[CLI] init failed virtualenv for python should print errors in red or not print Welcome message

[rothgar]

The Question

If I run cdk init --language python and I don't have python3-venv installed the Welcome message output scrolls the error messages off of the screen and are not obvious.

Error in the code references this command

aws-cdk/packages/aws-cdk/lib/init.ts

Line 323 in 0e96415

print('Unable to create virtualenv automatically');

The output is very helpful but ultimately not noticeable because it scrolls by so fast and is immediately followed by # Welcome to your CDK Python project! which made me assume the command was successful or previous errors were not important.

Executing Creating virtualenv...                                                                                                                                                                                                                                        
The virtual environment was not created successfully because ensurepip is not                                                                                                                                                                                           
available.  On Debian/Ubuntu systems, you need to install the python3-venv                                                                                                                                                                                              
package using the following command.                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                        
    apt-get install python3-venv                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                                        
You may need to use sudo with that command.  After installing the python3-venv                                                                                                                                                                                          
package, recreate your virtual environment.                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                                        
Failing command: ['$PWD/cdk-test/.env/bin/python3', '-Im', 'ensurepip', '--upgrade', '--default-pip']                                                                                                                                       
                                                                                                                                                                                                                                                                        
Unable to create virtualenv automatically                                                                                                                                                                                                                               
Please run python3 -m venv .env!

Ideally (for me) if there was an error with the virtualenv the welcome message would not be printed so the last output would be the error and how to fix it.

Environment

• CDK CLI Version: 1.46.0 (build 63860b2)
• OS: Ubuntu 18.04.4
• Language (Version): Python

Other information

I first ran into the problem running through the workshop when I was told to activate the virtualenv. It may also be helpful to update the workshop to point out if the .env/bin/activate file doesn't exist then something may have gone wrong and a user should try to install python3-venv and re-init the repo.

[MrArnoldPalmer]

@shivlaks the error in the init template is definitely easily missed. Can we make the output red and move it down so its not gone when the command finishes?

[shivlaks]

@MrArnoldPalmer @rothgar I moved the post installation steps towards the end so they'll be the last things you see when you init a template. Modified the messages to be warnings rather than errors, which would show up as yellow.

I'm not strongly opinionated that it must be yellow, but it feels reasonable given there are steps to reconcile and the project was still initialized. thoughts? feel free to comment on #8723 directly

[MrArnoldPalmer]

Sounds good. Thanks!