Configuring logging for Azure Functions created with PowerShell involves setting up the logging levels and using appropriate cmdlets to write logs. Here's how you can do it:
1. Setting Log Levels in `host.json`**
To control the logging level for your Azure Functions, you need to modify the `host.json` file. This file allows you to set the threshold for logs written to the console. You can specify a default log level for all functions or override it for specific functions.
For example, to enable verbose logging for all functions and debug logging for a specific function named `MyFunction`, you would use the following configuration:
json
"logging": {
"logLevel": {
"Function.MyFunction": "Debug",
"default": "Trace"
}
}
2. Using PowerShell Logging Cmdlets**
PowerShell provides several cmdlets that map to different log levels in Azure Functions:
- Error: Use `Write-Error`.
- Warning: Use `Write-Warning`.
- Information: Use `Write-Information`, `Write-Host`, or `Write-Output`.
- Debug: Use `Write-Debug`.
- Trace: Use `Write-Progress` or `Write-Verbose`.
However, to see verbose and debug level logs, you must also configure the log level threshold in `host.json` as mentioned above.
3. Configuring Debug and Verbose Preferences**
To ensure that debug and verbose messages are properly logged, you can set the `$DebugPreference`, `$VerbosePreference`, and `$ErrorPreference` variables to `'Continue'` in your PowerShell profile or at the beginning of your script. This will allow all debug and verbose messages to be logged without needing to specify switches like `-Verbose` or `-Debug` with each cmdlet.
4. Monitoring Logs**
For Azure Functions running in Azure, you can use Application Insights to monitor and query function logs. For local development, logs are written to the file system by default, but you can view them in the console by setting the `AZURE_FUNCTIONS_ENVIRONMENT` environment variable to `Development` before starting the Function App[1][6].
Example of Logging in a PowerShell Azure Function
Here's a simple example of how you might log information in a PowerShell Azure Function:
powershell
# Example logging in a PowerShell Azure Function
Write-Host "This is an Information level log."
Write-Information "This is also an Information level log."
Write-Warning "This is a Warning level log."
Write-Error "This is an Error level log."
# To see verbose or debug logs, ensure the log level is set appropriately in host.json
Write-Verbose "This is a Verbose level log." -Verbose
Write-Debug "This is a Debug level log."
Remember, to see verbose and debug logs, you must configure the log level threshold in `host.json` and possibly adjust the preferences as described above.
Citations:
[1] https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-powershell
[2] https://dev.to/cloudskills/azure-functions-creating-a-powershell-event-based-function-1aah
[3] https://stefanstranger.github.io/2019/05/17/AzureFunctionsPowerShellLogging/
[4] https://stackoverflow.com/questions/75194965/azure-functions-powershell-how-to-use-table-input-binding/75284835
[5] https://blog.simonw.se/designing-azure-functions-for-powershell/
[6] https://docs.azure.cn/en-us/azure-functions/functions-monitoring
[7] https://markscholman.com/2019/07/azure-functions-logging-in-powershell/
[8] https://docs.azure.cn/en-us/azure-functions/functions-app-settings
[9] https://stackoverflow.com/questions/68556800/logging-in-appinsights-using-powershell-in-azure-functions
[10] https://learn.microsoft.com/en-us/azure/azure-functions/configure-monitoring