aws_cdk.aws_elasticloadbalancingv2: object has no attribute 'metric'

[alistaim]

Description

When i lookup an existing Application Load Balancer using the ARN, I can't seem to access metrics associated with it through the metric*(s) methods. I also get a default ARN returned for the object.

Reproduction Steps

alb = elbv2.ApplicationLoadBalancer.from_lookup(self, "ALB", load_balancer_arn=arn) ## arn:aws:elasticloadbalancing:us-east-1:<AccNo>:loadbalancer/app/lb-test/<Id> metric = alb.metric(elbv2.HttpCodeElb.ELB_4XX_COUNT) print(metric)

What did you expect to happen?

To get the metric object back so that I can create a Cloudwatch Alarm based off of this.

What actually happened?

I get an error saying that the object has no attribute metric :
Traceback (most recent call last): File "app.py", line 13, in <module> ALBStack(app, "ALBStack", env=deploy_env) File "/Users/mclean/code/alerts-poc/.venv/lib/python3.8/site-packages/jsii/_runtime.py", line 83, in __call__ inst = super().__call__(*args, **kwargs) File "/Users/mclean/code/alerts-poc/stacks/alb.py", line 22, in __init__ metric = alb.metric(elbv2.HttpCodeElb.ELB_4XX_COUNT) File "/Users/mclean/code/alerts-poc/.venv/lib/python3.8/site-packages/jsii/_reference_map.py", line 149, in __getattr__ raise AttributeError(f"'%s' object has no attribute '%s'" % (type_info, name)) AttributeError: '<class 'aws_cdk.core.Resource'>+<class 'aws_cdk.aws_elasticloadbalancingv2._IApplicationLoadBalancerProxy'>' object has no attribute 'metric'

Also if I do :

print(alb.load_balancer_arn)
I get back :
arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/application/my-load-balancer/50dc6c495c0c9188
which looks completely wrong and looks to be some kind of default value.

Environment

• CDK CLI Version :1.95.1 (build ed2bbe6)
• Framework Version: aws-cdk.aws-elasticloadbalancingv2==1.95.1
• Node.js Version: v13.8.0
• OS : MacOS 10.15.7
• Language (Version): Python 3.8

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This is 🐛 Bug Report

[njlynch]

Hi @alistaim ,

The imported load balancer is an IApplicationLoadBalancer, which doesn't currently support the metric methods. See #10850 for an existing feature request to add them.

In regards to the dummy value from the lookup, this default value arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/application/my-load-balancer/50dc6c495c0c9188 is returned when the context lookup has not yet happened or failed for whatever reason (e.g., permissions). You may need to reset your context (see https://docs.aws.amazon.com/cdk/latest/guide/context.html) to pick up the correct value.

I'm going to close this out as a duplicate of #10850. Please 👍 that issue and follow progress there.

Thanks!

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[SamStephens]

@njlynch unless I've misunderstood what's going on, this issue was closed in error. #10850 is about metric methods on IApplicationTargetGroup. This issue is about metric methods on IApplicationLoadBalancer.

[edisongustavo]

This is now fixed by #23853