EventHubs logs_build/host.json missing required "version" property for Azure Functions v4

[tanmoycloud]

Bug Report

Description

The EventHubs/target/logs_build/host.json file is missing the required "version": "2.0" property, which causes the Azure Functions v4 runtime to fail with:

Microsoft.Azure.WebJobs.Script: The host.json file is missing the required 'version' property.

Current logs_build/host.json

json { "eventHub": { "maxBatchSize": 400, "prefetchCount": 800, "batchCheckpointFrequency": 1 }, "functions": [ "EventHubs_Logs" ], "functionTimeout": "00:10:00" }

Issues

1. Missing "version": "2.0" — Required by Azure Functions v2+ runtime. Without it, the function app fails to start on ~4 (v4).
2. Uses deprecated eventHub key — Should be eventHubs (plural) for v2+ host.json schema. See Azure EventHub bindings configuration.
3. Missing extensionBundle — The v2+ runtime requires an extension bundle declaration for EventHub bindings.
4. Missing logging configuration — The metrics_build/host.json already has proper logging config, but logs_build does not.

Expected logs_build/host.json

json { "version": "2.0", "extensionBundle": { "id": "Microsoft.Azure.Functions.ExtensionBundle", "version": "[4.0.0, 5.0.0)" }, "eventHubs": { "maxEventBatchSize": 400, "maxWaitTime": "00:05:00", "batchCheckpointFrequency": 1, "prefetchCount": 800 }, "logging": { "applicationInsights": { "samplingSettings": { "isEnabled": false } }, "logLevel": { "default": "Warning", "Host.Aggregator": "Trace", "Host.Results": "Information", "Function": "Information" } }, "functions": [ "EventHubs_Logs" ], "functionTimeout": "00:10:00" }

This should match the structure already used in metrics_build/host.json (which is correct).

Environment

• Azure Functions runtime: ~4 (v4)
• Deployment method: az functionapp deployment source config (external git)
• host.json reference: https://learn.microsoft.com/en-us/azure/azure-functions/functions-host-json
• EventHub bindings v2+ config: https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-event-hubs#host-json

Note

The EventHubs log and metric integrations are marked as deprecated in the README. However, the logs_build/host.json should still be fixed for users currently running these functions, as it prevents the function app from starting entirely.

[tanmoycloud]

cc @sumoanema @himanshu219 — could you take a look? The logs_build/host.json is missing the required version property, breaking Azure Functions v4 deployments. The metrics_build/host.json is already correct.

[sumoanema]

hi @tanmoycloud - Thanks for your contribution. But the EventHub collection for collecting logs and metrics have has been deprecated as mentioned here and here . We are not maintaining it anymore. We will suggest to migrate to the new methods of collection as suggested in the above links for collecting azure logs and metrics.