Deploy .NET Core Agent Using Init Containers

An example illustrating how to deploy on Kubernetes a sample application with the .NET Core Agent using an init container (a.k.a. sidecar).

The init containers option, available in Kubernetes, is used to run additional containers at application startup. You can use this option to deploy your Seeker Agents without modifying your application images. This is achieved by downloading an Agent package using an init container, and loading it to the application container dynamically.

Save the following code snippet in a file, for example, dotnet.yml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dotnet
  namespace: apps
spec:
  selector:
    matchLabels:
      app: dotnet
  template:
    metadata:
      labels:
        app: dotnet
    spec:      
      initContainers:
          # Download the .NET Core Agent package and extract it to the shared folder /seeker.
        - name: download-agent
          image: busybox:stable
          command:
            - /bin/sh
            - -c
            - |              
              echo "Download Seeker Agent from: ${SEEKER_SERVER_URL}/rest/api/latest/installers/agents/binaries/DOTNETCORE?osFamily=LINUX"
              wget --no-check-certificate -O /tmp/seeker.zip "${SEEKER_SERVER_URL}/rest/api/latest/installers/agents/binaries/DOTNETCORE?osFamily=LINUX"
              unzip -d /seeker /tmp/seeker.zip              
              rm -f /tmp/seeker.zip

          # Set the env variables below to point to your own server and project.
          env:
            - name: SEEKER_SERVER_URL
              value: "https://seeker-server:8443"
            - name: SEEKER_PROJECT_KEY
              value: "dotnet-k8s"
          volumeMounts:
            - name: seeker-agent
              mountPath: "/seeker"
      containers:
        - name: dotnet
          image: mcr.microsoft.com/dotnet/samples:aspnetapp
          ports:
            - containerPort: 80          
           env:
            - name: SEEKER_SERVER_URL
              value: "https://seeker-server:8443"
            - name: SEEKER_PROJECT_KEY
              value: "dotnet-k8s"
              # Instruct the CLR to load the .NET Core Agent on its start
            - name: CORECLR_PROFILER_PATH
              value: "/seeker/x64/Agent.Profiler-Dnc.so"
            - name: CORECLR_ENABLE_PROFILING
              value: "1"
            - name: CORECLR_PROFILER
              value: "{C7AD49B3-093B-4AB1-A241-1E4365DD8901}"
          volumeMounts:
            - name: seeker-agent
              mountPath: "/seeker"
      volumes:
        - name: seeker-agent
          emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: dotnet-service
  namespace: apps
spec:
  type: NodePort
  selector:
    app: dotnet
  ports:
    - name: "http"
      protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 31081

If you are using an Alpine Linux-based Docker image, save the following snippet as dotnet-alpine.yml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dotnet-alpine
  namespace: apps
spec:
  selector:
    matchLabels:
      app: dotnet-alpine
  template:
    metadata:
      labels:
        app: dotnet-alpine
    spec:      
      initContainers:
          # Download the .NET Core Agent package and extract it to the shared folder /seeker.
        - name: download-agent
          image: busybox:stable
          command:
            - /bin/sh
            - -c
            - |              
              echo "Download Seeker Agent from: ${SEEKER_SERVER_URL}/rest/api/latest/installers/agents/binaries/DOTNETCORE?osFamily=LINUX"
              wget --no-check-certificate -O /tmp/seeker.zip "${SEEKER_SERVER_URL}/rest/api/latest/installers/agents/binaries/DOTNETCORE?osFamily=LINUX"
              unzip -d /seeker /tmp/seeker.zip              
              rm -f /tmp/seeker.zip

          # Set the env variables below to point to your own server and project.
          env:
            - name: SEEKER_SERVER_URL
              value: "https://seeker-server:8443"
            - name: SEEKER_PROJECT_KEY
              value: "dotnet-alpine-k8s"
          volumeMounts:
            - name: seeker-agent
              mountPath: "/seeker"
      containers:
        - name: dotnet-alpine
          image: mcr.microsoft.com/dotnet/samples:aspnetapp
          ports:
            - containerPort: 80          
           env:
            - name: SEEKER_SERVER_URL
              value: "https://seeker-server:8443"
            - name: SEEKER_PROJECT_KEY
              value: "dotnet-alpine-k8s"
              # Instruct the CLR to load the .NET Core Agent on its start
            - name: CORECLR_PROFILER_PATH
              value: "/seeker/musl-x64/Agent.Profiler-Dnc.so"
            - name: CORECLR_ENABLE_PROFILING
              value: "1"
            - name: CORECLR_PROFILER
              value: "{C7AD49B3-093B-4AB1-A241-1E4365DD8901}"
            - name: LD_LIBRARY_PATH
              value: ""$LD_LIBRARY_PATH:"/seeker/musl-x64/"
          volumeMounts:
            - name: seeker-agent
              mountPath: "/seeker"
      volumes:
        - name: seeker-agent
          emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: dotnet-alpine-service
  namespace: apps
spec:
  type: NodePort
  selector:
    app: dotnet-alpine
  ports:
    - name: "http"
      protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 31081

Deploy the application:
```
kubectl apply -f dotnet.yml
```
or
```
kubectl apply -f dotnet-alpine.yml
```
The application starts with the CORECLR_* variable that instructs the CLR to load the Agent on its start.