feat: add HealthCheck for remote kms

pkg/kms/webkms/remotekms.go

@@ -15,6 +15,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 	"strings"
 	"time"
 
@@ -305,6 +306,28 @@ func (r *RemoteKMS) createKey(kt kms.KeyType) (string, []byte, error) {
 	return httpResp.KeyURL, httpResp.PublicKey, nil
 }
 
+// HealthCheck check kms.
+func (r *RemoteKMS) HealthCheck() error {
+	parseURL, err := url.Parse(r.keystoreURL)
+	if err != nil {
+		return err
+	}
+
+	resp, err := r.getHTTPRequest(parseURL.Scheme + "://" + parseURL.Host + "/healthcheck")
+	if err != nil {
+		return err
+	}
+
+	// handle response
+	defer closeResponseBody(resp.Body, logger, "HealthCheck")
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("kms health check return %d status code", resp.StatusCode)
+	}
+
+	return nil
+}
+
 // Get key handle for the given KeyID remotely
 // Returns:
 //  - handle instance representing a remote keystore URL including KeyID

pkg/kms/webkms/remotekms_test.go

@@ -272,6 +272,27 @@ func TestCreateKeyWithLocationInResponseBody(t *testing.T) {
 	require.Contains(t, err.Error(), "failingUnmarshal always fails")
 }
 
+func TestHealthCheck(t *testing.T) {
+	hf := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusServiceUnavailable)
+	})
+
+	server, url, client := CreateMockHTTPServerAndClient(t, hf)
+	defaultKeystoreURL := fmt.Sprintf("%s/%s", strings.ReplaceAll(KeystoreEndpoint,
+		"{serverEndpoint}", url), defaultKeyStoreID)
+
+	defer func() {
+		e := server.Close()
+		require.NoError(t, e)
+	}()
+
+	remoteKMS := New(defaultKeystoreURL, client)
+
+	err := remoteKMS.HealthCheck()
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "kms health check return 503 status code")
+}
+
 func TestRemoteKeyStoreWithHeadersFunc(t *testing.T) {
 	xRootCapabilityHeaderValue := []byte("DUMMY")