Issue running on Mac with Brew

[andersgs]

On my Mac, python executable is the system python2. to get to python3 I use the exec python3 (installed via homebrew).

But, running:

anvil-app-server --app MyTodoList

Fails with the following issue:

[INFO  anvil.app-server.dispatch] Launching built-in downlink...
/System/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python: No module named anvil_downlink_host

Which suggests the runtime is looking for anvil_downlink_host in the wrong location, as I installed anvil-runtime-server in my homebrew installation.

So, I ran brew info python3 and picked up the bin folder that has python linked to my brew installation and then ran:

PATH=/usr/local/opt/python/libexec/bin:$PATH anvil-app-server --app MyTodoList

I was then able to get things to work.

This is a perennial issue with Python never enforcing python3 as the proper executable name.

Thought others might find this helpful.

Thank you for releasing Anvil as open-source! Very excited to give it a go.

PS. System info:

• MacOSX 10.15.4
• Homebrew 2.2.15
• Homebrew/homebrew-core (git revision cb163; last commit 2020-05-06)
• Homebrew/homebrew-cask (git revision 2748d; last commit 2020-05-06)
• PATH: usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/TeX/texbin:/opt/X11/bin:/Library/Apple/usr/bin

[daviesian]

Thanks for the detailed report, and the workaround for others. We would always recommend installing anvil-app-server in a virtualenv - does that also solve the problem for you?

[meredydd]

It looks like this was the issue!

(We were launching the subprocess with the system default python interpreter, rather than your chosen interpreter. This will be fixed in the next release of the App Server. In the meantime, running the App Server in a virtualenv will solve the problem!)

[andersgs]

@daviesian just to confirm that it works in a virtualenv. Cheers. :)