The CloudWatch embedded metric format (EMF) is a JSON specification used to instruct CloudWatch Logs to automatically extract metric values embedded in structured log events.
cloudwatch-embedded-metrics provides type-safe utilities to create EMF-compliant objects.
Please consult AWS documentation for information on sending logs to CloudWatch.
npm install cloudwatch-embedded-metrics
Use the emf utility to create events by specifying the desired namespaces, metrics and dimensions and corresponding values.
import { emf, Unit } from "cloudwatch-embedded-metrics";
function addItemsEvent(request, response) {
return emf({
namespaces: ["my-company/services"],
metrics: {
"my-company/services": [
["duration", Unit.Milliseconds],
["errors": Unit.Count],
],
},
dimensions: {
"my-company/services": [
["environment", "serviceName"],
["environment", "serviceName", "endpointName"],
],
},
metricTargets: {
duration: response.duration,
errors: response.ok ? 0 : 1,
},
dimensionTargets: {
environment: "prod",
serviceName: "shopping-cart-service",
endpointName: "add-items",
},
properties: {
userId: request.userId,
cartId: request.cartId,
items: request.items,
},
});
}Generators make it easy to reuse the same configuration (namespaces, metrics and dimensions) for multiple events.
import { createMetricGenerator, Unit } from "cloudwatch-embedded-metrics";
const generator = createMetricGenerator({
namespaces: ["my-company/services"],
metrics: {
"my-company/services": [
["duration", Unit.Milliseconds],
["errors": Unit.Count],
],
},
dimensions: {
"my-company/services": [
["environment", "serviceName"],
["environment", "serviceName", "endpointName"],
],
},
});
function addItemsEvent(request, response) {
return generator({
metricTargets: {
duration: response.duration,
errors: response.ok ? 0 : 1,
},
dimensionTargets: {
environment: "prod",
serviceName: "shopping-cart-service",
endpointName: "add-items",
},
});
}
function removeItemsEvent(request, response) {
return generator({
metricTargets: {
duration: response.duration,
errors: response.ok ? 0 : 1,
},
dimensionTargets: {
environment: "prod",
serviceName: "shopping-cart-service",
endpointName: "remove-items",
},
});
}