Azure – Print function not working without flush=True when used with the While loop

As mentioned, Azure Runbooks have output buffering, and this can sometimes prevent the immediate display of print statements within loops.

• Even though you added flush=True to print, the loop might be running so continuously that the output buffering is not flushed in time. Try adding additional flush calls, or consider logging instead of using print.

• Remove the while True loop and test with a finite loop or a time-limited loop to see if you can isolate the issue.

Neither is printing. Code updated to your suggestion so you can see where I have placed the additional print statements.

The script may be blocking before reaching the get_vm_status function or while executing the function itself.

Start by adding a print statement right before calling get_vm_status to check if it’s being called at all. Then, in the get_vm_status function, place prints just before each major operation to track its execution.

Updated code:

import time
import random
import smtplib
import inspect
import string
from datetime import datetime
from email.mime.text import MIMEText
from azure.common.credentials import ServicePrincipalCredentials
from azure.mgmt.compute import ComputeManagementClient
from azure.core.exceptions import ClientAuthenticationError

# Azure setup
subscription_id = 'xxx'  
resource_group_name = 'xxx'  
vm_name = 'xxx'  

# Authentication of Azure's Service Principal
def service_principal_authentication():
    """Checks the Authentication of Azure's Service Principal """
    print("Authenticating Service Principal....")
    try:
        credentials = ServicePrincipalCredentials(
            client_id='xxx',
            secret='xxx',
            tenant='xxx'
        )
        print("Service Principal Authenticity Verified")
        return ComputeManagementClient(credentials, subscription_id)
    except Exception as e:
        print(f"There was an error with the authenticating the Service Principal: {e}")
    except ClientAuthenticationError as e:
        print(f"Client Authentication Error {e}")

# Email setup
sender_email = 'xxx'  
receiver_email = 'xxxx' 
smtp_server = 'xxx'   
smtp_port = 587
smtp_password = 'xxx'  

def send_notification(subject, body):
    """Send an email notification."""
    msg = MIMEText(body)
    msg['Subject'] = subject
    msg['From'] = sender_email
    msg['To'] = receiver_email

    try:
        with smtplib.SMTP(smtp_server, smtp_port) as server:
            server.starttls()
            server.login(sender_email, smtp_password)
            server.sendmail(sender_email, receiver_email, msg.as_string())
            print("Email sent successfully!")
    except Exception as e:
        print(f"{e} in ", inspect.stack()[0].function)

def get_vm_status(compute_client):
    """Retrieve the current status of the VM."""
    print("Entering get_vm_status function.....", flush=True)
    try:
        print("Retrieving VM status......", flush=True)
        # Explicitly request the instance view
        vm = compute_client.virtual_machines.get(resource_group_name, vm_name, expand='instanceView')
        
        # Check if instance view is available
        if vm.instance_view:
            print(f"Can you see this message? {inspect.stack()[0].function}", flush=True)
            return vm.instance_view.statuses[1].code  # Assuming the status is at index 1
        else:
            print("Instance view is not available.", flush=True)
            return None
        
    except ClientAuthenticationError as e:
        print(f"There was a client authentication error {e}", flush=True)
    except Exception as e:
        print(f"Error retrieving VM status: {e}, in function {inspect.stack()[0].function}", flush=True)

def generate_incident_reference_number():
    incident_timestamp = datetime.utcnow().strftime("%Y%m%d%H%M%S")
    incident_number = ''.join(random.choices(string.ascii_uppercase + string.digits, k=10))
    return f"INC{incident_timestamp}{incident_number}"

def log_to_azure_monitor():
    pass

def main():
    print("Entering loop.....", flush=True)
    while True:
        print("Before calling get_vm_status....", flush=True)  # Debug print before calling the function
        compute_client = service_principal_authentication()
        previous_vm_status = None
        current_vm_status = get_vm_status(compute_client)

        if current_vm_status != previous_vm_status:
            incident_number = generate_incident_reference_number()
            print(f"This has changed {current_vm_status} - {previous_vm_status} - {incident_number}", flush=True)
        else:
            print(f"This has remained the same {current_vm_status}", flush=True)
        previous_vm_status = current_vm_status
        time.sleep(10)

if __name__ == "__main__":
    main()

• If "Before calling get_vm_status...." doesn’t appear, the issue lies in the initialization of the compute_client or the service_principal_authentication() method.
• If "Retrieving VM status......" doesn’t appear, the issue is in the API call to retrieve the VM status.
• If "Can you see this message?" doesn’t print, the function may not be returning or completing as expected.