Python boto ec2 - How do I wait till an image is created or failed

Question

I am writing a code to iterate through all available instances and create an AMI for them as below:

for reservation in reservations:
    ......
    ami_id = ec2_conn.create_image(instance.id, ami_name, description=ami_desc, no_reboot=True)

But how do I wait till an image is created before proceeding with the creation of next image? Because I need to track the status of each ami created.

I know that I can retrieve the state using:

image_status = get_image(ami_id).state

So, do I iterate through the list of ami_ids created and then fetch the state for each of them? If so, then what if the image is still pending when I read the state of the image? How will I find out if the image creation has failed eventually?

Thanks.

Answer 1

If I understand correctly, you want to initiate the create_image call and then wait until the server-side operation completes before moving on. To do this, you have to poll the EC2 service periodically until the state of the image is either available (meaning it succeeded) or failed (meaning it failed). The code would look something like this:

import time
...
image_id = ec2_conn.create_image(instance.id, ...)
image = ec2_conn.get_all_images(image_ids=[image_id])[0]
while image.state == 'pending':
    time.sleep(5)
    image.update()
if image.state == 'available':
    # success, do something here
else:
    # handle failure here