Deduplicate parsing used when applying annotations

To apply the special "tag all" annotation, we need the names of the
containers in a controller. Instead of having a struct definition to
parse just for this, use the existing resource parsing, extending it
just enough to get the containers from things that have containers.

The prior code also failed to take into account List resources and
multidocs; this is no longer a problem since the resource package
already accounts for them.

cluster/kubernetes/policies.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 
 	"github.com/pkg/errors"
-	yaml "gopkg.in/yaml.v2"
 
 	"github.com/weaveworks/flux"
 	"github.com/weaveworks/flux/cluster/kubernetes/resource"
@@ -22,7 +21,7 @@ func (m *Manifests) UpdatePolicies(in []byte, resourceID flux.ResourceID, update
 	// what all the containers are.
 	if tagAll, ok := add.Get(policy.TagAll); ok {
 		add = add.Without(policy.TagAll)
-		containers, err := parseForContainers(in)
+		containers, err := parseForContainers(resourceID, in)
 		if err != nil {
 			return nil, err
 		}
@@ -48,45 +47,21 @@ func (m *Manifests) UpdatePolicies(in []byte, resourceID flux.ResourceID, update
 	return (KubeYAML{}).Annotate(in, ns, kind, name, args...)
 }
 
-type containerManifest struct {
-	Spec struct {
-		Template struct {
-			Spec struct {
-				Containers []struct {
-					Name  string `yaml:"name"`
-					Image string `yaml:"image"`
-				} `yaml:"containers"`
-			} `yaml:"spec"`
-		} `yaml:"template"`
-		JobTemplate struct {
-			Spec struct {
-				Template struct {
-					Spec struct {
-						Containers []struct {
-							Name  string `yaml:"name"`
-							Image string `yaml:"image"`
-						} `yaml:"containers"`
-					} `yaml:"spec"`
-				} `yaml:"template"`
-			} `yaml:"spec"`
-		} `yaml:"jobTemplate"`
-	} `yaml:"spec"`
-}
-
-func parseForContainers(def []byte) ([]string, error) {
-	var m containerManifest
-	if err := yaml.Unmarshal(def, &m); err != nil {
-		return nil, errors.Wrap(err, "decoding manifest")
+func parseForContainers(id flux.ResourceID, def []byte) ([]string, error) {
+	all, err := resource.ParseMultidoc(def, "stdin")
+	if err != nil {
+		return nil, err
 	}
-
-	var names []string
-	for _, c := range m.Spec.Template.Spec.Containers {
-		names = append(names, c.Name)
+	res, ok := all[id.String()]
+	if !ok {
+		return nil, errors.New("resource " + id.String() + " not found")
 	}
-	for _, c := range m.Spec.JobTemplate.Spec.Template.Spec.Containers {
-		names = append(names, c.Name)
+	workload, ok := res.(resource.Workload)
+	if !ok {
+		return nil, errors.New("resource " + id.String() + " does not have containers")
 	}
-	return names, nil
+
+	return workload.ContainerNames(), nil
 }
 
 func (m *Manifests) ServicesWithPolicies(root string) (policy.ResourceMap, error) {

cluster/kubernetes/resource/cronjob.go

@@ -2,4 +2,17 @@ package resource
 
 type CronJob struct {
 	baseObject
+	Spec CronJobSpec
+}
+
+type CronJobSpec struct {
+	JobTemplate struct {
+		Spec struct {
+			Template PodTemplate
+		}
+	}
+}
+
+func (c CronJob) ContainerNames() []string {
+	return c.Spec.JobTemplate.Spec.Template.ContainerNames()
 }

cluster/kubernetes/resource/daemonset.go

@@ -8,3 +8,7 @@ type DaemonSet struct {
 type DaemonSetSpec struct {
 	Template PodTemplate
 }
+
+func (ds DaemonSet) ContainerNames() []string {
+	return ds.Spec.Template.ContainerNames()
+}

cluster/kubernetes/resource/deployment.go

@@ -9,3 +9,7 @@ type DeploymentSpec struct {
 	Replicas int
 	Template PodTemplate
 }
+
+func (d Deployment) ContainerNames() []string {
+	return d.Spec.Template.ContainerNames()
+}

cluster/kubernetes/resource/resource.go

@@ -15,6 +15,11 @@ const (
 	PolicyPrefix = "flux.weave.works/"
 )
 
+// Use for extracting the list of containers out of a resource.
+type Workload interface {
+	ContainerNames() []string
+}
+
 // -- unmarshaling code for specific object and field types
 
 // struct to embed in objects, to provide default implementation

cluster/kubernetes/resource/spec.go

@@ -13,6 +13,14 @@ type PodTemplate struct {
 	Spec     PodSpec
 }
 
+func (t PodTemplate) ContainerNames() []string {
+	var result []string
+	for _, c := range t.Spec.Containers {
+		result = append(result, c.Name)
+	}
+	return result
+}
+
 type PodSpec struct {
 	ImagePullSecrets []struct{ Name string }
 	Volumes          []Volume

cluster/kubernetes/resource/statefulset.go

@@ -9,3 +9,7 @@ type StatefulSetSpec struct {
 	Replicas int
 	Template PodTemplate
 }
+
+func (ss StatefulSet) ContainerNames() []string {
+	return ss.Spec.Template.ContainerNames()
+}