Does nginx fastcgi_pass support variables? - php

Question

I would like to use dynamic host resolution with nginx and fastcgi_pass.
When fastcgi_pass $wphost:9000; is set in the conf then nginx displays the error
[error] 7#7: *1 wordpress.docker could not be resolved (3: Host not found),
but when I set fastcgi_pass wordpress.docker:9000;it is working except for the fact the that after a wordpress restart nginx still points to an old ip.
server {
listen [::]:80;
include /etc/nginx/ssl/ssl.conf;
server_name app.domain.*;
root /var/www/html;
index index.php index.html index.htm;
resolver 172.17.42.1 valid=60s;
resolver_timeout 3s;
location / {
try_files $uri $uri/ /index.php?q=$uri&$args; ## First attempt to serve request as file, then as directory, then fall back to index.html
}
#error_page 404 /404.html;
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
set $wphost wordpress.docker;
# pass the PHP scripts to FastCGI server listening on wordpress.docker
location ~ \.php$ {
client_max_body_size 25M;
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass $wphost:9000;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_index index.php;
include fastcgi_params;
}
location ~* \.(jpg|jpeg|gif|png|css|js|ico|xml)$ {
add_header Pragma public;
add_header Cache-Control "public, must-revalidate, proxy-revalidate";
access_log off;
log_not_found off;
expires 168h;
}
# deny access to . files, for security
location ~ /\. {
access_log off;
log_not_found off;
deny all;
}
}
I have different virtual host configuration where I use proxy_pass http://$hostname; and in this setup everything is working as expected and the host is found.
After trying different options I wonder if fastcgi_pass does support variables

Answer 1

It does work if you pass the upstream as a variable instead, for example:
upstream fastcgi_backend1 {
server php_node1:9000;
}
upstream fastcgi_backend2 {
server php_node2:9000;
}
server {
listen 80;
server_name _;
set $FASTCGI_BACKEND1 fastcgi_backend1;
set $FASTCGI_BACKEND2 fastcgi_backend2;
location ~ ^/site1/index.php$ {
fastcgi_pass $FASTCGI_BACKEND1;
}
location ~ ^/site2/index.php$ {
fastcgi_pass $FASTCGI_BACKEND2;
}
}