Yes, it is possible to test changes to the `host.json` file without redeploying the entire app, especially in Azure Functions. You can override specific `host.json` settings using application settings. This allows you to modify or configure settings for a specific environment without changing the `host.json` file itself.
For example, if you want to disable Application Insights sampling locally, you can add an application setting like `"AzureFunctionsJobHost__logging__applicationInsights__samplingSettings__isEnabled":"false"` in your `local.settings.json` file. This way, you can test the changes locally without affecting the production environment or redeploying the app[1][2][5].
However, if you need to test changes directly in the `host.json` file, you would typically need to redeploy the app to see those changes take effect in a production environment. But using application settings provides a flexible way to test different configurations without redeployment.
Citations:
[1] https://learn.microsoft.com/en-us/azure/azure-functions/functions-host-json
[2] https://docs.azure.cn/en-us/azure-functions/functions-app-settings
[3] https://stackoverflow.com/questions/66936480/what-should-i-use-to-host-a-public-json-file-that-rarely-changes-without-redeplo
[4] https://answers.netlify.com/t/any-way-to-update-a-json-file-on-your-site-without-having-to-redeploy-the-entire-site/44950
[5] https://dev.to/massimobonanni/azure-functions-tips-override-the-hostjson-settings-21mi
[6] https://learn.microsoft.com/en-us/azure/logic-apps/edit-app-settings-host-settings
[7] https://github.com/Azure/azure-functions-host/issues/3718
[8] https://learn.microsoft.com/en-us/azure/azure-functions/configure-monitoring
[9] https://firebase.google.com/docs/hosting/test-preview-deploy
[10] https://github.com/Azure/Azure-Functions/issues/383