Problem with inheriting fastcgi params


#1

I have my normal fastcgi params in my main nginx.conf file, under server
{}

i.e.:

fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT $document_root;
fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param GATEWAY_INTERFACE CGI/1.1;
fastcgi_param SERVER_SOFTWARE nginx/$nginx_version;
fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $http_host;
fastcgi_ignore_client_abort on;
fastcgi_buffers 32 8k;
fastcgi_index index.php;

The problem is, whenever I want to add a variable (maybe override too,
I forget) it seems to clear all the other ones out:

           location ~ \.php$ {
                    fastcgi_pass 127.0.0.1:11003;
                    fastcgi_param HTTPS on;
            }

Now, only fastcgi_param HTTPS is set. no more SCRIPT_FILENAME so it’s
broken.

I would assume it would be able to inherit everything globally and
only add to the fastcgi_params on demand.

This is using nginx 0.7.55 or thereabouts but it’s been an issue I’ve
noticed in the past too.

Can nginx support this?


#2

On Fri, 2009-06-05 at 12:36 -0700, Michael S. wrote:

fastcgi_param REQUEST_URI $request_uri;
fastcgi_ignore_client_abort on;
}

Now, only fastcgi_param HTTPS is set. no more SCRIPT_FILENAME so it’s broken.

I would assume it would be able to inherit everything globally and
only add to the fastcgi_params on demand.

This is using nginx 0.7.55 or thereabouts but it’s been an issue I’ve
noticed in the past too.

Can nginx support this?

Put your params in a separate file and include them wherever they are
needed:

location ~ .php$ {
include /etc/nginx/fastcgi_params;
fastcgi_pass 127.0.0.1:11003;
fastcgi_param HTTPS on;
}

This doesn’t incur any additional overhead.

Cliff


#3

I used to do that but realized I could do it the other way.

First I’d like to know if this is even supported. Might be a tiny bug
that could wind up messing up something else.

Depending on the outcome, I’ll probably wind up moving out the stuff
to a fastcgi_params anyway, though.


#4

Hello!

On Fri, Jun 05, 2009 at 12:36:36PM -0700, Michael S. wrote:

fastcgi_param REQUEST_URI $request_uri;
fastcgi_ignore_client_abort on;
}

Now, only fastcgi_param HTTPS is set. no more SCRIPT_FILENAME so it’s broken.

It’s expected and documented behaviour. All array-type settings
behave like this: they are inherited from upper levels only if
none defined at this particular level.

Maxim D.


#5

On Fri, Jun 5, 2009 at 1:17 PM, Maxim D. removed_email_address@domain.invalid wrote:

fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param REMOTE_PORT $remote_port;

        location ~ .php$ {
            fastcgi_pass 127.0.0.1:11003;
            fastcgi_param HTTPS on;
        }

Now, only fastcgi_param HTTPS is set. no more SCRIPT_FILENAME so it’s broken.

It’s expected and documented behaviour. Â All array-type settings
behave like this: they are inherited from upper levels only if
none defined at this particular level.

So instead of appending the array (or replacing an existing index) I
am essentially resetting the array completely?

Is there a usage model where it makes sense that this should be a
supported behavior? Logically it seems like it should be supported,
but I guess under the hood it’s a one line change or a very major
change.


#6

On Fri, 2009-06-05 at 13:49 -0700, Michael S. wrote:

fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param REMOTE_ADDR $remote_addr;
I forget) it seems to clear all the other ones out:
none defined at this particular level.

So instead of appending the array (or replacing an existing index) I
am essentially resetting the array completely?

Is there a usage model where it makes sense that this should be a
supported behavior? Logically it seems like it should be supported,
but I guess under the hood it’s a one line change or a very major
change.

I believe the idea is that inheritance can lead to subtle side-effects
in large configurations. You might include a several files and not
realize that one of them is affecting the configuration several
files/locations away.

Cliff


#7

On Fri, Jun 5, 2009 at 2:12 PM, Cliff W. removed_email_address@domain.invalid wrote:

Interesting. Â I was aware of the limitation Michael mentions, but
didn’t realize this was the particular mechanism. Â So I assume that
“array-type” is indicated by the variable prefixes, i.e. fastcgi_,
proxy_
, etc?

See, there -is- a use case out there somewhere!
:slight_smile:


#8

Hello!

On Fri, Jun 05, 2009 at 02:12:50PM -0700, Cliff W. wrote:

fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param REMOTE_ADDR $remote_addr;
I forget) it seems to clear all the other ones out:
none defined at this particular level.

Interesting. I was aware of the limitation Michael mentions, but
didn’t realize this was the particular mechanism. So I assume that
“array-type” is indicated by the variable prefixes, i.e. fastcgi_,
proxy_
, etc?

Yes, it’s generic mechanism. No, “array-type” isn’t indicated by
anything. It’s just includes any directives that may be repeated
and effectively append items to some array internally. This
includes access_log, error_log, fastcgi_param, proxy_set_header,
ssi_types (and other *_types as well), access rules (allow + deny)
and so on.

From user-level point of view this behaviour is part of config
syntax. If it wasn’t working this way - some other syntax would be
required to make it possible to clear inherited values.

From developer point of view - it’s just easy. Inheritance
involve just copy of array pointer from upper level if there are
no directives defined at particular level.

Maxim D.


#9

On Jun 5, 2009, at 7:03 PM, Maxim D. removed_email_address@domain.invalid wrote:

server {}
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_buffers 32 8k;
}
“array-type” is indicated by the variable prefixes, i.e. fastcgi_*,
syntax. If it wasn’t working this way - some other syntax would be
required to make it possible to clear inherited values.

From developer point of view - it’s just easy. Inheritance
involve just copy of array pointer from upper level if there are
no directives defined at particular level.

Doesn’t that mean it could be supported how I originally had asked?


#10

On Sat, 2009-06-06 at 00:17 +0400, Maxim D. wrote:

fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param REMOTE_PORT $remote_port;

           location ~ \.php$ {
                    fastcgi_pass 127.0.0.1:11003;
                    fastcgi_param HTTPS on;
            }

Now, only fastcgi_param HTTPS is set. no more SCRIPT_FILENAME so it’s broken.

It’s expected and documented behaviour. All array-type settings
behave like this: they are inherited from upper levels only if
none defined at this particular level.

Interesting. I was aware of the limitation Michael mentions, but
didn’t realize this was the particular mechanism. So I assume that
“array-type” is indicated by the variable prefixes, i.e. fastcgi_,
proxy_
, etc?

If you’ll confirm this, I’ll get it into the FAQ.

Cliff


#11

On Sat, 2009-06-06 at 06:03 +0400, Maxim D. wrote:

didn’t realize this was the particular mechanism. So I assume that
From user-level point of view this behaviour is part of config
syntax. If it wasn’t working this way - some other syntax would be
required to make it possible to clear inherited values.

From developer point of view - it’s just easy. Inheritance
involve just copy of array pointer from upper level if there are
no directives defined at particular level.

I guess what I’m looking for (from a user point of view), is how to
describe why (and more importantly when) setting one variable affects
others. If there were an obvious pattern in naming conventions (or
even a simple, externally maintained list in the wiki) of array
variables I think it would make this behavior less surprising. I write
a bit of code myself, so your description makes perfect sense as to how
things work internally, but this doesn’t necessarily lend itself (from a
user perspective) to predicting which variables might fall into this
category.

Cliff