docker containers can't talk to each other - php

Question

I have 3 docker containers that are supposed to talk to each other. A very classic stack with nginx, php-fpm and mariadb.
My stack used to work, but now my containers can't seem to talk to each other anymore, and I don't know what changed. The nginx can't talk to the php-fpm, and the php-fpm can't talk to mariadb.
Here is the docker-compose I use :
version: '3'
services:
web-nginx:
image: nginx:stable-alpine
container_name: web-nginx
restart: always
ports:
- "80:80"
web-php:
restart: always
build:
context: ./php
dockerfile: Dockerfile
container_name: web-php
web-mariadb:
build:
context: ./mariadb
dockerfile: Dockerfile
restart: always
container_name: web-mariadb
ports:
- "3306:3306"
The content of docker-compose ps :
docker-compose ps
Name Command State Ports
-----------------------------------------------------------------------------
web-mariadb docker-entrypoint.sh mysqld Up 0.0.0.0:3306->3306/tcp
web-nginx /docker-entrypoint.sh ngin ... Up 0.0.0.0:80->80/tcp
web-php docker-php-entrypoint php-fpm Up 9000/tcp
My DockerFiles :
FROM php:fpm-alpine
ENV USER=docker
ENV UID=1000
RUN adduser \
--disabled-password \
--gecos "" \
--home "$(pwd)" \
--no-create-home \
--uid "$UID" \
"$USER"
[...]
USER docker
FROM mariadb
RUN echo max_allowed_packet=512M >> /etc/mysql/my.cnf
The nginx.conf file
[...]
http {
[...]
server {
listen 80;
server_name localhost;
location / {
root /usr/share/nginx/html;
index index.php index.html index.htm;
}
location ~ \.php$ {
root /usr/share/nginx/html;
include fastcgi_params;
fastcgi_pass web-php:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME /script$fastcgi_script_name;
}
}
}
So my php-fpm is supposed to be accessed through port 9000 while mariadb listens to the classical 3306.
Between containers, ping commands are OK, but nc are not (I use nc because telnet is not bundled in alpine images):
docker exec -u 0 -it web-nginx sh #I use -u 0 to be root because otherwise ping is not allowed in the container
/ # ping -c1 web-php
PING web-php (172.22.0.3): 56 data bytes
64 bytes from 172.22.0.3: seq=0 ttl=64 time=0.156 ms
--- web-php ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.156/0.156/0.156 ms
/ # nc -v web-php 9000
nc: web-php (172.22.0.3:9000): Host is unreachable
docker exec -u 0 -it web-php sh
ping -c1 web-mariadb
PING web-mariadb (172.22.0.4): 56 data bytes
64 bytes from 172.22.0.4: seq=0 ttl=64 time=0.199 ms
--- web-mariadb ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.199/0.199/0.199 ms
/var/www/html # nc -v web-mariadb 3306
nc: web-mariadb (172.22.0.4:3306): Host is unreachable
Here is the docker inspect command :
[
{
"Name": "web_default",
"Id": "e458e63d89e3f6e2c35644aa03f377dc9fba6975b4b8838727b85c57c3b183ba",
"Created": "2021-01-28T15:00:06.814105722+01:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "172.22.0.0/16",
"Gateway": "172.22.0.1"
}
]
},
"Internal": false,
"Attachable": true,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"af441d802fd26173ea98ca81b85eb48cbea36b65b867df46b6ddb2f5ac484816": {
"Name": "web-nginx",
"EndpointID": "6b69e2033b3de50c86161cbec103843de5f83ab53ecebd557ff66ae57adaae04",
"MacAddress": "02:42:ac:16:00:02",
"IPv4Address": "172.22.0.2/16",
"IPv6Address": ""
},
"be99788a48d03fb51288aab6373596c41ed8adcbcf8ceaa8ae2ece1e0aa10843": {
"Name": "web-mariadb",
"EndpointID": "8f52e8fe97f24161934b9ab3dcdde9da69aeb80388deb3f6442dd089554e30f0",
"MacAddress": "02:42:ac:16:00:04",
"IPv4Address": "172.22.0.4/16",
"IPv6Address": ""
},
"f1d2aa6a6c2e156416da3ca0424336380b01950d6f0990203a2d0484ad0d04a5": {
"Name": "web-php",
"EndpointID": "7e6b95ccb7da5bcdd3754d1965820e429bdf5370cecee0bceb29c79138d36e0e",
"MacAddress": "02:42:ac:16:00:03",
"IPv4Address": "172.22.0.3/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {
"com.docker.compose.network": "default",
"com.docker.compose.project": "web",
"com.docker.compose.version": "1.27.4"
}
}
]
Since ping works between containers, I assume network is correct, but ports are not opened.
Also, I noticed that my containers can't reach internet. Any ping to google or just "outside" is rejected.
I tried restarting the docker service and even reboot my server, but no luck.
I don't know how to troubleshoot this.
Server running centos 8 :
Linux myserver 4.18.0-240.10.1.el8_3.x86_64
Docker version 20.10.2, build 2291f61
Any help much appreciated.
Thanks !