Assign ssh.localPort automatically to an available port

- The hostagent now speaks REST API over `ha.sock` to provide the port information.
  See `pkg/hostagent/api`.

- For backward compatibility, the "default" instance uses port 60022 by default.

Close issue 131

Signed-off-by: Akihiro Suda <[email protected]>

cmd/limactl/hostagent.go

@@ -4,11 +4,16 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
+	"net/http"
 	"os"
 	"os/signal"
 	"strconv"
 
+	"github.com/gorilla/mux"
 	"github.com/lima-vm/lima/pkg/hostagent"
+	"github.com/lima-vm/lima/pkg/hostagent/api/server"
+	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
 
@@ -21,6 +26,7 @@ func newHostagentCommand() *cobra.Command {
 		Hidden: true,
 	}
 	hostagentCommand.Flags().StringP("pidfile", "p", "", "write pid to file")
+	hostagentCommand.Flags().String("socket", "", "hostagent socket")
 	return hostagentCommand
 }
 
@@ -38,6 +44,13 @@ func hostagentAction(cmd *cobra.Command, args []string) error {
 		}
 		defer os.RemoveAll(pidfile)
 	}
+	socket, err := cmd.Flags().GetString("socket")
+	if err != nil {
+		return err
+	}
+	if socket == "" {
+		return fmt.Errorf("socket must be specified (limactl version mismatch?)")
+	}
 
 	instName := args[0]
 
@@ -51,6 +64,28 @@ func hostagentAction(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
+
+	backend := &server.Backend{
+		Agent: ha,
+	}
+	r := mux.NewRouter()
+	server.AddRoutes(r, backend)
+	srv := &http.Server{Handler: r}
+	err = os.RemoveAll(socket)
+	if err != nil {
+		return err
+	}
+	l, err := net.Listen("unix", socket)
+	if err != nil {
+		return err
+	}
+	go func() {
+		defer os.RemoveAll(socket)
+		defer srv.Close()
+		if serveErr := srv.Serve(l); serveErr != nil {
+			logrus.WithError(serveErr).Warn("hostagent API server exited with an error")
+		}
+	}()
 	return ha.Run(cmd.Context())
 }
 

docs/internal.md

@@ -50,6 +50,7 @@ Guest agent:
 
 Host agent:
 - `ha.pid`: hostagent PID
+- `ha.sock`: hostagent REST API
 - `ha.stdout.log`: hostagent stdout (JSON lines, see `pkg/hostagent/events.Event`)
 - `ha.stderr.log`: hostagent stderr (human-readable messages)
 

examples/alpine.yaml

@@ -1,3 +1,4 @@
+# This example requires Lima v0.7.0 or later.
 images:
 - location: https://github.com/lima-vm/alpine-lima/releases/download/v0.1.5/alpine-lima-std-3.13.5-x86_64.iso
   arch: "x86_64"
@@ -9,11 +10,6 @@ mounts:
 - location: "/tmp/lima"
   writable: true
 
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60020
-
 firmware:
   legacyBIOS: true
 

examples/archlinux.yaml

@@ -1,4 +1,4 @@
-# This example requires Lima v0.5.0 or later
+# This example requires Lima v0.7.0 or later
 arch: "x86_64"
 images:
   # NOTE: the image is periodically rotated, if you face 404, see https://mirror.pkgbuild.com/images/ to find the latest image.
@@ -10,9 +10,5 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60050
 firmware:
   legacyBIOS: true

examples/debian.yaml

@@ -1,3 +1,4 @@
+# This example requires Lima v0.7.0 or later
 images:
   - location: "https://cloud.debian.org/images/cloud/bullseye/daily/20210916-767/debian-11-generic-amd64-daily-20210916-767.qcow2"
     arch: "x86_64"
@@ -10,7 +11,3 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60030

examples/fedora.yaml

@@ -1,3 +1,4 @@
+# This example requires Lima v0.7.0 or later.
 arch: "x86_64"
 images:
   - location: "https://download.fedoraproject.org/pub/fedora/linux/releases/34/Cloud/x86_64/images/Fedora-Cloud-Base-34-1.2.x86_64.qcow2"
@@ -8,10 +9,5 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60024
-
 firmware:
   legacyBIOS: true

examples/k3s.yaml

@@ -8,6 +8,8 @@
 # $ kubectl get no
 # NAME       STATUS   ROLES                  AGE   VERSION
 # lima-k3s   Ready    control-plane,master   69s   v1.21.1+k3s1
+#
+# This example requires Lima v0.7.0 or later.
 
 images:
   # Hint: run `limactl prune` to invalidate the "current" cache
@@ -19,9 +21,6 @@ images:
 # Mounts are disabled in this example, but can be enabled optionally.
 mounts: []
 
-ssh:
-  localPort: 60022
-
 # containerd is managed by k3s, not by Lima, so the values are set to false here.
 containerd:
   system: false

examples/opensuse.yaml

@@ -1,4 +1,4 @@
-# This example requires Lima v0.5.0 or later
+# This example requires Lima v0.7.0 or later
 images:
   # Hint: run `limactl prune` to invalidate the "Current" cache
   - location: https://download.opensuse.org/distribution/leap/15.3/appliances/openSUSE-Leap-15.3-JeOS.x86_64-15.3-OpenStack-Cloud-Current.qcow2
@@ -9,7 +9,3 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60044

examples/ubuntu.yaml

@@ -1,3 +1,4 @@
+# This example requires Lima v0.7.0 or later.
 images:
   # Hint: run `limactl prune` to invalidate the "current" cache
   - location: "https://cloud-images.ubuntu.com/hirsute/current/hirsute-server-cloudimg-amd64.img"
@@ -9,7 +10,3 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60023

examples/vmnet.yaml

@@ -12,11 +12,6 @@ mounts:
     writable: false
   - location: "/tmp/lima"
     writable: true
-ssh:
-  # localPort is changed from 60022 to avoid conflicting with the default.
-  # (TODO: assign localPort automatically)
-  localPort: 60105
-
 networks:
   # The instance can get routable IP addresses from the vmnet framework using
   # https://github.com/lima-vm/vde_vmnet. Available networks are defined in

pkg/guestagent/api/api.go

@@ -6,11 +6,6 @@ import (
 	"time"
 )
 
-// ErrorJSON is returned with "application/json" content type and non-2XX status code
-type ErrorJSON struct {
-	Message string `json:"message"`
-}
-
 var (
 	IPv4loopback1 = net.IPv4(127, 0, 0, 1)
 )

pkg/guestagent/api/server/server.go

@@ -8,6 +8,7 @@ import (
 	"github.com/gorilla/mux"
 	"github.com/lima-vm/lima/pkg/guestagent"
 	"github.com/lima-vm/lima/pkg/guestagent/api"
+	"github.com/lima-vm/lima/pkg/httputil"
 	"github.com/sirupsen/logrus"
 )
 
@@ -19,7 +20,7 @@ func (b *Backend) onError(w http.ResponseWriter, r *http.Request, err error, ec
 	w.WriteHeader(ec)
 	w.Header().Set("Content-Type", "application/json")
 	// it is safe to return the err to the client, because the client is reliable
-	e := api.ErrorJSON{
+	e := httputil.ErrorJSON{
 		Message: err.Error(),
 	}
 	_ = json.NewEncoder(w).Encode(e)

pkg/hostagent/api/api.go

@@ -0,0 +1,5 @@
+package api
+
+type Info struct {
+	SSHLocalPort int `json:"sshLocalPort,omitempty"`
+}

pkg/hostagent/api/client/client.go

@@ -0,0 +1,64 @@
+package client
+
+// Forked from https://github.com/rootless-containers/rootlesskit/blob/v0.14.2/pkg/api/client/client.go
+// Apache License 2.0
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/lima-vm/lima/pkg/hostagent/api"
+	"github.com/lima-vm/lima/pkg/httpclientutil"
+)
+
+type HostAgentClient interface {
+	HTTPClient() *http.Client
+	Info(context.Context) (*api.Info, error)
+}
+
+// NewHostAgentClient creates a client.
+// socketPath is a path to the UNIX socket, without unix:// prefix.
+func NewHostAgentClient(socketPath string) (HostAgentClient, error) {
+	hc, err := httpclientutil.NewHTTPClientWithSocketPath(socketPath)
+	if err != nil {
+		return nil, err
+	}
+	return NewHostAgentClientWithHTTPClient(hc), nil
+}
+
+func NewHostAgentClientWithHTTPClient(hc *http.Client) HostAgentClient {
+	return &client{
+		Client:    hc,
+		version:   "v1",
+		dummyHost: "lima-hostagent",
+	}
+}
+
+type client struct {
+	*http.Client
+	// version is always "v1"
+	// TODO(AkihiroSuda): negotiate the version
+	version   string
+	dummyHost string
+}
+
+func (c *client) HTTPClient() *http.Client {
+	return c.Client
+}
+
+func (c *client) Info(ctx context.Context) (*api.Info, error) {
+	u := fmt.Sprintf("http://%s/%s/info", c.dummyHost, c.version)
+	resp, err := httpclientutil.Get(ctx, c.HTTPClient(), u)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	var info api.Info
+	dec := json.NewDecoder(resp.Body)
+	if err := dec.Decode(&info); err != nil {
+		return nil, err
+	}
+	return &info, nil
+}

pkg/hostagent/api/server/server.go

@@ -0,0 +1,51 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/lima-vm/lima/pkg/hostagent"
+	"github.com/lima-vm/lima/pkg/httputil"
+)
+
+type Backend struct {
+	Agent *hostagent.HostAgent
+}
+
+func (b *Backend) onError(w http.ResponseWriter, r *http.Request, err error, ec int) {
+	w.WriteHeader(ec)
+	w.Header().Set("Content-Type", "application/json")
+	// it is safe to return the err to the client, because the client is reliable
+	e := httputil.ErrorJSON{
+		Message: err.Error(),
+	}
+	_ = json.NewEncoder(w).Encode(e)
+}
+
+// GetInfo is the handler for GET /v{N}/info
+func (b *Backend) GetInfo(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	info, err := b.Agent.Info(ctx)
+	if err != nil {
+		b.onError(w, r, err, http.StatusInternalServerError)
+		return
+	}
+	m, err := json.Marshal(info)
+	if err != nil {
+		b.onError(w, r, err, http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(m)
+}
+
+func AddRoutes(r *mux.Router, b *Backend) {
+	v1 := r.PathPrefix("/v1").Subrouter()
+	v1.Path("/info").Methods("GET").HandlerFunc(b.GetInfo)
+}

pkg/hostagent/dns.go

@@ -112,7 +112,7 @@ func (a *HostAgent) StartDNS() (*dns.Server, error) {
 	if err != nil {
 		panic(err)
 	}
-	addr := fmt.Sprintf("127.0.0.1:%d", a.y.SSH.LocalPort)
+	addr := fmt.Sprintf("127.0.0.1:%d", a.sshLocalPort)
 	server := &dns.Server{Net: "udp", Addr: addr, Handler: h}
 	go func() {
 		if e := server.ListenAndServe(); e != nil {