How do I set up SSH tunnel from inside docker image droplet to access another droplet's MySQL Database?

I have a droplet with a docker image hosting Appsmith - a low-code development platform. I want to set up an Appsmith datasource to a MySQL instance on another droplet that is not in the client droplet’s network. I’m not real good at Linux so I definitely need some guidance. I can connect to the server via SSH tunnel from my laptop.

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March 27, 2024


You should be able to do that using a similar approach as to how you would go about when trying to configure access to another MySQL Droplet even when it’s not being inside a docker container.

By default, MySQL is configured to listen for connections only from the local machine. You need to change this so that it can accept connections from your Appsmith droplet.

Also if you do not have a user, create one. Create a user (or use an existing one) and grant privileges. Replace appsmith_user, password, and appsmith_droplet_ip with appropriate values:

CREATE USER 'appsmith_user'@'appsmith_droplet_ip' IDENTIFIED BY 'password'; GRANT ALL PRIVILEGES ON *.* TO 'appsmith_user'@'appsmith_droplet_ip'; FLUSH PRIVILEGES;

If either of your droplets has a firewall enabled, you’ll need to configure it to allow the necessary traffic:

  1. MySQL Server Droplet:

    • Allow incoming connections on port 3306 (MySQL’s default port) from the Appsmith droplet’s IP address.

    • Using ufw (Uncomplicated Firewall) as an example:

      bashCopy code sudo ufw allow from appsmith_droplet_ip to any port 3306

  2. Appsmith Droplet:

    • Usually, outgoing connections are allowed, but if you have set up strict outbound rules, ensure that the droplet can make outbound requests to the MySQL server droplet on port 3306.

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