cpp-app.yaml

# Turnkey C++ debug target — no registry, no image build.
# Source from a ConfigMap; an initContainer on gcc:13-bookworm compiles with
# DWARF debug info (-g -O0 -gdwarf-4, unstripped) into an emptyDir, and a
# stock debian:12-slim runtime runs the binary. gcc:13-bookworm and
# debian:12 share a glibc generation; -static-libgcc/-static-libstdc++
# remove the remaining library skew.
#
# There is no debug agent and no debug port: compiled code is debugged by
# sending the debugger to the pod as an ephemeral container that attaches
# by PID (../kubernetes/debug-sidecar.sh, docs/kubernetes.md pattern B).
#
#   kubectl apply -f cpp-app.yaml
#   kubectl wait --for=condition=available deployment/cpp-demo
#   ./debug-sidecar.sh app=cpp-demo
#
# Attach preset: see attach-presets.md (#cpp).
apiVersion: v1
kind: ConfigMap
metadata:
  name: cpp-demo-src
data:
  app.cpp: |
    #include <cstdio>
    #include <string>
    #include <unistd.h>

    int tick(int counter) {
        std::string label = "tick-" + std::to_string(counter);
        int total = counter * 2;
        std::printf("%s: total=%d\n", label.c_str(), total);
        std::fflush(stdout);
        return total;
    }

    int main() {
        int counter = 0;
        while (true) {
            ++counter;
            tick(counter);
            sleep(2);
        }
    }
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: cpp-demo
  labels:
    app: cpp-demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: cpp-demo
  template:
    metadata:
      labels:
        app: cpp-demo
    spec:
      initContainers:
        - name: compile
          image: gcc:13-bookworm
          command:
            - g++
            - -g
            - -O0
            - -gdwarf-4
            - -static-libgcc
            - -static-libstdc++
            - -o
            - /shared/app
            - /app/app.cpp
          volumeMounts:
            - name: src
              mountPath: /app
            - name: shared
              mountPath: /shared
      containers:
        - name: app # kubectl debug --target=app
          image: debian:12-slim
          command: ["/shared/app"]
          volumeMounts:
            - name: shared
              mountPath: /shared
          resources:
            requests:
              cpu: 50m
              memory: 64Mi
            limits:
              memory: 256Mi
      volumes:
        - name: src
          configMap:
            name: cpp-demo-src
        - name: shared
          emptyDir: {}