Hello.
I’ve deployed my docker app (built in Ktor) via fly.io in ktor app.
Then I’ve done everything specified here → Use a MySQL Database · Fly Docs I’ve named it db app.
For anyone with the same issue, MYSQL_DATABASE secret on my ktor app should be set to:
jdbc:mysql://{your app name}.internal/{your db name}
{your app name} is name of the application when you did “fly launch” process. {your db name} is the name you specified in fly.toml under MYSQL_DATABASE key.