Module ngx_http_proxy_module

Example Configuration
Directives
     proxy_bind
     proxy_buffer_size
     proxy_buffering
     proxy_buffers
     proxy_busy_buffers_size
     proxy_cache
     proxy_cache_bypass
     proxy_cache_key
     proxy_cache_lock
     proxy_cache_lock_timeout
     proxy_cache_methods
     proxy_cache_min_uses
     proxy_cache_path
     proxy_cache_purge
     proxy_cache_revalidate
     proxy_cache_use_stale
     proxy_cache_valid
     proxy_connect_timeout
     proxy_cookie_domain
     proxy_cookie_path
     proxy_force_ranges
     proxy_headers_hash_bucket_size
     proxy_headers_hash_max_size
     proxy_hide_header
     proxy_http_version
     proxy_ignore_client_abort
     proxy_ignore_headers
     proxy_intercept_errors
     proxy_limit_rate
     proxy_max_temp_file_size
     proxy_method
     proxy_next_upstream
     proxy_next_upstream_timeout
     proxy_next_upstream_tries
     proxy_no_cache
     proxy_pass
     proxy_pass_header
     proxy_read_timeout
     proxy_pass_request_body
     proxy_pass_request_headers
     proxy_redirect
     proxy_send_lowat
     proxy_send_timeout
     proxy_set_body
     proxy_set_header
     proxy_ssl_ciphers
     proxy_ssl_crl
     proxy_ssl_name
     proxy_ssl_server_name
     proxy_ssl_session_reuse
     proxy_ssl_protocols
     proxy_ssl_trusted_certificate
     proxy_ssl_verify
     proxy_ssl_verify_depth
     proxy_store
     proxy_store_access
     proxy_temp_file_write_size
     proxy_temp_path
Embedded Variables

The ngx_http_proxy_module module allows passing requests to another server.

Example Configuration

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

Directives

Syntax: proxy_bind address | off;
Default:
Context: http, server, location

This directive appeared in version 0.8.22.

Makes outgoing connections to a proxied server originate from the specified local IP address. 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.

Syntax: proxy_buffer_size size;
Default:
proxy_buffer_size 4k|8k;
Context: http, server, location

Sets the size of the buffer size 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 the size of one buffer set by the proxy_buffers directive. It can be made smaller, however.

Syntax: proxy_buffering on | off;
Default:
proxy_buffering on;
Context: http, server, location

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.

Syntax: proxy_buffers number size;
Default:
proxy_buffers 8 4k|8k;
Context: http, server, location

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.

Syntax: proxy_busy_buffers_size size;
Default:
proxy_busy_buffers_size 8k|16k;
Context: http, server, location

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.

Syntax: proxy_cache zone | off;
Default:
proxy_cache off;
Context: http, server, location

Defines a shared memory zone used for caching. The same zone can be used in several places. The off parameter disables caching inherited from the previous configuration level.

Syntax: proxy_cache_bypass string ...;
Default:
Context: http, server, location

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.

Syntax: proxy_cache_key string;
Default:
proxy_cache_key $scheme$proxy_host$request_uri;
Context: http, server, location

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;

Syntax: proxy_cache_lock on | off;
Default:
proxy_cache_lock off;
Context: http, server, location

This directive appeared in version 1.1.12.

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.

Syntax: proxy_cache_lock_timeout time;
Default:
proxy_cache_lock_timeout 5s;
Context: http, server, location

This directive appeared in version 1.1.12.

Sets a timeout for proxy_cache_lock.

Syntax: proxy_cache_methods GET | HEAD | POST ...;
Default:
proxy_cache_methods GET HEAD;
Context: http, server, location

This directive appeared in version 0.7.59.

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.

Syntax: proxy_cache_min_uses number;
Default:
proxy_cache_min_uses 1;
Context: http, server, location

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

Syntax: proxy_cache_path path [levels=levels] keys_zone=name:size [inactive=time] [max_size=size] [loader_files=number] [loader_sleep=time] [loader_threshold=time];
Default:
Context: http

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. 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, set by the proxy_temp_path directive, are put on the same file system.

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.

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. When this size is exceeded, it removes the least recently used data.

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 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.

Syntax: proxy_cache_purge string ...;
Default:
Context: http, server, location

This directive appeared in version 1.5.7.

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.

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.

Syntax: proxy_cache_revalidate on | off;
Default:
proxy_cache_revalidate off;
Context: http, server, location

This directive appeared in version 1.5.7.

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

Syntax: proxy_cache_use_stale error | timeout | invalid_header | updating | http_500 | http_502 | http_503 | http_504 | http_403 | http_404 | off ...;
Default:
proxy_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 proxied server. The directive’s parameters match the parameters of the proxy_next_upstream directive.

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.

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

Syntax: proxy_cache_valid [code ...] time;
Default:
Context: http, server, location

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

Syntax: proxy_connect_timeout time;
Default:
proxy_connect_timeout 60s;
Context: http, server, location

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

Syntax: proxy_cookie_domain off;
proxy_cookie_domain domain replacement;
Default:
proxy_cookie_domain off;
Context: http, server, location

This directive appeared in version 1.1.15.

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;

There could be several proxy_cookie_domain directives:

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

The off parameter cancels the effect of all proxy_cookie_domain directives on the current level:

proxy_cookie_domain off;
proxy_cookie_domain localhost example.org;
proxy_cookie_domain www.example.org example.org;

Syntax: proxy_cookie_path off;
proxy_cookie_path path replacement;
Default:
proxy_cookie_path off;
Context: http, server, location

This directive appeared in version 1.1.15.

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;

There could be several proxy_cookie_path directives:

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

The off parameter cancels the effect of all proxy_cookie_path directives on the current level:

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

Syntax: proxy_force_ranges on | off;
Default:
proxy_force_ranges off;
Context: http, server, location

This directive appeared in version 1.7.7.

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

Syntax: proxy_headers_hash_bucket_size size;
Default:
proxy_headers_hash_bucket_size 64;
Context: http, server, location

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.

Syntax: proxy_headers_hash_max_size size;
Default:
proxy_headers_hash_max_size 512;
Context: http, server, location

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.

Syntax: proxy_hide_header field;
Default:
Context: http, server, location

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.

Syntax: proxy_http_version 1.0 | 1.1;
Default:
proxy_http_version 1.0;
Context: http, server, location

This directive appeared in version 1.1.4.

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

Syntax: proxy_ignore_client_abort on | off;
Default:
proxy_ignore_client_abort off;
Context: http, server, location

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

Syntax: proxy_ignore_headers field ...;
Default:
Context: http, server, location

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:

Syntax: proxy_intercept_errors on | off;
Default:
proxy_intercept_errors off;
Context: http, server, location

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

Syntax: proxy_limit_rate rate;
Default:
proxy_limit_rate 0;
Context: http, server, location

This directive appeared in version 1.7.7.

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.

Syntax: proxy_max_temp_file_size size;
Default:
proxy_max_temp_file_size 1024m;
Context: http, server, location

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.

Syntax: proxy_method method;
Default:
Context: http, server, location

Specifies the HTTP method to use in requests forwarded to the proxied server instead of the method from the client request.

Syntax: proxy_next_upstream error | timeout | invalid_header | http_500 | http_502 | http_503 | http_504 | http_403 | http_404 | off ...;
Default:
proxy_next_upstream error timeout;
Context: http, server, location

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;
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 and http_504 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.

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 allowed to pass a request to the next server. The 0 value turns off this limitation.

Syntax: proxy_next_upstream_tries number;
Default:
proxy_next_upstream_tries 0;
Context: http, server, location

This directive appeared in version 1.7.5.

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

Syntax: proxy_no_cache string ...;
Default:
Context: http, server, location

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.

Syntax: proxy_pass URL;
Default:
Context: location, if in location, limit_except

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.

A request URI is passed to the server as follows:

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

A server name, its port and the passed URI can also be specified using variables:

proxy_pass http://$host$uri;

or even like this:

proxy_pass $request;

In this case, the server name is searched among the described server groups, and, if not found, is determined using a resolver.

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

Syntax: proxy_pass_header field;
Default:
Context: http, server, location

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

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_pass_request_body on | off;
Default:
proxy_pass_request_body on;
Context: http, server, location

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.

Syntax: proxy_pass_request_headers on | off;
Default:
proxy_pass_request_headers on;
Context: http, server, location

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.

Syntax: proxy_redirect default;
proxy_redirect off;
proxy_redirect redirect replacement;
Default:
proxy_redirect default;
Context: http, server, location

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;

There could be several proxy_redirect directives:

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

The off parameter cancels the effect of all proxy_redirect directives on the current level:

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

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

proxy_redirect / /;

Syntax: proxy_send_lowat size;
Default:
proxy_send_lowat 0;
Context: http, server, location

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.

Syntax: proxy_send_timeout time;
Default:
proxy_send_timeout 60s;
Context: http, server, location

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.

Syntax: proxy_set_body value;
Default:
Context: http, server, location

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

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:

proxy_set_header Host       $proxy_host;
proxy_set_header Connection close;

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 "";

Syntax: proxy_ssl_ciphers ciphers;
Default:
proxy_ssl_ciphers DEFAULT;
Context: http, server, location

This directive appeared in version 1.5.6.

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.

Syntax: proxy_ssl_crl file;
Default:
Context: http, server, location

This directive appeared in version 1.7.0.

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

Syntax: proxy_ssl_name name;
Default:
proxy_ssl_name $proxy_host;
Context: http, server, location

This directive appeared in version 1.7.0.

Allows to override 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.

Syntax: proxy_ssl_server_name on | off;
Default:
proxy_ssl_server_name off;
Context: http, server, location

This directive appeared in version 1.7.0.

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.

Syntax: proxy_ssl_session_reuse on | off;
Default:
proxy_ssl_session_reuse on;
Context: http, server, location

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.

Syntax: proxy_ssl_protocols [SSLv2] [SSLv3] [TLSv1] [TLSv1.1] [TLSv1.2];
Default:
proxy_ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2;
Context: http, server, location

This directive appeared in version 1.5.6.

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

Syntax: proxy_ssl_trusted_certificate file;
Default:
Context: http, server, location

This directive appeared in version 1.7.0.

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

Syntax: proxy_ssl_verify on | off;
Default:
proxy_ssl_verify off;
Context: http, server, location

This directive appeared in version 1.7.0.

Enables or disables verification of the proxied HTTPS server certificate.

Syntax: proxy_ssl_verify_depth number;
Default:
proxy_ssl_verify_depth 1;
Context: http, server, location

This directive appeared in version 1.7.0.

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

Syntax: proxy_store on | off | string;
Default:
proxy_store off;
Context: http, server, location

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;
}

Syntax: proxy_store_access users:permissions ...;
Default:
proxy_store_access user:rw;
Context: http, server, location

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;

Syntax: proxy_temp_file_write_size size;
Default:
proxy_temp_file_write_size 8k|16k;
Context: http, server, location

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.

Syntax: proxy_temp_path path [level1 [level2 [level3]]];
Default:
proxy_temp_path proxy_temp;
Context: http, server, location

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

Embedded Variables

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.