Visual Studio Code – Dev Containers: Attach to Running Containers … to Container in minikube/kind

Since your goal is to debug a Go application with Delve (remotely), I think you should refer to How can I use Delve for remote debugging? and Debugging with Go extension instead.

Most of the guides below are copied from those docs.

1. Start a headless instance of Delve inside the pod like this:

   dlv attach --headless --listen :4040 [pid] [/path/to/executable]
   

   Note: I encountered an error when running this command in a pod: Could not attach to pid 1: this could be caused by a kernel security setting, try writing "0" to /proc/sys/kernel/yama/ptrace_scope. In order to try the solution myself, I created a docker image to start the Delve server directly like this (see Dockerfile in the attachments section):

   CMD ["/app/dlv", "exec", "/app/goapp", "--listen=:4040", "--headless=true", "--api-version=2", "--log"]
   

2. Forward the port to make the debug server available from outside:

   kubectl port-forward [pod name] 4040
   

3. In vscode, create the .vscode/launch.json file:

   {
     "version": "0.2.0",
     "configurations": [
       {
         "name": "Connect to pod",
         "type": "go",
         "request": "attach",
         "mode": "remote",
         "host": "localhost",
         "port": 4040,
         "debugAdapter": "dlv-dap",
         "substitutePath": [{ "from": "${workspaceFolder}", "to": "/app" }]
       }
     ]
   }
   

   It’s important to set substitutePath correctly so that you can see the source code in vscode. Since the source code of my demo app is copied to /app and built from there (built with docker), the path recorded in the binary is /app/main.go, so I have to map from ${workspaceFolder} to /app.

4. In vscode, start debugging with this configuration.

   

Attachments

1. main.go:

   package main
   
   import "net/http"
   
   func main() {
       _ = http.ListenAndServe(":8080", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
           _, _ = w.Write([]byte("hello world!"))
       }))
   }
   

2. Dockerfile:

   # syntax=docker/dockerfile:1
   
   # =============== build stage ===============
   FROM golang:1.18.4-alpine3.16 AS build
   WORKDIR /app
   
   RUN go install github.com/go-delve/delve/cmd/dlv@latest
   
   COPY . ./
   RUN go build -o goapp -v main.go
   
   # =============== final stage ===============
   FROM alpine:3.16.1 AS final
   
   WORKDIR /app
   COPY --from=build /app/goapp ./
   COPY --from=build /go/bin/dlv ./
   CMD ["/app/dlv", "exec", "/app/goapp", "--listen=:4040", "--headless=true", "--api-version=2", "--log"]
   

   • Build image from this file: docker build -t goapp:1.0 -f Dockerfile ..
   • Load the image into kind node (yes, I’m testing with kind): kind load docker-image goapp:1.0.

3. goapp.yaml:

   apiVersion: v1
   kind: Pod
   metadata:
     name: goapp
     labels:
       app: goapp
   spec:
     containers:
       - name: goapp
         image: goapp:1.0
         imagePullPolicy: Never
         ports:
           - containerPort: 8080
           - containerPort: 4040
   

   • Create a pod defined by this file: kubectl apply -f goapp.yaml.