added extra-secret annotation for adding kube-secrets

agent-inject/agent/agent.go

@@ -123,6 +123,10 @@ type Agent struct {
 	// SetSecurityContext controls whether the injected containers have a
 	// SecurityContext set.
 	SetSecurityContext bool
+
+ 	// ExtraSecret is the Kubernetes secret to mount as a volume in the Vault agent container
+	// which can be referenced by the Agent config for secrets. Mounted at /vault/custom/
+	ExtraSecret string
 }
 
 type Secret struct {
@@ -228,6 +232,7 @@ func New(pod *corev1.Pod, patches []*jsonpatch.JsonPatchOperation) (*Agent, erro
 		ServiceAccountName: saName,
 		ServiceAccountPath: saPath,
 		Status:             pod.Annotations[AnnotationAgentStatus],
+		ExtraSecret:        pod.Annotations[AnnotationAgentExtraSecret],
 		Vault: Vault{
 			Address:          pod.Annotations[AnnotationVaultService],
 			AuthPath:         pod.Annotations[AnnotationVaultAuthPath],
@@ -375,6 +380,14 @@ func (a *Agent) Patch() ([]byte, error) {
 			"/spec/volumes")...)
 	}
 
+	// Add ExtraSecret if one was provided
+	if a.ExtraSecret != "" {
+		a.Patches = append(a.Patches, addVolumes(
+			a.Pod.Spec.Volumes,
+			[]corev1.Volume{a.ContainerExtraSecretVolume()},
+			"/spec/volumes")...)
+	}
+
 	// Add TLS Secret if one was provided
 	if a.Vault.TLSSecret != "" {
 		a.Patches = append(a.Patches, addVolumes(

agent-inject/agent/annotations.go

@@ -81,6 +81,10 @@ const (
 	// configuration file and templates can be found.
 	AnnotationAgentConfigMap = "vault.hashicorp.com/agent-configmap"
 
+	// AnnotationAgentExtraSecret is the name of a Kubernetes secret that will be mounted
+	// into the Vault agent container so that the agent config can reference secrets.
+	AnnotationAgentExtraSecret = "vault.hashicorp.com/agent-extra-secret"
+
 	// AnnotationAgentLimitsCPU sets the CPU limit on the Vault Agent containers.
 	AnnotationAgentLimitsCPU = "vault.hashicorp.com/agent-limits-cpu"
 

agent-inject/agent/container_init_sidecar.go

@@ -26,6 +26,14 @@ func (a *Agent) ContainerInitSidecar() (corev1.Container, error) {
 	}
 	volumeMounts = append(volumeMounts, a.ContainerVolumeMounts()...)
 
+	if a.ExtraSecret != "" {
+		volumeMounts = append(volumeMounts, corev1.VolumeMount{
+			Name:      extraSecretVolumeName,
+			MountPath: extraSecretVolumePath,
+			ReadOnly:  true,
+		})
+	}
+
 	arg := DefaultContainerArg
 
 	if a.ConfigMapName != "" {

agent-inject/agent/container_sidecar.go

@@ -37,6 +37,14 @@ func (a *Agent) ContainerSidecar() (corev1.Container, error) {
 	}
 	volumeMounts = append(volumeMounts, a.ContainerVolumeMounts()...)
 
+	if a.ExtraSecret != "" {
+		volumeMounts = append(volumeMounts, corev1.VolumeMount{
+			Name:      extraSecretVolumeName,
+			MountPath: extraSecretVolumePath,
+			ReadOnly:  true,
+		})
+	}
+
 	arg := DefaultContainerArg
 
 	if a.ConfigMapName != "" {

agent-inject/agent/container_sidecar_test.go

@@ -28,6 +28,9 @@ func TestContainerSidecarVolume(t *testing.T) {
 		AnnotationVaultSecretVolumePath: "/etc/default_path",
 
 		fmt.Sprintf("%s-%s", AnnotationAgentInjectSecret, "secret3"): "secret/secret3",
+
+		// Test adding an extra secret from Kube secrets for reference by Agent config
+		fmt.Sprintf("%s", AnnotationAgentExtraSecret): "extrasecret",
 	}
 
 	pod := testPod(annotations)
@@ -46,7 +49,7 @@ func TestContainerSidecarVolume(t *testing.T) {
 	container, err := agent.ContainerSidecar()
 
 	// One token volume mount, one config volume mount and two secrets volume mounts
-	require.Equal(t, 4, len(container.VolumeMounts))
+	require.Equal(t, 5, len(container.VolumeMounts))
 
 	require.Equal(
 		t,
@@ -71,6 +74,11 @@ func TestContainerSidecarVolume(t *testing.T) {
 				MountPath: "/etc/container_environment",
 				ReadOnly:  false,
 			},
+			corev1.VolumeMount{
+				Name:      extraSecretVolumeName,
+				MountPath: extraSecretVolumePath,
+				ReadOnly:  true,
+			},
 		},
 		container.VolumeMounts,
 	)

agent-inject/agent/container_volume.go

@@ -17,6 +17,8 @@ const (
 	tlsSecretVolumeName    = "vault-tls-secrets"
 	tlsSecretVolumePath    = "/vault/tls"
 	secretVolumePath       = "/vault/secrets"
+	extraSecretVolumeName  = "extra-secrets"
+	extraSecretVolumePath  = "/vault/custom"
 )
 
 func (a *Agent) getUniqueMountPaths() []string {
@@ -104,6 +106,19 @@ func (a *Agent) ContainerConfigMapVolume() corev1.Volume {
 	}
 }
 
+// ContainerExtraSecretVolume returns a volume to mount a Kube secret
+// if the user supplied one.
+func (a *Agent) ContainerExtraSecretVolume() corev1.Volume {
+	return corev1.Volume{
+		Name: extraSecretVolumeName,
+		VolumeSource: corev1.VolumeSource{
+			Secret: &corev1.SecretVolumeSource{
+				SecretName: a.ExtraSecret,
+			},
+		},
+	}
+}
+
 // ContainerTLSSecretVolume returns a volume to mount TLS secrets
 // if the user supplied any.
 func (a *Agent) ContainerTLSSecretVolume() corev1.Volume {