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kubeconfig.go
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kubeconfig.go
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package kubeconfig
import (
"encoding/json"
"fmt"
"os"
"os/exec"
"path"
"path/filepath"
"regexp"
"strings"
"github.com/gofrs/flock"
"github.com/kballard/go-shellquote"
"github.com/kris-nova/logger"
"github.com/pkg/errors"
"k8s.io/client-go/tools/clientcmd"
clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
api "github.com/weaveworks/eksctl/pkg/apis/eksctl.io/v1alpha5"
"github.com/weaveworks/eksctl/pkg/utils"
"github.com/weaveworks/eksctl/pkg/utils/file"
"github.com/weaveworks/eksctl/pkg/utils/kubectl"
)
const (
// AWSIAMAuthenticator defines the name of the AWS IAM authenticator
AWSIAMAuthenticator = "aws-iam-authenticator"
// AWSEKSAuthenticator defines the recently added `aws eks get-token` command
AWSEKSAuthenticator = "aws"
// AWSIAMAuthenticatorMinimumBetaVersion this is the minimum version at which aws-iam-authenticator uses v1beta1 as APIVersion
AWSIAMAuthenticatorMinimumBetaVersion = "0.5.3"
// AWSCLIv1MinimumBetaVersion this is the minimum version at which aws-cli v1 uses v1beta1 as APIVersion
AWSCLIv1MinimumBetaVersion = "1.23.9"
// AWSCLIv2MinimumBetaVersion this is the minimum version at which aws-cli v2 uses v1beta1 as APIVersion
AWSCLIv2MinimumBetaVersion = "2.6.3"
alphaAPIVersion = "client.authentication.k8s.io/v1alpha1"
betaAPIVersion = "client.authentication.k8s.io/v1beta1"
)
var (
execCommand = exec.Command
execLookPath = exec.LookPath
newVersionManager = kubectl.NewVersionManager
lookupAuthenticator = func() (string, bool) {
for _, cmd := range authenticatorCommands() {
_, err := exec.LookPath(cmd)
if err == nil {
return cmd, true
}
}
return "", false
}
)
// DefaultPath defines the default path
func DefaultPath() string {
if env := os.Getenv(clientcmd.RecommendedConfigPathEnvVar); len(env) > 0 {
return env
}
return clientcmd.RecommendedHomeFile
}
// authenticatorCommands returns all authenticator commands.
func authenticatorCommands() []string {
return []string{
AWSIAMAuthenticator,
AWSEKSAuthenticator,
}
}
// ConfigBuilder can create a client-go clientcmd Config
type ConfigBuilder struct {
cluster clientcmdapi.Cluster
clusterName string
username string
}
// Build creates the Config with the ConfigBuilder settings
func (cb *ConfigBuilder) Build() *clientcmdapi.Config {
contextName := fmt.Sprintf("%s@%s", cb.username, cb.clusterName)
return &clientcmdapi.Config{
Clusters: map[string]*clientcmdapi.Cluster{
cb.clusterName: &cb.cluster,
},
Contexts: map[string]*clientcmdapi.Context{
contextName: {
Cluster: cb.clusterName,
AuthInfo: contextName,
},
},
AuthInfos: map[string]*clientcmdapi.AuthInfo{
contextName: {},
},
CurrentContext: contextName,
}
}
// NewBuilder returns a minimal ConfigBuilder
func NewBuilder(metadata *api.ClusterMeta, status *api.ClusterStatus, username string) *ConfigBuilder {
cluster := clientcmdapi.Cluster{
Server: status.Endpoint,
CertificateAuthorityData: status.CertificateAuthorityData,
}
return &ConfigBuilder{
cluster: cluster,
clusterName: metadata.String(),
username: username,
}
}
// UseCertificateAuthorityFile sets the config to use CA from file for TLS
// communication instead of the CA retrieved from EKS
func (cb *ConfigBuilder) UseCertificateAuthorityFile(path string) *ConfigBuilder {
cb.cluster.CertificateAuthority = path
cb.cluster.CertificateAuthorityData = []byte{}
return cb
}
// UseSystemCA sets the config to use the system CAs for TLS communication
// instead of the CA retrieved from EKS
func (cb *ConfigBuilder) UseSystemCA() *ConfigBuilder {
cb.cluster.CertificateAuthority = ""
cb.cluster.CertificateAuthorityData = []byte{}
return cb
}
// ClusterInfo holds the cluster info.
type ClusterInfo interface {
// ID returns the cluster ID.
// This can either be the name of the cluster or a UUID.
ID() string
// Meta returns the cluster metadata.
Meta() *api.ClusterMeta
// GetStatus returns the cluster status.
GetStatus() *api.ClusterStatus
}
// NewForUser returns a Config suitable for a user by respecting
// provider settings
func NewForUser(cluster ClusterInfo, username string) *clientcmdapi.Config {
configBuilder := NewBuilder(cluster.Meta(), cluster.GetStatus(), username)
if os.Getenv("KUBECONFIG_USE_SYSTEM_CA") != "" {
configBuilder.UseSystemCA()
}
return configBuilder.Build()
}
// NewForKubectl creates configuration for a user with kubectl by configuring
// a suitable authenticator and respecting provider settings
func NewForKubectl(cluster ClusterInfo, username, roleARN, profile string) *clientcmdapi.Config {
config := NewForUser(cluster, username)
authenticator, found := lookupAuthenticator()
if !found {
// fall back to aws-iam-authenticator
authenticator = AWSIAMAuthenticator
}
AppendAuthenticator(config, cluster, authenticator, roleARN, profile)
return config
}
// AppendAuthenticator appends the AWS IAM authenticator, and
// if profile is non-empty string it sets AWS_PROFILE environment
// variable also
func AppendAuthenticator(config *clientcmdapi.Config, cluster ClusterInfo, authenticatorCMD, roleARN, profile string) {
var (
args []string
roleARNFlag string
)
execConfig := &clientcmdapi.ExecConfig{
APIVersion: alphaAPIVersion,
Command: authenticatorCMD,
Env: []clientcmdapi.ExecEnvVar{
{
Name: "AWS_STS_REGIONAL_ENDPOINTS",
Value: "regional",
},
},
ProvideClusterInfo: false,
}
meta := cluster.Meta()
switch authenticatorCMD {
case AWSIAMAuthenticator:
// if version is above or equal to v0.5.3 we change the APIVersion to v1beta1.
if authenticatorIsBetaVersion, err := authenticatorIsAboveVersion(AWSIAMAuthenticatorMinimumBetaVersion); err != nil {
logger.Warning("failed to determine authenticator version, leaving API version as default v1alpha1: %v", err)
} else if authenticatorIsBetaVersion {
execConfig.APIVersion = betaAPIVersion
}
args = []string{"token", "-i", cluster.ID()}
roleARNFlag = "-r"
if meta.Region != "" {
execConfig.Env = append(execConfig.Env, clientcmdapi.ExecEnvVar{
Name: "AWS_DEFAULT_REGION",
Value: meta.Region,
})
}
case AWSEKSAuthenticator:
// if [aws-cli v1/aws-cli v2] is above or equal to [v1.23.9/v2.6.3] respectively, we change the APIVersion to v1beta1.
if awsCLIIsBetaVersion, err := awsCliIsAboveVersion(); err != nil {
logger.Warning("failed to determine authenticator version, leaving API version as default v1alpha1: %v", err)
} else if awsCLIIsBetaVersion {
execConfig.APIVersion = betaAPIVersion
}
args = []string{"eks", "get-token", "--output", "json", "--cluster-name", cluster.ID()}
roleARNFlag = "--role-arn"
if meta.Region != "" {
args = append(args, "--region", meta.Region)
}
}
// If the alpha API version is selected, check the kubectl version
// If kubectl 1.24.0 or above is detected, override with the beta API version
// kubectl 1.24.0 removes the alpha API version, so it will never work
// Therefore as a best effort try the beta version even if it might not work
if execConfig.APIVersion == alphaAPIVersion {
if clientVersion, err := newVersionManager().ClientVersion(); err == nil {
// Silently ignore errors because kubectl is not required to run eksctl
compareVersions, err := utils.CompareVersions(strings.TrimLeft(clientVersion, "v"), "1.24.0")
if err == nil && compareVersions >= 0 {
execConfig.APIVersion = betaAPIVersion
}
}
}
if roleARN != "" {
args = append(args, roleARNFlag, roleARN)
}
execConfig.Args = args
if profile != "" {
execConfig.Env = append(execConfig.Env, clientcmdapi.ExecEnvVar{
Name: "AWS_PROFILE",
Value: profile,
})
}
config.AuthInfos[config.CurrentContext] = &clientcmdapi.AuthInfo{
Exec: execConfig,
}
}
// AWSAuthenticatorVersionFormat is the format in which aws-iam-authenticator displays version information:
// {"Version":"0.5.5","Commit":"85e50980d9d916ae95882176c18f14ae145f916f"}
type AWSAuthenticatorVersionFormat struct {
Version string `json:"Version"`
}
func awsCliIsAboveVersion() (bool, error) {
awsCliVersion := getAWSCLIVersion()
compareVersions, err := utils.CompareVersions(awsCliVersion, "2.0.0")
if err != nil {
return false, fmt.Errorf("failed to parse versions: %w", err)
}
// AWS CLI provides beta in two separate major versions. One for v1 and one for v2.
// Being above a single version doesn't necessarily mean that we are in the clear.
// Thus, first check which major version we are dealing with, then check if beta is
// supported for that major version.
if compareVersions < 0 {
compareVersions, err = utils.CompareVersions(awsCliVersion, AWSCLIv1MinimumBetaVersion)
} else {
compareVersions, err = utils.CompareVersions(awsCliVersion, AWSCLIv2MinimumBetaVersion)
}
if err != nil {
return false, fmt.Errorf("failed to parse versions: %w", err)
}
return compareVersions >= 0, nil
}
func getAWSCLIVersion() string {
cmd := execCommand("aws", "--version")
output, err := cmd.Output()
if err != nil {
return ""
}
r := regexp.MustCompile(`aws-cli/([\d.]*)`)
matches := r.FindStringSubmatch(string(output))
if len(matches) != 2 {
return ""
}
return matches[1]
}
func authenticatorIsAboveVersion(version string) (bool, error) {
authenticatorVersion, err := getAWSIAMAuthenticatorVersion()
if err != nil {
return false, fmt.Errorf("failed to retrieve authenticator version: %w", err)
}
compareVersions, err := utils.CompareVersions(authenticatorVersion, version)
if err != nil {
return false, fmt.Errorf("failed to parse versions: %w", err)
}
return compareVersions >= 0, nil
}
func getAWSIAMAuthenticatorVersion() (string, error) {
cmd := execCommand(AWSIAMAuthenticator, "version")
output, err := cmd.Output()
if err != nil {
return "", fmt.Errorf("failed to run aws-iam-authenticator version command: %w", err)
}
var parsedVersion AWSAuthenticatorVersionFormat
if err := json.Unmarshal(output, &parsedVersion); err != nil {
return "", fmt.Errorf("failed to parse version information: %w", err)
}
return parsedVersion.Version, nil
}
func lockFileName(filePath string) string {
return filepath.Join(os.TempDir(), fmt.Sprintf("%x.eksctl.lock", utils.FnvHash(filePath)))
}
// ensureDirectory should probably be handled in flock
func ensureDirectory(filePath string) error {
dir := filepath.Dir(filePath)
if _, err := os.Stat(dir); os.IsNotExist(err) {
if err = os.MkdirAll(dir, 0755); err != nil {
return err
}
}
return nil
}
func lockConfigFile(filePath string) (*flock.Flock, error) {
lockFileName := lockFileName(filePath)
// Make sure the directory exists, otherwise flock fails
if err := ensureDirectory(lockFileName); err != nil {
return nil, err
}
flock := flock.New(lockFileName)
err := flock.Lock()
if err != nil {
return nil, errors.Wrap(err, "failed to obtain exclusive lock on kubeconfig lockfile")
}
return flock, nil
}
func unlockConfigFile(fl *flock.Flock) error {
err := fl.Unlock()
if err != nil {
return errors.Wrap(err, "failed to release exclusive lock on kubeconfig lockfile")
}
return nil
}
// Write will write Kubernetes client configuration to a file.
// If path isn't specified then the path will be determined by client-go.
// If file pointed to by path doesn't exist it will be created.
// If the file already exists then the configuration will be merged with the existing file.
func Write(path string, newConfig clientcmdapi.Config, setContext bool) (string, error) {
configAccess := getConfigAccess(path)
configFileName := configAccess.GetDefaultFilename()
fl, err := lockConfigFile(configFileName)
if err != nil {
return "", err
}
defer func() {
if err := unlockConfigFile(fl); err != nil {
logger.Critical(err.Error())
}
}()
config, err := configAccess.GetStartingConfig()
if err != nil {
return "", errors.Wrapf(err, "unable to read existing kubeconfig file %q", path)
}
logger.Debug("merging kubeconfig files")
merged := merge(config, &newConfig)
if setContext && newConfig.CurrentContext != "" {
logger.Debug("setting current-context to %s", newConfig.CurrentContext)
merged.CurrentContext = newConfig.CurrentContext
}
if err := clientcmd.ModifyConfig(configAccess, *merged, true); err != nil {
return "", errors.Wrapf(err, "unable to modify kubeconfig %s", path)
}
return configFileName, nil
}
func getConfigAccess(explicitPath string) clientcmd.ConfigAccess {
pathOptions := clientcmd.NewDefaultPathOptions()
if explicitPath != "" && explicitPath != DefaultPath() {
pathOptions.LoadingRules.ExplicitPath = explicitPath
}
return interface{}(pathOptions).(clientcmd.ConfigAccess)
}
func merge(existing *clientcmdapi.Config, tomerge *clientcmdapi.Config) *clientcmdapi.Config {
for k, v := range tomerge.Clusters {
existing.Clusters[k] = v
}
for k, v := range tomerge.AuthInfos {
existing.AuthInfos[k] = v
}
for k, v := range tomerge.Contexts {
existing.Contexts[k] = v
}
return existing
}
// AutoPath returns the path for the auto-generated kubeconfig
func AutoPath(name string) string {
return path.Join(clientcmd.RecommendedConfigDir, "eksctl", "clusters", name)
}
func isValidConfig(p, name string) error {
clientConfig, err := clientcmd.LoadFromFile(p)
if err != nil {
return errors.Wrapf(err, "unable to load config %q", p)
}
if err := clientcmd.ConfirmUsable(*clientConfig, ""); err != nil {
return errors.Wrapf(err, "unable to parse config %q", p)
}
// we want to make sure we only delete config files that haven't be modified by the user
// checking context name is a good start, we might want ot do deeper checks later, e.g. checksum,
// as we don't want to delete any files by accident that didn't belong to us
ctxFmtErr := fmt.Errorf("unable to verify ownership of config %q, unexpected contex name %q", p, clientConfig.CurrentContext)
ctx := strings.Split(clientConfig.CurrentContext, "@")
if len(ctx) != 2 {
return ctxFmtErr
}
if strings.HasPrefix(ctx[1], name+".") && strings.HasSuffix(ctx[1], ".eksctl.io") {
return nil
}
return ctxFmtErr
}
// MaybeDeleteConfig will delete the auto-generated kubeconfig, if it exists
func MaybeDeleteConfig(meta *api.ClusterMeta) {
p := AutoPath(meta.Name)
if file.Exists(p) {
fl, err := lockConfigFile(p)
if err != nil {
logger.Critical(err.Error())
return
}
defer func() {
if err := unlockConfigFile(fl); err != nil {
logger.Critical(err.Error())
}
}()
if err := isValidConfig(p, meta.Name); err != nil {
logger.Debug(err.Error())
return
}
if err := os.Remove(p); err != nil {
logger.Debug("ignoring error while removing auto-generated config file %q: %s", p, err.Error())
}
return
}
configAccess := getConfigAccess(DefaultPath())
defaultFilename := configAccess.GetDefaultFilename()
fl, err := lockConfigFile(defaultFilename)
if err != nil {
logger.Critical(err.Error())
return
}
defer func() {
if err := unlockConfigFile(fl); err != nil {
logger.Critical(err.Error())
}
}()
config, err := configAccess.GetStartingConfig()
if err != nil {
logger.Debug("error reading kubeconfig file %q: %s", DefaultPath(), err.Error())
return
}
if !deleteClusterInfo(config, meta) {
return
}
if err := clientcmd.ModifyConfig(configAccess, *config, true); err != nil {
logger.Debug("ignoring error while failing to update config file %q: %s", DefaultPath(), err.Error())
} else {
logger.Success("kubeconfig has been updated")
}
}
// deleteClusterInfo removes a cluster's information from the kubeconfig if the cluster name
// provided by ctl matches a eksctl-created cluster in the kubeconfig
// returns 'true' if the existing config has changes and 'false' otherwise
func deleteClusterInfo(existing *clientcmdapi.Config, meta *api.ClusterMeta) bool {
isChanged := false
clusterName := meta.String()
if _, ok := existing.Clusters[clusterName]; ok {
delete(existing.Clusters, clusterName)
logger.Debug("removed cluster %q from kubeconfig", clusterName)
isChanged = true
}
var currentContextName string
for name, context := range existing.Contexts {
if context.Cluster == clusterName {
delete(existing.Contexts, name)
logger.Debug("removed context for %q from kubeconfig", name)
isChanged = true
if _, ok := existing.AuthInfos[name]; ok {
delete(existing.AuthInfos, name)
logger.Debug("removed user for %q from kubeconfig", name)
}
currentContextName = name
break
}
}
if existing.CurrentContext == currentContextName {
existing.CurrentContext = ""
logger.Debug("reset current-context in kubeconfig to %q", currentContextName)
isChanged = true
}
if parts := strings.Split(existing.CurrentContext, "@"); len(parts) == 2 {
if strings.HasSuffix(parts[1], "eksctl.io") {
if _, ok := existing.Contexts[existing.CurrentContext]; !ok {
existing.CurrentContext = ""
logger.Debug("reset stale current-context in kubeconfig", currentContextName)
isChanged = true
}
}
}
return isChanged
}
// CheckAllCommands check version of kubectl, and if it can be used with either
// of the authenticator commands; most importantly it validates if kubectl can
// use kubeconfig we've created for it
func CheckAllCommands(kubeconfigPath string, isContextSet bool, contextName string, env []string) error {
authenticator, found := lookupAuthenticator()
if !found {
return fmt.Errorf("could not find any of the authenticator commands: %s", strings.Join(authenticatorCommands(), ", "))
}
logger.Debug("found authenticator: %s", authenticator)
kubectlPath, err := execLookPath(kubectl.Command)
if err != nil {
return fmt.Errorf("kubectl not found, v1.10.0 or newer is required")
}
logger.Debug("kubectl: %q", kubectlPath)
vm := newVersionManager()
clientVersion, err := vm.ClientVersion()
if err != nil {
return fmt.Errorf("getting kubectl version: %w", err)
}
logger.Debug("kubectl version: %s", clientVersion)
err = vm.ValidateVersion(clientVersion, kubectl.Client)
if err != nil {
return fmt.Errorf("validating kubectl version: %w", err)
}
if kubeconfigPath != "" {
var args []string
if kubeconfigPath != clientcmd.RecommendedHomeFile {
args = append(args, fmt.Sprintf("--kubeconfig=%s", kubeconfigPath))
}
if !isContextSet {
args = append(args, fmt.Sprintf("--context=%s", contextName))
}
suggestion := fmt.Sprintf("(check '%s')", fmtCmd(append(args, "version")))
serverVersion, err := vm.ServerVersion(env, args)
if err != nil {
return fmt.Errorf("getting Kubernetes version on EKS cluster: %w %s", err, suggestion)
}
err = vm.ValidateVersion(serverVersion, kubectl.Server)
if err != nil {
return fmt.Errorf("validating Kubernetes version returned by EKS API: %w", err)
}
logger.Info("kubectl command should work with %q, try '%s'", kubeconfigPath, fmtCmd(append(args, "get", "nodes")))
} else {
logger.Debug("skipping kubectl integration checks, as writing kubeconfig file is disabled")
}
return nil
}
func fmtCmd(args []string) string {
cmd := []string{kubectl.Command}
cmd = append(cmd, args...)
return shellquote.Join(cmd...)
}