Add remote debugging support for Node.js on Linux App Service plans

[mrcrane]

This will address #1344 and it is the culmination of the refactoring work already done in microsoft/vscode-azuretools#522 and microsoft/vscode-azureappservice#1045

Given that the refactoring has already been done, this code is fairly straightforward. The main concern is around the fact that there is already a feature in place that supports Java remote debugging on Windows.

A few months ago (sorry for the delay) @fiveisprime @nturinski and I discussed this issue and we decided to go with 2 different remote debugging feature flags so that we can maintain both experiences for the time being. Since we expect this Node.js experience to be the main experience moving forward, I have reappropriated the enableRemoteDebugging flag (Python support is coming soon). Java debugging support will now be enabled using enableJavaRemoteDebugging. The settings page will now look like:

I'm happy to hear any feedback on how to make that experience less confusing.

More notes:

• Kudu is not available on Linux consumption, so we are still working with the Functions team to understand how this will work for that use case. Without Kudu we will likely need a new solution alongside this one.
• I have tested the Java remote debugging experience with this new code and it is still working
• Other than changing the feature flag, I have left the Java debugging experience untouched. It still uses the "Attach Debugger" wording unlike the "Start Remote Debugging" that we use for the App Service experience.
• In order to get Java debugging working with the new remote debugging code we would need the new tunneling API to be ported to Windows (it is currently Linux-only) and the Java runtime to respect the remoteDebuggingEnabled setting. This is feasible but probably low priority.

[ejizba]

Based on the PR description - this only works on dedicated plans? I feel like that should be highlighted in the messaging since consumption is so much more popular

[mrcrane]

Yes this only works on dedicated plans so far. I have tried to highlight that in all of the messaging, including this error message:

Azure Remote Debugging is currently only supported for Node.js Function Apps running on Linux App Service plans.

All of the Azure Portal UI I have seen refers to dedicated plans as App Service plans, so I am trying to use that same terminology. For example, in the UI to create a Function App:

I'm happy to update the messaging if you have a suggestion about how to improve it. @fiveisprime Any thoughts?

[ejizba]

Ah didn't realize you were using "App Service Plan" to differentiate. I see what you mean about the dropdown, but even the portal is inconsistent. It lists consumption plans as app service plans (after creating):

What about something like this:

Azure Remote Debugging is currently only supported for Node.js Function Apps running on Linux App Service plans (excluding consumption plans).

I know it's kinda ugly, but again it seems like a super important distinction since the majority of plans will be consumption.

We could also consider splitting the message out into separate cases:

• Remote Debugging is currently only supported for Linux Function Apps.
• Remote Debugging is currently only supported for Node.js Function Apps.
• Remote Debugging is currently not supported for Function Apps running on consumption plans.

[mrcrane]

I looked into the conditional messaging approach but I wasn't able to find a good solution.

I went ahead and changed the messaging to be very clear, for this message and also for the description of the feature flag. Let me know what you think.

[mrcrane]

I rebased on master and force-pushed to resolve merge conflicts.

[ejizba]

Thanks!