client: add retryable client with default

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/grpc-ecosystem/go-grpc-middleware v1.3.0
 	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.12.0
+	github.com/hashicorp/go-retryablehttp v0.7.1
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/magiconair/properties v1.8.6
 	github.com/prometheus/client_golang v1.13.0
@@ -93,7 +94,6 @@ require (
 	github.com/hashicorp/go-immutable-radix v1.3.1 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-plugin v1.4.5 // indirect
-	github.com/hashicorp/go-retryablehttp v0.7.1 // indirect
 	github.com/hashicorp/go-rootcerts v1.0.2 // indirect
 	github.com/hashicorp/go-secure-stdlib/mlock v0.1.2 // indirect
 	github.com/hashicorp/go-secure-stdlib/parseutil v0.1.7 // indirect

pkg/api/client.go

@@ -27,6 +27,8 @@ import (
 	"net/url"
 	"path"
 	"time"
+
+	"github.com/hashicorp/go-retryablehttp"
 )
 
 type CertificateResponse struct {
@@ -61,8 +63,12 @@ const (
 	rootCertPath    = "/api/v1/rootCert"
 )
 
-// SigstorePublicServerURL is the URL of Sigstore's public Fulcio service.
-const SigstorePublicServerURL = "https://fulcio.sigstore.dev"
+const (
+	// SigstorePublicServerURL is the URL of Sigstore's public Fulcio service.
+	SigstorePublicServerURL = "https://fulcio.sigstore.dev"
+	// DefaultRetryCount is the default number of retries.
+	DefaultRetryCount = 3
+)
 
 // LegacyClient is the interface for accessing the Fulcio API.
 type LegacyClient interface {
@@ -80,13 +86,15 @@ type ClientOption func(*clientOptions)
 func NewClient(url *url.URL, opts ...ClientOption) LegacyClient {
 	o := makeOptions(opts...)
 
+	retryableClient := retryablehttp.NewClient()
+	retryableClient.RetryMax = int(o.RetryCount)
+
+	httpClient := retryableClient.StandardClient()
+	httpClient.Timeout = o.Timeout
+	httpClient.Transport = createRoundTripper(httpClient.Transport, o)
 	return &client{
 		baseURL: url,
-		client: &http.Client{
-			Transport: createRoundTripper(http.DefaultTransport, o),
-			Timeout:   o.Timeout,
-		},
-	}
+		client:  httpClient}
 }
 
 type client struct {
@@ -179,13 +187,15 @@ func (c *client) RootCert() (*RootResponse, error) {
 }
 
 type clientOptions struct {
-	UserAgent string
-	Timeout   time.Duration
+	UserAgent  string
+	Timeout    time.Duration
+	RetryCount uint
 }
 
 func makeOptions(opts ...ClientOption) *clientOptions {
 	o := &clientOptions{
-		UserAgent: "",
+		UserAgent:  "",
+		RetryCount: DefaultRetryCount,
 	}
 
 	for _, opt := range opts {
@@ -209,6 +219,13 @@ func WithUserAgent(userAgent string) ClientOption {
 	}
 }
 
+// WithRetryCount sets the number of retries.
+func WithRetryCount(retryCount uint) ClientOption {
+	return func(o *clientOptions) {
+		o.RetryCount = retryCount
+	}
+}
+
 type roundTripper struct {
 	http.RoundTripper
 	UserAgent string

pkg/api/client_test.go

@@ -60,3 +60,32 @@ func TestTimeoutOption(t *testing.T) {
 		t.Error("expected client to specifically have a timeout error")
 	}
 }
+
+func TestRetryCountOption(t *testing.T) {
+	currentCount := 0
+	expectedCount := 2
+	ts := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			currentCount++
+			file := []byte{}
+
+			if currentCount < expectedCount {
+				w.WriteHeader(http.StatusInternalServerError)
+			} else {
+				w.WriteHeader(http.StatusOK)
+				_, _ = w.Write(file)
+			}
+
+		}))
+
+	lc := NewClient(nil, WithRetryCount(2))
+	c, ok := lc.(*client)
+	if !ok {
+		t.Fatal("wrong legacy client implementation")
+	}
+
+	_, err := c.client.Get(ts.URL)
+	if err != nil {
+		t.Error("expected client to retry requestt")
+	}
+}