Cannot apply addLambdaFunctions via aspect: "We detected an Aspect was added via another Aspect, and will not be applied"

[mhenniges]

Expected Behavior

I attempted to write an aspect that would automatically set up tracing for my nodeJS lambdas. I expected this would result in full instrumentation of these functions without multiple source file edits.

Actual Behavior

Aspect fails to apply with an error "We detected an Aspect was added via another Aspect, and will not be applied".

Steps to Reproduce the Problem

Example aspect for datadog:

abstract class TraceAgentBase implements IAspect {

    protected readonly props: DatadogProps;
    protected readonly ddtrace: Datadog;
    // protected readonly scope: IConstruct;

    protected constructor(ddtrace: Datadog, props: DatadogProps) {
        this.props = props;
        this.ddtrace = ddtrace
    }

    public visit(node: IConstruct): void {
        if (node instanceof NodejsFunction) {
            this.applyNodeTracingToLambda(node)
        }
    }
    protected abstract applyNodeTracingToLambda(resource: NodejsFunction): void;
}
`
export class TraceAgent extends TraceAgentBase  {
    constructor(ddtrace: Datadog, props: DatadogProps) {
        super(ddtrace, props);
    }
    protected applyNodeTracingToLambda(resource: NodejsFunction) {
        this.ddtrace.addLambdaFunctions([resource])
        resource.addEnvironment('DD_MERGE_XRAY_TRACES', 'true');
        const cfnFunc = resource.node.defaultChild as CfnFunction;
        cfnFunc.tracingConfig = {mode: Tracing.ACTIVE};
    }
}

apply to stack with something like this:

        Aspects.of(runner).add(new TraceAgent(ddtrace, {
            apiKey: DatadogAPISecret.secretValue.toString(),
            nodeLayerVersion: 78,
            extensionLayerVersion: 23,
            env: 'dev',
            service: serviceName,
            version: '0.1.2-datadog',
            captureLambdaPayload: true,
        }));

Specifications

• Datadog Lambda Layer version: 23
• Node version: 78

Stacktrace

None available

After much debugging, I've tracked this down to the use of Tags.of() in addCdkConstructVersionTag and setTags() calls starting here - Tags.of() is an aspect as well.

Has anybody else hit this, and did you work around it successfully? Has there been any thought or exploration into how to make the datadog construct aspect-compatible?

Although not ideal, I believe this can be solved by using something like construct.tags.setTag(key, value, 100, true) to set tags directly, rather than calling the aspect to do the same. There won't be much (any?) cascading of tags to child objects in this case, so really not much is lost.

Happy to make a PR if there is no objection.

[astuyve]

Hey @mhenniges - this library wasn't specifically written to be implemented to support an Aspect, but we'd happily look at any PR you'd submit for this. Thanks!

[felixmagnus]

Hey @mhenniges - we just ran into the same problem 😄 Did you come up with any workaround for this yet?
Would be great if you could share any findings - thanks!

[maherio]

I believe the only other suggested way to add tags is with Tag.visit(), which appears to add the tag without making use of an Aspect (thus making it compatible from within another Aspect). I implemented this as a workaround (in python):

cfn_function: CfnFunction = function.node.default_child
Tag(key=TagKeys.ENV.value, value="my-env").visit(construct=cfn_function)
Tag(key=TagKeys.SERVICE.value, value="my-service").visit(construct=cfn_function)
Tag(key=TagKeys.VERSION.value, value="my-version").visit(construct=cfn_function)

[astuyve]

sweet, I can try it with #251 when I get more time