[management] Add vLLM e2e test (#6649)

* Add vLLM to Agent Network

* Add vllm e2e test

e2e/harness/vllm.go

@@ -0,0 +1,113 @@
+//go:build e2e
+
+package harness
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/docker/docker/api/types/container"
+	"github.com/testcontainers/testcontainers-go"
+	"github.com/testcontainers/testcontainers-go/wait"
+)
+
+const (
+	vllmImage = "nginx:alpine"
+	vllmAlias = "vllm"
+	vllmPort  = "8000/tcp"
+	// VLLMModel is the served model id the mock advertises and echoes back. It
+	// matches a real small model commonly served by vLLM so the provider's
+	// enumerated model and the client's request line up.
+	VLLMModel = "Qwen/Qwen2.5-0.5B-Instruct"
+)
+
+// vllmNginxConf emulates a vLLM OpenAI-compatible server over plain HTTP (vLLM's
+// default: no TLS, port 8000). It answers /v1/models with a one-model list and
+// any chat/completions path with a canned OpenAI-shaped chat completion carrying
+// a non-zero usage block, so the proxy's OpenAI parser records real token
+// consumption. Running actual vLLM in CI is infeasible (GPU + multi-GB model
+// download), so this stands in for the wire contract the proxy depends on.
+const vllmNginxConf = `pid /tmp/nginx.pid;
+events {}
+http {
+  server {
+    listen 8000;
+    location = /v1/models {
+      default_type application/json;
+      return 200 '{"object":"list","data":[{"id":"Qwen/Qwen2.5-0.5B-Instruct","object":"model","owned_by":"vllm"}]}';
+    }
+    location / {
+      default_type application/json;
+      return 200 '{"id":"chatcmpl-e2e-vllm","object":"chat.completion","created":1700000000,"model":"Qwen/Qwen2.5-0.5B-Instruct","choices":[{"index":0,"message":{"role":"assistant","content":"pong"},"finish_reason":"stop"}],"usage":{"prompt_tokens":11,"completion_tokens":2,"total_tokens":13}}';
+    }
+  }
+}
+`
+
+// VLLM is a mock vLLM OpenAI-compatible server on the combined server's network,
+// reachable at http://vllm:8000. A "vllm" provider points at it to exercise the
+// proxy's support for self-hosted OpenAI-compatible backends.
+type VLLM struct {
+	container testcontainers.Container
+	workDir   string
+	// URL is the upstream URL the vllm provider points at (http://<alias>:8000).
+	URL string
+}
+
+// StartVLLM runs the mock vLLM server on the shared network over plain HTTP.
+func StartVLLM(ctx context.Context, c *Combined) (*VLLM, error) {
+	workDir, err := os.MkdirTemp("/tmp", "nb-e2e-vllm-*")
+	if err != nil {
+		return nil, fmt.Errorf("create vllm work dir: %w", err)
+	}
+	// Widen so the (non-root worker) nginx container can traverse the bind mount.
+	if err := os.Chmod(workDir, 0o755); err != nil { //nolint:gosec // throwaway e2e config dir
+		return nil, fmt.Errorf("chmod vllm dir: %w", err)
+	}
+	if err := os.WriteFile(filepath.Join(workDir, "nginx.conf"), []byte(vllmNginxConf), 0o644); err != nil { //nolint:gosec // non-secret e2e config
+		return nil, fmt.Errorf("write nginx conf: %w", err)
+	}
+
+	req := testcontainers.ContainerRequest{
+		Image:          vllmImage,
+		ExposedPorts:   []string{vllmPort},
+		Networks:       []string{c.network.Name},
+		NetworkAliases: map[string][]string{c.network.Name: {vllmAlias}},
+		Cmd:            []string{"nginx", "-c", "/conf/nginx.conf", "-g", "daemon off;"},
+		HostConfigModifier: func(hc *container.HostConfig) {
+			hc.Binds = append(hc.Binds, workDir+":/conf:ro")
+		},
+		WaitingFor: wait.ForListeningPort(vllmPort).WithStartupTimeout(60 * time.Second),
+	}
+
+	ctr, err := testcontainers.GenericContainer(ctx, testcontainers.GenericContainerRequest{
+		ContainerRequest: req,
+		Started:          true,
+	})
+	if err != nil {
+		_ = os.RemoveAll(workDir)
+		return nil, fmt.Errorf("start vllm container: %w", err)
+	}
+
+	return &VLLM{container: ctr, workDir: workDir, URL: "http://" + vllmAlias + ":8000"}, nil
+}
+
+// Logs returns the vLLM container logs, for diagnostics on failure.
+func (v *VLLM) Logs(ctx context.Context) string {
+	return containerLogs(ctx, v.container)
+}
+
+// Terminate stops the vLLM container and cleans its work dir.
+func (v *VLLM) Terminate(ctx context.Context) error {
+	var err error
+	if v.container != nil {
+		err = v.container.Terminate(ctx)
+	}
+	if v.workDir != "" {
+		_ = os.RemoveAll(v.workDir)
+	}
+	return err
+}