variables (1.7.9). The off parameter disables caching inherited from the previous configuration level.

proxy_cache_background_update off;

Allows starting a background subrequest to update an expired cache item, while a stale cached response is returned to the client. Note that it is necessary to allow the usage of a stale cached response when it is being updated.

Defines conditions under which the response will not be taken from a cache. 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:

proxy_cache_bypass $cookie_nocache $arg_nocache$arg_comment;
proxy_cache_bypass $http_pragma    $http_authorization;

Can be used along with the proxy_no_cache directive.

proxy_cache_convert_head on;

Enables or disables the conversion of the “HEAD” method to “GET” for caching. When the conversion is disabled, the cache key should be configured to include the $request_method.

proxy_cache_key $scheme$proxy_host$request_uri;

Defines a key for caching, for example

proxy_cache_key "$host$request_uri $cookie_user";

By default, the directive’s value is close to the string

proxy_cache_key $scheme$proxy_host$uri$is_args$args;

proxy_cache_lock off;

When enabled, only one request at a time will be allowed to populate a new cache element identified according to the proxy_cache_key directive by passing a request to a proxied server. Other requests of the same cache element will either wait for a response to appear in the cache or the cache lock for this element to be released, up to the time set by the proxy_cache_lock_timeout directive.

proxy_cache_lock_age 5s;

If the last request passed to the proxied server for populating a new cache element has not completed for the specified time, one more request may be passed to the proxied server.

proxy_cache_lock_timeout 5s;

Sets a timeout for proxy_cache_lock. When the time expires, the request will be passed to the proxied server, however, the response will not be cached.

Before 1.7.8, the response could be cached.

Sets an offset in bytes for byte-range requests. If the range is beyond the offset, the range request will be passed to the proxied server and the response will not be cached.

proxy_cache_methods GET HEAD;

If the client request method is listed in this directive then the response will be cached. “GET” and “HEAD” methods are always added to the list, though it is recommended to specify them explicitly. See also the proxy_no_cache directive.

proxy_cache_min_uses 1;

Sets the number of requests after which the response will be cached.

Sets the path and other parameters of a cache. Cache data are stored in files. The file name in a cache is a result of applying the MD5 function to the cache key. The levels parameter defines hierarchy levels of a cache: from 1 to 3, each level accepts values 1 or 2. For example, in the following configuration

proxy_cache_path /data/nginx/cache levels=1:2 keys_zone=one:10m;

file names in a cache will look like this:

/data/nginx/cache/c/29/b7f54b2df7773722d382f4809d65029c

A cached response is first written to a temporary file, and then the file is renamed. Starting from version 0.8.9, temporary files and the cache can be put on different file systems. However, be aware that in this case a file is copied across two file systems instead of the cheap renaming operation. It is thus recommended that for any given location both cache and a directory holding temporary files are put on the same file system. The directory for temporary files is set based on the use_temp_path parameter (1.7.10). If this parameter is omitted or set to the value on, the directory set by the proxy_temp_path directive for the given location will be used. If the value is set to off, temporary files will be put directly in the cache directory.

In addition, all active keys and information about data are stored in a shared memory zone, whose name and size are configured by the keys_zone parameter. One megabyte zone can store about 8 thousand keys.

As part of commercial subscription, the shared memory zone also stores extended cache information, thus, it is required to specify a larger zone size for the same number of keys. For example, one megabyte zone can store about 4 thousand keys.

Cached data that are not accessed during the time specified by the inactive parameter get removed from the cache regardless of their freshness. By default, inactive is set to 10 minutes.

The special “cache manager” process monitors the maximum cache size set by the max_size parameter, and the minimum amount of free space set by the min_free (1.19.1) parameter on the file system with cache. When the size is exceeded or there is not enough free space, it removes the least recently used data. The data is removed in iterations configured by manager_files, manager_threshold, and manager_sleep parameters (1.11.5). During one iteration no more than manager_files items are deleted (by default, 100). The duration of one iteration is limited by the manager_threshold parameter (by default, 200 milliseconds). Between iterations, a pause configured by the manager_sleep parameter (by default, 50 milliseconds) is made.

A minute after the start the special “cache loader” process is activated. It loads information about previously cached data stored on file system into a cache zone. The loading is also done in iterations. During one iteration no more than loader_files items are loaded (by default, 100). Besides, the duration of one iteration is limited by the loader_threshold parameter (by default, 200 milliseconds). Between iterations, a pause configured by the loader_sleep parameter (by default, 50 milliseconds) is made.

Additionally, the following parameters are available as part of our commercial subscription:

purger=on|off

Instructs whether cache entries that match a wildcard key will be removed from the disk by the cache purger (1.7.12). Setting the parameter to on (default is off) will activate the “cache purger” process that permanently iterates through all cache entries and deletes the entries that match the wildcard key.

purger_files=number

Sets the number of items that will be scanned during one iteration (1.7.12). By default, purger_files is set to 10.

purger_threshold=number

Sets the duration of one iteration (1.7.12). By default, purger_threshold is set to 50 milliseconds.

purger_sleep=number

Sets a pause between iterations (1.7.12). By default, purger_sleep is set to 50 milliseconds.

In versions 1.7.3, 1.7.7, and 1.11.10 cache header format has been changed. Previously cached responses will be considered invalid after upgrading to a newer nginx version.

Defines conditions under which the request will be considered a cache purge request. If at least one value of the string parameters is not empty and is not equal to “0” then the cache entry with a corresponding cache key is removed. The result of successful operation is indicated by returning the 204 (No Content) response.

If the cache key of a purge request ends with an asterisk (“*”), all cache entries matching the wildcard key will be removed from the cache. However, these entries will remain on the disk until they are deleted for either inactivity, or processed by the cache purger (1.7.12), or a client attempts to access them.

Example configuration:

proxy_cache_path /data/nginx/cache keys_zone=cache_zone:10m;

map $request_method $purge_method {
    PURGE   1;
    default 0;
}

server {
    ...
    location / {
        proxy_pass http://backend;
        proxy_cache cache_zone;
        proxy_cache_key $uri;
        proxy_cache_purge $purge_method;
    }
}

This functionality is available as part of our commercial subscription.

proxy_cache_revalidate off;

Enables revalidation of expired cache items using conditional requests with the “If-Modified-Since” and “If-None-Match” header fields.

proxy_cache_use_stale off;

Determines in which cases a stale cached response can be used during communication with the proxied server. The directive’s parameters match the parameters of the proxy_next_upstream directive.

The error parameter also permits using a stale cached response if a proxied server to process a request cannot be selected.

Additionally, the updating parameter permits using a stale cached response if it is currently being updated. This allows minimizing the number of accesses to proxied servers when updating cached data.

Using a stale cached response can also be enabled directly in the response header for a specified number of seconds after the response became stale (1.11.10). This has lower priority than using the directive parameters.

• The “stale-while-revalidate” extension of the “Cache-Control” header field permits using a stale cached response if it is currently being updated.
• The “stale-if-error” extension of the “Cache-Control” header field permits using a stale cached response in case of an error.

To minimize the number of accesses to proxied servers when populating a new cache element, the proxy_cache_lock directive can be used.

Sets caching time for different response codes. For example, the following directives

proxy_cache_valid 200 302 10m;
proxy_cache_valid 404      1m;

set 10 minutes of caching for responses with codes 200 and 302 and 1 minute for responses with code 404.

If only caching time is specified

proxy_cache_valid 5m;

then only 200, 301, and 302 responses are cached.

In addition, the any parameter can be specified to cache any responses:

proxy_cache_valid 200 302 10m;
proxy_cache_valid 301      1h;
proxy_cache_valid any      1m;

Parameters of caching can also be set directly in the response header. This has higher priority than setting of caching time using the directive.

• The “X-Accel-Expires” header field sets caching time of a response in seconds. The zero value disables caching for a response. If the value starts with the @ prefix, it sets an absolute time in seconds since Epoch, up to which the response may be cached.
• If the header does not include the “X-Accel-Expires” field, parameters of caching may be set in the header fields “Expires” or “Cache-Control”.
• If the header includes the “Set-Cookie” field, such a response will not be cached.
• If the header includes the “Vary” field with the special value “*”, such a response will not be cached (1.7.7). If the header includes the “Vary” field with another value, such a response will be cached taking into account the corresponding request header fields (1.7.7).

Processing of one or more of these response header fields can be disabled using the proxy_ignore_headers directive.

proxy_connect_timeout 60s;

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

proxy_cookie_domain off;

Sets a text that should be changed in the domain attribute of the “Set-Cookie” header fields of a proxied server response. Suppose a proxied server returned the “Set-Cookie” header field with the attribute “domain=localhost”. The directive

proxy_cookie_domain localhost example.org;

will rewrite this attribute to “domain=example.org”.

A dot at the beginning of the domain and replacement strings and the domain attribute is ignored. Matching is case-insensitive.

The domain and replacement strings can contain variables:

proxy_cookie_domain www.$host $host;

The directive can also be specified using regular expressions. In this case, domain should start from the “~” symbol. A regular expression can contain named and positional captures, and replacement can reference them:

proxy_cookie_domain ~\.(?P<sl_domain>[-0-9a-z]+\.[a-z]+)$ $sl_domain;

Several proxy_cookie_domain directives can be specified on the same level:

proxy_cookie_domain localhost example.org;
proxy_cookie_domain ~\.([a-z]+\.[a-z]+)$ $1;

If several directives can be applied to the cookie, the first matching directive will be chosen.

The off parameter cancels the effect of the proxy_cookie_domain directives inherited from the previous configuration level.

proxy_cookie_flags off;

Sets one or more flags for the cookie. The cookie can contain text, variables, and their combinations. The flag can contain text, variables, and their combinations (1.19.8). The secure, httponly, samesite=strict, samesite=lax, samesite=none parameters add the corresponding flags. The nosecure, nohttponly, nosamesite parameters remove the corresponding flags.

The cookie can also be specified using regular expressions. In this case, cookie should start from the “~” symbol.

Several proxy_cookie_flags directives can be specified on the same configuration level:

proxy_cookie_flags one httponly;
proxy_cookie_flags ~ nosecure samesite=strict;

If several directives can be applied to the cookie, the first matching directive will be chosen. In the example, the httponly flag is added to the cookie one, for all other cookies the samesite=strict flag is added and the secure flag is deleted.

The off parameter cancels the effect of the proxy_cookie_flags directives inherited from the previous configuration level.

proxy_cookie_path off;

Sets a text that should be changed in the path attribute of the “Set-Cookie” header fields of a proxied server response. Suppose a proxied server returned the “Set-Cookie” header field with the attribute “path=/two/some/uri/”. The directive

proxy_cookie_path /two/ /;

will rewrite this attribute to “path=/some/uri/”.

The path and replacement strings can contain variables:

proxy_cookie_path $uri /some$uri;

The directive can also be specified using regular expressions. In this case, path should either start from the “~” symbol for a case-sensitive matching, or from the “~*” symbols for case-insensitive matching. The regular expression can contain named and positional captures, and replacement can reference them:

proxy_cookie_path ~*^/user/([^/]+) /u/$1;

Several proxy_cookie_path directives can be specified on the same level:

proxy_cookie_path /one/ /;
proxy_cookie_path / /two/;

If several directives can be applied to the cookie, the first matching directive will be chosen.

The off parameter cancels the effect of the proxy_cookie_path directives inherited from the previous configuration level.

proxy_force_ranges off;

Enables byte-range support for both cached and uncached responses from the proxied server regardless of the “Accept-Ranges” field in these responses.

proxy_headers_hash_bucket_size 64;

Sets the bucket size for hash tables used by the proxy_hide_header and proxy_set_header directives. The details of setting up hash tables are provided in a separate document.

proxy_headers_hash_max_size 512;

Sets the maximum size of hash tables used by the proxy_hide_header and proxy_set_header directives. The details of setting up hash tables are provided in a separate document.

By default, nginx does not pass the header fields “Date”, “Server”, “X-Pad”, and “X-Accel-...” from the response of a proxied server to a client. The proxy_hide_header directive sets additional fields that will not be passed. If, on the contrary, the passing of fields needs to be permitted, the proxy_pass_header directive can be used.

proxy_http_version 1.0;

Sets the HTTP protocol version for proxying. By default, version 1.0 is used. Version 1.1 is recommended for use with keepalive connections and NTLM authentication.

proxy_ignore_client_abort off;

Determines whether the connection with a proxied server should be closed when a client closes the connection without waiting for a response.

Disables processing of certain response header fields from the proxied server. The following fields can be ignored: “X-Accel-Redirect”, “X-Accel-Expires”, “X-Accel-Limit-Rate” (1.1.6), “X-Accel-Buffering” (1.1.6), “X-Accel-Charset” (1.1.6), “Expires”, “Cache-Control”, “Set-Cookie” (0.8.44), and “Vary” (1.7.7).

If not disabled, processing of these header fields has the following effect:

• “X-Accel-Expires”, “Expires”, “Cache-Control”, “Set-Cookie”, and “Vary” set the parameters of response caching;
• “X-Accel-Redirect” performs an internal redirect to the specified URI;
• “X-Accel-Limit-Rate” sets the rate limit for transmission of a response to a client;
• “X-Accel-Buffering” enables or disables buffering of a response;
• “X-Accel-Charset” sets the desired charset of a response.

proxy_intercept_errors off;

Determines whether proxied responses with codes greater than or equal to 300 should be passed to a client or be intercepted and redirected to nginx for processing with the error_page directive.

proxy_limit_rate 0;

Limits the speed of reading the response from the proxied server. The rate is specified in bytes per second. The zero value disables rate limiting. The limit is set per a request, and so if nginx simultaneously opens two connections to the proxied server, the overall rate will be twice as much as the specified limit. The limitation works only if buffering of responses from the proxied server is enabled.

proxy_max_temp_file_size 1024m;

When buffering of responses from the proxied server is enabled, and the whole response does not fit into the buffers set by the proxy_buffer_size and proxy_buffers directives, a part of the response can be saved to a temporary file. This directive sets the maximum size of the temporary file. The size of data written to the temporary file at a time is set by the proxy_temp_file_write_size directive.

The zero value disables buffering of responses to temporary files.

This restriction does not apply to responses that will be cached or stored on disk.

Specifies the HTTP method to use in requests forwarded to the proxied server instead of the method from the client request. Parameter value can contain variables (1.11.6).

proxy_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 a request to it, or reading the response header;

timeout

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

invalid_header

a server returned an empty or invalid response;

http_500

a server returned a response with the code 500;

http_502

a server returned a response with the code 502;

http_503

a server returned a response with the code 503;

http_504

a server returned a response with the code 504;

http_403

a server returned a response with the code 403;

http_404

a server returned a response with the code 404;

http_429

a server returned a response with the code 429 (1.11.13);

non_idempotent

normally, requests with a non-idempotent method (POST, LOCK, PATCH) are not passed to the next server if a request has been sent to an upstream server (1.9.13); enabling this option explicitly allows retrying such requests;

off

disables passing a request to the next server.

One should bear in mind that passing a request to the next server is only possible if nothing has been sent to a client yet. That is, if an error or timeout occurs in the middle of the transferring of a response, fixing this is impossible.

The directive also defines what is considered an unsuccessful attempt of communication with a server. The cases of error, timeout and invalid_header are always considered unsuccessful attempts, even if they are not specified in the directive. The cases of http_500, http_502, http_503, http_504, and http_429 are considered unsuccessful attempts only if they are specified in the directive. The cases of http_403 and http_404 are never considered unsuccessful attempts.

Passing a request to the next server can be limited by the number of tries and by time.

proxy_next_upstream_timeout 0;

Limits the time during which a request can be passed to the next server. The 0 value turns off this limitation.

proxy_next_upstream_tries 0;

Limits the number of possible tries for passing a request to the next server. The 0 value turns off this limitation.

Defines conditions under which the response will not be saved to a cache. 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:

proxy_no_cache $cookie_nocache $arg_nocache$arg_comment;
proxy_no_cache $http_pragma    $http_authorization;

Can be used along with the proxy_cache_bypass directive.

Sets the protocol and address of a proxied server and an optional URI to which a location should be mapped. As a protocol, “http” or “https” can be specified. The address can be specified as a domain name or IP address, and an optional port:

proxy_pass http://localhost:8000/uri/;

or as a UNIX-domain socket path specified after the word “unix” and enclosed in colons:

proxy_pass http://unix:/tmp/backend.socket:/uri/;

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.

Parameter value can contain variables. In this case, if an address is specified as a domain name, the name is searched among the described server groups, and, if not found, is determined using a resolver.

A request URI is passed to the server as follows:

• If the proxy_pass directive is specified with a URI, then when a request is passed to the server, the part of a normalized request URI matching the location is replaced by a URI specified in the directive:

  location /name/ {
      proxy_pass http://127.0.0.1/remote/;
  }
  

• If proxy_pass is specified without a URI, the request URI is passed to the server in the same form as sent by a client when the original request is processed, or the full normalized request URI is passed when processing the changed URI:

  location /some/path/ {
      proxy_pass http://127.0.0.1;
  }
  

  Before version 1.1.12, if proxy_pass is specified without a URI, the original request URI might be passed instead of the changed URI in some cases.

In some cases, the part of a request URI to be replaced cannot be determined:

• When location is specified using a regular expression, and also inside named locations.

  In these cases, proxy_pass should be specified without a URI.

• When the URI is changed inside a proxied location using the rewrite directive, and this same configuration will be used to process a request (break):

  location /name/ {
      rewrite    /name/([^/]+) /users?name=$1 break;
      proxy_pass http://127.0.0.1;
  }
  

  In this case, the URI specified in the directive is ignored and the full changed request URI is passed to the server.

• When variables are used in proxy_pass:

  location /name/ {
      proxy_pass http://127.0.0.1$request_uri;
  }
  

  In this case, if URI is specified in the directive, it is passed to the server as is, replacing the original request URI.

WebSocket proxying requires special configuration and is supported since version 1.3.13.

Permits passing otherwise disabled header fields from a proxied server to a client.

proxy_pass_request_body on;

Indicates whether the original request body is passed to the proxied server.

location /x-accel-redirect-here/ {
    proxy_method GET;
    proxy_pass_request_body off;
    proxy_set_header Content-Length "";

    proxy_pass ...
}

See also the proxy_set_header and proxy_pass_request_headers directives.

proxy_pass_request_headers on;

Indicates whether the header fields of the original request are passed to the proxied server.

location /x-accel-redirect-here/ {
    proxy_method GET;
    proxy_pass_request_headers off;
    proxy_pass_request_body off;

    proxy_pass ...
}

See also the proxy_set_header and proxy_pass_request_body directives.

proxy_read_timeout 60s;

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.

proxy_redirect default;

Sets the text that should be changed in the “Location” and “Refresh” header fields of a proxied server response. Suppose a proxied server returned the header field “Location: http://localhost:8000/two/some/uri/”. The directive

proxy_redirect http://localhost:8000/two/ http://frontend/one/;

will rewrite this string to “Location: http://frontend/one/some/uri/”.

A server name may be omitted in the replacement string:

proxy_redirect http://localhost:8000/two/ /;

then the primary server’s name and port, if different from 80, will be inserted.

The default replacement specified by the default parameter uses the parameters of the location and proxy_pass directives. Hence, the two configurations below are equivalent:

location /one/ {
    proxy_pass     http://upstream:port/two/;
    proxy_redirect default;

location /one/ {
    proxy_pass     http://upstream:port/two/;
    proxy_redirect http://upstream:port/two/ /one/;

The default parameter is not permitted if proxy_pass is specified using variables.

A replacement string can contain variables:

proxy_redirect http://localhost:8000/ http://$host:$server_port/;

A redirect can also contain (1.1.11) variables:

proxy_redirect http://$proxy_host:8000/ /;

The directive can be specified (1.1.11) using regular expressions. In this case, redirect should either start with the “~” symbol for a case-sensitive matching, or with the “~*” symbols for case-insensitive matching. The regular expression can contain named and positional captures, and replacement can reference them:

proxy_redirect ~^(http://[^:]+):\d+(/.+)$ $1$2;
proxy_redirect ~*/user/([^/]+)/(.+)$      http://$1.example.com/$2;

Several proxy_redirect directives can be specified on the same level:

proxy_redirect default;
proxy_redirect http://localhost:8000/  /;
proxy_redirect http://www.example.com/ /;

If several directives can be applied to the header fields of a proxied server response, the first matching directive will be chosen.

The off parameter cancels the effect of the proxy_redirect directives inherited from the previous configuration level.

Using this directive, it is also possible to add host names to relative redirects issued by a proxied server:

proxy_redirect / /;

proxy_request_buffering on;

Enables or disables buffering of a client request body.

When buffering is enabled, the entire request body is read from the client before sending the request to a proxied server.

When buffering is disabled, the request body is sent to the proxied server immediately as it is received. In this case, the request cannot be passed to the next server if nginx already started sending the request body.

When HTTP/1.1 chunked transfer encoding is used to send the original request body, the request body will be buffered regardless of the directive value unless HTTP/1.1 is enabled for proxying.

proxy_send_lowat 0;

If the directive is set to a non-zero value, nginx will try to minimize the number of send operations on outgoing connections to a proxied server by using either NOTE_LOWAT flag of the kqueue method, or the SO_SNDLOWAT socket option, with the specified size.

This directive is ignored on Linux, Solaris, and Windows.

proxy_send_timeout 60s;

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

Allows redefining the request body passed to the proxied server. The value can contain text, variables, and their combination.

proxy_set_header Host $proxy_host;

proxy_set_header Connection close;

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 configuration level if and only if there are no proxy_set_header directives defined on the current level. By default, only two fields are redefined:

proxy_set_header Host       $proxy_host;
proxy_set_header Connection close;

If caching is enabled, the header fields “If-Modified-Since”, “If-Unmodified-Since”, “If-None-Match”, “If-Match”, “Range”, and “If-Range” from the original request are not passed to the proxied server.

An unchanged “Host” request header field can be passed like this:

proxy_set_header Host       $http_host;

However, if this field is not present in a client request header then nothing will be passed. In such a case it is better to use the $host variable - its value equals the server name in the “Host” request header field or the primary server name if this field is not present:

proxy_set_header Host       $host;

In addition, the server name can be passed together with the port of the proxied server:

proxy_set_header Host       $host:$proxy_port;

If the value of a header field is an empty string then this field will not be passed to a proxied server:

proxy_set_header Accept-Encoding "";

proxy_socket_keepalive off;

Configures the “TCP keepalive” behavior for outgoing connections to a proxied server. By default, the operating system’s settings are in effect for the socket. If the directive is set to the value “on”, the SO_KEEPALIVE socket option is turned on for the socket.

Specifies a file with the certificate in the PEM format used for authentication to a proxied HTTPS server.

Since version 1.21.0, variables can be used in the file name.

Specifies a file with the secret key in the PEM format used for authentication to a proxied HTTPS server.

The value engine:name:id can be specified instead of the file (1.7.9), which loads a secret key with a specified id from the OpenSSL engine name.

Since version 1.21.0, variables can be used in the file name.

proxy_ssl_ciphers DEFAULT;

Specifies the enabled ciphers for requests to a proxied HTTPS server. The ciphers are specified in the format understood by the OpenSSL library.

The full list can be viewed using the “openssl ciphers” command.

Sets arbitrary OpenSSL configuration commands when establishing a connection with the proxied HTTPS server.

The directive is supported when using OpenSSL 1.0.2 or higher.

Several proxy_ssl_conf_command directives can be specified on the same level. These directives are inherited from the previous configuration level if and only if there are no proxy_ssl_conf_command directives defined on the current level.

Note that configuring OpenSSL directly might result in unexpected behavior.

Specifies a file with revoked certificates (CRL) in the PEM format used to verify the certificate of the proxied HTTPS server.

proxy_ssl_name $proxy_host;

Allows overriding the server name used to verify the certificate of the proxied HTTPS server and to be passed through SNI when establishing a connection with the proxied HTTPS server.

By default, the host part of the proxy_pass URL is used.

Specifies a file with passphrases for secret keys where each passphrase is specified on a separate line. Passphrases are tried in turn when loading the key.

proxy_ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

Enables the specified protocols for requests to a proxied HTTPS server.

proxy_ssl_server_name off;

Enables or disables passing of the server name through TLS Server Name Indication extension (SNI, RFC 6066) when establishing a connection with the proxied HTTPS server.

proxy_ssl_session_reuse on;

Determines whether SSL sessions can be reused when working with the proxied server. If the errors “SSL3_GET_FINISHED:digest check failed” appear in the logs, try disabling session reuse.

Specifies a file with trusted CA certificates in the PEM format used to verify the certificate of the proxied HTTPS server.

proxy_ssl_verify off;

Enables or disables verification of the proxied HTTPS server certificate.

proxy_ssl_verify_depth 1;

Sets the verification depth in the proxied HTTPS server certificates chain.

proxy_store off;

Enables saving of files to a disk. The on parameter saves files with paths corresponding to the directives alias or root. The off parameter disables saving of files. In addition, the file name can be set explicitly using the string with variables:

proxy_store /data/www$original_uri;

The modification time of files is set according to the received “Last-Modified” response header field. The response is first written to a temporary file, and then the file is renamed. Starting from version 0.8.9, temporary files and the persistent store can be put on different file systems. However, be aware that in this case a file is copied across two file systems instead of the cheap renaming operation. It is thus recommended that for any given location both saved files and a directory holding temporary files, set by the proxy_temp_path directive, are put on the same file system.

This directive can be used to create local copies of static unchangeable files, e.g.:

location /images/ {
    root               /data/www;
    error_page         404 = /fetch$uri;
}

location /fetch/ {
    internal;

    proxy_pass         http://backend/;
    proxy_store        on;
    proxy_store_access user:rw group:rw all:r;
    proxy_temp_path    /data/temp;

    alias              /data/www/;
}

or like this:

location /images/ {
    root               /data/www;
    error_page         404 = @fetch;
}

location @fetch {
    internal;

    proxy_pass         http://backend;
    proxy_store        on;
    proxy_store_access user:rw group:rw all:r;
    proxy_temp_path    /data/temp;

    root               /data/www;
}

proxy_store_access user:rw;

Sets access permissions for newly created files and directories, e.g.:

proxy_store_access user:rw group:rw all:r;

If any group or all access permissions are specified then user permissions may be omitted:

proxy_store_access group:rw all:r;

proxy_temp_file_write_size 8k|16k;

Limits the size of data written to a temporary file at a time, when buffering of responses from the proxied server to temporary files is enabled. By default, size is limited by two buffers set by the proxy_buffer_size and proxy_buffers directives. The maximum size of a temporary file is set by the proxy_max_temp_file_size directive.

proxy_temp_path proxy_temp;

Defines a directory for storing temporary files with data received from proxied servers. Up to three-level subdirectory hierarchy can be used underneath the specified directory. For example, in the following configuration

proxy_temp_path /spool/nginx/proxy_temp 1 2;

a temporary file might look like this:

/spool/nginx/proxy_temp/7/45/00000123457

See also the use_temp_path parameter of the proxy_cache_path directive.

The ngx_http_proxy_module module supports embedded variables that can be used to compose headers using the proxy_set_header directive:

$proxy_host

name and port of a proxied server as specified in the proxy_pass directive;

$proxy_port

port of a proxied server as specified in the proxy_pass directive, or the protocol’s default port;

$proxy_add_x_forwarded_for

the “X-Forwarded-For” client request header field with the $remote_addr variable appended to it, separated by a comma. If the “X-Forwarded-For” field is not present in the client request header, the $proxy_add_x_forwarded_for variable is equal to the $remote_addr variable.