Add vsock-backed VM port inspection

Let the host ask the guest vsock agent to run ss so open ports can be surfaced without SSHing in manually.

Add a narrow /ports agent endpoint, a daemon vm.ports RPC that enriches listeners with <hostname>.vm endpoints and best-effort HTTP links, and a concurrent 'banger vm ports' CLI table for one or more VMs.

Update the guest package contract to include ss for rebuilt Debian images, allow the guest agent package in the shell-out policy, and cover the new parsing/RPC/CLI flow in tests.

Verified with GOCACHE=/tmp/banger-gocache go test ./... outside the sandbox, make build, bash -n customize.sh make-rootfs-void.sh verify.sh, and ./banger vm ports --help.
This commit is contained in:
Thales Maciel 2026-03-19 15:52:11 -03:00
parent 3ed78fdcfc
commit c298ed2fc1
No known key found for this signature in database
GPG key ID: 33112E6833C34679
11 changed files with 1029 additions and 23 deletions

View file

@ -345,6 +345,13 @@ func (d *Daemon) dispatch(ctx context.Context, req rpc.Request) rpc.Response {
}
result, err := d.PingVM(ctx, params.IDOrName)
return marshalResultOrError(result, err)
case "vm.ports":
params, err := rpc.DecodeParams[api.VMRefParams](req)
if err != nil {
return rpc.NewError("bad_request", err.Error())
}
result, err := d.PortsVM(ctx, params.IDOrName)
return marshalResultOrError(result, err)
case "image.list":
images, err := d.store.ListImages(ctx)
return marshalResultOrError(api.ImageListResult{Images: images}, err)

126
internal/daemon/ports.go Normal file
View file

@ -0,0 +1,126 @@
package daemon
import (
"context"
"errors"
"fmt"
"io"
"net"
"net/http"
"sort"
"strconv"
"strings"
"time"
"banger/internal/api"
"banger/internal/model"
"banger/internal/system"
"banger/internal/vmdns"
"banger/internal/vsockagent"
)
const httpProbeTimeout = 750 * time.Millisecond
func (d *Daemon) PortsVM(ctx context.Context, idOrName string) (result api.VMPortsResult, err error) {
_, err = d.withVMLockByRef(ctx, idOrName, func(vm model.VMRecord) (model.VMRecord, error) {
result.Name = vm.Name
result.DNSName = strings.TrimSpace(vm.Runtime.DNSName)
if result.DNSName == "" && strings.TrimSpace(vm.Name) != "" {
result.DNSName = vmdns.RecordName(vm.Name)
}
if vm.State != model.VMStateRunning || !system.ProcessRunning(vm.Runtime.PID, vm.Runtime.APISockPath) {
return model.VMRecord{}, fmt.Errorf("vm %s is not running", vm.Name)
}
if strings.TrimSpace(vm.Runtime.GuestIP) == "" {
return model.VMRecord{}, errors.New("vm has no guest IP")
}
if strings.TrimSpace(vm.Runtime.VSockPath) == "" {
return model.VMRecord{}, errors.New("vm has no vsock path")
}
if vm.Runtime.VSockCID == 0 {
return model.VMRecord{}, errors.New("vm has no vsock cid")
}
if err := d.ensureSocketAccess(ctx, vm.Runtime.VSockPath, "firecracker vsock socket"); err != nil {
return model.VMRecord{}, err
}
portsCtx, cancel := context.WithTimeout(ctx, 3*time.Second)
defer cancel()
listeners, err := vsockagent.Ports(portsCtx, d.logger, vm.Runtime.VSockPath)
if err != nil {
return model.VMRecord{}, err
}
result.Ports = buildVMPorts(vm, listeners)
return vm, nil
})
return result, err
}
func buildVMPorts(vm model.VMRecord, listeners []vsockagent.PortListener) []api.VMPort {
endpointHost := strings.TrimSpace(vm.Runtime.DNSName)
if endpointHost == "" {
endpointHost = strings.TrimSpace(vm.Runtime.GuestIP)
}
probeHost := strings.TrimSpace(vm.Runtime.GuestIP)
ports := make([]api.VMPort, 0, len(listeners))
for _, listener := range listeners {
if listener.Port <= 0 {
continue
}
port := api.VMPort{
Proto: strings.ToLower(strings.TrimSpace(listener.Proto)),
BindAddress: strings.TrimSpace(listener.BindAddress),
Port: listener.Port,
PID: listener.PID,
Process: strings.TrimSpace(listener.Process),
Command: strings.TrimSpace(listener.Command),
Endpoint: net.JoinHostPort(endpointHost, strconv.Itoa(listener.Port)),
}
if port.Command == "" {
port.Command = port.Process
}
if port.Proto == "tcp" && probeHost != "" && endpointHost != "" && probeHTTPListener(probeHost, listener.Port) {
port.WebURL = "http://" + net.JoinHostPort(endpointHost, strconv.Itoa(listener.Port)) + "/"
}
ports = append(ports, port)
}
sort.Slice(ports, func(i, j int) bool {
if ports[i].Proto != ports[j].Proto {
return ports[i].Proto < ports[j].Proto
}
if ports[i].Port != ports[j].Port {
return ports[i].Port < ports[j].Port
}
if ports[i].Process != ports[j].Process {
return ports[i].Process < ports[j].Process
}
return ports[i].Command < ports[j].Command
})
return ports
}
func probeHTTPListener(guestIP string, port int) bool {
if strings.TrimSpace(guestIP) == "" || port <= 0 {
return false
}
url := "http://" + net.JoinHostPort(strings.TrimSpace(guestIP), strconv.Itoa(port)) + "/"
req, err := http.NewRequest(http.MethodGet, url, nil)
if err != nil {
return false
}
client := &http.Client{
Timeout: httpProbeTimeout,
CheckRedirect: func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
},
Transport: &http.Transport{
Proxy: nil,
},
}
resp, err := client.Do(req)
if err != nil {
return false
}
defer resp.Body.Close()
_, _ = io.Copy(io.Discard, io.LimitReader(resp.Body, 1))
return resp.ProtoMajor >= 1
}

View file

@ -10,6 +10,7 @@ import (
"fmt"
"net"
"net/http"
"net/http/httptest"
"os"
"os/exec"
"path/filepath"
@ -427,6 +428,145 @@ func TestHealthVMReturnsFalseForStoppedVM(t *testing.T) {
}
}
func TestPortsVMReturnsEnrichedPortsAndWebURL(t *testing.T) {
t.Parallel()
ctx := context.Background()
db := openDaemonStore(t)
apiSock := filepath.Join(t.TempDir(), "fc.sock")
fake := startFakeFirecrackerProcess(t, apiSock)
t.Cleanup(func() {
_ = fake.Process.Kill()
_ = fake.Wait()
})
webServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusNoContent)
}))
t.Cleanup(webServer.Close)
webAddr, err := net.ResolveTCPAddr("tcp", strings.TrimPrefix(webServer.URL, "http://"))
if err != nil {
t.Fatalf("ResolveTCPAddr: %v", err)
}
vsockSock := filepath.Join(t.TempDir(), "fc.vsock")
listener, err := net.Listen("unix", vsockSock)
if err != nil {
t.Fatalf("listen vsock: %v", err)
}
t.Cleanup(func() {
_ = listener.Close()
_ = os.Remove(vsockSock)
})
serverDone := make(chan error, 1)
go func() {
conn, err := listener.Accept()
if err != nil {
serverDone <- err
return
}
defer conn.Close()
buf := make([]byte, 1024)
n, err := conn.Read(buf)
if err != nil {
serverDone <- err
return
}
if got := string(buf[:n]); got != "CONNECT 42070\n" {
serverDone <- fmt.Errorf("unexpected connect message %q", got)
return
}
if _, err := conn.Write([]byte("OK 1\n")); err != nil {
serverDone <- err
return
}
reqBuf := make([]byte, 0, 1024)
for {
n, err = conn.Read(buf)
if err != nil {
serverDone <- err
return
}
reqBuf = append(reqBuf, buf[:n]...)
if strings.Contains(string(reqBuf), "\r\n\r\n") {
break
}
}
if got := string(reqBuf); !strings.Contains(got, "GET /ports HTTP/1.1\r\n") {
serverDone <- fmt.Errorf("unexpected ports payload %q", got)
return
}
body := fmt.Sprintf(`{"listeners":[{"proto":"tcp","bind_address":"0.0.0.0","port":%d,"pid":44,"process":"python3","command":"python3 -m http.server %d"},{"proto":"udp","bind_address":"0.0.0.0","port":53,"pid":1,"process":"dnsd","command":"dnsd --foreground"}]}`, webAddr.Port, webAddr.Port)
resp := fmt.Sprintf("HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: %d\r\n\r\n%s", len(body), body)
_, err = conn.Write([]byte(resp))
serverDone <- err
}()
vm := testVM("ports", "image-ports", "127.0.0.1")
vm.State = model.VMStateRunning
vm.Runtime.State = model.VMStateRunning
vm.Runtime.PID = fake.Process.Pid
vm.Runtime.APISockPath = apiSock
vm.Runtime.VSockPath = vsockSock
vm.Runtime.VSockCID = 10043
upsertDaemonVM(t, ctx, db, vm)
runner := &scriptedRunner{
t: t,
steps: []runnerStep{
sudoStep("", nil, "chown", fmt.Sprintf("%d:%d", os.Getuid(), os.Getgid()), vsockSock),
sudoStep("", nil, "chmod", "600", vsockSock),
},
}
d := &Daemon{store: db, runner: runner}
result, err := d.PortsVM(ctx, vm.Name)
if err != nil {
t.Fatalf("PortsVM: %v", err)
}
if result.Name != vm.Name || result.DNSName != vm.Runtime.DNSName {
t.Fatalf("result = %+v, want name/dns", result)
}
if len(result.Ports) != 2 {
t.Fatalf("ports = %+v, want 2 entries", result.Ports)
}
wantWeb := fmt.Sprintf("http://ports.vm:%d/", webAddr.Port)
var tcpPort, udpPort api.VMPort
for _, port := range result.Ports {
switch port.Proto {
case "tcp":
tcpPort = port
case "udp":
udpPort = port
}
}
if udpPort.Endpoint != "ports.vm:53" || udpPort.WebURL != "" {
t.Fatalf("udp port = %+v, want endpoint only", udpPort)
}
if tcpPort.Endpoint != net.JoinHostPort("ports.vm", strconv.Itoa(webAddr.Port)) || tcpPort.WebURL != wantWeb {
t.Fatalf("tcp port = %+v, want web url %q", tcpPort, wantWeb)
}
runner.assertExhausted()
if err := <-serverDone; err != nil {
t.Fatalf("server: %v", err)
}
}
func TestPortsVMReturnsErrorForStoppedVM(t *testing.T) {
t.Parallel()
ctx := context.Background()
db := openDaemonStore(t)
vm := testVM("stopped-ports", "image-stopped", "172.16.0.50")
upsertDaemonVM(t, ctx, db, vm)
d := &Daemon{store: db}
_, err := d.PortsVM(ctx, vm.Name)
if err == nil || !strings.Contains(err.Error(), "is not running") {
t.Fatalf("PortsVM error = %v, want not running", err)
}
}
func TestSetVMDiskResizeFailsPreflightWhenToolsMissing(t *testing.T) {
ctx := context.Background()
db := openDaemonStore(t)