nginx

Module ngx_http_fastcgi_module


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Example Configuration
Directives
     fastcgi_bind
     fastcgi_buffer_size
     fastcgi_buffering
     fastcgi_buffers
     fastcgi_busy_buffers_size
     fastcgi_cache
     fastcgi_cache_bypass
     fastcgi_cache_key
     fastcgi_cache_lock
     fastcgi_cache_lock_timeout
     fastcgi_cache_methods
     fastcgi_cache_min_uses
     fastcgi_cache_path
     fastcgi_cache_purge
     fastcgi_cache_revalidate
     fastcgi_cache_use_stale
     fastcgi_cache_valid
     fastcgi_catch_stderr
     fastcgi_connect_timeout
     fastcgi_hide_header
     fastcgi_ignore_client_abort
     fastcgi_ignore_headers
     fastcgi_index
     fastcgi_intercept_errors
     fastcgi_keep_conn
     fastcgi_max_temp_file_size
     fastcgi_next_upstream
     fastcgi_no_cache
     fastcgi_param
     fastcgi_pass
     fastcgi_pass_header
     fastcgi_read_timeout
     fastcgi_pass_request_body
     fastcgi_pass_request_headers
     fastcgi_send_lowat
     fastcgi_send_timeout
     fastcgi_split_path_info
     fastcgi_store
     fastcgi_store_access
     fastcgi_temp_file_write_size
     fastcgi_temp_path
Parameters Passed to a FastCGI Server
Embedded Variables

The ngx_http_fastcgi_module module allows passing requests to a FastCGI server.

Example Configuration

location / {
    fastcgi_pass  localhost:9000;
    fastcgi_index index.php;

    fastcgi_param SCRIPT_FILENAME /home/www/scripts/php$fastcgi_script_name;
    fastcgi_param QUERY_STRING    $query_string;
    fastcgi_param REQUEST_METHOD  $request_method;
    fastcgi_param CONTENT_TYPE    $content_type;
    fastcgi_param CONTENT_LENGTH  $content_length;
}

Directives

syntax: fastcgi_bind address | off;
default:
context: http, server, location

This directive appeared in version 0.8.22.

Makes outgoing connections to a FastCGI 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 fastcgi_bind directive inherited from the previous configuration level, which allows the system to auto-assign the local IP address.

syntax: fastcgi_buffer_size size;
default:
fastcgi_buffer_size 4k|8k;
context: http, server, location

Sets the size of the buffer used for reading the first part of the response received from the FastCGI 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 fastcgi_buffers directive. It can be made smaller, however.

syntax: fastcgi_buffering on | off;
default:
fastcgi_buffering on;
context: http, server, location

This directive appeared in version 1.5.6.

Enables or disables buffering of responses from the FastCGI server.

When buffering is enabled, nginx receives a response from the FastCGI server as soon as possible, saving it into the buffers set by the fastcgi_buffer_size and fastcgi_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 fastcgi_max_temp_file_size and fastcgi_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 FastCGI server. The maximum size of the data that nginx can receive from the server at a time is set by the fastcgi_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 fastcgi_ignore_headers directive.

syntax: fastcgi_buffers number size;
default:
fastcgi_buffers 8 4k|8k;
context: http, server, location

Sets the number and size of the buffers used for reading a response from the FastCGI 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: fastcgi_busy_buffers_size size;
default:
fastcgi_busy_buffers_size 8k|16k;
context: http, server, location

When buffering of responses from the FastCGI 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 fastcgi_buffer_size and fastcgi_buffers directives.

syntax: fastcgi_cache zone | off;
default:
fastcgi_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: fastcgi_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:

fastcgi_cache_bypass $cookie_nocache $arg_nocache$arg_comment;
fastcgi_cache_bypass $http_pragma    $http_authorization;

Can be used along with the fastcgi_no_cache directive.

syntax: fastcgi_cache_key string;
default:
context: http, server, location

Defines a key for caching, for example

fastcgi_cache_key localhost:9000$request_uri;

syntax: fastcgi_cache_lock on | off;
default:
fastcgi_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 fastcgi_cache_key directive by passing a request to a FastCGI 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 fastcgi_cache_lock_timeout directive.

syntax: fastcgi_cache_lock_timeout time;
default:
fastcgi_cache_lock_timeout 5s;
context: http, server, location

This directive appeared in version 1.1.12.

Sets a timeout for fastcgi_cache_lock.

syntax: fastcgi_cache_methods GET | HEAD | POST ...;
default:
fastcgi_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 fastcgi_no_cache directive.

syntax: fastcgi_cache_min_uses number;
default:
fastcgi_cache_min_uses 1;
context: http, server, location

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

syntax: fastcgi_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. Both the key and file name in a cache are a result of applying the MD5 function to the proxied URL. The levels parameter defines hierarchy levels of a cache. For example, in the following configuration

fastcgi_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 fastcgi_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. 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: fastcgi_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:

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

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

server {
    ...
    location / {
        fastcgi_pass backend;
        fastcgi_cache cache_zone;
        fastcgi_cache_key $uri;
        fastcgi_cache_purge $purge_method;
    }
}

This functionality is available as part of our commercial subscription.

syntax: fastcgi_cache_revalidate on | off;
default:
fastcgi_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” header field.

syntax: fastcgi_cache_use_stale error | timeout | invalid_header | updating | http_500 | http_503 | http_403 | http_404 | off ...;
default:
fastcgi_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 FastCGI server. The directive’s parameters match the parameters of the fastcgi_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 FastCGI servers when updating cached data.

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

syntax: fastcgi_cache_valid [code ...] time;
default:
context: http, server, location

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

fastcgi_cache_valid 200 302 10m;
fastcgi_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

fastcgi_cache_valid 5m;

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

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

fastcgi_cache_valid 200 302 10m;
fastcgi_cache_valid 301      1h;
fastcgi_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 fastcgi_ignore_headers directive.

syntax: fastcgi_catch_stderr string;
default:
context: http, server, location

Sets a string to search for in the error stream of a response received from a FastCGI server. If the string is found then it is considered that the FastCGI server has returned an invalid response. This allows handling application errors in nginx, for example:

location /php {
    fastcgi_pass backend:9000;
    ...
    fastcgi_catch_stderr "PHP Fatal error";
    fastcgi_next_upstream error timeout invalid_header;
}

syntax: fastcgi_connect_timeout time;
default:
fastcgi_connect_timeout 60s;
context: http, server, location

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

syntax: fastcgi_hide_header field;
default:
context: http, server, location

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

syntax: fastcgi_ignore_client_abort on | off;
default:
fastcgi_ignore_client_abort off;
context: http, server, location

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

syntax: fastcgi_ignore_headers field ...;
default:
context: http, server, location

Disables processing of certain response header fields from the FastCGI 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”, and “Set-Cookie” (0.8.44).

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

  • “X-Accel-Expires”, “Expires”, “Cache-Control”, and “Set-Cookie” 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.

syntax: fastcgi_index name;
default:
context: http, server, location

Sets a file name that will be appended after a URI that ends with a slash, in the value of the $fastcgi_script_name variable. For example, with these settings

fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /home/www/scripts/php$fastcgi_script_name;

and the “/page.php” request, the SCRIPT_FILENAME parameter will be equal to “/home/www/scripts/php/page.php”, and with the “/” request it will be equal to “/home/www/scripts/php/index.php”.

syntax: fastcgi_intercept_errors on | off;
default:
fastcgi_intercept_errors off;
context: http, server, location

Determines whether FastCGI server 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: fastcgi_keep_conn on | off;
default:
fastcgi_keep_conn off;
context: http, server, location

This directive appeared in version 1.1.4.

By default, a FastCGI server will close a connection right after sending the response. However, when this directive is set to the value on, nginx will instruct a FastCGI server to keep connections open. This is necessary, in particular, for keepalive connections to FastCGI servers to function.

syntax: fastcgi_max_temp_file_size size;
default:
fastcgi_max_temp_file_size 1024m;
context: http, server, location

When buffering of responses from the FastCGI server is enabled, and the whole response does not fit into the memory buffers set by the fastcgi_buffer_size and fastcgi_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 fastcgi_temp_file_write_size directive.

The zero value disables buffering of responses to temporary files.

syntax: fastcgi_next_upstream error | timeout | invalid_header | http_500 | http_503 | http_403 | http_404 | off ...;
default:
fastcgi_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_503
a server returned a response with the code 503;
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 and http_503 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.

syntax: fastcgi_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:

fastcgi_no_cache $cookie_nocache $arg_nocache$arg_comment;
fastcgi_no_cache $http_pragma    $http_authorization;

Can be used along with the fastcgi_cache_bypass directive.

syntax: fastcgi_param parameter value [if_not_empty];
default:
context: http, server, location

Sets a parameter that should be passed to the FastCGI server. The value can contain text, variables, and their combination. These directives are inherited from the previous level if and only if there are no fastcgi_param directives defined on the current level.

The following example shows the minimum required settings for PHP:

fastcgi_param SCRIPT_FILENAME /home/www/scripts/php$fastcgi_script_name;
fastcgi_param QUERY_STRING    $query_string;

The SCRIPT_FILENAME parameter is used in PHP for determining the script name, and the QUERY_STRING parameter is used to pass request parameters.

For scripts that process POST requests, the following three parameters are also required:

fastcgi_param REQUEST_METHOD  $request_method;
fastcgi_param CONTENT_TYPE    $content_type;
fastcgi_param CONTENT_LENGTH  $content_length;

If PHP was built with the --enable-force-cgi-redirect configuration parameter, the REDIRECT_STATUS parameter should also be passed with the value “200”:

fastcgi_param REDIRECT_STATUS 200;

If a directive is specified with if_not_empty (1.1.11) then such a parameter will not be passed to the server until its value is not empty:

fastcgi_param HTTPS           $https if_not_empty;

syntax: fastcgi_pass address;
default:
context: location, if in location

Sets the address of a FastCGI server. The address can be specified as a domain name or IP address, and an optional port:

fastcgi_pass localhost:9000;

or as a UNIX-domain socket path:

fastcgi_pass unix:/tmp/fastcgi.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.

syntax: fastcgi_pass_header field;
default:
context: http, server, location

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

syntax: fastcgi_read_timeout time;
default:
fastcgi_read_timeout 60s;
context: http, server, location

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

syntax: fastcgi_pass_request_body on | off;
default:
fastcgi_pass_request_body on;
context: http, server, location

Indicates whether the original request body is passed to the FastCGI server. See also the fastcgi_pass_request_headers directive.

syntax: fastcgi_pass_request_headers on | off;
default:
fastcgi_pass_request_headers on;
context: http, server, location

Indicates whether the header fields of the original request are passed to the FastCGI server. See also the fastcgi_pass_request_body directive.

syntax: fastcgi_send_lowat size;
default:
fastcgi_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 FastCGI 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: fastcgi_send_timeout time;
default:
fastcgi_send_timeout 60s;
context: http, server, location

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

syntax: fastcgi_split_path_info regex;
default:
context: location

Defines a regular expression that captures a value for the $fastcgi_path_info variable. The regular expression should have two captures: the first becomes a value of the $fastcgi_script_name variable, the second becomes a value of the $fastcgi_path_info variable. For example, with these settings

location ~ ^(.+\.php)(.*)$ {
    fastcgi_split_path_info       ^(.+\.php)(.*)$;
    fastcgi_param SCRIPT_FILENAME /path/to/php$fastcgi_script_name;
    fastcgi_param PATH_INFO       $fastcgi_path_info;

and the “/show.php/article/0001” request, the SCRIPT_FILENAME parameter will be equal to “/path/to/php/show.php”, and the PATH_INFO parameter will be equal to “/article/0001”.

syntax: fastcgi_store on | off | string;
default:
fastcgi_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:

fastcgi_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 fastcgi_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;

    fastcgi_pass         backend:9000;
    ...

    fastcgi_store        on;
    fastcgi_store_access user:rw group:rw all:r;
    fastcgi_temp_path    /data/temp;

    alias                /data/www/;
}

syntax: fastcgi_store_access users:permissions ...;
default:
fastcgi_store_access user:rw;
context: http, server, location

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

fastcgi_store_access user:rw group:rw all:r;

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

fastcgi_store_access group:rw all:r;

syntax: fastcgi_temp_file_write_size size;
default:
fastcgi_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 FastCGI server to temporary files is enabled. By default, size is limited by two buffers set by the fastcgi_buffer_size and fastcgi_buffers directives. The maximum size of a temporary file is set by the fastcgi_max_temp_file_size directive.

syntax: fastcgi_temp_path path [level1 [level2 [level3]]];
default:
fastcgi_temp_path fastcgi_temp;
context: http, server, location

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

fastcgi_temp_path /spool/nginx/fastcgi_temp 1 2;

a temporary file might look like this:

/spool/nginx/fastcgi_temp/7/45/00000123457

Parameters Passed to a FastCGI Server

HTTP request header fields are passed to a FastCGI server as parameters. In applications and scripts running as FastCGI servers, these parameters are usually made available as environment variables. For example, the “User-Agent” header field is passed as the HTTP_USER_AGENT parameter. In addition to HTTP request header fields, it is possible to pass arbitrary parameters using the fastcgi_param directive.

Embedded Variables

The ngx_http_fastcgi_module module supports embedded variables that can be used to set parameters using the fastcgi_param directive:

$fastcgi_script_name
request URI or, if a URI ends with a slash, request URI with an index file name configured by the fastcgi_index directive appended to it. This variable can be used to set the SCRIPT_FILENAME and PATH_TRANSLATED parameters that determine the script name in PHP. For example, for the “/info/” request with the following directives
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /home/www/scripts/php$fastcgi_script_name;
the SCRIPT_FILENAME parameter will be equal to “/home/www/scripts/php/info/index.php”.

When using the fastcgi_split_path_info directive, the $fastcgi_script_name variable equals the value of the first capture set by the directive.

$fastcgi_path_info
the value of the second capture set by the fastcgi_split_path_info directive. This variable can be used to set the PATH_INFO parameter.