Tridion.ContentManager.Config contains this information.
The database info is encrypted, follow the steps outlined here to read it.
From the linked article:
To decrypt the configuration file, start with making a temporary directory somewhere to put the Tridion.ContentManager.config file. For this example we'll use
c:\temp. From a new command prompt:
Copy the Tridion.ContentManager.config file to this directory and rename this file to web.config. Remember that the tool (aspnet_regiis.exe) was designed for web applications, so this is the reason why this step is necessary.
copy c:\tridion_install_dir\config\Tridion.ContentManager.config c:\temp\web.config
Now it's time to decrypt the parts that are encrypted in this config file.
c:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -pdf "database" c:\temp