Docker Containers (MariaDb, AspNet) Can't Communicate on Compose Network

Question

I've setup a Docker-Compose file that creates a mariadb database and aspnet backend (both from docker files I've written). If I expose ports and run the containers outside of a compose (using localhost) or set network_mode: "host" in the docker-compose file then the app interacts as expected. However, using the default bridge network that the compose generates any command between containers seems to timeout.

I've attempted to run a networking container (nicolaka/netshoot) attached to the same network and ping the relevant containers via the DNS name. The name resolves to the IP address and then the ping hangs, I've also run and attached a mysql container and attempted connecting to the mariadb container which results in a timeout.

This all looks to be some networking issue in my setup. Config listed below, any help would be much appreciated!

MariaDb DockerFile

ARG VERSION=10.4
FROM mariadb/server:${VERSION}
ENV MYSQL_ROOT_PASSWORD ****
EXPOSE 3306

AspNet DockerFile

FROM mcr.microsoft.com/dotnet/aspnet:5.0
# Container SetUp
EXPOSE 80
# .NET specific
COPY ToDoListBackEnd.Api/bin/Release/net5.0/publish ToDoListBackEnd/
WORKDIR /ToDoListBackEnd
ENTRYPOINT ["dotnet", "ToDoListBackEnd.Api.dll"]

ComposeFile:

version: '3.3'
services:
  db: # Service Hosting MariaDb
    build: ./Database
    container_name: todolist-database
    ports:
      - "6001:3306"
    volumes:
      - todo-db:/var/lib/mysql
    restart: always 
    environment:
      MYSQL_ROOT_PASSWORD: ***
      MYSQL_DATABASE: ToDoList
      MYSQL_USER: root
      MYSQL_PASSWORD: ***
    
  backend: # Backend C# Service
    build: ./BackEnd
    container_name: todolist-backend
    ports:
      - "5002:80"
    restart: always
    depends_on: 
      - db
    links: 
      - db
volumes:
  todo-db:

Network Config

{
    "Name": "todolist_default",
    "Id": "6dd07863467b35ece5e00f400ca03c0c1b9950a5f8d5a6538b47889ac2dcae68",
    "Created": "2021-04-21T19:39:58.329215937+01:00",
    "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": {
        "01f10355356ea8d194b9de6c6e9ead0af5398ad8d10dc743a70927c88532f3ef": {
            "Name": "todolist-database",
            "EndpointID": "9b69958ff0a1c9ff7cf62f3478965fdef0622fd3fe98922bebee4ebe72aa9508",
            "MacAddress": "02:42:ac:17:00:03",
            "IPv4Address": "172.23.0.3/16",
            "IPv6Address": ""
        },
        "356092a918beb6a0a021d369fd5f76e556e54ebad3c1b8fa626ce33fd66af579": {
            "Name": "mysqlTest",
            "EndpointID": "3ae06081e831c8f94bc36c59cd085561b81685da164011c5e6438ffd0d1bb6c2",
            "MacAddress": "02:42:ac:17:00:02",
            "IPv4Address": "172.23.0.2/16",
            "IPv6Address": ""
        },
        "61bbc2047065f01732ddd0e7db492c0708144cb6ede7ee0b5466c708c36d9639": {
            "Name": "todolist-backend",
            "EndpointID": "06c46938e05ba48955c75a63a65268d4259c30ad9bb7a23f2d15c04299d644da",
            "MacAddress": "02:42:ac:17:00:05",
            "IPv4Address": "172.23.0.5/16",
            "IPv6Address": ""
        }
    },
    "Options": {},
    "Labels": {
        "com.docker.compose.network": "default",
        "com.docker.compose.project": "todolist",
        "com.docker.compose.version": "1.29.1"
    },
    "CreatedTime": 1619030398329
}

my.cnf from inside the mariadb container

# MariaDB database server configuration file.
#
# You can copy this file to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
# 
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
#user       = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc_messages_dir = /usr/share/mysql
lc_messages = en_US
#skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
#bind-address       = 127.0.0.1
#
# * Fine Tuning
#
max_connections     = 100
connect_timeout     = 5
wait_timeout        = 600
max_allowed_packet  = 16M
thread_cache_size       = 128
sort_buffer_size    = 4M
bulk_insert_buffer_size = 16M
tmp_table_size      = 32M
max_heap_table_size = 32M
#
# * MyISAM
#
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched. On error, make copy and try a repair.
myisam_recover_options = BACKUP
key_buffer_size     = 128M
#open-files-limit   = 2000
table_open_cache    = 400
myisam_sort_buffer_size = 512M
concurrent_insert   = 2
read_buffer_size    = 2M
read_rnd_buffer_size    = 1M
#
# * Query Cache Configuration
#
# Cache only tiny result sets, so we can fit more in the query cache.
query_cache_limit       = 128K
query_cache_size        = 64M
# for more write intensive setups, set to DEMAND or OFF
#query_cache_type       = DEMAND
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# we do want to know about network errors and such
#log_warnings       = 2
#
# Enable the slow query log to see queries with especially long duration
#slow_query_log[={0|1}]
slow_query_log_file = /var/log/mysql/mariadb-slow.log
long_query_time = 10
#log_slow_rate_limit    = 1000
#log_slow_verbosity = query_plan

#log-queries-not-using-indexes
#log_slow_admin_statements
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#report_host        = master1
#auto_increment_increment = 2
#auto_increment_offset  = 1
#log_bin            = /var/log/mysql/mariadb-bin
#log_bin_index      = /var/log/mysql/mariadb-bin.index
# not fab for performance, but safer
#sync_binlog        = 1
expire_logs_days    = 10
max_binlog_size         = 100M
# slaves
#relay_log      = /var/log/mysql/relay-bin
#relay_log_index    = /var/log/mysql/relay-bin.index
#relay_log_info_file    = /var/log/mysql/relay-bin.info
#log_slave_updates
#read_only
#
# If applications support it, this stricter sql_mode prevents some
# mistakes like inserting invalid dates etc.
#sql_mode       = NO_ENGINE_SUBSTITUTION,TRADITIONAL
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
default_storage_engine  = InnoDB
innodb_buffer_pool_size = 256M
innodb_log_buffer_size  = 8M
innodb_file_per_table   = 1
innodb_open_files   = 400
innodb_io_capacity  = 400
innodb_flush_method = O_DIRECT
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem

#
# * Galera-related settings
#
[galera]
# Mandatory settings
#wsrep_on=ON
#wsrep_provider=
#wsrep_cluster_address=
#binlog_format=row
#default_storage_engine=InnoDB
#innodb_autoinc_lock_mode=2
#
# Allow server to accept connections on all interfaces.
#
bind-address=0.0.0.0
#
# Optional setting
#wsrep_slave_threads=1
#innodb_flush_log_at_trx_commit=0

[mysqldump]
quick
quote-names
max_allowed_packet  = 16M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completion

[isamchk]
key_buffer      = 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!include /etc/mysql/mariadb.cnf
!includedir /etc/mysql/conf.d/

Thanks again for any help!

Answer 1

So I seem to have fixed the issue. Turns out to be an issue with the OS (Arch Linux) not docker, I found this out by running the same files on a Windows system.

For any arch users I've listed my steps out at https://bbs.archlinux.org/viewtopic.php?pid=1973008#p1973008