funcy-containers
Develop Azure Python functions using several workflows:
| Workflow | Python is Installed | Function is Executed | F5/Debug Experience Supported |
|---|---|---|---|
| VsCode Remote-Containers | Container | Container | Yes |
| Local development (host) - for reference | Host | Host | Yes |
NOTE: The hot-reload workflow was removed but incorporated into the VsCode Remote-Containers workflow.
Workflow: VsCode Remote-Containers
The assumption for this workflow is:
- VsCode runs on the Windows host
- Docker for Desktop is running on WSL2
The following Visual Studio extensions must be installed first:
- ms-vscode-remote.remote-containers
To start working in the container, from VsCode:
- Press Ctrl+Shift+P to bring up the palette
- Select Dev Containers: Open Folder In Container...
- Select the root of this repository.
You are now developing 'in' the container.
Check that VsCode recognised the Tasks
If you see this error when you try to F5/Debug:
...or you see this error in the Output tab:
...you will need to Close the Remote Connection (Ctrl+Shift+P; Remote: Close Remote Connection) and then re-open the folder (Ctrl+Shift+P; Dev Containers: Reopen in Container).
There appears to be a known bug whereby tasks.json is parsed by VsCode but before extensions are installed; to prevent that issue occurring, settings.json has been augmented with this setting:
"task.allowAutomaticTasks": "off"
Debugging (F5 experience)
To launch the Azure Function under the Debugger, just press F5.
Set a breakpoint in init.py and then invoke the function:
curl http://localhost:7071/api/funcy-python
Hot reload
When source code changes, we want to automatically restart the function. There are complications to doing this when we mount Windows Filesystem into WSL2 (see references below); as a workaround we can use nodemon to 'poll' the file system (--legacy-watch) and restart the function if the source code changes.
To install nodemon as its dependencies:
apt-get update
apt-get install -y npm
npm install -g nodemon
To use the hot reload workflow within the container:
nodemon -w funcy-python/*py -w funcy-python/function.json --legacy-watch --exec "func host start --verbose"
Python Virtual Environments
Python Virtual Environments are not required for this use case.
Workflow: Local development (host)
Tasks have been configured to support interactive debugging on the host.
Launching the function
To launch the function manually:
func host start --verbose
The function is "hot reload" by default on the host: it will automatically reload after changes to the function are saved.
Debugging (F5 experience)
To launch the Azure Function under the Debugger, just press F5.
Set a breakpoint in init.py and then invoke the function:
curl http://localhost:7071/api/funcy-python
Python Virtual Environments
Python Virtual Environments have been disabled for this project on the host.
To enable it, in settings.json, add the following line:
"azureFunctions.pythonVenv": ".venv"
Then execute this command:
python -m venv .venv
References
| Reference | Link |
|---|---|
| Add --watch support to func start | Azure/azure-functions-core-tools#1239 (comment) |
| File changes on Windows doe not trigger notifications in Linux apps | microsoft/WSL#4739 |
| Develop 'in' WSL2 - all code is in the WSL2 instance so notifications work | https://code.visualstudio.com/blogs/2019/09/03/wsl2 |