Implement workaround for kubernetes/kubeadm#857

apis/defaults.go

@@ -1,6 +1,8 @@
 package apis
 
 import (
+	"fmt"
+
 	"github.com/platform9/nodeadm/constants"
 	kubeadmv1alpha1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
 )
@@ -25,7 +27,7 @@ func SetInitDefaults(config *InitConfiguration) {
 func SetInitDynamicDefaults(config *InitConfiguration) error {
 	nodeName, err := constants.GetHostnameOverride()
 	if err != nil {
-		return err
+		return fmt.Errorf("unable to dervice hostname override: %v", err)
 	}
 	config.MasterConfiguration.NodeName = nodeName
 	return nil

cmd/nodeinit.go

@@ -8,6 +8,9 @@ import (
 	"path/filepath"
 
 	"github.com/ghodss/yaml"
+
+	"github.com/platform9/nodeadm/workarounds"
+
 	"github.com/platform9/nodeadm/apis"
 	"github.com/platform9/nodeadm/constants"
 	"github.com/platform9/nodeadm/deprecated"
@@ -55,6 +58,11 @@ var nodeCmdInit = &cobra.Command{
 
 		kubeadmInit(constants.KUBEADM_CONFIG)
 
+		log.Println("Applying workaround for https://github.com/kubernetes/kubeadm/issues/857")
+		if err := workarounds.EnsureKubeProxyRespectsHostoverride(); err != nil {
+			log.Fatalf("Failed to apply workaround: %v", err)
+		}
+
 		networkInit(config)
 	},
 }

workarounds/kubeadm_issue_857.go

@@ -0,0 +1,143 @@
+package workarounds
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/platform9/nodeadm/constants"
+)
+
+const (
+	// patchTemplate has one formatting parameter: the kube-proxy image name, a string
+	patchTemplate = `[
+    {
+        "op": "add",
+        "path": "/spec/template/spec/volumes/-",
+        "value": {
+                "name": "shared-data",
+                "mountPath": "/shared-data"
+            }
+    },
+    {
+        "op": "add",
+        "path": "/spec/template/spec/containers/0/volumeMounts/-",
+        "value": {
+                "name": "shared-data",
+                "mountPath": "/shared-data"
+            }
+    },
+    {
+        "op": "replace",
+        "path": "/spec/template/spec/containers/0/command/1",
+        "value": "--config=/shared-data/config.conf"
+    },
+    {
+        "op": "add",
+        "path": "/spec/template/spec/initContainers",
+        "value": [
+                {
+                    "command": [
+                        "sh",
+                        "-c",
+                        "/bin/sed \"s/hostnameOverride: \\\"\\\"/hostnameOverride: $(NODE_NAME)/\" /var/lib/kube-proxy/config.conf > /shared-data/config.conf"
+                    ],
+                    "env": [
+                        {
+                            "name": "NODE_NAME",
+                            "valueFrom": {
+                                "fieldRef": {
+                                    "apiVersion": "v1",
+                                    "fieldPath": "spec.nodeName"
+                                }
+                            }
+                        }
+                    ],
+                    "image": "%s",
+                    "imagePullPolicy": "IfNotPresent",
+                    "name": "update-config-file",
+                    "volumeMounts": [
+                    {
+                        "mountPath": "/var/lib/kube-proxy",
+                        "name": "kube-proxy"
+                    },
+                    {
+                        "mountPath": "/shared-data",
+                        "name": "shared-data"
+                    }
+                    ]
+                }
+            ]
+    }
+]`
+
+	resultIfPatched = "--config=/shared-data/config.conf"
+)
+
+// EnsureKubeProxyRespectsHostoverride patches the kube-proxy daemonset so that
+// kube-proxy respects the hostnameOverride setting. The function is idempotent.
+// See: https://github.com/kubernetes/kubeadm/issues/857
+func EnsureKubeProxyRespectsHostoverride() error {
+	log.Println("[workarounds] Checking whether kube-proxy daemonset is patched")
+	patched, err := isPatchedKubeProxyDaemonSet()
+	if err != nil {
+		return fmt.Errorf("unable to check if kube-proxy daemonset is patched: %v", err)
+	}
+	if patched {
+		log.Println("[workarounds] Kube-proxy daemonset already patched. Continuing. ")
+		return nil
+	}
+	log.Println("[workarounds] Patching kube-proxy daemonset")
+	err = patchKubeProxyDaemonSet()
+	if err != nil {
+		return fmt.Errorf("unable to patch kube-proxy daemonset: %v", err)
+	}
+	log.Println("[workarounds] Patched kube-proxy daemonset")
+	return nil
+}
+
+func isPatchedKubeProxyDaemonSet() (bool, error) {
+	name := "/bin/sh"
+	// If this field was changed, we assume the patch was applied. Because the
+	// entire patch applies or is rejected, we can infer that the other fields
+	// were updated as expected. We assume the daemonset was not edited by hand.
+	arg := fmt.Sprintf("%s --kubeconfig=%s --namespace=kube-system get daemonset kube-proxy -ojsonpath='{.spec.template.spec.containers[0].command[1]}'", filepath.Join(constants.BASE_INSTALL_DIR, constants.KubectlFilename), constants.AdminKubeconfigFile)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	var stdout, stderr bytes.Buffer
+	cmd := exec.CommandContext(ctx, name, "-c", arg)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return false, fmt.Errorf("error running %q: %v (stdout: %s) (stderr: %s)", strings.Join(cmd.Args, " "), err, string(stdout.Bytes()), string(stderr.Bytes()))
+	}
+
+	if strings.Compare(string(stdout.Bytes()), resultIfPatched) == 0 {
+		return true, nil
+	}
+	return false, nil
+}
+
+func patchKubeProxyDaemonSet() error {
+	patchWithKubeProxyVersion := fmt.Sprintf(patchTemplate, fmt.Sprintf("k8s.gcr.io/kube-proxy-amd64:%s", constants.KUBERNETES_VERSION))
+	name := "/bin/sh"
+	arg := fmt.Sprintf("%s --kubeconfig=%s --namespace=kube-system patch --type=json daemonset kube-proxy --patch='%s'", filepath.Join(constants.BASE_INSTALL_DIR, constants.KubectlFilename), constants.AdminKubeconfigFile, patchWithKubeProxyVersion)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	var stdout, stderr bytes.Buffer
+	cmd := exec.CommandContext(ctx, name, "-c", arg)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("error running %q: %v (stdout: %s) (stderr: %s)", strings.Join(cmd.Args, " "), err, string(stdout.Bytes()), string(stderr.Bytes()))
+	}
+
+	return nil
+}