webserver process permissions problems on vagrant+nginx+php fpm - php

Question

I have a vagrant box with a LEMP (linux, nginx, mariadb, php) stack for developing a webapp and I am currently having some issues configuring nginx and php-fpm. I am using puppet and puPHPet to provision the VM.
It seems that the combo php-fpm and nginx are unable to write files (ie. log files generated, assets published by the framework (yii2) etc).
This project worked just fine using apache instead of nginx, so I would discard a programming issue and I have been following the guidelines for nginx installation and still getting messages such as "The directory is not writable by the Web process" or "Permission denied" like errors.
As recommended I set /etc/php5/fpm/php.ini the option cgi.fix_pathinfo = 0.
nginx/sites-available/site.conf
server {
listen *:80;
server_name site.dev;
client_max_body_size 128M;
root /var/www/frontend/web;
index index.php;
access_log /var/log/nginx/test.access.log;
error_log /var/log/nginx/test.error.log;
location / {
root /var/www/frontend/web;
try_files $uri $uri/ index.php /index.php$is_args$args;
}
location ~ \.php$ {
root /var/www/frontend/web;
index index.html index.htm index.php;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $request_filename;
fastcgi_param APP_ENV dev;
fastcgi_pass 127.0.0.1:9000;
fastcgi_split_path_info ^(.+\.php)(/.*)$;
include fastcgi_params;
}
sendfile off;
}
php-fpm/www.conf
user = www-data
group = www-data
listen-owner = www-data
listen-group = www-data
listen-mode = 0660
I've seen other posts where listen-mode is commented out, I tried both methods and setting mode to 0666 but still no luck.
I tried also setting permissions from the out and the inside of the vagrant to 0777 over the folders that I know that the framework uses to write data but still no luck.
I have a very similar project at work configured just the same that it works but this one doesn't and I can't find the difference (in fact I took config files from this project to set up the new one after the first failed attempt).
ps aux | grep php
root php-fpm: master process (/etc/php5/fpm/php-fpm.conf)
www-data php-fpm: pool www
www-data php-fpm: pool www
Directories in the different projects seem to have the same permissions number yet onw eorks and the other doesn't.
I'm completely clueless! Ideas are very welcomed!