FastCGI: Unable to open primary script on NGinx and PHP-FPM

Question

I am apparently not the only one with this problem, but after trying every suggested solution for couple I reached I point where I don't know what to do.

I am running Ubuntu 16.04, NGinx and PHP-FPM.

The nginx.conf is the default one, I only set a more informative log format.

The user rights seem to be okay: NGinx and PHP_FPM run under user www-data. Document-Root owner is www-data. FPM-Pool owner is www-data. Socket-file is there and writable.

I already tried setting folder- and file-permissions to the weakest (chmod 777): No result.

This is my server.conf, as you can see from commented lines, I tried a bunch of tricks - with no effect:

server { listen 8080; # listen 8080 default_server; # listen [::]:8080 default_server; server_name example.com www.example.com root /var/www/nginx/; index index.php; access_log /var/log/nginx/scripts.log scripts; gzip on; gzip_comp_level 3; gzip_types text/plain text/css application/javascript image/*; location ~ \.php$ { if ($uri !~ "^/uploads/") { fastcgi_pass unix:/run/php/php-fpm-www.sock; } include fastcgi.conf; # include snippets/fastcgi-php.conf; include fastcgi_params; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_param SCRIPT_NAME $fastcgi_script_name; } # Block access to .htaccess location ~ \.htaccess { deny all; } } 

That's the fpm-pool config:

[www] listen = /run/php/php-fpm-$pool.sock user = www-data group = www-data listen.owner = www-data listen.group = www-data php_admin_flag[allow_url_fopen] = off php_admin_flag[allow_url_include] = off php_admin_value[memory_limit] = 128M pm = dynamic pm.max_children = 5 pm.start_servers = 1 pm.min_spare_servers = 1 pm.max_spare_servers = 3 chdir = / chroot = /var/www/nginx/ php_flag[display_errors] = on php_admin_value[error_log] = /var/log/fpm-php.www.log php_admin_flag[log_errors] = on catch_workers_output = yes 

This is the output of the nginx' access.log:

/var/www/nginx/index.php > GET /index.php HTTP/1.1 

And that's the actual error.log:

2018/08/29 17:34:27 [error] 24020#24020: *47 FastCGI sent in stderr: "Unable to open primary script: /var/www/nginx/index.php (No such file or directory)" while reading response header from upstream, client: 213.61.37.18, server: example.com, request: "GET /index.php HTTP/1.1", upstream: "fastcgi://unix:/run/php/php-fpm-www.sock:", host: "example.com:8080" 

Answer 1

I found the error for myself after the hint of @michael - thanks for the enlightenment.

I am using chroot, because the goal is to "jail" every website in it's own environment / folder. So I set the root of this particular environment to the real filesystem location /var/www/nginx.

Inside the server configuration of NGinx I pass the fastcgi parameter SCRIPT_FILENAME with a leading $document_root.

fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; 

In NGinx $document_root references the root-directive. The $document_root is, of course /var/www/nginx

But the PHP-environment has a "changed root" (/ means /var/www/nginx). That means, that PHP now is looking for index.php in the folder /var/www/nginx. But as the root folder is only "virtual", PHP's /var/www/nginx actualy points to this location on the real filesystem: /var/www/nginx/var/www/nginx.

So changing the parameter to this will fix the error.

fastcgi_param SCRIPT_FILENAME $fastcgi_script_name;