130 lines
3.7 KiB
Go
130 lines
3.7 KiB
Go
package kubernetes
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import (
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"context"
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"fmt"
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"os"
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"github.com/hashicorp/vault/api"
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)
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type KubernetesAuth struct {
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roleName string
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mountPath string
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serviceAccountToken string
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}
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var _ api.AuthMethod = (*KubernetesAuth)(nil)
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type LoginOption func(a *KubernetesAuth) error
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const (
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defaultMountPath = "kubernetes"
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defaultServiceAccountTokenPath = "/var/run/secrets/kubernetes.io/serviceaccount/token"
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)
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// NewKubernetesAuth creates a KubernetesAuth struct which can be passed to
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// the client.Auth().Login method to authenticate to Vault. The roleName
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// parameter should be the name of the role in Vault that was created with
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// this app's Kubernetes service account bound to it.
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//
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// The Kubernetes service account token JWT is retrieved from
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// /var/run/secrets/kubernetes.io/serviceaccount/token by default. To change this
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// path, pass the WithServiceAccountTokenPath option. To instead pass the
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// JWT directly as a string, or to read the value from an environment
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// variable, use WithServiceAccountToken and WithServiceAccountTokenEnv respectively.
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//
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// Supported options: WithMountPath, WithServiceAccountTokenPath, WithServiceAccountTokenEnv, WithServiceAccountToken
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func NewKubernetesAuth(roleName string, opts ...LoginOption) (*KubernetesAuth, error) {
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if roleName == "" {
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return nil, fmt.Errorf("no role name was provided")
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}
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a := &KubernetesAuth{
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roleName: roleName,
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mountPath: defaultMountPath,
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}
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// Loop through each option
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for _, opt := range opts {
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// Call the option giving the instantiated
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// *KubernetesAuth as the argument
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err := opt(a)
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if err != nil {
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return nil, fmt.Errorf("error with login option: %w", err)
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}
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}
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if a.serviceAccountToken == "" {
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token, err := readTokenFromFile(defaultServiceAccountTokenPath)
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if err != nil {
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return nil, fmt.Errorf("error reading service account token from default location: %w", err)
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}
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a.serviceAccountToken = token
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}
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// return the modified auth struct instance
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return a, nil
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}
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func (a *KubernetesAuth) Login(ctx context.Context, client *api.Client) (*api.Secret, error) {
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loginData := map[string]interface{}{
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"jwt": a.serviceAccountToken,
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"role": a.roleName,
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}
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path := fmt.Sprintf("auth/%s/login", a.mountPath)
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resp, err := client.Logical().Write(path, loginData)
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if err != nil {
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return nil, fmt.Errorf("unable to log in with Kubernetes auth: %w", err)
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}
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return resp, nil
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}
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func WithMountPath(mountPath string) LoginOption {
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return func(a *KubernetesAuth) error {
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a.mountPath = mountPath
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return nil
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}
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}
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// WithServiceAccountTokenPath allows you to specify a different path to
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// where your application's Kubernetes service account token is mounted,
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// instead of the default of /var/run/secrets/kubernetes.io/serviceaccount/token
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func WithServiceAccountTokenPath(pathToToken string) LoginOption {
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return func(a *KubernetesAuth) error {
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token, err := readTokenFromFile(pathToToken)
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if err != nil {
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return fmt.Errorf("unable to read service account token from file: %w", err)
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}
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a.serviceAccountToken = token
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return nil
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}
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}
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func WithServiceAccountToken(jwt string) LoginOption {
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return func(a *KubernetesAuth) error {
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a.serviceAccountToken = jwt
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return nil
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}
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}
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func WithServiceAccountTokenEnv(envVar string) LoginOption {
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return func(a *KubernetesAuth) error {
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token := os.Getenv(envVar)
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if token == "" {
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return fmt.Errorf("service account token was specified with an environment variable with an empty value")
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}
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a.serviceAccountToken = token
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return nil
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}
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}
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func readTokenFromFile(filepath string) (string, error) {
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jwt, err := os.ReadFile(filepath)
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if err != nil {
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return "", fmt.Errorf("unable to read file containing service account token: %w", err)
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}
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return string(jwt), nil
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}
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