Docker, Nginx, PHP-FPM : problems with connection - php

Question

I've taken on a project built on Docker containers and I'm having it to run smoothly.
My containers build successfully, but when I try getting to the website, nginx gives me a 502 with this error in the logs:
connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "fastcgi://172.17.0.6:9000", host: "localhost:2000"
Which, from what I've read would be a problem with the link between my two containers.
I've tried changing the listen parameter of php-fpm directly to 0.0.0.0:9000 as seen on Nginx+PHP-FPM: connection refused while connecting to upstream (502) but this gave rise to a new error I don't fully understand either:
*11 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "fastcgi://172.17.0.6:9000", host: "localhost:2000"
Does anyone has an idea of what is failing and how to fix it ?
The docker-compose part regarding theses two services is:
elinoi-webserver:
build: .
dockerfile: docker/Dockerfile.nginx.conf
container_name: elinoi-webserver
volumes:
- .:/var/www/elinoi.com
ports:
- "2000:80"
links:
- elinoi-php-fpm
elinoi-php-fpm:
build: .
dockerfile: docker/Dockerfile.php-fpm.conf
container_name: elinoi-php-fpm
volumes:
- .:/var/www/elinoi.com
- /var/docker_volumes/elinoi.com/shared:/var/www/elinoi.com/shared
ports:
- "22001:22"
links:
- elinoi-mailhog
- elinoi-memcached
- elinoi-mysql
- elinoi-redis
The nginx conf file is:
server {
listen 80 default;
root /var/www/elinoi.com/current/web;
rewrite ^/app\.php/?(.*)$ /$1 permanent;
try_files $uri #rewriteapp;
location #rewriteapp {
rewrite ^(.*)$ /app.php/$1 last;
}
# Deny all . files
location ~ /\. {
deny all;
}
location ~ ^/(app|app_dev)\.php(/|$) {
fastcgi_pass elinoi-php-fpm:9000;
fastcgi_split_path_info ^(.+\.php)(/.*)$;
include fastcgi_params;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_index app.php;
send_timeout 1800;
fastcgi_read_timeout 1800;
}
# Statics
location /(bundles|media) {
access_log off;
expires 30d;
try_files $uri #rewriteapp;
}
}
The Dockerfile for the elinoi-php-fpm service is :
FROM phpdockerio/php7-fpm:latest
# Install selected extensions
RUN apt-get update \
&& apt-get -y --no-install-recommends install php7.0-memcached php7.0-mysql php7.0-redis php7.0-gd php7.0-imagick php7.0-intl php7.0-xdebug php7.0-mbstring \
&& apt-get -y --no-install-recommends install nodejs npm nodejs-legacy vim ruby-full git build-essential libffi-dev \
&& apt-get clean \
&& rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
RUN npm install -g bower
RUN npm install -g less
RUN gem install sass
# If you're using symfony and the vagranted environment, I strongly recommend you change your AppKernel to use the following temporary folders
# for cache, logs and sessions, otherwise application performance may suffer due to these being shared over NFS back to the host
RUN mkdir -p "/tmp/elinoi/cache" \
&& mkdir -p "/tmp/elinoi/logs" \
&& mkdir -p "/tmp/elinoi/sessions" \
&& chown www-data:www-data -R "/tmp/elinoi"
RUN apt-get update \
&& apt-get -y --no-install-recommends install openssh-server \
&& apt-get clean \
&& rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
RUN mkdir /var/run/sshd
RUN echo 'root:screencast' | chpasswd
RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
# SSH login fix. Otherwise user is kicked off after login
RUN sed 's#session\s*required\s*pam_loginuid.so#session optional pam_loginuid.so#g' -i /etc/pam.d/sshd
ENV NOTVISIBLE "in users profile"
RUN echo "export VISIBLE=now" >> /etc/profile
EXPOSE 22
ADD docker/.ssh /root/.ssh
RUN chmod 700 /root/.ssh/authorized_keys
CMD ["/usr/sbin/sshd", "-D"]
WORKDIR "/var/www/elinoi.com"
The Dockerfile for the elinoi-webserver is:
FROM smebberson/alpine-nginx:latest
COPY /docker/nginx.conf /etc/nginx/conf.d/default.conf
WORKDIR "/var/www/elinoi.com"

Answer 1

There can only be one CMD instruction in a Dockerfile. If you list
more than one CMD then only the last CMD will take effect.
The original Dockerfile ends with:
CMD /usr/bin/php-fpm
and the Dockerfile of the elinoi-php-fpm service ends with the following CMD layer:
CMD ["/usr/sbin/sshd", "-D"]
So, only sshd is started after container creates. php-fpm is not started there.
That's why nginx constantly returns 502 error, because php backend is not working at all.
You can fix your issue the following ways:
1. Docker Alpine linux running 2 programs
2. Simply delete sshd part from the elinoi-php-fpm service.