How to setup connection to mysql docker container?

Question

MySQL

Good afternoon, I'm trying to deal with docker, set up compose, everything works with one exception, when I try to connect to mysql I get an error: "SQLSTATE[HY000] [2002] Connection refused".
docker-compose.yml:

version: "3.1"
services:

    memcached:
      image: memcached:alpine
      container_name: tkdruzhba-memcached

    redis:
      image: redis:alpine
      container_name: tkdruzhba-redis

    mysql:
      image: mysql:8.0
      container_name: tkdruzhba-mysql
      working_dir: /application
      volumes:
        - .:/application
      environment:
        - MYSQL_DATABASE=dev
        - MYSQL_USER=dev
        - MYSQL_PASSWORD=devpass
        - MYSQL_ROOT_PASSWORD=root
      ports:
        - "3306:3306"

    phpmyadmin:
      image: phpmyadmin/phpmyadmin
      container_name: phpmyadmin
      environment:
       - PMA_ARBITRARY=1
       - PMA_HOST=mysql
      restart: always
      ports:
       - 8083:80
      volumes:
       - /sessions

    webserver:
      image: nginx:alpine
      container_name: tkdruzhba-webserver
      working_dir: /application
      volumes:
          - .:/application
          - ./phpdocker/nginx/nginx.conf:/etc/nginx/conf.d/default.conf
      ports:
       - "8080:80"

    php-fpm:
      build: phpdocker/php-fpm
      container_name: tkdruzhba-php-fpm
      working_dir: /application
      volumes:
        - .:/application
        - ./phpdocker/php-fpm/php-ini-overrides.ini:/etc/php/7.1/fpm/conf.d/99-overrides.ini

php-fpm/dockerfile:

FROM phpdockerio/php71-fpm:latest
WORKDIR "/application"

# Fix debconf warnings upon build
ARG DEBIAN_FRONTEND=noninteractive

# Install selected extensions and other stuff
RUN apt-get update \
    && apt-get -y --no-install-recommends install  php-memcached php7.1-mysql php-redis php7.1-ldap \
    && apt-get clean; rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /usr/share/doc/*

# Install git
RUN apt-get update \
    && apt-get -y install git \
    && apt-get clean; rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /usr/share/doc/*

Answer 1

in containers that need access to mysql:

depends_on:
    - mysql

are only needed for outside access, remove them from the mysql container
if you need mysql shell, then run this command:
example from postgres

docker exec -it название_запущенного_контейнера bash -c 'PGPASSWORD="$POSTGRES_PASSWORD" psql -U "$POSTGRES_USER" -d "$POSTGRES_DB"'