Allow custom args on deployment spec (#143)

* feat(custom args): enable support for custom args on deployment spec

* tests(template): add template tests for the new args parameter

charts/k8s-service/templates/_deployment_spec.tpl

@@ -159,7 +159,10 @@ spec:
           command:
 {{ toYaml .Values.containerCommand | indent 12 }}
           {{- end }}
-
+          {{- if .Values.containerArgs }}
+          args:
+{{ toYaml .Values.containerArgs | indent 12 }}
+          {{- end }}
           {{- if index $hasInjectionTypes "exposePorts" }}
           ports:
             {{- /*

charts/k8s-service/values.yaml

@@ -1,3 +1,4 @@
+---
 #----------------------------------------------------------------------------------------------------------------------
 # CHART PARAMETERS
 # This file declares the configuration input values for the k8s-service Helm chart.
@@ -34,7 +35,6 @@
 # applicationName is a string that names the application. This is used to label the pod and to name the main application
 # container in the pod spec. The label is keyed under "gruntwork.io/app-name"
 
-
 #----------------------------------------------------------------------------------------------------------------------
 # OPTIONAL VALUES
 # These values have defaults, but may be overridden by the operator
@@ -50,6 +50,16 @@
 #   - "Hello World"
 containerCommand: null
 
+# containerArgs is a list of strings that indicate custom args that will be passed to the container (CMD) place of the default
+# configured on the image. Omit to use the default args configured in the image
+#
+# Example (run echo "Hello World"):
+#
+# containerArgs:
+#   - "echo"
+#   - "Hello World"
+containerArgs: null
+
 # containerPorts is a map that specifies the ports to open on the container. This is a nested map: the first map lists
 # the named ports, while the second layer lists the port spec. The named references can be used to refer to the specific
 # port of the container in other resources, like Service.
@@ -126,7 +136,6 @@ securityContext: {}
 #   fsGroup: 2000
 podSecurityContext: {}
 
-
 # shutdownDelay is the number of seconds to delay the shutdown sequence of the Pod by. This is implemented as a sleep
 # call in the preStop hook. By default, this chart includes a preStop hook with a shutdown delay for eventual
 # consistency reasons. You can read more about why you might want to do this in

test/k8s_service_template_test.go

@@ -600,6 +600,34 @@ func TestK8SServiceWithContainerCommandHasCommandSpec(t *testing.T) {
 	assert.Equal(t, appContainer.Command, []string{"echo", "Hello world"})
 }
 
+// Test that omitting containerArgs does not set args attribute on the Deployment container spec.
+func TestK8SServiceDefaultHasNullArgSpec(t *testing.T) {
+	t.Parallel()
+
+	deployment := renderK8SServiceDeploymentWithSetValues(t, map[string]string{})
+	renderedPodContainers := deployment.Spec.Template.Spec.Containers
+	require.Equal(t, len(renderedPodContainers), 1)
+	appContainer := renderedPodContainers[0]
+	assert.Nil(t, appContainer.Args)
+}
+
+// Test that setting containerCommand sets the command attribute on the Deployment container spec.
+func TestK8SServiceWithContainerArgsHasArgsSpec(t *testing.T) {
+	t.Parallel()
+
+	deployment := renderK8SServiceDeploymentWithSetValues(
+		t,
+		map[string]string{
+			"containerArgs[0]": "echo",
+			"containerArgs[1]": "Hello world",
+		},
+	)
+	renderedPodContainers := deployment.Spec.Template.Spec.Containers
+	require.Equal(t, len(renderedPodContainers), 1)
+	appContainer := renderedPodContainers[0]
+	assert.Equal(t, appContainer.Args, []string{"echo", "Hello world"})
+}
+
 // Test that providing tls configuration to Ingress renders correctly
 func TestK8SServiceIngressMultiCert(t *testing.T) {
 	t.Parallel()