feat: add support for sourcing images from a configmap

Author: dcherman

README.md

@@ -22,6 +22,7 @@ image-cache-daemon [flags]
 ### Options
 
 ```
+      --configmap-selector string               The selector to use when monitoring for ConfigMap sources (default "app.kubernetes.io/part-of=image-cache-daemon")
   -h, --help                                    help for image-cache-daemon
       --image stringArray                       Images that should be pre-fetched
       --node-name string                        The node name to pull to
@@ -33,4 +34,28 @@ image-cache-daemon [flags]
       --watch-argo-cluster-workflow-templates   Whether or not to watch cluster workflow templates (default true)
       --watch-argo-cron-workflows               Whether or not to watch cron workflows (default true)
       --watch-argo-workflow-templates           Whether or not to watch workflow templates (default true)
+      --watch-configmaps                        Whether or not to watch ConfigMaps for images to pull.  Must match the --config-map-selector (default true)
+```
+
+## Sources
+
+### ConfigMap
+
+The ConfigMap source is useful when you want to separate the list of images that you're pulling from the installation of the cache daemon.  It's also useful if you have a dynamic list
+of images to pull that aren't part of one of the other sources.
+
+By default, all ConfigMaps that match the label selector `"app.kubernetes.io/part-of=image-cache-daemon"` will be considered as a source for the cache daemon in any namespace that it has privileges to read.  If you would like to restrict the set of ConfigMaps that it reads, you can so do by changing the selector, or restricting the namespaces that the cache daemon can read via RBAC.
+
+Example Usage:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: my-image-configmap
+  labels:
+    app.kubernetes.io/part-of: image-cache-daemon
+data:
+  images: |
+    ["alpine", "debian"]
 ```

cmd/image-cache-daemon.go

@@ -29,7 +29,7 @@ import (
 	"syscall"
 	"time"
 
-	argoclientset "github.com/argoproj/argo/pkg/client/clientset/versioned"
+	argoclientset "github.com/argoproj/argo-workflows/v3/pkg/client/clientset/versioned"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -44,16 +44,18 @@ import (
 
 func NewImageCacheDaemonCommand() *cobra.Command {
 	var (
-		images       []string
-		nodeName     string
-		podName      string
-		podUUID      string
-		podNamespace string
+		images            []string
+		configmapSelector string
+		nodeName          string
+		podName           string
+		podUUID           string
+		podNamespace      string
 
 		wardenImage                       string
 		watchArgoWorkflowTemplates        bool
 		watchArgoClusterWorkflowTemplates bool
 		watchArgoCronWorkflows            bool
+		watchConfigMaps                   bool
 		resyncPeriod                      time.Duration
 	)
 
@@ -126,6 +128,13 @@ func NewImageCacheDaemonCommand() *cobra.Command {
 				go workflowTemplateSource.Run(ctx)
 			}
 
+			if watchConfigMaps {
+				logrus.Info("watching configmaps for images to pull")
+				configmapSource := source.NewConfigMapSource(kubeclient, resyncPeriod, source.WithConfigMapSelector(configmapSelector))
+				ip.AddSource(ctx, configmapSource)
+				go configmapSource.Run(ctx)
+			}
+
 			go ip.Run(ctx)
 
 			stopCh := make(chan os.Signal, 1)
@@ -147,9 +156,11 @@ func NewImageCacheDaemonCommand() *cobra.Command {
 	rootCmd.Flags().StringVar(&podUUID, "pod-uid", os.Getenv("POD_UUD"), "The owning pod UID")
 	rootCmd.Flags().StringVar(&podNamespace, "pod-namespace", os.Getenv("POD_NAMESPACE"), "The namespace this pod is running in")
 	rootCmd.Flags().StringVar(&wardenImage, "warden-image", "exiges/image-cache-warden:latest", "The image that copies a binary to pulled containers to replace the entrypoint")
+	rootCmd.Flags().StringVar(&configmapSelector, "configmap-selector", "app.kubernetes.io/part-of=image-cache-daemon", "The selector to use when monitoring for ConfigMap sources")
 	rootCmd.Flags().BoolVar(&watchArgoWorkflowTemplates, "watch-argo-workflow-templates", true, "Whether or not to watch workflow templates")
 	rootCmd.Flags().BoolVar(&watchArgoClusterWorkflowTemplates, "watch-argo-cluster-workflow-templates", true, "Whether or not to watch cluster workflow templates")
 	rootCmd.Flags().BoolVar(&watchArgoCronWorkflows, "watch-argo-cron-workflows", true, "Whether or not to watch cron workflows")
+	rootCmd.Flags().BoolVar(&watchConfigMaps, "watch-configmaps", true, "Whether or not to watch ConfigMaps for images to pull.  Must match the --config-map-selector")
 	rootCmd.Flags().DurationVar(&resyncPeriod, "resync-period", time.Minute*15, "How often the daemon should re-pull images from all of the sources.  Set to 0 to disable.")
 
 	return rootCmd

go.mod

@@ -3,18 +3,21 @@ module github.com/dcherman/image-cache-daemon
 go 1.16
 
 require (
-	github.com/argoproj/argo v0.0.0-20201121022849-310e099f8252
+	github.com/argoproj/argo-workflows/v3 v3.1.6
 	github.com/benbjohnson/clock v1.1.0
-	github.com/imdario/mergo v0.3.11 // indirect
-	github.com/sirupsen/logrus v1.7.0
+	github.com/google/uuid v1.2.0 // indirect
+	github.com/onsi/gomega v1.10.3 // indirect
+	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/cobra v1.1.3
 	github.com/stretchr/testify v1.7.0
-	golang.org/x/sys v0.0.0-20210113181707-4bcb84eeeb78 // indirect
-	golang.org/x/time v0.0.0-20201208040808-7e3f01d25324 // indirect
-	google.golang.org/appengine v1.6.7 // indirect
-	k8s.io/api v0.17.17
-	k8s.io/apimachinery v0.17.17
-	k8s.io/client-go v0.17.17
+	golang.org/x/sys v0.0.0-20210426230700-d19ff857e887 // indirect
+	google.golang.org/genproto v0.0.0-20201110150050-8816d57aaa9a // indirect
+	google.golang.org/grpc v1.33.2 // indirect
+	google.golang.org/protobuf v1.26.0 // indirect
+	k8s.io/api v0.21.0
+	k8s.io/apimachinery v0.21.0
+	k8s.io/client-go v0.21.0
+	sigs.k8s.io/yaml v1.2.0
 )
 
 replace sigs.k8s.io/controller-tools => sigs.k8s.io/controller-tools v0.2.9