Provided by: nginx-confgen_2.0-1_amd64 bug

NAME

       nginx-confgen - A preprocessor and macro system for nginx(-like) configuration files.

SYNOPSIS

       nginx-confgen -i input.conf -o output.conf

DESCRIPTION

       nginx-confgen can be used to do pre-processing for nginx configuration files (and other
       configuration files with a similar syntax). It has support for "compile-time" macro
       expansion and variable interpolation, which should make it less tedious to maintain large
       and complex configurations.

       nginx-confgen works by parsing the input into a syntax tree, modifying this tree, and then
       formatting the tree to generate the output. It is completely oblivious to nginx contexts
       and directives, so it is possible to do nonsensical transformations and generate incorrect
       configuration files. Comments in the input file will not be present in the output. See
       also the "BUGS & WARTS" below.

       WARNING: Do NOT use nginx-confgen with untrusted input, the "pre_exec" directive allows,
       by design, arbitrary code execution.

OPTIONS

       The following command-line options are supported:

       -h  Show help text.

       -V, --version
           Show program version.

       -i FILE
           Use the given file name as input file. If this option is not given or set to "-", then
           the file will be read from standard input.

       -o FILE
           Write the output to the given file. If this option is not given or set to "-", then
           the file will be written to standard output.

       -I DIR
           Set the search path for pre_include directives. This option can be given multiple
           times to search several directories in order. If this option is not given, then
           include files are resolved relative to the directory that nginx-confgen is run from
           (i.e. "-I .").

DIRECTIVES

       nginx-confgen recognizes and interprets the following directives:

   pre_include
       Similar to the "include" directive in nginx, except that the file is included during
       preprocessing. The included file may contain any preprocessing directives supported by
       nginx-confgen. Variables and macros defined in the included file will be available in the
       parent file.

       Relative paths are searched for in the directories given with the "-I" flag.

   pre_set
       Similar to the "set" directive in nginx, except that variables defined with "pre_set" are
       resolved during preprocessing. Variables are set in the order that they are encountered in
       the configuration file, regardless of scoping. For example:

         pre_set $var outer;
         location / {
           pre_set $var inner;
         }
         # $var is "inner" at this point.

       Only variables that are known to nginx-confgen will be substituted, unknown variables are
       assumed to be run-time variables for nginx and will be left alone without warning. For
       example:

         pre_set $ip 127.0.0.1;
         deny $ip;      # This will output as: block 127.0.0.1;
         deny $otherip; # This will output as: block $otherip;

   pre_exec
       Run a shell command, and store the output in a variable. For example, nginx will not use
       your system's DNS resolution methods to resolve domain names.  Instead you need to
       manually set a "resolver" address. With the following hack you can fetch the nameserver
       from "/etc/resolv.conf" and use that as the "resolver":

         pre_exec $nameserver "grep nameserver /etc/resolv.conf \\
                               | head -n 1 | sed 's/^nameserver //'";
         resolver $nameserver;

       (The "\\" is necessary, otherwise your shell will consider the newline as a new command).

   pre_if
       Similar to the "if" directive in nginx, except that this is evaluated during
       preprocessing. Braces around the condition are optional. Some examples:

         pre_if -f $certdir/ocsp.der {
           ssl_stapling on;
           ssl_stapling_file $certdir/ocsp.der;
         }
         pre_if (!-f $certdir/ocsp.der) {
           ssl_stapling off;
         }

         # You can have different configuration depending on the name of
         # the system on which nginx-confgen runs. Like... yeah.
         pre_exec $hostname 'hostname';
         pre_if $hostname ~* ^proxy_for_(.+) {
           proxy_pass http://$1/;
         }

   pre_warn
       This directive, when interpreted, will generate a warning to the standard error of nginx-
       confgen. Can be used to signal that a special configuration is being used:

         pre_if -e /etc/offline-mode {
           pre_warn "Putting website in offline mode!";
         }

       Or to warn about certain directives:

         pre_macro proxy_cache $var {
           pre_warn "Using proxy_cache with $var violates company policy!";

           # But we can output it anyway.
           proxy_cache $var;
         }

   macro
       Define a macro, which is a configuration block that you can later refer to.  The general
       syntax is as follows:

         macro macro_name $var1 $var2 @remaining_vars &block_var {
           # contents
         }

       The optional @remaining_vars argument will capture any number of variables and can be
       passed to another directive inside the macro contents. The optional &block_var allows the
       macro to be invoked with a block argument, which will expand to any number of directives.
       Some examples:

         macro le {
           location /.well-known/acme-challenge {
             alias /etc/letsencrypt/challenge;
           }
         }
         # Usage:
         le;

         macro redir $path $to {
           location $path {
             return 301 $to;
           }
         }
         # Usage:
         redir / http://blicky.net/;

         macro vhost $primary_name @aliases &block {
           server {
             listen [::]:443 ssl;
             server_name $primary_name @aliases;
             ssl_certificate $crtdir/$primary_name/fullchain.pem;
             ssl_certificate_key $crtdir/$primary_name/privkey.pem;
             █
           }
         }
         # Usage:
         vhost example.com {
           root /var/www/example.com;
         }
         vhost example.org alias.example.org {
           root /var/www/example.org;
         }

       Note that these are hygienic macros, so variable capture is predictable (but not
       necessarily the most useful):

         pre_var $dest /a;
         macro redir {
           # This will be /a, regardless of the context in which this macro is called.
           return 301 $dest;
         }
         # $dest is still '/a' inside the macro after this new variable definition.
         pre_var $dest /b;
         redir;

       Similarly, macro arguments will not be available inside &block expansion or nested macro
       expansion and any variables set inside a macro will not be available outside of the macro
       body.

BUGS & WARTS

       nginx-confgen is a quickly written hack to solve a particular use case, it is quite likely
       to have some weird behavior and bugs. In particular, processing performance may suffer on
       large configuration files with may macros and/or variables. Performance has simply not
       been a problem for me, but if you do run into trouble with your use case, let me know so I
       can fix it.

       Comments and whitespace in the input files are thrown away and ignored. The generated
       output is completely reformatted.

       The nginx configuration syntax is not as regular as I had hoped. It's possible for nginx
       modules to extend the syntax somewhat. A good example is the types directive in
       ngx_http_core_module. While nginx-confgen should be able to handle the types directive
       just fine, other extensions may cause syntax errors or will not survive a round-trip
       through nginx-confgen.  This applies to all *_by_lua_block directives in the
       ngx_http_lua_module.  The _by_lua directives that accept a string should work just fine.

AUTHOR

       nginx-confgen is written by Yoran Heling <projects@yorhel.nl>

       Web: <https://dev.yorhel.nl/nginx-confgen>