Access network_interface generates an error

[lmayorga1980]

cdktf & Language Versions

cdktf version: 0.10.1
language: python

Affected Resource(s)

Access instance details

  #Query a GCP Image filtered by Family        
        gcp_image = DataGoogleComputeImage(self, id = "windows_image", family = "windows-2019", project="windows-cloud" )

        #Get the network interface
        net_int = ComputeInstanceNetworkInterface(subnetwork ="<SUBNETWORK>",subnetwork_project = "<SHARED-PROJECT>")

        #Create a new vm
        instance = ComputeInstance(self,id = "sample-vm", machine_type="e2-standard-4", name="cdktf-instance-1", 
                        boot_disk= ComputeInstanceBootDisk(initialize_params=ComputeInstanceBootDiskInitializeParams(image=gcp_image.name)),
                        network_interface=[net_int], zone= "us-east4-a"
        )

        #Output 
        TerraformOutput(self, "instance_ip", instance.network_interface[0].network_ip)

Debug Output

    Traceback (most recent call last):
      File "/Users/user/terraform-learning/cdktf-gcp/gcp/main.py", line 37, in <module>
        GcpBasicVmStack(app, "gcp")
      File "/Users/user/.local/share/virtualenvs/gcp-XHqyQSdy/lib/python3.9/site-packages/jsii/_runtime.py", line 86, in __call__
        inst = super().__call__(*args, **kwargs)
      File "/Users/user/terraform-learning/cdktf-gcp/gcp/main.py", line 34, in __init__
        TerraformOutput(self, "instance_ip", instance.network_interface[0].network_ip)
    TypeError: 'InterfaceDynamicProxy' object is not subscriptable

Expected Behavior

Should be able to retrieve the instance ip in the output

Actual Behavior

Exception

Steps to Reproduce

Important Factoids

References

• #0000

[jsteinich]

This isn't directly supported at this time. A possible workaround:

TerraformOutput(self, "instance_ip", Fn.lookup(Fn.element(instance.network_interface, 0), "network_ip", "default"))

[lmayorga1980]

TerraformOutput(self, "instance_ip", Fn.lookup(Fn.element(instance.network_interface, 0), "network_ip","default"))

Synth command: pipenv run python main.py
Error:         non-zero exit code 1

Command output on stderr:

    Traceback (most recent call last):
      File "/Users/user/terraform-learning/cdktf-gcp/gcp/main.py", line 38, in <module>
        GcpBasicVmStack(app, "gcp")
      File "/Users/user/.local/share/virtualenvs/gcp-XHqyQSdy/lib/python3.9/site-packages/jsii/_runtime.py", line 86, in __call__
        inst = super().__call__(*args, **kwargs)
      File "/Users/user/terraform-learning/cdktf-gcp/gcp/main.py", line 35, in __init__
        TerraformOutput(self, "instance_ip", Fn.lookup(Fn.element(instance.network_interface, 0), "network_ip",default_value=""))
      File "/Users/user/.local/share/virtualenvs/gcp-XHqyQSdy/lib/python3.9/site-packages/jsii/_runtime.py", line 86, in __call__
        inst = super().__call__(*args, **kwargs)
    TypeError: __init__() takes 3 positional arguments but 4 were given

[jsteinich]

TerraformOutput(self, "instance_ip", value=Fn.lookup(Fn.element(instance.network_interface, 0), "network_ip", "default"))

Missed explicitly setting the value property on the output.

[lmayorga1980]

The workaround works.

[ansgarm]

@jsteinich do we already have another issue that is tracking the work required for this to function without the need for a workaround?

[jsteinich]

@jsteinich do we already have another issue that is tracking the work required for this to function without the need for a workaround?

#25 or #1610 should cover it.

[github-actions]

I'm going to lock this issue because it has been closed for 30 days. This helps our maintainers find and focus on the active issues. If you've found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.