Docker container running but connection reset on browser Apache - php

Question

I had my Docker setup yesterday with Apache PHP with a single index.php file to run "hello world" and it was working properly. But today out of nowhere, it has started to misbehave.
Here is my very simple docker-compose.yml:
version: '3'
services:
db:
image: mysql:5.7
environment:
MYSQL_ROOT_PASSWORD: my_secret_pw_shh
MYSQL_DATABASE: test_db
MYSQL_USER: devuser
MYSQL_PASSWORD: devpass
ports:
- "9906:3306"
web:
image: php:7.2.2-apache
container_name: php_web
depends_on:
- db
volumes:
- ./php/:/var/www/html/
ports:
- "8100:80"
stdin_open: true
tty: true
The issue that I'm facing is that, when I browse localhost:8100, it shows connection is reset. I don't have any application engaging this port 8100. Moreover, after a lot of failed research I managed to find out that Docker has it's own IP address inside the container and it exposes IP outside to get itself connected. However, I tried using network_mode to host as well but no luck.
I can share logs, which of no use as there are no errors they are really simple as it should be. There is not breaking in Apache config, the issue seems to be in IP mapping.
I've also looked docker network inspect {{network_name}} but no luck. I noticed that each Docker image creates the it's network during the first build. I'd like you to see:
docker network inspect test_default
[
{
"Name": "test_default",
"Id": "018e7845456beaabee1cd729da9c1d14440f13f93f4f606f700ff0013804246d",
"Created": "2022-02-03T23:51:25.740391332+05:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "172.23.0.0/16",
"Gateway": "172.23.0.1"
}
]
},
"Internal": false,
"Attachable": true,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {},
"Labels": {
"com.docker.compose.network": "default",
"com.docker.compose.project": "test",
"com.docker.compose.version": "1.29.2"
}
}
]
This is the output of network of my container.
I tried creating custom network following tutorial on Docker but still no luck.
After a bit of research, I also got to know if the IPs that are assigned to docker0 are colliding with some of my other gateways, then it happens which I didn't notice that any ip-address range is being collided.
In case you ask for my bridge IP here it is:
docker network inspect bridge
[
{
"Name": "bridge",
"Id": "12b99dd622ac5d09e45cf935cc2db907b4249140bbd2fb397db5dc81a1d70ab0",
"Created": "2022-02-03T22:03:26.564919187+05:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": null,
"Config": [
{
"Subnet": "172.17.0.0/16",
"Gateway": "172.17.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {
"com.docker.network.bridge.default_bridge": "true",
"com.docker.network.bridge.enable_icc": "true",
"com.docker.network.bridge.enable_ip_masquerade": "true",
"com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
"com.docker.network.bridge.name": "docker0",
"com.docker.network.driver.mtu": "1500"
},
"Labels": {}
}
]
And my system netstat -nr shows this result:
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 wlp0s20f3
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-4c91e6855bcb
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0
172.18.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-4c91e6855bcb
172.19.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-9711f2bb8edf
172.22.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-2211a05bcc3d
172.23.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-018e7845456b
172.28.0.0 0.0.0.0 255.255.0.0 U 0 0 0 br-55c64ea21f40
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlp0s20f3
asad#sav-dev--asad:/var/www/test$
I used the following commands,
netstat -nr for all
docker network inspect bridge
^^ FOR MY BRIDGE NETWORK
Everything seems fine but what happened all of a sudden that it has stopped working. Apache is running with no issues, here are the logs:
8aa94fcb082a_php_web | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.23.0.3. Set the 'ServerName' directive globally to suppress this message
8aa94fcb082a_php_web | AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.23.0.3. Set the 'ServerName' directive globally to suppress this message
8aa94fcb082a_php_web | [Thu Feb 03 20:20:54.830485 2022] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.25 (Debian) PHP/7.2.2 configured -- resuming normal operations
8aa94fcb082a_php_web | [Thu Feb 03 20:20:54.830543 2022] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND'
I read somewhere to curl the IP inside the container, but the responses from inside the container weren't also up to the mark. They were refusing the connection.
When I do my docker-compose up and the written port gets engaged I get this.
sudo netstat -pna | grep 8100
tcp 0 0 0.0.0.0:8100 0.0.0.0:* LISTEN 1123608/docker-prox
tcp6 0 0 :::8100 :::* LISTEN 1123617/docker-prox
otherwise I don't.
P.S: I tried reinstalling docker-compose, and Docker engine twice, rebuilding image, removing containers etc. but it didn't help me.