How to run two or more apps in localhost - docker

Question

I am getting started with docker and docker-compose. I have the tutorials and I use docker-compose.yml file to run one of my sites in my local machine.
I can see my site running by going to http://localhost
My problem now is trying to run more than one site. If one of my sites is running and I try to run another site using docker-compose up -d I get the following error.
$ docker-compose up -d
Creating network "exampleCOM_default" with driver "bridge"
Creating exampleCOMphp-fpm ...
Creating exampleCOMmariadb ... error
ERROR: for exampleCOMmariadb Cannot start service db: driver failed programming external connectivity on endpoint exampleCOMmariadb (999572f33113c9fce034b4ed72aaCreating exampleCOMphp-fpm ... done
eady allocated
Creating exampleCOMnginx ... error
ERROR: for exampleCOMnginx Cannot start service nginx: driver failed programming external connectivity on endpoint exampleCOMnginx (9dc04f8b06825d7ff535afb1101933be7435c68f4350f845c756fc93e1a0322c): Bind for 0.0.0.0:443 failed: port is already allocated
ERROR: for db Cannot start service db: driver failed programming external connectivity on endpoint exampleCOMmariadb (999572f33113c9fce034b4ed72aa072708f6f477eb2af8ad614c0126ca457b64): Bind for 0.0.0.0:3306 failed: port is already allocated
ERROR: for nginx Cannot start service nginx: driver failed programming external connectivity on endpoint exampleCOMnginx (9dc04f8b06825d7ff535afb1101933be7435c68f4350f845c756fc93e1a0322c): Bind for 0.0.0.0:443 failed: port is already allocated
Encountered errors while bringing up the project.
This is my docker-compose file. I am using LEMP stack (PHP, NGINX, MARIADB)
version: '3'
services:
db:
container_name: ${SITE_NAME}_mariadb
build:
context: ./mariadb
volumes:
- ./mariadb/scripts:/docker-entrypoint-initdb.d
- ./.data/db:/var/lib/mysql
- ./logs/mariadb:/var/log/mysql
environment:
MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
MYSQL_DATABASE: ${MYSQL_DATABASE}
MYSQL_USER: ${MYSQL_USER}
MYSQL_PASSWORD: ${MYSQL_PASSWORD}
ports:
- '${MYSQL_PORT:-3306}:3306'
command:
'mysqld --innodb-flush-method=fsync'
networks:
- default
restart: always
nginx:
container_name: ${SITE_NAME}_nginx
build:
context: ./nginx
args:
- 'php-fpm'
- '9000'
volumes:
- ${APP_PATH}:/var/www/app
- ./logs/nginx/:/var/log/nginx
ports:
- "80:80"
- "443:443"
depends_on:
- php-fpm
networks:
- default
restart: always
php-fpm:
container_name: ${SITE_NAME}_php-fpm
build:
context: ./php7-fpm
args:
TIMEZONE: ${TIMEZONE}
volumes:
- ${APP_PATH}:/var/www/app
- ./php7-fpm/config/php.ini:/usr/local/etc/php/php.ini
environment:
DB_HOST: db
DB_PORT: 3306
DB_DATABASE: ${MYSQL_DATABASE}
DB_USERNAME: ${MYSQL_USER}
DB_PASSWORD: ${MYSQL_PASSWORD}
networks:
- default
restart: always
networks:
default:
driver: bridge

Answer 1

The host port you have mapped to is preventing you from starting another instance of the service even though the docker-compose creates a private network.
You can solve this problem by using random host ports assigned by docker-compose.
The ports entry in docker-compose is
ports
host_port:container_port
If you specify only the container port host port is randomly assigned. See here

Answer 2

You can provide the host_port values in ranges.
In below example, i've run the nginx containers and started multiple nginx containers that are automatically exposed to host ports based on the range values [30000-30005].
Command:
docker run -p 30000-30005:80 --name nginx1 -d nginx
Output:
9083d5fc97e0 nginx ... Up 2 seconds 0.0.0.0:30001->80/tcp nginx1
f2f9de1efd8c nginx ... Up 24 seconds 0.0.0.0:30000->80/tcp nginx