Docker rails can't connect mysql - mysql

Question

I am trying to connect mysql database. Here I am using two docker container one for mysql and one for rails. I am using this docker compose file:
version: '3'
services:
db:
image: mysql:5.7
restart: always
environment:
MYSQL_ROOT_PASSWORD: password
volumes:
- ./mydata:/var/lib/mysql
ports:
- "3307:3306"
web:
build: .
command: bundle exec rails s -p 3000 -b '0.0.0.0'
volumes:
- .:/myapp
ports:
- "3000:3000"
When I am running docker compose up and I can see my containers are running my docker ps command show me:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d1bc75bbb4f7 mysql "docker-entrypoint.s…" 22 seconds ago Up 19 seconds 0.0.0.0:3307->3306/tcp aaupf_db_1
2ccb0882c390 aaupf_web "bundle exec rails s…" 12 minutes ago Up 9 minutes 0.0.0.0:3000->3000/tcp aaupf_web_1
I am using this code in my database.yml:
development:
adapter: mysql2
encoding: utf8
reconnect: false
database: sample_sqlite3_development
pool: 5
username: root
password: password
host: 127.0.0.1
port: 3307
But I am getting this error in rails:
Can't connect to MySQL server on '127.0.0.1' (111 "Connection refused")
I can connect mysql using mysql workbench I don't know what do I need to do in order to connect my rails app to mysql.

Answer 1

Try using host: db in your database.yml. This should link your web and mysql container.
https://docs.docker.com/v17.09/compose/rails/#connect-the-database
default: &default
adapter: postgresql
encoding: unicode
host: db
username: postgres
password:
pool: 5
development:
<<: *default
database: myapp_development
test:
<<: *default
database: myapp_test

Answer 2

Firstly, you should check if you are able to login into mysql from console using command
mysql -u root -p
You don't need mysql workbench to connect your docker rails to local database.
For connecting to local db:
docker-compose.yml
version: '3'
services:
db:
image: mysql:5.7
restart: always
environment:
MYSQL_ROOT_PASSWORD: password
MYSQL_USER: root
MYSQL_PASSWORD: password
web:
build: .
command: bundle exec rails s -p 3000 -b '0.0.0.0'
volumes:
- .:/myapp
depends_on:
- db
network_mode: "host"
environment:
DB_USER: root
DB_PASSWORD: password
DB_HOST: 127.0.0.1
The option network_mode: "host" enables connection to local db.
config/database.yml:
default: &default
adapter: mysql2
encoding: utf8mb4
pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
username: <%= ENV['DB_USER'] %>
password: <%= ENV['DB_PASSWORD'] %>
host: <%= ENV['DB_HOST'] %>
development:
<<: *default

Answer 3

Try below one:
version: '3'
services:
db:
image: mariadb
environment:
MYSQL_ROOT_PASSWORD: root
MYSQL_USERNAME: root
MYSQL_PASSWORD: root
ports:
- "3306:3306"
volumes:
- ./tmp/db_data:/var/lib/mysql/data
web:
build: .
command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
volumes:
- .:/myapp
ports:
- "3000:3000"
depends_on:
- db