Nginx+PHP-FPM: connection refused while connecting to upstream (502) - php

Question

I know there's a ton of posts regarding 502 Bad Gateway, but I haven't been able to solve this problem. I'm using Docker Compose to create separate containers for Nginx and PHP-FPM.
Error I get loading PHP files in the browser (HTML files render fine):
tc-web | 2018/01/22 19:22:46 [error] 5#5: *4 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: localhost, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://172.18.0.2:9000", host: "localhost:8080"
tc-web | 172.18.0.1 - - [22/Jan/2018:19:22:46 +0000] "GET /info.php HTTP/1.1" 502 575 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"
I've tried tweaking the various configs, using Unix socket, etc., for hours, and I still get 502 errors with PHP files. Can you spot what's wrong?
Here are all required files..
docker-composer.yml:
version: '3'
services:
web:
build:
context: ./docker/nginx
image: tc-web:0.1.0
container_name: tc-web
volumes:
# test files
- ./temp.html:/var/www/html/index.html
- ./temp.php:/var/www/html/info.php
ports:
- 8080:80
depends_on:
- php-fpm
php-fpm:
build:
context: ./docker/php-fpm
image: tc-php:0.1.0
container_name: tc-php
volumes:
- ./temp.html:/var/www/html/index.html
- ./temp.php:/var/www/html/info.php
docker/nginx/Dockerfile:
FROM nginx:1.13.8
# Install programs
RUN apt-get update
RUN apt-get install -y nano && \
apt-get install -y git && \
apt-get install -y procps
RUN mkdir -p /var/www/html
COPY nginx.conf /etc/nginx/nginx.conf
COPY default.conf /etc/nginx/conf.d/default.conf
docker/nginx/nginx.conf:
user www-data;
worker_processes 1;
# error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
sendfile on;
#tcp_nopush on;
keepalive_timeout 65;
#gzip on;
include /etc/nginx/conf.d/default.conf;
}
docker/nginx/default.conf:
server {
listen 80;
server_name localhost;
root /var/www/html;
location / {
try_files $uri $uri/ /index.php?$query_string;
}
location ~* \.php$ {
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass php-fpm:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
}
docker/php-fpm/Dockerfile:
FROM php:7.0-fpm
# Install programs
RUN apt-get update
RUN apt-get install -y nano && \
apt-get install -y procps
RUN mkdir -p /var/www/html
COPY php-fpm.conf /usr/local/etc/php-fpm.conf
COPY www.conf /usr/local/etc/php-fpm.d/www.conf
docker/php-fpm/php-fpm.conf:
[global]
include=etc/php-fpm.d/www.conf
docker/php-fpm/www.conf:
[global]
;daemonize = no
; if we send this to /proc/self/fd/1, it never appears
error_log = /proc/self/fd/2
[www]
user = www-data
group = www-data
listen = 127.0.0.1:9000
;listen = /var/run/php-fpm/php7-fpm.sock
;listen.owner = www-data
;listen.group = www-data
;listen.mode = 0660
access.log = /proc/self/fd/2
pm = dynamic
pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3
; Ensure worker stdout and stderr are sent to the main error log.
catch_workers_output = yes

Answer 1

Problem could be in the www.conf file.
You are listening to 127.0.0.1:9000 but this way the service won't be reachable outside the container.
Try binding to 0.0.0.0:9000:
listen = 0.0.0.0:9000

Answer 2

This may sound very obvious, but another common issue would be that php-fpm is not installed. This can happen even though systemctl might say that the service is running but it's not really running anything. In my case, I had also installed PHP 8 with it's own fpm package, so if you have multiple php installations, there could have been a mix up with which fpm version you installed.