I found some info about installation flow here.
App installation involves an OAuth process that allows a user to accept any requested permissions. After authorization, an Installed App is created.
So I tried to follow this instruction. I managed to register an Automation App and see it under the ‘/apps’ endpoint.
The CLIENT_ID and CLIENT_SECRET were created successfully. When I go to the ‘Website URL’ from the server log, I’m able to log in with my SmartThings account credentials.
On this step the URL in my web browser looks like this:
https://api.smartthings.com/oauth/authorize?client_id=my_client_id&response_type=code&redirect_uri=https%3A%2F%2Fmy_app.eu.ngrok.io%2Foauth%2Fcallback&code_challenge_method=S256
BUT!!! When I click the ‘Authorize’ button I get a 500 error from SmartThings.
Error:
GET /oauth/callback?error=invalid_request&error_description=The+request+is+malformed. 500
What should I get according to docs:
https://my_app.eu.ngrok.io/oauth/callback?code=blablabla&state=blablabla
In conclusion, I cannot install my app, because I cannot authorize it. The authorization code cannot be generated through endpoint https://api.smartthings.com/v1/oauth/authorize.