Add ability to authorize using a Service Account (vmware#562)

* add ability to authorize using a service account

---------

Signed-off-by: Adam Jasinski <jasinskia@vmware.com>

.changes/v2.20.0/562-improvements.md

@@ -0,0 +1,2 @@
+* Add `SetServiceAccountApiToken` method of `*VCDClient` that allows 
+  authenticating using a service account token file and handles the refresh token rotation [GH-562]

README.md

@@ -114,7 +114,7 @@ func main() {
 
 ## Authentication
 
-You can authenticate to the vCD in four ways:
+You can authenticate to the vCD in five ways:
 
 * With a System Administration user and password (`administrator@system`)
 * With an Organization user and password (`tenant-admin@org-name`)
@@ -133,6 +133,11 @@ For the above two methods, you use:
 The file `scripts/get_token.sh` provides a handy method of extracting the token
 (`x-vcloud-authorization` value) for future use.
 
+* With a service account token (the file needs to have `r+w` rights)
+```go
+	err := vcdClient.SetServiceAccountApiToken(Org, "tokenfile.json")
+```
+
 * SAML user and password (works with ADFS as IdP using WS-TRUST endpoint
   "/adfs/services/trust/13/usernamemixed"). One must pass `govcd.WithSamlAdfs(true,customAdfsRptId)`
   and username must be formatted so that ADFS understands it ('user@contoso.com' or

govcd/api_token.go

@@ -9,9 +9,13 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/fs"
 	"net/http"
 	"net/url"
+	"os"
+	"path"
 	"strings"
+	"time"
 
 	"github.com/vmware/go-vcloud-director/v2/types/v56"
 	"github.com/vmware/go-vcloud-director/v2/util"
@@ -31,6 +35,47 @@ func (vcdClient *VCDClient) SetApiToken(org, apiToken string) (*types.ApiTokenRe
 	return tokenRefresh, nil
 }
 
+// SetServiceAccountApiToken reads the current Service Account API token,
+// sets the client's bearer token and fetches a new API token for next
+// authentication request using SetApiToken and overwrites the old file.
+func (vcdClient *VCDClient) SetServiceAccountApiToken(org, apiTokenFile string) error {
+	if vcdClient.Client.APIVCDMaxVersionIs("< 37.0") {
+		version, err := vcdClient.Client.GetVcdFullVersion()
+		if err == nil {
+			return fmt.Errorf("minimum version for Service Account authentication is 10.4 - Version detected: %s", version.Version)
+		}
+		// If we can't get the VCD version, we return API version info
+		return fmt.Errorf("minimum API version for Service Account authentication is 37.0 - Version detected: %s", vcdClient.Client.APIVersion)
+	}
+
+	saApiToken := &types.ApiTokenRefresh{}
+	// Read file contents and unmarshal them to saApiToken
+	err := readFileAndUnmarshalJSON(apiTokenFile, saApiToken)
+	if err != nil {
+		return err
+	}
+
+	// Get bearer token and update the refresh token for the next authentication request
+	saApiToken, err = vcdClient.SetApiToken(org, saApiToken.RefreshToken)
+	if err != nil {
+		return err
+	}
+
+	// leave only the refresh token to not leave any sensitive information
+	saApiToken = &types.ApiTokenRefresh{
+		RefreshToken: saApiToken.RefreshToken,
+		TokenType:    "Service Account",
+		UpdatedBy:    vcdClient.Client.UserAgent,
+		UpdatedOn:    time.Now().Format(time.RFC3339),
+	}
+	err = marshalJSONAndWriteToFile(apiTokenFile, saApiToken, 0600)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // GetBearerTokenFromApiToken uses an API token to retrieve a bearer token
 // using the refresh token operation.
 func (vcdClient *VCDClient) GetBearerTokenFromApiToken(org, token string) (*types.ApiTokenRefresh, error) {
@@ -112,3 +157,34 @@ func (vcdClient *VCDClient) GetBearerTokenFromApiToken(org, token string) (*type
 	}
 	return &tokenDef, nil
 }
+
+// readFileAndUnmarshalJSON reads a file and unmarshals it to the given variable
+func readFileAndUnmarshalJSON(filename string, object any) error {
+	data, err := os.ReadFile(path.Clean(filename))
+	if err != nil {
+		return fmt.Errorf("failed to read from file: %s", err)
+	}
+
+	err = json.Unmarshal(data, object)
+	if err != nil {
+		return fmt.Errorf("failed to unmarshal file contents to the object: %s", err)
+	}
+
+	return nil
+}
+
+// marshalJSONAndWriteToFile marshalls the given object into JSON and writes
+// to a file with the given permissions in octal format (e.g 0600)
+func marshalJSONAndWriteToFile(filename string, object any, permissions int) error {
+	data, err := json.MarshalIndent(object, " ", " ")
+	if err != nil {
+		return fmt.Errorf("error marshalling object to JSON: %s", err)
+	}
+
+	err = os.WriteFile(filename, data, fs.FileMode(permissions))
+	if err != nil {
+		return fmt.Errorf("error writing to the file: %s", err)
+	}
+
+	return nil
+}

govcd/api_token_unit_test.go

@@ -0,0 +1,75 @@
+//go:build unit || ALL
+
+/*
+* Copyright 2023 VMware, Inc.  All rights reserved.  Licensed under the Apache v2 License.
+ */
+
+package govcd
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_readFileAndUnmarshalJSON(t *testing.T) {
+	type args struct {
+		filename string
+		object   *testEntity
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *testEntity
+		wantErr bool
+	}{
+		{
+			name: "simpleCase",
+			args: args{
+				filename: "test-resources/test.json",
+				object:   &testEntity{},
+			},
+			want:    &testEntity{Name: "test"},
+			wantErr: false,
+		},
+		{
+			name: "emptyFile",
+			args: args{
+				filename: "test-resources/test_empty.json",
+				object:   &testEntity{},
+			},
+			want:    &testEntity{},
+			wantErr: true,
+		},
+		{
+			name: "emptyJSON",
+			args: args{
+				filename: "test-resources/test_emptyjson.json",
+				object:   &testEntity{},
+			},
+			want:    &testEntity{},
+			wantErr: false,
+		},
+		{
+			name: "nonexistentFile",
+			args: args{
+				filename: "thisfiledoesntexist.json",
+				object:   &testEntity{},
+			},
+			want:    &testEntity{},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := readFileAndUnmarshalJSON(tt.args.filename, tt.args.object)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("readFileAndUnmarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			if !reflect.DeepEqual(tt.args.object, tt.want) {
+				t.Errorf("readFileAndUnmarshalJSON() = %v, want %v", tt.args.object, tt.want)
+			}
+		})
+	}
+}

govcd/generic_functions.go

@@ -1,6 +1,8 @@
 package govcd
 
-import "fmt"
+import (
+	"fmt"
+)
 
 // oneOrError is used to cover up a common pattern in this codebase which is usually used in
 // GetXByName functions.

govcd/generic_functions_unit_test.go

@@ -3,7 +3,6 @@
 /*
 * Copyright 2023 VMware, Inc.  All rights reserved.  Licensed under the Apache v2 License.
  */
-
 package govcd
 
 import (
@@ -29,9 +28,9 @@ func Test_oneOrError(t *testing.T) {
 			args: args{
 				key:         "name",
 				name:        "test",
-				entitySlice: []*testEntity{{name: "test"}},
+				entitySlice: []*testEntity{{Name: "test"}},
 			},
-			want:    &testEntity{name: "test"},
+			want:    &testEntity{Name: "test"},
 			wantErr: false,
 		},
 		{
@@ -50,7 +49,7 @@ func Test_oneOrError(t *testing.T) {
 			args: args{
 				key:         "name",
 				name:        "test",
-				entitySlice: []*testEntity{{name: "test"}, {name: "best"}},
+				entitySlice: []*testEntity{{Name: "test"}, {Name: "best"}},
 			},
 			want:    nil,
 			wantErr: true,
@@ -60,7 +59,7 @@ func Test_oneOrError(t *testing.T) {
 			args: args{
 				key:         "name",
 				name:        "test",
-				entitySlice: []*testEntity{{name: "test"}, {name: "best"}, {name: "rest"}},
+				entitySlice: []*testEntity{{Name: "test"}, {Name: "best"}, {Name: "rest"}},
 			},
 			want:    nil,
 			wantErr: true,
@@ -98,5 +97,5 @@ func Test_oneOrError(t *testing.T) {
 }
 
 type testEntity struct {
-	name string
+	Name string `json:"name"`
 }

govcd/test-resources/test.json

@@ -0,0 +1 @@
+{ "Name": "test" }

govcd/test-resources/test_emptyJSON.json

@@ -0,0 +1 @@
+{}

types/v56/types.go

@@ -3257,10 +3257,12 @@ type UpdateVdcStorageProfiles struct {
 
 // ApiTokenRefresh contains the access token resulting from a refresh_token operation
 type ApiTokenRefresh struct {
-	AccessToken  string      `json:"access_token"`
-	TokenType    string      `json:"token_type"`
-	ExpiresIn    int         `json:"expires_in"`
-	RefreshToken interface{} `json:"refresh_token"`
+	AccessToken  string `json:"access_token,omitempty"`
+	TokenType    string `json:"token_type,omitempty"`
+	ExpiresIn    int    `json:"expires_in,omitempty"`
+	RefreshToken string `json:"refresh_token,omitempty"`
+	UpdatedBy    string `json:"updated_by,omitempty"`
+	UpdatedOn    string `json:"updated_on,omitempty"`
 }
 
 /**/