Tags concatenated

[VitoMakarevich]

I'm using an extension in Java 11 environment.
Lambda gradle part is: implementation 'com.datadoghq:datadog-lambda-java:1.4.3'
Here is the code I use to create metrics:

    final Map<String, Object> tags = Map.of(REQUEST_TYPE_TAG, queryType.getAlias(), CUSTOMER_TAG, customerUUID);
    this.datadogAgentSupplier.get().metric(METRIC_NAME, 1, tags);
    
    final Map<String, Object> tags = Map.of(CUSTOMER_TAG, customerUUID);
    this.datadogAgentSupplier.get().metric(METRIC_NAME, 1, tags);

I'm using Lambda with docker. The dockerfile part is:

FROM datadog/lambda-extension:21 as datadog-extension

# Building runtime container
FROM amazon/aws-lambda-java:11

COPY --from=datadog-extension /opt /opt

The lambda env variables are:

    DD_API_KEY : data.aws_ssm_parameter.datadog_secret.value
    DD_LOGS_INJECTION : "false"
    DD_JMXFETCH_ENABLED : "false"
    DD_TRACE_ENABLED : "false"
    DD_SERVERLESS_LOGS_ENABLED: "false"
    DD_ENV : var.environment_id
    DD_SERVICE : "querying"

The issue I have is that tags are concatenated, e.g. if I submit both customer and query-type, I receive query-type:incremental_querycustomer:x5ncbrfd54k8jka3hwij6ur, I've tried a couple of extension versions(17, 19, 21), unfortunately, it gives me the same result.

I've also tried to change the extension log level, here is what I see when it's set to debug:

"tags": [
                "env:staging-iad",
                "service:querying",
                "query-type:incremental_querycustomer:x5ncbrfd54k8jka3hwij6ur"

The debugger shows that {"m":"dap.request","v":1.0,"t":["query_type:incremental_query","customer:x5ncbrfd54k8jka3hwij6ur"],"e":1648642299} is written to stdout from datadog lambda java. I've seen this log in the production
2022-03-30T17:16:58.399+03:00 | {"level":"DEBUG","message":"datadog: Setting the writer to extension"} this means that extension is used.
I also tried with simple tag values like "1" and "2". Example

    final Map<String, Object> tags = Map.of(REQUEST_TYPE_TAG, "1", CUSTOMER_TAG, "2");
    this.datadogAgentSupplier.get().metric(METRIC_NAME, 1, tags);

unfortunately, the tags are still concatenated(group by customer_tag value is 2query-type:1)

[VitoMakarevich]

I've found a bug... https://github.com/DataDog/datadog-lambda-java/blob/main/src/main/java/com/datadoghq/datadog_lambda_java/MetricWriter.java#L64 here the code isn't format tags properly https://replit.com/@VitaliyMakarevi/PepperyAgileMatrix#Main.java

[IvanTopolcic]

Thanks for the report! You're right on the money -- it seems like we're not adding a , between each of the key:value pairs. Since you reported the issue, I wanted to give you the chance to submit a PR yourself. Of course you don't have to, but I figure I'd ask before I go ahead and submit the PR in case you wanted to contribute 😄

[VitoMakarevich]

I will do tomorrow, thank you!

[VitoMakarevich]

Created fix PR DataDog/datadog-lambda-java#77