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Create optional kube-dns configmap if needed
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* fix: create the optional kube-dns configmap if needed

* review: apply @jspdown suggestions
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@kevinpollet
kevinpollet authored Jul 3, 2020
1 parent 2be1234 commit 1f68d54
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Showing 15 changed files with 201 additions and 140 deletions.
194 changes: 93 additions & 101 deletions pkg/dns/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -55,8 +55,7 @@ func NewClient(logger logrus.FieldLogger, kubeClient kubernetes.Interface) *Clie
}
}

// CheckDNSProvider checks that the DNS provider that is deployed in the cluster
// is supported and returns it.
// CheckDNSProvider checks that the DNS provider deployed in the cluster is supported and returns it.
func (c *Client) CheckDNSProvider() (Provider, error) {
c.logger.Info("Checking DNS provider")

Expand Down Expand Up @@ -134,7 +133,7 @@ func (c *Client) kubeDNSMatch() (bool, error) {
}

if err != nil {
return false, fmt.Errorf("unable to get KubeDNS deployment in namesapce %q: %w", metav1.NamespaceSystem, err)
return false, fmt.Errorf("unable to get KubeDNS deployment in namespace %q: %w", metav1.NamespaceSystem, err)
}

c.logger.Info("KubeDNS match")
Expand Down Expand Up @@ -170,7 +169,7 @@ func (c *Client) ConfigureCoreDNS(coreDNSNamespace, clusterDomain, maeshNamespac
}

func (c *Client) patchCoreDNSConfig(deployment *appsv1.Deployment, clusterDomain, maeshNamespace string) (*corev1.ConfigMap, error) {
customConfigMap, err := c.getConfigMap(deployment.Namespace, "coredns-custom")
customConfigMap, err := c.getConfigMap(deployment, "coredns-custom")

// For AKS the CoreDNS config have to be added to the coredns-custom ConfigMap.
// See https://docs.microsoft.com/en-us/azure/aks/coredns-custom
Expand All @@ -184,11 +183,7 @@ func (c *Client) patchCoreDNSConfig(deployment *appsv1.Deployment, clusterDomain
return customConfigMap, nil
}

if !kerrors.IsNotFound(err) {
return nil, fmt.Errorf("unable to get coredns-custom configmap: %w", err)
}

coreDNSConfigMap, err := c.getCorefileConfigMap(deployment)
coreDNSConfigMap, err := c.getConfigMap(deployment, "coredns")
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -245,102 +240,75 @@ maesh:53 {
func (c *Client) ConfigureKubeDNS(clusterDomain, maeshNamespace string) error {
c.logger.Debug("Patching KubeDNS")

deployment, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get("kube-dns", metav1.GetOptions{})
kubeDNSDeployment, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get("kube-dns", metav1.GetOptions{})
if err != nil {
return err
}

var (
serviceIP string
ebo = backoff.NewConstantBackOff(10 * time.Second)
)

c.logger.Debug("Getting CoreDNS service IP")

if err = backoff.Retry(safe.OperationWithRecover(func() error {
svc, errSvc := c.kubeClient.CoreV1().Services(maeshNamespace).Get("coredns", metav1.GetOptions{})
if errSvc != nil {
return fmt.Errorf("unable get the service %q in namespace %q: %w", "coredns", "maesh", errSvc)
var coreDNSServiceIP string

operation := func() error {
svc, svcErr := c.kubeClient.CoreV1().Services(maeshNamespace).Get("coredns", metav1.GetOptions{})
if svcErr != nil {
return fmt.Errorf("unable to get coredns service in namespace %q: %w", maeshNamespace, err)
}

if svc.Spec.ClusterIP == "" {
return fmt.Errorf("service %q has no clusterIP", "coredns")
return fmt.Errorf("coredns service in namespace %q has no clusterip", maeshNamespace)
}

serviceIP = svc.Spec.ClusterIP
coreDNSServiceIP = svc.Spec.ClusterIP

return nil
}), backoff.WithMaxRetries(ebo, 12)); err != nil {
return fmt.Errorf("unable get the service %q in namespace %q: %w", "coredns", "maesh", err)
}

configMap, err := c.getKubeDNSConfigMap(deployment)
if err != nil {
if err = backoff.Retry(safe.OperationWithRecover(operation), backoff.WithMaxRetries(backoff.NewConstantBackOff(10*time.Second), 12)); err != nil {
return err
}

c.logger.Debug("Patching KubeDNS configmap with IP", serviceIP)
c.logger.Debugf("Patching KubeDNS ConfigMap with CoreDNS service IP %q", coreDNSServiceIP)

if err := c.patchKubeDNSConfigMap(configMap, deployment.Namespace, serviceIP); err != nil {
if err := c.patchKubeDNSConfig(kubeDNSDeployment, coreDNSServiceIP); err != nil {
return err
}

c.logger.Debug("Patching CoreDNS configmap")

if err := c.ConfigureCoreDNS(maeshNamespace, clusterDomain, maeshNamespace); err != nil {
return err
}

if err := c.restartPods(deployment); err != nil {
if err := c.restartPods(kubeDNSDeployment); err != nil {
return err
}

return nil
}

// getKubeDNSConfigMap parses the deployment and returns the associated configuration configmap.
func (c *Client) getKubeDNSConfigMap(kubeDeployment *appsv1.Deployment) (*corev1.ConfigMap, error) {
for _, volume := range kubeDeployment.Spec.Template.Spec.Volumes {
if volume.ConfigMap == nil {
continue
}

cfgMap, err := c.kubeClient.CoreV1().ConfigMaps(kubeDeployment.Namespace).Get(volume.ConfigMap.Name, metav1.GetOptions{})
if err != nil {
return nil, err
}

return cfgMap, nil
}

return nil, errors.New("corefile configmap not found")
}

func (c *Client) patchKubeDNSConfigMap(kubeConfigMap *corev1.ConfigMap, namespace, coreDNSIp string) error {
originalBlock, exist := kubeConfigMap.Data["stubDomains"]
if !exist {
originalBlock = "{}"
func (c *Client) patchKubeDNSConfig(deployment *appsv1.Deployment, coreDNSServiceIP string) error {
configMap, err := c.getOrCreateConfigMap(deployment, "kube-dns")
if err != nil {
return err
}

stubDomains := make(map[string][]string)
if err := json.Unmarshal([]byte(originalBlock), &stubDomains); err != nil {
return err
}

stubDomains["maesh"] = []string{coreDNSIp}
if stubDomainsStr := configMap.Data["stubDomains"]; stubDomainsStr != "" {
if err = json.Unmarshal([]byte(stubDomainsStr), &stubDomains); err != nil {
return fmt.Errorf("unable to unmarshal stub domains: %w", err)
}
}

var newData []byte
stubDomains["maesh"] = []string{coreDNSServiceIP}

newData, err := json.Marshal(stubDomains)
configMapData, err := json.Marshal(stubDomains)
if err != nil {
return err
}

if kubeConfigMap.Data == nil {
kubeConfigMap.Data = make(map[string]string)
return fmt.Errorf("unable to marshal stub domains: %w", err)
}

kubeConfigMap.Data["stubDomains"] = string(newData)
configMap.Data["stubDomains"] = string(configMapData)

if _, err := c.kubeClient.CoreV1().ConfigMaps(namespace).Update(kubeConfigMap); err != nil {
if _, err := c.kubeClient.CoreV1().ConfigMaps(configMap.Namespace).Update(configMap); err != nil {
return err
}

Expand Down Expand Up @@ -388,7 +356,7 @@ func (c *Client) RestoreCoreDNS() error {
}

func (c *Client) unpatchCoreDNSConfig(deployment *appsv1.Deployment) (*corev1.ConfigMap, error) {
customConfigMap, err := c.getConfigMap(deployment.Namespace, "coredns-custom")
customConfigMap, err := c.getConfigMap(deployment, "coredns-custom")

// For AKS the CoreDNS config have to be removed from the coredns-custom ConfigMap.
// See https://docs.microsoft.com/en-us/azure/aks/coredns-custom
Expand All @@ -397,11 +365,7 @@ func (c *Client) unpatchCoreDNSConfig(deployment *appsv1.Deployment) (*corev1.Co
return customConfigMap, nil
}

if !kerrors.IsNotFound(err) {
return nil, fmt.Errorf("unable to get coredns-custom configmap: %w", err)
}

coreDNSConfigMap, err := c.getCorefileConfigMap(deployment)
coreDNSConfigMap, err := c.getConfigMap(deployment, "coredns")
if err != nil {
return nil, err
}
Expand All @@ -427,78 +391,89 @@ func (c *Client) unpatchCoreDNSConfig(deployment *appsv1.Deployment) (*corev1.Co

// RestoreKubeDNS restores the KubeDNS configuration to pre-install state.
func (c *Client) RestoreKubeDNS() error {
deployment, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get("kube-dns", metav1.GetOptions{})
kubeDNSDeployment, err := c.kubeClient.AppsV1().Deployments(metav1.NamespaceSystem).Get("kube-dns", metav1.GetOptions{})
if err != nil {
return err
}

// Get the currently loaded KubeDNS ConfigMap.
configMap, err := c.getKubeDNSConfigMap(deployment)
configMap, err := c.getConfigMap(kubeDNSDeployment, "kube-dns")
if err != nil {
return err
}

// Check if stubDomains are still defined.
originalBlock, exist := configMap.Data["stubDomains"]
if !exist {
stubDomainsStr := configMap.Data["stubDomains"]
if stubDomainsStr == "" {
return nil
}

stubDomains := make(map[string][]string)
if err = json.Unmarshal([]byte(originalBlock), &stubDomains); err != nil {
return fmt.Errorf("could not unmarshal stubdomains: %w", err)
if err = json.Unmarshal([]byte(stubDomainsStr), &stubDomains); err != nil {
return fmt.Errorf("unable to unmarshal stubdomains: %w", err)
}

// Delete our stubDomain.
delete(stubDomains, "maesh")

newData, err := json.Marshal(stubDomains)
configMapData, err := json.Marshal(stubDomains)
if err != nil {
return err
}

// If there are no stubDomains left, delete the field.
if string(newData) == "{}" {
delete(configMap.Data, "stubDomains")
} else {
configMap.Data["stubDomains"] = string(newData)
}
configMap.Data["stubDomains"] = string(configMapData)

// Update the KubeDNS configmap to the backup.
if _, err := c.kubeClient.CoreV1().ConfigMaps(configMap.Namespace).Update(configMap); err != nil {
return err
}

if err := c.restartPods(deployment); err != nil {
if err := c.restartPods(kubeDNSDeployment); err != nil {
return err
}

return nil
}

func (c *Client) getCorefileConfigMap(deployment *appsv1.Deployment) (*corev1.ConfigMap, error) {
for _, volume := range deployment.Spec.Template.Spec.Volumes {
if volume.ConfigMap == nil {
continue
}
// getOrCreateConfigMap parses the deployment and returns the ConfigMap with the given name. This method will create the
// corresponding ConfigMap if the associated volume is marked as optional and the ConfigMap is not found.
func (c *Client) getOrCreateConfigMap(deployment *appsv1.Deployment, name string) (*corev1.ConfigMap, error) {
volumeSrc, err := getConfigMapVolumeSource(deployment, name)
if err != nil {
return nil, err
}

configMap, err := c.getConfigMap(deployment.Namespace, volume.ConfigMap.Name)
if err != nil {
return nil, err
}
configMap, err := c.kubeClient.CoreV1().ConfigMaps(deployment.Namespace).Get(volumeSrc.Name, metav1.GetOptions{})

if _, exists := configMap.Data["Corefile"]; !exists {
continue
if kerrors.IsNotFound(err) && volumeSrc.Optional != nil && *volumeSrc.Optional {
configMap = &corev1.ConfigMap{
ObjectMeta: metav1.ObjectMeta{
Name: name,
Namespace: deployment.Namespace,
},
}

return configMap, nil
configMap, err = c.kubeClient.CoreV1().ConfigMaps(deployment.Namespace).Create(configMap)
}

if err != nil {
return nil, err
}

if configMap.Data == nil {
configMap.Data = make(map[string]string)
}

return nil, errors.New("corefile configmap not found")
return configMap, err
}

func (c *Client) getConfigMap(namespace, name string) (*corev1.ConfigMap, error) {
configMap, err := c.kubeClient.CoreV1().ConfigMaps(namespace).Get(name, metav1.GetOptions{})
// getConfigMap parses the deployment and returns the ConfigMap with the given name.
func (c *Client) getConfigMap(deployment *appsv1.Deployment, name string) (*corev1.ConfigMap, error) {
volumeSrc, err := getConfigMapVolumeSource(deployment, name)
if err != nil {
return nil, err
}

configMap, err := c.kubeClient.CoreV1().ConfigMaps(deployment.Namespace).Get(volumeSrc.Name, metav1.GetOptions{})
if err != nil {
return nil, err
}
Expand All @@ -509,3 +484,20 @@ func (c *Client) getConfigMap(namespace, name string) (*corev1.ConfigMap, error)

return configMap, nil
}

// getConfigMapVolumeSource returns the ConfigMapVolumeSource corresponding to the ConfigMap with the given name.
func getConfigMapVolumeSource(deployment *appsv1.Deployment, name string) (*corev1.ConfigMapVolumeSource, error) {
for _, volume := range deployment.Spec.Template.Spec.Volumes {
if volume.ConfigMap == nil {
continue
}

if volume.ConfigMap.Name != name {
continue
}

return volume.ConfigMap, nil
}

return nil, fmt.Errorf("configmap %q cannot be found", name)
}
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