500 Sever error

[magicman32]

when I run docker compose up -d
it fires up
I goto ip address and error page appears
but when I check .env file the app key is not being generated which Im guessing could be the problem
so on reddit I found the command
docker exec -it linkace_app_1 php artisan key:generate
I execute and tell it yes to proceed, its says it generated an app key
but when I check the .env file its not been written to file

Please advice
can I generate key to be shown and then cut and paste in .env file?