Using variables in nginx.conf with 'set'

Server NGINX
1

It seems like the set command was designed for use in a narrow set of
circumstances. But I think it would be a lot more useful if the
variables
it defines could be used globally with any directive.

I am trying to use the ‘set’ command in order to define my own variables
that define things that may vary by server in a main nginx.conf file so
that
a generic reusable include file can later use those variables. It seems
that the variables only work in certain places with certain directives.

Is there a reason I can’t use variables set this way more widely? I
would
like to be able to use variables like this anywhere in the config files.

In the example below, I define two variables with the ‘set’ command,
$rootfolder and $backend.

The $rootfolder variable doesn’t work with the include directive and the
$backend doesn’t work with the proxy_pass directive.
But the $rootfolder does work with the $alias directive.

#main nginx.conf
server
{
listen 80;
server_name www.justatest.xxx
set $rootfolder /Development
set $backend http://127.0.0.1:8080

This doesn’t work!

include $rootfolder/mytest/vhost.conf;

have to use this instead

include /Development/mytest/vhost.conf;
}

#vhost.conf include

location /
{
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Rewrite-URL $request_uri;

this doesn’t work!

proxy_pass $backend;

have to use this instead

proxy_pass http://127.0.0.1:8080;
}

location /resources/
{

this DOES work

alias $websites/www/resources/;
}

–Thanks

2

lol

2010/10/22 Arthur B. [email protected]

3

Hello!

On Fri, Oct 22, 2010 at 08:27:52AM -0400, Arthur B. wrote:

It seems like the set command was designed for use in a narrow set of
circumstances. But I think it would be a lot more useful if the variables
it defines could be used globally with any directive.

I am trying to use the ‘set’ command in order to define my own variables
that define things that may vary by server in a main nginx.conf file so that
a generic reusable include file can later use those variables. It seems
that the variables only work in certain places with certain directives.

In nginx, variables are not something which “may vary by server”, it’s
something which is request-specific and evaluated at runtime.

Something which vary on per-server basis (usually referred as
“configuration macros” here) isn’t present in nginx at all.
Consider using your favorite template engine (e.g. make + sed) or
try server-specific includes.

Is there a reason I can’t use variables set this way more widely? I would
like to be able to use variables like this anywhere in the config files.

In the example below, I define two variables with the ‘set’ command,
$rootfolder and $backend.

The $rootfolder variable doesn’t work with the include directive and the

Include directives are evaluated during configuration parsing on
server startup. There is no request being processed, and no
variables.

$backend doesn’t work with the proxy_pass directive.

Actually it does (since 0.6.18). Though this requires resolver to
be defined and implies address parsing and resolving if backend
address given as domain name. Additionally, it has another
semantics than normal proxy_pass - with variables you have to
specify full url of the resource to request (or only server,
0.8.25+), semantics of “proxy_pass with URI” doesn’t apply.

Maxim D.

p.s. Just to summarise the above: you don’t need variables, you
need configuration macros. These aren’t implemented, but you are
free to use your favorite template engine.

4

Yes, I thought about using an external macro processor to achieve the
desired effect, but was hoping I could do without that.

So you are saying that even though it works for the $rootfolder in my
example, it is setting it to that value on each request. Which is using
it
in an unintended and inefficient way?

Thanks.

5

Maybe this will help you -

Posted at Nginx Forum: