Merge pull request #6 from pingidentity/GetAccessToken

Add service account access token source

go.mod

@@ -2,4 +2,21 @@ module github.com/pingidentity/identitycloud-go-client
 
 go 1.21
 
-require golang.org/x/oauth2 v0.23.0
+require (
+	github.com/google/uuid v1.6.0
+	github.com/lestrrat-go/jwx/v2 v2.1.2
+	golang.org/x/oauth2 v0.23.0
+)
+
+require (
+	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0 // indirect
+	github.com/goccy/go-json v0.10.3 // indirect
+	github.com/lestrrat-go/blackmagic v1.0.2 // indirect
+	github.com/lestrrat-go/httpcc v1.0.1 // indirect
+	github.com/lestrrat-go/httprc v1.0.6 // indirect
+	github.com/lestrrat-go/iter v1.0.2 // indirect
+	github.com/lestrrat-go/option v1.0.1 // indirect
+	github.com/segmentio/asm v1.2.0 // indirect
+	golang.org/x/crypto v0.28.0 // indirect
+	golang.org/x/sys v0.26.0 // indirect
+)

go.sum

@@ -1,4 +1,42 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0 h1:rpfIENRNNilwHwZeG5+P150SMrnNEcHYvcCuK6dPZSg=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0/go.mod h1:v57UDF4pDQJcEfFUCRop3lJL149eHGSe9Jvczhzjo/0=
+github.com/goccy/go-json v0.10.3 h1:KZ5WoDbxAIgm2HNbYckL0se1fHD6rz5j4ywS6ebzDqA=
+github.com/goccy/go-json v0.10.3/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/lestrrat-go/blackmagic v1.0.2 h1:Cg2gVSc9h7sz9NOByczrbUvLopQmXrfFx//N+AkAr5k=
+github.com/lestrrat-go/blackmagic v1.0.2/go.mod h1:UrEqBzIR2U6CnzVyUtfM6oZNMt/7O7Vohk2J0OGSAtU=
+github.com/lestrrat-go/httpcc v1.0.1 h1:ydWCStUeJLkpYyjLDHihupbn2tYmZ7m22BGkcvZZrIE=
+github.com/lestrrat-go/httpcc v1.0.1/go.mod h1:qiltp3Mt56+55GPVCbTdM9MlqhvzyuL6W/NMDA8vA5E=
+github.com/lestrrat-go/httprc v1.0.6 h1:qgmgIRhpvBqexMJjA/PmwSvhNk679oqD1RbovdCGW8k=
+github.com/lestrrat-go/httprc v1.0.6/go.mod h1:mwwz3JMTPBjHUkkDv/IGJ39aALInZLrhBp0X7KGUZlo=
+github.com/lestrrat-go/iter v1.0.2 h1:gMXo1q4c2pHmC3dn8LzRhJfP1ceCbgSiT9lUydIzltI=
+github.com/lestrrat-go/iter v1.0.2/go.mod h1:Momfcq3AnRlRjI5b5O8/G5/BvpzrhoFTZcn06fEOPt4=
+github.com/lestrrat-go/jwx/v2 v2.1.2 h1:6poete4MPsO8+LAEVhpdrNI4Xp2xdiafgl2RD89moBc=
+github.com/lestrrat-go/jwx/v2 v2.1.2/go.mod h1:pO+Gz9whn7MPdbsqSJzG8TlEpMZCwQDXnFJ+zsUVh8Y=
+github.com/lestrrat-go/option v1.0.1 h1:oAzP2fvZGQKWkvHa1/SAcFolBEca1oN+mQ7eooNBEYU=
+github.com/lestrrat-go/option v1.0.1/go.mod h1:5ZHFbivi4xwXxhxY9XHDe2FHo6/Z7WWmtT7T5nBBp3I=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/segmentio/asm v1.2.0 h1:9BQrFxC+YOHJlTlHGkTrFWf59nbL3XnCoFLTwDCI7ys=
+github.com/segmentio/asm v1.2.0/go.mod h1:BqMnlJP91P8d+4ibuonYZw9mfnzI9HfxselHZr5aAcs=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/crypto v0.28.0 h1:GBDwsMXVQi34v5CCYUm2jkJvu4cbtru2U4TN2PSyQnw=
+golang.org/x/crypto v0.28.0/go.mod h1:rmgy+3RHxRZMyY0jjAJShp2zgEdOqj2AO7U0pYmeQ7U=
 golang.org/x/oauth2 v0.23.0 h1:PbgcYx2W7i4LvjJWEbf0ngHV6qJYr86PkAV3bXdLEbs=
 golang.org/x/oauth2 v0.23.0/go.mod h1:XYTD2NtWslqkgxebSiOHnXEap4TF09sJSc7H1sXbhtI=
+golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
+golang.org/x/sys v0.26.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

identitycloud/access_token.go

@@ -0,0 +1,92 @@
+package identitycloud
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/lestrrat-go/jwx/v2/jwa"
+	"github.com/lestrrat-go/jwx/v2/jwk"
+	"github.com/lestrrat-go/jwx/v2/jwt"
+	"golang.org/x/oauth2"
+)
+
+var (
+	_ oauth2.TokenSource = ServiceAccountTokenSource{}
+)
+
+type ServiceAccountTokenSource struct {
+	TenantFqdn               string
+	ServiceAccountId         string
+	ServiceAccountPrivateKey string
+	Scopes                   []string
+}
+
+func (s ServiceAccountTokenSource) Token() (*oauth2.Token, error) {
+	jwt, err := s.buildJwt()
+	if err != nil {
+		return nil, fmt.Errorf("failed to build jwt: %w", err)
+	}
+
+	formData := url.Values{}
+	formData.Add("client_id", "service-account")
+	formData.Add("grant_type", "urn:ietf:params:oauth:grant-type:jwt-bearer")
+	formData.Add("assertion", jwt)
+	formData.Add("scope", strings.Join(s.Scopes, " "))
+
+	httpClient := &http.Client{}
+	httpResp, err := httpClient.Post(s.tokenUrl(), "application/x-www-form-urlencoded", strings.NewReader(formData.Encode()))
+	if err != nil {
+		return nil, fmt.Errorf("failed to request access token with service account: %w", err)
+	}
+
+	defer httpResp.Body.Close()
+	body, err := io.ReadAll(httpResp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read access token response body: %w", err)
+	}
+
+	var token oauth2.Token
+	err = json.Unmarshal(body, &token)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal access token response: %w", err)
+	}
+
+	token.Expiry = time.Now().Add(time.Duration(token.ExpiresIn) * time.Second)
+
+	return &token, nil
+}
+
+func (s ServiceAccountTokenSource) buildJwt() (string, error) {
+	key, err := jwk.ParseKey([]byte(s.ServiceAccountPrivateKey))
+	if err != nil {
+		return "", fmt.Errorf("failed to parse private key: %w", err)
+	}
+
+	tok, err := jwt.NewBuilder().
+		Issuer(s.ServiceAccountId).
+		Subject(s.ServiceAccountId).
+		Expiration(time.Now().Add(time.Second * 899)).
+		JwtID(uuid.New().String()).
+		Audience([]string{s.tokenUrl()}).
+		Build()
+	if err != nil {
+		return "", fmt.Errorf("failed to build jwt: %w", err)
+	}
+
+	token, err := jwt.Sign(tok, jwt.WithKey(jwa.RS256, key))
+	if err != nil {
+		return "", fmt.Errorf("failed to sign jwt: %w", err)
+	}
+
+	return string(token), nil
+}
+
+func (s ServiceAccountTokenSource) tokenUrl() string {
+	return fmt.Sprintf("https://%s:443/am/oauth2/access_token", s.TenantFqdn)
+}