feat: add support node backed emptyDirs (#106)

charts/k8s-service/templates/_deployment_spec.tpl

@@ -71,6 +71,9 @@ We need this because certain sections are omitted if there are no volumes or env
 {{- if gt (len .Values.scratchPaths) 0 -}}
   {{- $_ := set $hasInjectionTypes "hasVolume" true -}}
 {{- end -}}
+{{- if gt (len .Values.emptyDirs) 0 -}}
+  {{- $_ := set $hasInjectionTypes "hasVolume" true -}}
+{{- end -}}
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -307,6 +310,10 @@ spec:
             - name: {{ $name }}
               mountPath: {{ quote $value }}
           {{- end }}
+          {{- range $name, $value := .Values.emptyDirs }}
+            - name: {{ $name }}
+              mountPath: {{ quote $value }}
+          {{- end }}
           {{- /* END VOLUME MOUNT LOGIC */ -}}
 
         {{- range $key, $value := .Values.sideCarContainers }}
@@ -380,6 +387,10 @@ spec:
           emptyDir:
             medium: "Memory"
     {{- end }}
+    {{- range $name, $value := .Values.emptyDirs }}
+        - name: {{ $name }}
+          emptyDir: {}
+    {{- end }}
     {{- /* END VOLUME LOGIC */ -}}
 
     {{- with .Values.nodeSelector }}

charts/k8s-service/values.yaml

@@ -465,6 +465,15 @@ persistentVolumes: {}
 #   example: /mnt/scratch
 scratchPaths: {}
 
+# emptyDirs is a map of key value pairs that specifies which paths in the container should be setup as an emptyDir volume.
+# Under the hood each entry in the map is converted to a volume stored on whatever medium that backs the node
+# (disk, SSD, network storage) and mounted into the container on the path provided as the value.
+#
+# EXAMPLE:
+# emptyDirs:
+#   example: /mnt/example
+emptyDirs: {}
+
 # secrets is a map that specifies the Secret resources that should be exposed to the main application container. Each entry in
 # the map represents a Secret resource. The key refers to the name of the Secret that should be exposed, with the value
 # specifying how to expose the Secret. The value is also a map and has the following attributes:

test/k8s_service_volume_template_test.go

@@ -1,3 +1,4 @@
+//go:build all || tpl
 // +build all tpl
 
 // NOTE: We use build flags to differentiate between template tests and integration tests so that you can conveniently
@@ -81,3 +82,36 @@ func TestK8SServiceDeploymentAddingPersistentVolumes(t *testing.T) {
 	assert.Equal(t, volName, volume.Name)
 	assert.Equal(t, volClaim, volume.PersistentVolumeClaim.ClaimName)
 }
+
+func TestK8SServiceDeploymentAddingEmptyDirs(t *testing.T) {
+	t.Parallel()
+
+	volName := "empty-dir"
+	volMountPath := "/mnt/empty"
+
+	deployment := renderK8SServiceDeploymentWithSetValues(
+		t,
+		map[string]string{
+			fmt.Sprintf("emptyDirs.%s", volName): volMountPath,
+		},
+	)
+
+	// Verify that there is only one container
+	renderedPodContainers := deployment.Spec.Template.Spec.Containers
+	require.Equal(t, len(renderedPodContainers), 1)
+	podContainer := renderedPodContainers[0]
+
+	// Verify that a mount has been created for the emptyDir
+	mounts := podContainer.VolumeMounts
+	assert.Equal(t, len(mounts), 1)
+	mount := mounts[0]
+	assert.Equal(t, volName, mount.Name)
+	assert.Equal(t, volMountPath, mount.MountPath)
+
+	// Verify that a volume has been declared for the emptyDir
+	volumes := deployment.Spec.Template.Spec.Volumes
+	assert.Equal(t, len(volumes), 1)
+	volume := volumes[0]
+	assert.Equal(t, volName, volume.Name)
+	assert.Empty(t, volume.EmptyDir)
+}