This demo will walk you through:

1. Installing Datadog into Kubernetes
2. Collecting default metrics
3. Collecting application specific metrics
4. Collecting custom Prometheus metrics

Install Datadog into Kubernetes using Helm chart

API_KEY="<YOUR DATADOG API KEY>"

helm repo add datadog https://helm.datadoghq.com

helm install datadog `
             --set datadog.site='datadoghq.com' `
             --set datadog.apiKey=$API_KEY `
             --set datadog.apm.enabled=true `
             datadog/datadog

View metrics on Datadog dashboard Deploy sample app expposing prometheus metrics on /metrics

kubectl apply -f app-deployment.yaml

Show Prometheus Nuget package config in dotnetcore-app/Startup.cs
View the metrics on /metrics
Now we want to collect these application metrics using Datadog

Configure Datadog to collect application metrics using datadog-values.yaml file

helm upgrade datadog -f datadog-values.yaml `
             --set datadog.site='datadoghq.com' `
             --set datadog.apiKey=$API_KEY `
             --set datadog.apm.enabled=true `
             datadog/datadog

View application specific metrics on Datadog dashboard -> Metrics -> Explorer
Creating custom metrics like page views counter in app code, in dotnetcore-app/Controllers/HomeController.cs
Viewing the custom metric in Datadog dashboard

References:
Datadog Helm chart: https://github.com/DataDog/helm-charts/tree/master/charts/datadog
Autodiscovery in Datadog: https://docs.datadoghq.com/agent/kubernetes/integrations/?tab=kubernetes
Prometheus libraries: https://prometheus.io/docs/instrumenting/clientlibs/