Support for default dimensions

[DahShahar]

Hi, sorry in advance if this is already something supported by the library and I couldn't find it.

What?

I'm trying to override the default dimensions to remove things that aren't useful to me, such as LogGroup and ServiceType.

I can't find a way to actually do this. I see from the Configuration in the README that I can set namespace which is also useful, but not enough.

I thought there'd be a similar way to handle Dimensions, but there aren't. Ideally, I'd like to be able to create a single MetricsLogger in my application and wire it in as needed. That logger should always have the dimensions I want as baseline, and some methods might add more.

I recognize that this wouldn't work for an environment variable configuration, but how about something like:

const { Configuration } = require("aws-embedded-metrics");

Configuration.dimensions = [{
    version: 'N+1' // Latest Lambda Version specific
  },
  {}  // Whole fleet metrics
];

This would allow me to alarm on both the "latest" Lambda version specific metrics, and the fleet as a whole as I'd be emitting metrics for both at the same rate. This is especially useful during deployments as I want to see how the newest version is doing.

An alternative would be to open up the constructor of the MetricsLogger. I see that it is technically public today, but we don't have access to the EnvironmentProvider (again, as far as I am able to tell).

Let me know what you think, and if there's already a way to do this I apologize in advance.

[markkuhn]

You can override default dimensions by using the setDimensions function.

From the documentation:

setDimensions(Record<String, String> | Record<String, String>[] dimensions, boolean useDefault)

Explicitly override all dimensions. This will remove the default dimensions unless the useDefault parameter is set to true (defaults to false).

// Overwrites custom dimensions - keeps default dimensions
setDimensions({Operation: "Aggregator"}, true)

// Overwrites custom dimensions - removes default dimensions
setDimensions([
  { Operation: "Aggregator" },
  { Operation: "Aggregator", DeviceType: "Actuator" }
])

Custom dimensions cannot be set in the configuration. You must do this in the MetricLogger.

Let me know if this answers your question.