Connect to AWS RDS from your local PC Docker environment

Overview

--Note on how to connect to RDS from the Docker environment on your local PC --In Docker development, it seems that you often create a container image of DB, but for some reason you want to use AWS RDS directly.

Premise

--Build a VPC environment and create an EC2 instance and RDS for connecting Rails applications to the Private subnet. --Service by Nat gateway or Endpoint "com.amazonaws.us-east-1.ssm Can be connected to --Ssm-agent is installed on your EC2 instance --Connect to EC2 instance with SSM without using a bastion server etc.

Local PC environment

Docker for mac

reference

https://dev.classmethod.jp/articles/session-manager-launches-tunneling-support-for-ssh-and-scp/#toc-10
https://blog.serverworks.co.jp/tech/2019/09/11/ssm-portfowarding/
https://qiita.com/lighttiger2505/items/ea33291639a8656d50b4
https://dev.classmethod.jp/articles/ssm-session-manager-private/

SSM settings

--Add the settings for SSM connection to the ssh config file

`config`


Host EC2 server instance ID]
    User [EC instance connection user]
    Port 22
    ServerAliveInterval 300
    IdentityFile ~/.ssh/id_rsa
    ProxyCommand sh -c "aws ssm start-session --target %h --document-name AWS-StartSSHSession --parameters 'portNumber=%p'"

--ssm Check ssh connection with ssm

$ ssh [EC2 server instance ID]

Connecting to RDS by port forwarding

--aws profile settings --Required when creating a tunnel by port forwarding

$ aws configure --profile=ssm-test

--Set the following in ssh-config

# SSH over Session Manager
host i-* mi-*
   ProxyCommand sh -c "aws ssm start-session --target %h --document-name AWS-StartSSHSession --parameters 'portNumber=%p' --profile=ssm-test"

--Creating a tunnel

ssh -i ~/.ssh/id_rsa [EC instance connection user]@[EC2 server instance ID] -L 13306:[RDS endpoint]:3306

--Perform connection check to rds

mysql -u [DB connection user] -h 127.0.0.1 -P 13306 -p

Rails settings

database.yml settings

--Specify the port number (13306) when port forwarding to RDS. --Specify "docker.for.mac.localhost" for host

default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: [RDS connection user]
  password: [RDS connection password]
  host: docker.for.mac.localhost
  port: 13306

With the above settings, you can connect to RDS from a Rails application started in a Docker container. When using for SSM connection and port forwarding, it is not necessary to release SG and NACL port numbers (22, 13306).