feature/init-containers (#104)

* adding initContainers property

* indentation

* adding doc and unit test

* formatting

Co-authored-by: David Salas <dsalas@alteryx.com>

charts/k8s-service/templates/_deployment_spec.tpl

@@ -314,6 +314,15 @@ spec:
 {{ toYaml $value | indent 10 }}
         {{- end }}
 
+
+    {{- if gt (len .Values.initContainers) 0 }}
+      initContainers:
+        {{- range $key, $value := .Values.initContainers }}
+        - name: {{ $key }}
+{{ toYaml $value | indent 10 }}
+        {{- end }}
+    {{- end }}
+
     {{- /* START IMAGE PULL SECRETS LOGIC */ -}}
     {{- if gt (len .Values.imagePullSecrets) 0 }}
       imagePullSecrets:

charts/k8s-service/values.yaml

@@ -154,6 +154,24 @@ shutdownDelay: 5
 #         value: docker
 sideCarContainers: {}
 
+# initContainers specifies any additional containers that should be deployed as init containers to the main application
+# container. This will be included in the Deployment container spec so that it will be included in the application Pod.
+# This is a nested map, where the first map key is used to name the container, with the nested map being injected as the
+# container spec.
+#
+# The following example specifies a flyway image as an init container with an environment variable, binding the
+# name `flyway`:
+#
+# EXAMPLE:
+#
+# initContainers:
+#   flyway:
+#     image: flyway/flyway
+#     env:
+#       - name: FLYWAY_LOCATIONS
+#         value: 'filesystem:/flyway/migrations'
+initContainers: {}
+
 # canary specifies test pod(s) that are deployed alongside your application's stable track pods.
 # It is useful for testing a new release candidate in a production environment with minimal disruption and
 # for allowing you to find any issues early.

test/k8s_service_template_test.go

@@ -635,6 +635,19 @@ func TestK8SServiceSideCarContainersRendersCorrectly(t *testing.T) {
 	assert.Equal(t, sideCarContainer.Image, "datadog/agent:latest")
 }
 
+func TestK8SServiceInitContainersRendersCorrectly(t *testing.T) {
+	t.Parallel()
+	deployment := renderK8SServiceDeploymentWithSetValues(
+		t,
+		map[string]string{
+			"initContainers.flyway.image": "flyway/flyway",
+		},
+	)
+	renderedContainers := deployment.Spec.Template.Spec.InitContainers
+	require.Equal(t, len(renderedContainers), 1)
+	assert.Equal(t, renderedContainers[0].Image, "flyway/flyway")
+}
+
 func TestK8SServiceDisableDefaultPort(t *testing.T) {
 	t.Parallel()
 	deployment := renderK8SServiceDeploymentWithSetValues(