diff --git a/metropolis/pkg/pki/testhelpers.go b/metropolis/pkg/pki/testhelpers.go
new file mode 100644
index 0000000..f975967
--- /dev/null
+++ b/metropolis/pkg/pki/testhelpers.go
@@ -0,0 +1,65 @@
+package pki
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"testing"
+)
+
+// EphemeralClusterCredentials returns a pair of node and manager
+// tls.Certificates signed by a CA certificate.
+//
+// All of these are ephemeral, ie. not stored anywhere - including the CA
+// certificate. This function is for use by tests which want to bring up a
+// minimum set of PKI credentials for a fake Metropolis cluster.
+func EphemeralClusterCredentials(t *testing.T) (node, manager tls.Certificate, ca *x509.Certificate) {
+	ctx := context.Background()
+
+	ns := Namespaced("unused")
+	caCert := Certificate{
+		Namespace: &ns,
+		Issuer:    SelfSigned,
+		Template:  CA("test cluster ca"),
+		Mode:      CertificateEphemeral,
+	}
+	caBytes, err := caCert.Ensure(ctx, nil)
+	if err != nil {
+		t.Fatalf("Could not ensure CA certificate: %v", err)
+	}
+	ca, err = x509.ParseCertificate(caBytes)
+	if err != nil {
+		t.Fatalf("Could not parse new CA certificate: %v", err)
+	}
+
+	nodeCert := Certificate{
+		Namespace: &ns,
+		Issuer:    &caCert,
+		Template:  Server([]string{"test-server"}, nil),
+		Mode:      CertificateEphemeral,
+	}
+	nodeBytes, err := nodeCert.Ensure(ctx, nil)
+	if err != nil {
+		t.Fatalf("Could not ensure node certificate: %v", err)
+	}
+	node = tls.Certificate{
+		Certificate: [][]byte{nodeBytes},
+		PrivateKey:  nodeCert.PrivateKey,
+	}
+
+	managerCert := Certificate{
+		Namespace: &ns,
+		Issuer:    &caCert,
+		Template:  Client("owner", nil),
+		Mode:      CertificateEphemeral,
+	}
+	managerBytes, err := managerCert.Ensure(ctx, nil)
+	if err != nil {
+		t.Fatalf("Could not ensure manager certificate: %v", err)
+	}
+	manager = tls.Certificate{
+		Certificate: [][]byte{managerBytes},
+		PrivateKey:  managerCert.PrivateKey,
+	}
+	return
+}