Add networks in config to allow attaching server to private net

.web-docs/components/builder/hcloud/README.md

@@ -122,6 +122,9 @@ builder.
   be upgraded to, without changing the disk size. Improves building performance.
   The resulting snapshot is compatible with smaller server types and disk sizes.
 
+- `networks` (array of integers) - List of Network IDs which should be
+  attached to the server private network interface at creation time.
+
 ## Basic Example
 
 Here is a basic example. It is completely valid as soon as you enter your own

builder/hcloud/config.go

@@ -43,6 +43,7 @@ type Config struct {
 	UserData       string            `mapstructure:"user_data"`
 	UserDataFile   string            `mapstructure:"user_data_file"`
 	SSHKeys        []string          `mapstructure:"ssh_keys"`
+	Networks       []int64           `mapstructure:"networks"`
 
 	RescueMode string `mapstructure:"rescue"`
 

builder/hcloud/step_create_server.go

@@ -69,20 +69,27 @@ func (s *stepCreateServer) Run(ctx context.Context, state multistep.StateBag) mu
 		ui.Message(fmt.Sprintf("Using image %s with ID %d", image.Description, image.ID))
 	}
 
+	var networks []*hcloud.Network
+	for _, k := range c.Networks {
+		networks = append(networks, &hcloud.Network{ID: k})
+	}
+
 	serverCreateOpts := hcloud.ServerCreateOpts{
 		Name:       c.ServerName,
 		ServerType: &hcloud.ServerType{Name: c.ServerType},
 		Image:      image,
 		SSHKeys:    sshKeys,
 		Location:   &hcloud.Location{Name: c.Location},
 		UserData:   userData,
+		Networks:   networks,
 	}
 
 	if c.UpgradeServerType != "" {
 		serverCreateOpts.StartAfterCreate = hcloud.Bool(false)
 	}
 
 	serverCreateResult, _, err := client.Server.Create(ctx, serverCreateOpts)
+
 	if err != nil {
 		err := fmt.Errorf("Error creating server: %s", err)
 		state.Put("error", err)

builder/hcloud/step_create_server_test.go

@@ -0,0 +1,203 @@
+package hcloud
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/hashicorp/packer-plugin-sdk/multistep"
+	packersdk "github.com/hashicorp/packer-plugin-sdk/packer"
+	"github.com/hetznercloud/hcloud-go/v2/hcloud"
+	"github.com/hetznercloud/hcloud-go/v2/hcloud/schema"
+)
+
+type Checker func(requestBody string, path string) error
+
+func TestStepCreateServer(t *testing.T) {
+	const snapName = "dummy-snap"
+	const imageName = "dummy-image"
+	const name = "dummy-name"
+	const location = "nbg1"
+	const serverType = "cpx11"
+	networks := []int64{1}
+
+	testCases := []struct {
+		name       string
+		config     Config
+		check      Checker
+		wantAction multistep.StepAction
+	}{
+		{
+			name:       "happy path",
+			wantAction: multistep.ActionContinue,
+			check: func(r string, path string) error {
+				if path == "/servers" {
+					payload := schema.ServerCreateRequest{}
+					err := json.Unmarshal([]byte(r), &payload)
+					if err != nil {
+						t.Errorf("server request not a json: got: (%s)", err)
+					}
+
+					if payload.Name != name {
+						t.Errorf("Incorrect name in request, expected '%s' found '%s'", name, payload.Name)
+					}
+
+					if payload.Image != imageName {
+						t.Errorf("Incorrect image in request, expected '%s' found '%s'", imageName, payload.Image)
+					}
+
+					if payload.Location != location {
+						t.Errorf("Incorrect location in request, expected '%s' found '%s'", location, payload.Location)
+					}
+
+					if payload.ServerType != serverType {
+						t.Errorf("Incorrect serverType in request, expected '%s' found '%s'", serverType, payload.ServerType)
+					}
+					if payload.Networks != nil {
+						t.Error("Networks should not be specified")
+					}
+				}
+				return nil
+			},
+		},
+		{
+			name:       "with netowork",
+			wantAction: multistep.ActionContinue,
+			config: Config{
+				Networks: networks,
+			},
+			check: func(r string, path string) error {
+				if path == "/servers" {
+					payload := schema.ServerCreateRequest{}
+					err := json.Unmarshal([]byte(r), &payload)
+					if err != nil {
+						t.Errorf("server request not a json: (%s)", err)
+					}
+					if payload.Networks[0] != networks[0] {
+						t.Errorf("network not set")
+					}
+				}
+				return nil
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			errors := make(chan error, 1)
+			state, teardown := setupStepCreateServer(errors, tc.check)
+			defer teardown()
+
+			step := &stepCreateServer{}
+
+			baseConfig := Config{
+				ServerName:   name,
+				Image:        imageName,
+				SnapshotName: snapName,
+				ServerType:   serverType,
+				Location:     location,
+				SSHKeys:      []string{"1"},
+			}
+
+			config := baseConfig
+			config.Networks = tc.config.Networks
+
+			if testing.Verbose() {
+				state.Put("ui", packersdk.TestUi(t))
+			} else {
+				// do not output to stdout or console
+				state.Put("ui", &packersdk.MockUi{})
+			}
+			state.Put("config", &config)
+			state.Put("ssh_key_id", int64(1))
+
+			if action := step.Run(context.Background(), state); action != tc.wantAction {
+				t.Errorf("step.Run: want: %v; got: %v", tc.wantAction, action)
+			}
+
+			select {
+			case err := <-errors:
+				t.Errorf("server: got: %s", err)
+			default:
+			}
+		})
+	}
+}
+
+// Configure a httptest server to reply to the requests done by stepCreateSnapshot.
+// React with the appropriate failCause.
+// Report errors on the errors channel (cannot use testing.T, it runs on a different goroutine).
+// Return a tuple (state, teardown) where:
+// - state (containing the client) is ready to be passed to the step.Run() method.
+// - teardown is a function meant to be deferred from the test.
+func setupStepCreateServer(
+	errors chan<- error,
+	checker Checker,
+) (*multistep.BasicStateBag, func()) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		buf, err := io.ReadAll(r.Body)
+		if err != nil {
+			errors <- fmt.Errorf("fake server: reading request: %s", err)
+			return
+		}
+		reqDump := fmt.Sprintf("fake server: request:\n    %s %s\n    body: %s",
+			r.Method, r.URL.Path, string(buf))
+		if testing.Verbose() {
+			fmt.Println(reqDump)
+		}
+
+		enc := json.NewEncoder(w)
+		var response interface{}
+		action := schema.Action{
+			ID:     1,
+			Status: "success",
+		}
+
+		if r.Method == http.MethodPost && r.URL.Path == "/servers" {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusCreated)
+			response = schema.ServerCreateResponse{Action: action}
+		}
+
+		if r.Method == http.MethodGet && r.URL.Path == "/actions/1" {
+			w.Header().Set("Content-Type", "application/json")
+			response = schema.ActionGetResponse{Action: action}
+		}
+
+		if r.Method == http.MethodGet && r.URL.Path == "/ssh_keys/1" {
+			w.Header().Set("Content-Type", "application/json")
+			response = schema.SSHKeyGetResponse{
+				SSHKey: schema.SSHKey{ID: 1},
+			}
+		}
+
+		if err := checker(string(buf), r.URL.Path); err != nil {
+			errors <- fmt.Errorf("Error in checker")
+		}
+
+		if response != nil {
+			if err := enc.Encode(response); err != nil {
+				errors <- fmt.Errorf("fake server: encoding reply: %s", err)
+			}
+			return
+		}
+
+		// no match: report error
+		w.WriteHeader(http.StatusBadRequest)
+		errors <- fmt.Errorf(reqDump)
+	}))
+
+	state := multistep.BasicStateBag{}
+	client := hcloud.NewClient(hcloud.WithEndpoint(ts.URL))
+	state.Put("hcloudClient", client)
+
+	teardown := func() {
+		ts.Close()
+	}
+	return &state, teardown
+}

docs/builders/hcloud.mdx

@@ -112,6 +112,9 @@ builder.
   be upgraded to, without changing the disk size. Improves building performance.
   The resulting snapshot is compatible with smaller server types and disk sizes.
 
+- `networks` (array of integers) - List of Network IDs which should be
+  attached to the server private network interface at creation time.
+
 ## Basic Example
 
 Here is a basic example. It is completely valid as soon as you enter your own