CODEWITHSUNDEEP
pythonamazon-web-servicesamazon-ec2boto3
bluethundr
bluethundr

Reputation: 1345

List availability zones in a subnet python boto3

I have a script that creates AWS instances and puts them in a subnet and availability zone.

But the availability zone has to correspond to the subnet, or else you get an error that says:

 An error occurred (InvalidParameterValue) when calling the RunInstances operation: Value (us-east-1f) for parameter availabilityZone is invalid. Subnet 'subnet-87bd70ca' is in the availability zone us-east-1c

This is the code I have so far:

import boto3
import objectpath
subnet_id = input("Enter the subnet id: ")
public_ip = input("Create a public ip (True|False): ")
private_ip = input("Enter the private IP address: ")
availability_zones = ec2_client.describe_availability_zones()
tree = objectpath.Tree(availability_zones)
availability_zones = set(tree.execute('$..ZoneName'))
availability_zones = list(availability_zones)
availability_zones = str(availability_zones).replace('[','').replace(']','').replace('\'','')
availability_zone = input("Enter the availability zone: ")
        instances = ec2_resource.create_instances(
        ImageId=image_id,
        InstanceType=instance_type,
        KeyName=key_name,
        MaxCount=max_count,
        MinCount=1,
        DryRun=False,
        DisableApiTermination=True,
        EbsOptimized=False,
        Placement={
            'AvailabilityZone': availability_zone,
            'Tenancy': tenancy,
        },
        InstanceInitiatedShutdownBehavior='stop',
        NetworkInterfaces=[
            {
                'AssociatePublicIpAddress': public_ip,
                'DeleteOnTermination': True,
                'DeviceIndex': 0,
                'PrivateIpAddress': private_ip,
                'SubnetId': subnet_id,
                'Groups': [
                    sg_id
                ]
            }
        ]
        )

Is there a way I can find out what availabilty zone a subnet belongs to?

Upvotes: 1

Views: 960

Answers (2)

John Rotenstein
John Rotenstein

Reputation: 270224

If you specify a subnet, there is no need to specify an Availability Zone.

This is because a subnet exists in only one Availability Zone. Therefore, supplying the subnet also tells EC2 which AZ to use.

Upvotes: 2

ekydfejj
ekydfejj

Reputation: 349

While i don't have the exact answer, i'm thinking you could find the function in boto that returns similar results to aws ec2 describe-subnets then create a validation function from that.

You should look into terraform, this is a wheel i had reinvented but doesn't need to be.

HTH

Upvotes: 0

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