How to set docker environment variables to my config.toml file

Question

In my project I have stored all the configuration values in config.toml file. now I want to change these variables using docker environment variables. Is this something possible ?..... The project is in go lang(not sure if this info is required)

The content of the config.toml file is as follows->

[mqtt]
    Hostname = "localhost"
    Port = 9096
    ClientID = "mailer_ms"
    Qos = 1

    [database]
        Hostname = "localhost"
        Port = 5984
        Username = "root"
        Password = "root"

Expected Output-> the value of username, port and password gets changed based on docker environment variables.

Please help me :)