I've played with Microsoft Bot Composer and have checked the extensibility points but it looks like it is not possible to deploy the bot to other clouds.
Please confirm my assumption.
My goal is to achieve deploying without additional development if possible.
Deploying a Composer bot is somewhat more complicated than deploying an ordinary Bot Framework bot because the Composer bot is not stored anywhere in a deployable state. Composer must bundle your specific Composer project files together with the centralized Composer runtime in order to create a deployable package.
However, Composer does come with a way to convert your Composer project into an ordinary bot project that can be deployed just like any web app. This is called exporting (or ejecting) the runtime. You can find out how to do that here.
To export your bot runtime:
Navigate to the Project Settings page of your Composer and find the Custom runtime section.
From the Custom runtime section, toggle Use custom runtime then select Get a new copy of the runtime code.
In the pop-up window select C# and select Okay. A copy of your bot's runtime will be added to the bot's project folder and can be accessed in the following directory:
C:\Users\UserName\Documents\Composer\bot\runtime.
