[Placeholder]Node.js Placeholders

[mhoeger]

We need to move the scope of the node.js worker's startup so that it can run in placeholder mode.

And this special casing must be done for Node.js placeholders to not have a bug: #4488

1. Whitelist node (Windows and Linux)

   azure-functions-host/src/WebJobs.Script/Rpc/RpcInitializationService.cs

   Line 30 in f1d0536

   new List<string>() { LanguageWorkerConstants.JavaLanguageWorkerName }

   azure-functions-host/src/WebJobs.Script/Rpc/RpcInitializationService.cs

   Line 34 in f1d0536

   new List<string>() { LanguageWorkerConstants.PythonLanguageWorkerName }

2. Cache node version (WEBSITE_DEFAULT_NODE_VERSION from App Settings) in Placeholder mode to be accessed later. Probably best here: https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script/Rpc/WebHostLanguageWorkerChannelManager.cs (backup: check with Brett if this is ok) https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script.WebHost/Standby/StandbyOptions.cs https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script.WebHost/Standby/StandbyOptionsSetup.cs
3. Update logic for IsSupportedRuntime to figure out if we should kill placeholder node.exe

   azure-functions-host/src/WebJobs.Script/Rpc/FunctionRegistration/FunctionDispatcher.cs

   Line 176 in f1d0536

   if (Utility.IsSupportedRuntime(_workerRuntime, _workerConfigs))

4. Run from zip only? (Verify if Portal editing will work.)

Test:

• Going through Placeholders
• Not going through Placeholders
• x64 and x86 tests (Placeholders only apply for x86)
• Node 8 vs 10
  • Node 10.0.0 (not latest) - no placeholders
  • Node ~10 (placeholder) and ~8 (no placeholder)
  • Node exact match for latest (10.15.2, placeholder)
• With / without RUN_FROM_PACKAGE

---

Breakdown of issues:

• Empty value environment variables - "map" types to not contain empty values for node #4488
• Implement node message types - Implement all the message types in StreamingMessage azure-functions-nodejs-worker#184
• Whitelist node placeholders - Whitelist Node.js for placeholders #4713
• Placeholders without Run From Zip - [Placeholder]Placeholders with out Run From Zip #4534
• Clean up usage of IsPlaceholderModeEnabled and InStandbyMode - Clean up usage of IsPlaceholderModeEnabled and InStandbyMode #4368
• Test - Test Node.js with placeholders #4712

[pragnagopa]

Changes needed:

• White list nodejs here: https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script/Rpc/RpcInitializationService.cs
• During specialization, update FunctionDispatcher to check for RunFromZip and verify WEBSITE_NODE_DEFAULT_VERSION is same as the placeholder version
  • If both conditions satisfy, use the placeholder process
  • If not, kill placeholder channels and continue with setting up the process within the JobHost.

[pragnagopa]

Adding more details on the picking node version

• Host needs to know what is the latest node 10 version on
  • Antares for windows apps
  • Linux for linux consumption apps
• Placeholder node.exe will be used only if WEBSITE_NODE_DEFAULT_VERSION is an exact match with the current node 10 latest version .

@mhoeger - Let me know if you have any further questions.

[pragnagopa]

cc @fabiocav
Adding more details on how to get the latest version of node

• Placeholder template site has, WEBSITE_NODE_DEFAULT_VERSION is set to ~10
• Cache value of WEBSITE_NODE_DEFAULT_VERSION during placeholder mode
• During specialization look for exact match,

[mhoeger]

azure-functions-host/src/WebJobs.Script/Rpc/FunctionRegistration/FunctionDispatcher.cs

Line 176 in f1d0536

if (Utility.IsSupportedRuntime(_workerRuntime, _workerConfigs))

[fabiocav]

@mhoeger moving this to Epics, can you please break this up and create the tasks we need to track?

[fabiocav]

Blocked on ANT83

[fabiocav]

Closing stale issue.