Add windows 32bit binary

2026-02-18 18:39:51 +00:00 · 2018-03-23 20:04:07 +09:00
24 changed files with 374 additions and 1089 deletions
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -6,12 +6,10 @@ jobs:
    working_directory: /go/src/github.com/int128/kubelogin
    steps:
      - checkout
-      - run: go get -v -t -d ./...
+      - run: go get -v -t -d
      - run: go get github.com/golang/lint/golint
      - run: golint
      - run: go build -v
-      - run: make -C integration-test/testdata
-      - run: go test -v ./...

  release:
    docker:
@@ -19,7 +17,7 @@ jobs:
    working_directory: /go/src/github.com/int128/kubelogin
    steps:
      - checkout
-      - run: go get -v -t -d ./...
+      - run: go get -v -t -d
      - run: go get github.com/mitchellh/gox
      - run: go get github.com/tcnksm/ghr
      - run: gox --osarch 'darwin/amd64 linux/amd64 windows/amd64 windows/386' -output 'dist/{{.Dir}}_{{.OS}}_{{.Arch}}'
--- a/.editorconfig
+++ b/.editorconfig
@@ -8,8 +8,3 @@ indent_size = 2

 [*.go]
 indent_style = tab
-indent_size = 4
-
-[Makefile]
-indent_style = tab
-indent_size = 4
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1 @@
 /kubelogin
-/.kubeconfig
--- a/README.md
+++ b/README.md
@@ -3,219 +3,118 @@
 `kubelogin` is a command to get an OpenID Connect (OIDC) token for `kubectl` authentication.


-## TL;DR
+## Getting Started

-1. Setup your OpenID Connect provider, e.g. Google Identity Platform or Keycloak.
-1. Setup your Kubernetes cluster.
-1. Setup your `kubectl`.
+Download [the latest release](https://github.com/int128/kubelogin/releases) and save it as `/usr/local/bin/kubelogin`.

-```
-% kubelogin --help
-2018/08/15 19:08:58 Usage:
-  kubelogin [OPTIONS]
-
-Application Options:
-      --kubeconfig=               Path to the kubeconfig file (default: ~/.kube/config) [$KUBECONFIG]
-      --insecure-skip-tls-verify  If set, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure
-                                  [$KUBELOGIN_INSECURE_SKIP_TLS_VERIFY]
-
-Help Options:
-  -h, --help        Show this help message
-```
-
-
-## Getting Started with Google Account
-
-### 1. Setup Google API
-
-Open [Google APIs Console](https://console.developers.google.com/apis/credentials) and create an OAuth client as follows:
-
- Application Type: Web application
- Redirect URL: `http://localhost:8000/`
-
-### 2. Setup Kubernetes cluster
-
-Configure your Kubernetes API Server accepts [OpenID Connect Tokens](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#openid-connect-tokens).
-If you are using [kops](https://github.com/kubernetes/kops), run `kops edit cluster` and append the following settings:
-
-```yaml
-spec:
-  kubeAPIServer:
-    oidcIssuerURL: https://accounts.google.com
-    oidcClientID: YOUR_CLIENT_ID.apps.googleusercontent.com
-```
-
-Here assign the `cluster-admin` role to your user.
-
-```yaml
-kind: ClusterRoleBinding
-apiVersion: rbac.authorization.k8s.io/v1
-metadata:
-  name: oidc-admin-group
-roleRef:
-  apiGroup: rbac.authorization.k8s.io
-  kind: ClusterRole
-  name: cluster-admin
-subjects:
- kind: User
-  name: https://accounts.google.com#1234567890
-```
-
-### 3. Setup kubectl and kubelogin
-
-Setup `kubectl` to authenticate with your identity provider.
-
-```sh
-kubectl config set-credentials CLUSTER_NAME \
-  --auth-provider oidc \
-  --auth-provider-arg idp-issuer-url=https://accounts.google.com \
-  --auth-provider-arg client-id=YOUR_CLIENT_ID.apps.googleusercontent.com \
-  --auth-provider-arg client-secret=YOUR_CLIENT_SECRET
-```
-
-Download [the latest release](https://github.com/int128/kubelogin/releases) and save it.
-
-Run `kubelogin` and open http://localhost:8000 in your browser.
+Run the command.

 ```
 % kubelogin
-2018/08/10 10:36:38 Reading .kubeconfig
-2018/08/10 10:36:38 Using current context: hello.k8s.local
-2018/08/10 10:36:41 Open http://localhost:8000 for authorization
-2018/08/10 10:36:45 GET /
-2018/08/10 10:37:07 GET /?state=...&session_state=...&code=ey...
-2018/08/10 10:37:08 Updated .kubeconfig
+2018/03/23 18:01:40 Reading config from /home/user/.kube/config
+2018/03/23 18:01:40 Using current context: hello.k8s.local
+2018/03/23 18:01:40 Using issuer: https://keycloak.example.com/auth/realms/hello
+2018/03/23 18:01:40 Using client ID: kubernetes
+2018/03/23 18:01:41 Starting OpenID Connect authentication:
+
+## Automatic (recommended)
+
+Open the following URL in the web browser:
+
+http://localhost:8000/
+
+## Manual
+
+If you cannot access to localhost, instead open the following URL:
+
+https://keycloak.example.com/auth/realms/hello/protocol/openid-connect/auth?client_id=kubernetes&redirect_uri=urn%3Aietf%3Awg%3Aoauth%3A2.0%3Aoob&response_type=code&scope=openid+email&state=********
+
+Enter the code:
 ```

-Now your `~/.kube/config` should be like:
+And then open http://localhost:8000.
+If you cannot access to localhost, you can choose manual interaction instead.
+
+`kubelogin` will update your `~/.kube/config` with the ID token and refresh token, as follows:

 ```yaml
+# ~/.kube/config (snip)
+current-context: hello.k8s.local
+contexts:
+- context:
+    cluster: hello.k8s.local
+    user: hello.k8s.local
+  name: hello.k8s.local
 users:
 - name: hello.k8s.local
  user:
    auth-provider:
      config:
-        idp-issuer-url: https://accounts.google.com
-        client-id: YOUR_CLIENT_ID.apps.googleusercontent.com
+        idp-issuer-url: https://keycloak.example.com/auth/realms/hello
+        client-id: kubernetes
        client-secret: YOUR_SECRET
-        id-token: ey...       # kubelogin will update ID token here
-        refresh-token: ey...  # kubelogin will update refresh token here
+        id-token: ey...       # kubelogin will update ID token
+        refresh-token: ey...  # kubelogin will update refresh token
      name: oidc
 ```

-Make sure you can access to the Kubernetes cluster.
+Make sure you can access to the cluster:

 ```
-% kubectl get nodes
-NAME                                    STATUS    ROLES     AGE       VERSION
-ip-1-2-3-4.us-west-2.compute.internal   Ready     node      21d       v1.9.6
-ip-1-2-3-5.us-west-2.compute.internal   Ready     node      20d       v1.9.6
+% kubectl version
+Client Version: version.Info{...}
+Server Version: version.Info{...}
 ```


-## Getting Started with Keycloak
+## Prerequisite

-### 1. Setup Keycloak
+You have to setup your OIDC identity provider and Kubernetes cluster.

-Create an OIDC client as follows:
+### 1. Setup OIDC Identity Provider

- Redirect URL: `http://localhost:8000/`
- Issuer URL: `https://keycloak.example.com/auth/realms/YOUR_REALM`
+This tutorial assumes you have created an OIDC client with the following:
+
+- Issuer URL: `https://keycloak.example.com/auth/realms/hello`
 - Client ID: `kubernetes`
- Groups claim: `groups`
+- Client Secret: `YOUR_CLIENT_SECRET`
+- Allowed redirect URLs:
+  - `http://localhost:8000/`
+  - `urn:ietf:wg:oauth:2.0:oob`
+- Groups claim: `groups` (optional for group based access controll)

-Then create a group `kubernetes:admin` and join to it.
+### 2. Setup Kubernetes API Server

-### 2. Setup Kubernetes cluster
+Configure the Kubernetes API server allows your identity provider.

-Configure your Kubernetes API Server accepts [OpenID Connect Tokens](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#openid-connect-tokens).
-If you are using [kops](https://github.com/kubernetes/kops), run `kops edit cluster` and append the following settings:
+If you are using kops, `kops edit cluster` and append the following settings:

 ```yaml
 spec:
  kubeAPIServer:
-    oidcIssuerURL: https://keycloak.example.com/auth/realms/YOUR_REALM
    oidcClientID: kubernetes
    oidcGroupsClaim: groups
+    oidcIssuerURL: https://keycloak.example.com/auth/realms/hello
 ```

-Here assign the `cluster-admin` role to the `kubernetes:admin` group.
+### 3. Setup kubectl

-```yaml
-kind: ClusterRoleBinding
-apiVersion: rbac.authorization.k8s.io/v1
-metadata:
-  name: keycloak-admin-group
-roleRef:
-  apiGroup: rbac.authorization.k8s.io
-  kind: ClusterRole
-  name: cluster-admin
-subjects:
- kind: Group
-  name: /kubernetes:admin
-```
-
-### 3. Setup kubectl and kubelogin
-
-Setup `kubectl` to authenticate with your identity provider.
+Run the following script to configure `kubectl` uses your identity provider:

 ```sh
-kubectl config set-credentials CLUSTER_NAME \
+CLUSTER_NAME=hello.k8s.local
+
+kubectl config set-credentials $CLUSTER_NAME \
  --auth-provider oidc \
-  --auth-provider-arg idp-issuer-url=https://keycloak.example.com/auth/realms/YOUR_REALM \
+  --auth-provider-arg idp-issuer-url=https://keycloak.example.com/auth/realms/hello \
  --auth-provider-arg client-id=kubernetes \
  --auth-provider-arg client-secret=YOUR_CLIENT_SECRET
+
+# Set the context
+kubectl config set-context $CLUSTER_NAME --cluster $CLUSTER_NAME --user $CLUSTER_NAME
 ```

-Download [the latest release](https://github.com/int128/kubelogin/releases) and save it.
-
-Run `kubelogin` and make sure you can access to the cluster.
-See the previous section for details.
-
-
-## Configuration
-
-### Kubeconfig
-
-You can set the environment variable `KUBECONFIG` to point the config file.
-Default to `~/.kube/config`.
-
-```sh
-export KUBECONFIG="$PWD/.kubeconfig"
-```
-
-### OpenID Connect Provider CA Certificate
-
-You can specify the CA certificate of your OpenID Connect provider by [`idp-certificate-authority` or `idp-certificate-authority-data` in the kubeconfig](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#using-kubectl).
-
-```sh
-kubectl config set-credentials CLUSTER_NAME \
-  --auth-provider-arg idp-certificate-authority=$PWD/ca.crt
-```
-
-### Setup script
-
-In actual team operation, you can share the following script to your team members for easy setup.
-
-```sh
-#!/bin/sh -xe
-CLUSTER_NAME="hello.k8s.local"
-
-export KUBECONFIG="$PWD/.kubeconfig"
-
-kubectl config set-cluster "$CLUSTER_NAME" \
-  --server https://api-xxx.xxx.elb.amazonaws.com \
-  --certificate-authority "$PWD/cluster.crt"
-
-kubectl config set-credentials "$CLUSTER_NAME" \
-  --auth-provider oidc \
-  --auth-provider-arg idp-issuer-url=https://accounts.google.com \
-  --auth-provider-arg client-id=YOUR_CLIENT_ID.apps.googleusercontent.com \
-  --auth-provider-arg client-secret=YOUR_CLIENT_SECRET
-
-kubectl config set-context "$CLUSTER_NAME" --cluster "$CLUSTER_NAME" --user "$CLUSTER_NAME"
-kubectl config use-context "$CLUSTER_NAME"
-```
+In actual team operation, you can distribute the script to your team members for easy setup.


 ## Contributions
@@ -223,12 +122,8 @@ kubectl config use-context "$CLUSTER_NAME"
 This is an open source software licensed under Apache License 2.0.
 Feel free to open issues and pull requests.

-### Build
+### How to build

 ```sh
 go get github.com/int128/kubelogin
 ```
-
-### Release
-
-CircleCI publishes the build to GitHub. See [.circleci/config.yml](.circleci/config.yml).
--- a/auth/authcode.go
+++ b/auth/authcode.go
@@ -1,107 +0,0 @@
-package auth
-
-import (
-	"context"
-	"crypto/rand"
-	"encoding/binary"
-	"fmt"
-	"log"
-	"net/http"
-
-	"golang.org/x/oauth2"
-)
-
-// BrowserAuthCodeFlow is a flow to get a token by browser interaction.
-type BrowserAuthCodeFlow struct {
-	oauth2.Config
-	Port int // HTTP server port
-}
-
-// GetToken returns a token.
-func (f *BrowserAuthCodeFlow) GetToken(ctx context.Context) (*oauth2.Token, error) {
-	f.Config.RedirectURL = fmt.Sprintf("http://localhost:%d/", f.Port)
-	state, err := generateState()
-	if err != nil {
-		return nil, fmt.Errorf("Could not generate state parameter: %s", err)
-	}
-	log.Printf("Open http://localhost:%d for authorization", f.Port)
-	code, err := f.getCode(ctx, &f.Config, state)
-	if err != nil {
-		return nil, err
-	}
-	token, err := f.Config.Exchange(ctx, code)
-	if err != nil {
-		return nil, fmt.Errorf("Could not exchange oauth code: %s", err)
-	}
-	return token, nil
-}
-
-func generateState() (string, error) {
-	var n uint64
-	if err := binary.Read(rand.Reader, binary.LittleEndian, &n); err != nil {
-		return "", err
-	}
-	return fmt.Sprintf("%x", n), nil
-}
-
-func (f *BrowserAuthCodeFlow) getCode(ctx context.Context, config *oauth2.Config, state string) (string, error) {
-	codeCh := make(chan string)
-	errCh := make(chan error)
-	server := http.Server{
-		Addr: fmt.Sprintf(":%d", f.Port),
-		Handler: &handler{
-			AuthCodeURL: config.AuthCodeURL(state),
-			Callback: func(code string, actualState string, err error) {
-				switch {
-				case err != nil:
-					errCh <- err
-				case actualState != state:
-					errCh <- fmt.Errorf("OAuth state did not match, should be %s but %s", state, actualState)
-				default:
-					codeCh <- code
-				}
-			},
-		},
-	}
-	go func() {
-		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-			errCh <- err
-		}
-	}()
-	select {
-	case err := <-errCh:
-		server.Shutdown(ctx)
-		return "", err
-	case code := <-codeCh:
-		server.Shutdown(ctx)
-		return code, nil
-	}
-}
-
-type handler struct {
-	AuthCodeURL string
-	Callback    func(code string, state string, err error)
-}
-
-func (s *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	log.Printf("%s %s", r.Method, r.RequestURI)
-	switch r.URL.Path {
-	case "/":
-		code := r.URL.Query().Get("code")
-		state := r.URL.Query().Get("state")
-		errorCode := r.URL.Query().Get("error")
-		errorDescription := r.URL.Query().Get("error_description")
-		switch {
-		case code != "":
-			s.Callback(code, state, nil)
-			fmt.Fprintf(w, "Back to command line.")
-		case errorCode != "":
-			s.Callback("", "", fmt.Errorf("OAuth Error: %s %s", errorCode, errorDescription))
-			fmt.Fprintf(w, "Back to command line.")
-		default:
-			http.Redirect(w, r, s.AuthCodeURL, 302)
-		}
-	default:
-		http.Error(w, "Not Found", 404)
-	}
-}
--- a/auth/oidc.go
+++ b/auth/oidc.go
@@ -1,60 +0,0 @@
-package auth
-
-import (
-	"context"
-	"fmt"
-
-	oidc "github.com/coreos/go-oidc"
-	"golang.org/x/oauth2"
-)
-
-// TokenSet is a set of tokens and claims.
-type TokenSet struct {
-	IDToken      string
-	RefreshToken string
-	Claims       *Claims
-}
-
-// Claims represents properties in the ID token.
-type Claims struct {
-	Email string `json:"email"`
-}
-
-// GetTokenSet retrieves a token from the OIDC provider.
-func GetTokenSet(ctx context.Context, issuer string, clientID string, clientSecret string) (*TokenSet, error) {
-	provider, err := oidc.NewProvider(ctx, issuer)
-	if err != nil {
-		return nil, fmt.Errorf("Could not access OIDC issuer: %s", err)
-	}
-	flow := BrowserAuthCodeFlow{
-		Port: 8000,
-		Config: oauth2.Config{
-			Endpoint:     provider.Endpoint(),
-			ClientID:     clientID,
-			ClientSecret: clientSecret,
-			Scopes:       []string{oidc.ScopeOpenID, "email"},
-		},
-	}
-	token, err := flow.GetToken(ctx)
-	if err != nil {
-		return nil, fmt.Errorf("Could not get a token: %s", err)
-	}
-	rawIDToken, ok := token.Extra("id_token").(string)
-	if !ok {
-		return nil, fmt.Errorf("id_token is missing in the token response: %s", token)
-	}
-	verifier := provider.Verifier(&oidc.Config{ClientID: clientID})
-	idToken, err := verifier.Verify(ctx, rawIDToken)
-	if err != nil {
-		return nil, fmt.Errorf("Could not verify the id_token: %s", err)
-	}
-	var claims Claims
-	if err := idToken.Claims(&claims); err != nil {
-		return nil, fmt.Errorf("Could not extract claims from the token response: %s", err)
-	}
-	return &TokenSet{
-		IDToken:      rawIDToken,
-		RefreshToken: token.RefreshToken,
-		Claims:       &claims,
-	}, nil
-}
--- a/cli/cli.go
+++ b/cli/cli.go
@@ -1,115 +0,0 @@
-package cli
-
-import (
-	"context"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/base64"
-	"fmt"
-	"io/ioutil"
-	"log"
-	"net/http"
-
-	"github.com/int128/kubelogin/auth"
-	"github.com/int128/kubelogin/kubeconfig"
-	flags "github.com/jessevdk/go-flags"
-	homedir "github.com/mitchellh/go-homedir"
-	"golang.org/x/oauth2"
-)
-
-// Parse parses command line arguments and returns a CLI instance.
-func Parse(args []string) (*CLI, error) {
-	var cli CLI
-	parser := flags.NewParser(&cli, flags.HelpFlag)
-	args, err := parser.Parse()
-	if err != nil {
-		return nil, err
-	}
-	if len(args) > 0 {
-		return nil, fmt.Errorf("Too many argument")
-	}
-	return &cli, nil
-}
-
-// CLI represents an interface of this command.
-type CLI struct {
-	KubeConfig    string `long:"kubeconfig" default:"~/.kube/config" env:"KUBECONFIG" description:"Path to the kubeconfig file"`
-	SkipTLSVerify bool   `long:"insecure-skip-tls-verify" env:"KUBELOGIN_INSECURE_SKIP_TLS_VERIFY" description:"If set, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure"`
-	// CertificateAuthority string `long:"certificate-authority" env:"KUBELOGIN_CERTIFICATE_AUTHORITY" description:"Path to a cert file for the certificate authority"`
-}
-
-// ExpandKubeConfig returns an expanded KubeConfig path.
-func (c *CLI) ExpandKubeConfig() (string, error) {
-	d, err := homedir.Expand(c.KubeConfig)
-	if err != nil {
-		return "", fmt.Errorf("Could not expand %s", c.KubeConfig)
-	}
-	return d, nil
-}
-
-// Run performs this command.
-func (c *CLI) Run(ctx context.Context) error {
-	path, err := c.ExpandKubeConfig()
-	if err != nil {
-		return err
-	}
-	log.Printf("Reading %s", path)
-	cfg, err := kubeconfig.Load(path)
-	if err != nil {
-		return fmt.Errorf("Could not load kubeconfig: %s", err)
-	}
-	log.Printf("Using current context: %s", cfg.CurrentContext)
-	authInfo := kubeconfig.FindCurrentAuthInfo(cfg)
-	if authInfo == nil {
-		return fmt.Errorf("Could not find current context: %s", cfg.CurrentContext)
-	}
-	authProvider, err := kubeconfig.ToOIDCAuthProviderConfig(authInfo)
-	if err != nil {
-		return fmt.Errorf("Could not find auth-provider: %s", err)
-	}
-	tlsConfig, err := c.tlsConfig(authProvider)
-	if err != nil {
-		return fmt.Errorf("Could not configure TLS: %s", err)
-	}
-	client := &http.Client{Transport: &http.Transport{TLSClientConfig: tlsConfig}}
-	ctx = context.WithValue(ctx, oauth2.HTTPClient, client)
-	token, err := auth.GetTokenSet(ctx, authProvider.IDPIssuerURL(), authProvider.ClientID(), authProvider.ClientSecret())
-	if err != nil {
-		return fmt.Errorf("Authentication error: %s", err)
-	}
-
-	authProvider.SetIDToken(token.IDToken)
-	authProvider.SetRefreshToken(token.RefreshToken)
-	kubeconfig.Write(cfg, path)
-	log.Printf("Updated %s", path)
-	return nil
-}
-
-func (c *CLI) tlsConfig(authProvider *kubeconfig.OIDCAuthProviderConfig) (*tls.Config, error) {
-	p := x509.NewCertPool()
-	if authProvider.IDPCertificateAuthority() != "" {
-		b, err := ioutil.ReadFile(authProvider.IDPCertificateAuthority())
-		if err != nil {
-			return nil, fmt.Errorf("Could not read idp-certificate-authority: %s", err)
-		}
-		if p.AppendCertsFromPEM(b) != true {
-			return nil, fmt.Errorf("Could not load CA certificate from idp-certificate-authority: %s", err)
-		}
-		log.Printf("Using CA certificate: %s", authProvider.IDPCertificateAuthority())
-	}
-	if authProvider.IDPCertificateAuthorityData() != "" {
-		b, err := base64.StdEncoding.DecodeString(authProvider.IDPCertificateAuthorityData())
-		if err != nil {
-			return nil, fmt.Errorf("Could not decode idp-certificate-authority-data: %s", err)
-		}
-		if p.AppendCertsFromPEM(b) != true {
-			return nil, fmt.Errorf("Could not load CA certificate from idp-certificate-authority-data: %s", err)
-		}
-		log.Printf("Using CA certificate of idp-certificate-authority-data")
-	}
-	cfg := &tls.Config{InsecureSkipVerify: c.SkipTLSVerify}
-	if len(p.Subjects()) > 0 {
-		cfg.RootCAs = p
-	}
-	return cfg, nil
-}
--- a/config.go
+++ b/config.go
@@ -0,0 +1,46 @@
+package main
+
+import (
+	"os"
+
+	"github.com/mitchellh/go-homedir"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/tools/clientcmd/api"
+)
+
+// GetCurrentAuthInfo returns the current authInfo
+func GetCurrentAuthInfo(config api.Config) *api.AuthInfo {
+	context := config.Contexts[config.CurrentContext]
+	if context == nil {
+		return nil
+	}
+	authInfo := config.AuthInfos[context.AuthInfo]
+	return authInfo
+}
+
+// ReadKubeConfig returns the current config
+func ReadKubeConfig(path string) (*api.Config, error) {
+	config, err := clientcmd.LoadFromFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return config, nil
+}
+
+// WriteKubeConfig writes the config
+func WriteKubeConfig(config api.Config, path string) error {
+	return clientcmd.WriteToFile(config, path)
+}
+
+// FindKubeConfig returns env:KUBECONFIG or ~/.kube/config
+func FindKubeConfig() (string, error) {
+	env := os.Getenv("KUBECONFIG")
+	if env != "" {
+		return env, nil
+	}
+	path, err := homedir.Expand("~/.kube/config")
+	if err != nil {
+		return "", err
+	}
+	return path, nil
+}
--- a/integration-test/auth.go
+++ b/integration-test/auth.go
@@ -1,104 +0,0 @@
-package integration
-
-import (
-	"crypto/rand"
-	"crypto/rsa"
-	"encoding/base64"
-	"fmt"
-	"html/template"
-	"log"
-	"math/big"
-	"net/http"
-	"testing"
-	"time"
-
-	jwt "github.com/dgrijalva/jwt-go"
-)
-
-// AuthHandler provides the stub handler for OIDC authentication.
-type AuthHandler struct {
-	// Values in templates
-	Issuer     string
-	AuthCode   string
-	IDToken    string
-	PrivateKey struct{ N, E string }
-
-	// Response templates
-	discoveryJSON *template.Template
-	tokenJSON     *template.Template
-	jwksJSON      *template.Template
-}
-
-// NewAuthHandler returns a new AuthHandler.
-func NewAuthHandler(t *testing.T, issuer string) *AuthHandler {
-	h := &AuthHandler{
-		Issuer:        issuer,
-		AuthCode:      "0b70006b-f62a-4438-aba5-c0b96775d8e5",
-		discoveryJSON: template.Must(template.ParseFiles("testdata/oidc-discovery.json")),
-		tokenJSON:     template.Must(template.ParseFiles("testdata/oidc-token.json")),
-		jwksJSON:      template.Must(template.ParseFiles("testdata/oidc-jwks.json")),
-	}
-	token := jwt.NewWithClaims(jwt.SigningMethodRS256, jwt.StandardClaims{
-		Issuer:    h.Issuer,
-		Audience:  "kubernetes",
-		ExpiresAt: time.Now().Add(time.Hour).Unix(),
-	})
-	k, err := rsa.GenerateKey(rand.Reader, 1024)
-	if err != nil {
-		t.Fatalf("Could not generate a key pair: %s", err)
-	}
-	h.IDToken, err = token.SignedString(k)
-	if err != nil {
-		t.Fatalf("Could not generate an ID token: %s", err)
-	}
-	h.PrivateKey.E = base64.RawURLEncoding.EncodeToString(big.NewInt(int64(k.E)).Bytes())
-	h.PrivateKey.N = base64.RawURLEncoding.EncodeToString(k.N.Bytes())
-	return h
-}
-
-func (s *AuthHandler) serveHTTP(w http.ResponseWriter, r *http.Request) error {
-	m := r.Method
-	p := r.URL.Path
-	log.Printf("[auth-server] %s %s", m, r.RequestURI)
-	switch {
-	case m == "GET" && p == "/.well-known/openid-configuration":
-		w.Header().Add("Content-Type", "application/json")
-		if err := s.discoveryJSON.Execute(w, s); err != nil {
-			return err
-		}
-	case m == "GET" && p == "/protocol/openid-connect/auth":
-		// Authentication Response
-		// http://openid.net/specs/openid-connect-core-1_0.html#AuthResponse
-		q := r.URL.Query()
-		to := fmt.Sprintf("%s?state=%s&code=%s", q.Get("redirect_uri"), q.Get("state"), s.AuthCode)
-		http.Redirect(w, r, to, 302)
-	case m == "POST" && p == "/protocol/openid-connect/token":
-		// Token Response
-		// http://openid.net/specs/openid-connect-core-1_0.html#TokenResponse
-		if err := r.ParseForm(); err != nil {
-			return err
-		}
-		if s.AuthCode != r.Form.Get("code") {
-			return fmt.Errorf("code wants %s but %s", s.AuthCode, r.Form.Get("code"))
-		}
-		w.Header().Add("Content-Type", "application/json")
-		if err := s.tokenJSON.Execute(w, s); err != nil {
-			return err
-		}
-	case m == "GET" && p == "/protocol/openid-connect/certs":
-		w.Header().Add("Content-Type", "application/json")
-		if err := s.jwksJSON.Execute(w, s); err != nil {
-			return err
-		}
-	default:
-		http.Error(w, "Not Found", 404)
-	}
-	return nil
-}
-
-func (s *AuthHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if err := s.serveHTTP(w, r); err != nil {
-		log.Printf("[auth-server] Error: %s", err)
-		w.WriteHeader(500)
-	}
-}
--- a/integration-test/integration_test.go
+++ b/integration-test/integration_test.go
@@ -1,160 +0,0 @@
-package integration
-
-import (
-	"context"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/base64"
-	"io/ioutil"
-	"net/http"
-	"os"
-	"testing"
-	"time"
-
-	"github.com/int128/kubelogin/cli"
-)
-
-const caCert = "testdata/authserver-ca.crt"
-const tlsCert = "testdata/authserver.crt"
-const tlsKey = "testdata/authserver.key"
-
-func Test(t *testing.T) {
-	ctx := context.Background()
-	authServer := &http.Server{
-		Addr:    "localhost:9000",
-		Handler: NewAuthHandler(t, "http://localhost:9000"),
-	}
-	defer authServer.Shutdown(ctx)
-	kubeconfig := createKubeconfig(t, &kubeconfigValues{
-		Issuer: "http://localhost:9000",
-	})
-	defer os.Remove(kubeconfig)
-
-	go listenAndServe(t, authServer)
-	go authenticate(t, &tls.Config{})
-
-	c := cli.CLI{
-		KubeConfig: kubeconfig,
-	}
-	if err := c.Run(ctx); err != nil {
-		t.Fatal(err)
-	}
-	verifyKubeconfig(t, kubeconfig)
-}
-
-func TestWithSkipTLSVerify(t *testing.T) {
-	ctx := context.Background()
-	authServer := &http.Server{
-		Addr:    "localhost:9000",
-		Handler: NewAuthHandler(t, "https://localhost:9000"),
-	}
-	defer authServer.Shutdown(ctx)
-	kubeconfig := createKubeconfig(t, &kubeconfigValues{
-		Issuer: "https://localhost:9000",
-	})
-	defer os.Remove(kubeconfig)
-
-	go listenAndServeTLS(t, authServer)
-	go authenticate(t, &tls.Config{InsecureSkipVerify: true})
-
-	c := cli.CLI{
-		KubeConfig:    kubeconfig,
-		SkipTLSVerify: true,
-	}
-	if err := c.Run(ctx); err != nil {
-		t.Fatal(err)
-	}
-	verifyKubeconfig(t, kubeconfig)
-}
-
-func TestWithCACert(t *testing.T) {
-	ctx := context.Background()
-	authServer := &http.Server{
-		Addr:    "localhost:9000",
-		Handler: NewAuthHandler(t, "https://localhost:9000"),
-	}
-	defer authServer.Shutdown(ctx)
-	kubeconfig := createKubeconfig(t, &kubeconfigValues{
-		Issuer:                  "https://localhost:9000",
-		IDPCertificateAuthority: caCert,
-	})
-	defer os.Remove(kubeconfig)
-
-	go listenAndServeTLS(t, authServer)
-	go authenticate(t, &tls.Config{RootCAs: loadCACert(t)})
-
-	c := cli.CLI{
-		KubeConfig: kubeconfig,
-	}
-	if err := c.Run(ctx); err != nil {
-		t.Fatal(err)
-	}
-	verifyKubeconfig(t, kubeconfig)
-}
-
-func TestWithCACertData(t *testing.T) {
-	ctx := context.Background()
-	authServer := &http.Server{
-		Addr:    "localhost:9000",
-		Handler: NewAuthHandler(t, "https://localhost:9000"),
-	}
-	defer authServer.Shutdown(ctx)
-	b, err := ioutil.ReadFile(caCert)
-	if err != nil {
-		t.Fatal(err)
-	}
-	kubeconfig := createKubeconfig(t, &kubeconfigValues{
-		Issuer: "https://localhost:9000",
-		IDPCertificateAuthorityData: base64.StdEncoding.EncodeToString(b),
-	})
-	defer os.Remove(kubeconfig)
-
-	go listenAndServeTLS(t, authServer)
-	go authenticate(t, &tls.Config{RootCAs: loadCACert(t)})
-
-	c := cli.CLI{
-		KubeConfig: kubeconfig,
-	}
-	if err := c.Run(ctx); err != nil {
-		t.Fatal(err)
-	}
-	verifyKubeconfig(t, kubeconfig)
-}
-
-func authenticate(t *testing.T, tlsConfig *tls.Config) {
-	t.Helper()
-	time.Sleep(100 * time.Millisecond)
-	client := http.Client{Transport: &http.Transport{TLSClientConfig: tlsConfig}}
-	res, err := client.Get("http://localhost:8000/")
-	if err != nil {
-		t.Error(err)
-		return
-	}
-	if res.StatusCode != 200 {
-		t.Errorf("StatusCode wants 200 but %d: res=%+v", res.StatusCode, res)
-	}
-}
-
-func loadCACert(t *testing.T) *x509.CertPool {
-	p := x509.NewCertPool()
-	b, err := ioutil.ReadFile(caCert)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !p.AppendCertsFromPEM(b) {
-		t.Fatalf("Could not AppendCertsFromPEM")
-	}
-	return p
-}
-
-func listenAndServe(t *testing.T, s *http.Server) {
-	if err := s.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-		t.Fatal(err)
-	}
-}
-
-func listenAndServeTLS(t *testing.T, s *http.Server) {
-	if err := s.ListenAndServeTLS(tlsCert, tlsKey); err != nil && err != http.ErrServerClosed {
-		t.Fatal(err)
-	}
-}
--- a/integration-test/kubeconfig.go
+++ b/integration-test/kubeconfig.go
@@ -1,44 +0,0 @@
-package integration
-
-import (
-	"html/template"
-	"io/ioutil"
-	"strings"
-	"testing"
-)
-
-type kubeconfigValues struct {
-	Issuer                      string
-	IDPCertificateAuthority     string
-	IDPCertificateAuthorityData string
-}
-
-func createKubeconfig(t *testing.T, v *kubeconfigValues) string {
-	t.Helper()
-	f, err := ioutil.TempFile("", "kubeconfig")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer f.Close()
-	tpl, err := template.ParseFiles("testdata/kubeconfig.yaml")
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := tpl.Execute(f, v); err != nil {
-		t.Fatal(err)
-	}
-	return f.Name()
-}
-
-func verifyKubeconfig(t *testing.T, kubeconfig string) {
-	b, err := ioutil.ReadFile(kubeconfig)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if strings.Index(string(b), "id-token: ey") == -1 {
-		t.Errorf("kubeconfig wants id-token but %s", string(b))
-	}
-	if strings.Index(string(b), "refresh-token: 44df4c82-5ce7-4260-b54d-1da0d396ef2a") == -1 {
-		t.Errorf("kubeconfig wants refresh-token but %s", string(b))
-	}
-}
--- a/integration-test/testdata/.gitignore
+++ b/integration-test/testdata/.gitignore
@@ -1,4 +0,0 @@
-/CA
-*.key
-*.csr
-*.crt
--- a/integration-test/testdata/Makefile
+++ b/integration-test/testdata/Makefile
@@ -1,50 +0,0 @@
-.PHONY: clean
-
-all: authserver.crt authserver-ca.crt
-
-clean:
-	rm -v authserver*
-
-authserver-ca.key:
-	openssl genrsa -out $@ 1024
-
-authserver-ca.csr: openssl.cnf authserver-ca.key
-	openssl req -config openssl.cnf \
-		-new \
-		-key authserver-ca.key \
-		-subj "/CN=Hello CA" \
-		-out $@
-	openssl req -noout -text -in $@
-
-authserver-ca.crt: authserver-ca.csr authserver-ca.key
-	openssl x509 -req \
-		-signkey authserver-ca.key \
-		-in authserver-ca.csr \
-		-out $@
-	openssl x509 -text -in $@
-
-authserver.key:
-	openssl genrsa -out $@ 1024
-
-authserver.csr: openssl.cnf authserver.key
-	openssl req -config openssl.cnf \
-		-new \
-		-key authserver.key \
-		-subj "/CN=localhost" \
-		-out $@
-	openssl req -noout -text -in $@
-
-authserver.crt: openssl.cnf authserver.csr authserver-ca.key authserver-ca.crt
-	rm -fr ./CA
-	mkdir -p ./CA
-	touch CA/index.txt
-	touch CA/index.txt.attr
-	echo 00 > CA/serial
-	openssl ca -config openssl.cnf \
-		-extensions v3_req \
-		-batch \
-		-cert authserver-ca.crt \
-		-keyfile authserver-ca.key \
-		-in authserver.csr \
-		-out $@
-	openssl x509 -text -in $@
--- a/integration-test/testdata/kubeconfig.yaml
+++ b/integration-test/testdata/kubeconfig.yaml
@@ -1,28 +0,0 @@
-apiVersion: v1
-kind: Config
-clusters:
-  - cluster:
-      server: https://api.hello.k8s.example.com
-      name: hello.k8s.local
-contexts:
- context:
-    cluster: hello.k8s.local
-    user: hello.k8s.local
-  name: hello.k8s.local
-current-context: hello.k8s.local
-preferences: {}
-users:
- name: hello.k8s.local
-  user:
-    auth-provider:
-      config:
-        client-id: kubernetes
-        client-secret: a3c508c3-73c9-42e2-ab14-487a1bf67c33
-        idp-issuer-url: {{ .Issuer }}
-#{{ if .IDPCertificateAuthority }}
-        idp-certificate-authority: {{ .IDPCertificateAuthority }}
-#{{ end }}
-#{{ if .IDPCertificateAuthorityData }}
-        idp-certificate-authority-data: {{ .IDPCertificateAuthorityData }}
-#{{ end }}
-      name: oidc
--- a/integration-test/testdata/oidc-discovery.json
+++ b/integration-test/testdata/oidc-discovery.json
@@ -1,85 +0,0 @@
-{
-  "issuer": "{{ .Issuer }}",
-  "authorization_endpoint": "{{ .Issuer }}/protocol/openid-connect/auth",
-  "token_endpoint": "{{ .Issuer }}/protocol/openid-connect/token",
-  "token_introspection_endpoint": "{{ .Issuer }}/protocol/openid-connect/token/introspect",
-  "userinfo_endpoint": "{{ .Issuer }}/protocol/openid-connect/userinfo",
-  "end_session_endpoint": "{{ .Issuer }}/protocol/openid-connect/logout",
-  "jwks_uri": "{{ .Issuer }}/protocol/openid-connect/certs",
-  "check_session_iframe": "{{ .Issuer }}/protocol/openid-connect/login-status-iframe.html",
-  "grant_types_supported": [
-    "authorization_code",
-    "implicit",
-    "refresh_token",
-    "password",
-    "client_credentials"
-  ],
-  "response_types_supported": [
-    "code",
-    "none",
-    "id_token",
-    "token",
-    "id_token token",
-    "code id_token",
-    "code token",
-    "code id_token token"
-  ],
-  "subject_types_supported": [
-    "public",
-    "pairwise"
-  ],
-  "id_token_signing_alg_values_supported": [
-    "RS256"
-  ],
-  "userinfo_signing_alg_values_supported": [
-    "RS256"
-  ],
-  "request_object_signing_alg_values_supported": [
-    "none",
-    "RS256"
-  ],
-  "response_modes_supported": [
-    "query",
-    "fragment",
-    "form_post"
-  ],
-  "registration_endpoint": "{{ .Issuer }}/clients-registrations/openid-connect",
-  "token_endpoint_auth_methods_supported": [
-    "private_key_jwt",
-    "client_secret_basic",
-    "client_secret_post",
-    "client_secret_jwt"
-  ],
-  "token_endpoint_auth_signing_alg_values_supported": [
-    "RS256"
-  ],
-  "claims_supported": [
-    "sub",
-    "iss",
-    "auth_time",
-    "name",
-    "given_name",
-    "family_name",
-    "preferred_username",
-    "email"
-  ],
-  "claim_types_supported": [
-    "normal"
-  ],
-  "claims_parameter_supported": false,
-  "scopes_supported": [
-    "openid",
-    "offline_access",
-    "phone",
-    "address",
-    "email",
-    "profile"
-  ],
-  "request_parameter_supported": true,
-  "request_uri_parameter_supported": true,
-  "code_challenge_methods_supported": [
-    "plain",
-    "S256"
-  ],
-  "tls_client_certificate_bound_access_tokens": true
-}
--- a/integration-test/testdata/oidc-jwks.json
+++ b/integration-test/testdata/oidc-jwks.json
@@ -1,12 +0,0 @@
-{
-  "keys": [
-    {
-      "kty": "RSA",
-      "alg": "RS256",
-      "use": "sig",
-      "kid": "xxx",
-      "n": "{{ .PrivateKey.N }}",
-      "e": "{{ .PrivateKey.E }}"
-    }
-  ]
-}
--- a/integration-test/testdata/oidc-token.json
+++ b/integration-test/testdata/oidc-token.json
@@ -1,7 +0,0 @@
-{
-  "access_token": "7eaae8ab-8f69-45d9-ab7c-73560cd9444d",
-  "token_type": "Bearer",
-  "refresh_token": "44df4c82-5ce7-4260-b54d-1da0d396ef2a",
-  "expires_in": 3600,
-  "id_token": "{{ .IDToken }}"
-}
--- a/integration-test/testdata/openssl.cnf
+++ b/integration-test/testdata/openssl.cnf
@@ -1,37 +0,0 @@
-[ ca ]
-default_ca      = CA_default
-
-[ CA_default ]
-dir             = ./CA
-certs           = $dir
-crl_dir         = $dir
-database        = $dir/index.txt
-new_certs_dir   = $dir
-default_md      = sha256
-policy          = policy_match
-serial          = $dir/serial
-default_days    = 365
-
-[ policy_match ]
-countryName             = optional
-stateOrProvinceName     = optional
-organizationName        = optional
-organizationalUnitName  = optional
-commonName              = supplied
-emailAddress            = optional
-
-[ req ]
-distinguished_name	= req_distinguished_name
-req_extensions = v3_req
-x509_extensions = v3_ca
-
-[ req_distinguished_name ]
-commonName			= Common Name (e.g. server FQDN or YOUR name)
-
-[ v3_req ]
-basicConstraints = CA:FALSE
-keyUsage = nonRepudiation, digitalSignature, keyEncipherment
-subjectAltName = DNS:localhost
-
-[ v3_ca ]
-basicConstraints = CA:true
--- a/kubeconfig/auth.go
+++ b/kubeconfig/auth.go
@@ -1,66 +0,0 @@
-package kubeconfig
-
-import (
-	"fmt"
-
-	"k8s.io/client-go/tools/clientcmd/api"
-)
-
-// FindCurrentAuthInfo returns the authInfo of current context.
-// If the current context does not exist, this returns nil.
-func FindCurrentAuthInfo(config *api.Config) *api.AuthInfo {
-	context := config.Contexts[config.CurrentContext]
-	if context == nil {
-		return nil
-	}
-	return config.AuthInfos[context.AuthInfo]
-}
-
-// ToOIDCAuthProviderConfig converts from api.AuthInfo to OIDCAuthProviderConfig.
-func ToOIDCAuthProviderConfig(authInfo *api.AuthInfo) (*OIDCAuthProviderConfig, error) {
-	if authInfo.AuthProvider == nil {
-		return nil, fmt.Errorf("auth-provider is not set, did you setup kubectl as listed here: https://github.com/int128/kubelogin#3-setup-kubectl")
-	}
-	if authInfo.AuthProvider.Name != "oidc" {
-		return nil, fmt.Errorf("auth-provider `%s` is not supported", authInfo.AuthProvider.Name)
-	}
-	return (*OIDCAuthProviderConfig)(authInfo.AuthProvider), nil
-}
-
-// OIDCAuthProviderConfig represents OIDC configuration in the kubeconfig.
-type OIDCAuthProviderConfig api.AuthProviderConfig
-
-// IDPIssuerURL returns the idp-issuer-url.
-func (c *OIDCAuthProviderConfig) IDPIssuerURL() string {
-	return c.Config["idp-issuer-url"]
-}
-
-// ClientID returns the client-id.
-func (c *OIDCAuthProviderConfig) ClientID() string {
-	return c.Config["client-id"]
-}
-
-// ClientSecret returns the client-secret.
-func (c *OIDCAuthProviderConfig) ClientSecret() string {
-	return c.Config["client-secret"]
-}
-
-// IDPCertificateAuthority returns the idp-certificate-authority.
-func (c *OIDCAuthProviderConfig) IDPCertificateAuthority() string {
-	return c.Config["idp-certificate-authority"]
-}
-
-// IDPCertificateAuthorityData returns the idp-certificate-authority-data.
-func (c *OIDCAuthProviderConfig) IDPCertificateAuthorityData() string {
-	return c.Config["idp-certificate-authority-data"]
-}
-
-// SetIDToken replaces the id-token.
-func (c *OIDCAuthProviderConfig) SetIDToken(idToken string) {
-	c.Config["id-token"] = idToken
-}
-
-// SetRefreshToken replaces the refresh-token.
-func (c *OIDCAuthProviderConfig) SetRefreshToken(refreshToken string) {
-	c.Config["refresh-token"] = refreshToken
-}
--- a/kubeconfig/kubeconfig.go
+++ b/kubeconfig/kubeconfig.go
@@ -1,22 +0,0 @@
-package kubeconfig
-
-import (
-	"fmt"
-
-	"k8s.io/client-go/tools/clientcmd"
-	"k8s.io/client-go/tools/clientcmd/api"
-)
-
-// Load loads the file and returns the Config.
-func Load(path string) (*api.Config, error) {
-	config, err := clientcmd.LoadFromFile(path)
-	if err != nil {
-		return nil, fmt.Errorf("Could not load kubeconfig from %s: %s", path, err)
-	}
-	return config, nil
-}
-
-// Write writes the config to the file.
-func Write(config *api.Config, path string) error {
-	return clientcmd.WriteToFile(*config, path)
-}
--- a/main.go
+++ b/main.go
@@ -1,20 +1,57 @@
 package main

 import (
-	"context"
 	"log"
-	"os"

-	"github.com/int128/kubelogin/cli"
+	"k8s.io/client-go/tools/clientcmd/api"
 )

 func main() {
-	c, err := cli.Parse(os.Args)
+	kubeConfigPath, err := FindKubeConfig()
 	if err != nil {
 		log.Fatal(err)
 	}
-	ctx := context.Background()
-	if err := c.Run(ctx); err != nil {
+
+	log.Printf("Reading config from %s", kubeConfigPath)
+	kubeConfig, err := ReadKubeConfig(kubeConfigPath)
+	if err != nil {
 		log.Fatal(err)
 	}
+	log.Printf("Using current context: %s", kubeConfig.CurrentContext)
+
+	authInfo := GetCurrentAuthInfo(*kubeConfig)
+	if authInfo == nil {
+		log.Fatal("Could not find the current user")
+	}
+	authProvider := authInfo.AuthProvider
+	if authProvider == nil {
+		log.Fatal("auth-provider is not set in the config")
+	}
+
+	switch authProvider.Name {
+	case "oidc":
+		if err := mutateConfigWithOIDC(authProvider); err != nil {
+			log.Fatal(err)
+		}
+		WriteKubeConfig(*kubeConfig, kubeConfigPath)
+		log.Printf("Updated %s", kubeConfigPath)
+
+	default:
+		log.Fatalf("Currently auth-provider `%s` is not supported", authProvider.Name)
+	}
+}
+
+func mutateConfigWithOIDC(authProvider *api.AuthProviderConfig) error {
+	issuer := authProvider.Config["idp-issuer-url"]
+	clientID := authProvider.Config["client-id"]
+	clientSecret := authProvider.Config["client-secret"]
+	log.Printf("Using issuer: %s", issuer)
+	log.Printf("Using client ID: %s", clientID)
+	oidcToken, err := GetOIDCToken(issuer, clientID, clientSecret)
+	if err != nil {
+		return err
+	}
+	authProvider.Config["id-token"] = oidcToken.IDToken
+	authProvider.Config["refresh-token"] = oidcToken.RefreshToken
+	return nil
 }
--- a/oidc.go
+++ b/oidc.go
@@ -0,0 +1,130 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"log"
+
+	"github.com/coreos/go-oidc"
+	"golang.org/x/oauth2"
+)
+
+// OIDCToken is a token set
+type OIDCToken struct {
+	IDToken      string
+	RefreshToken string
+}
+
+// GetOIDCToken returns a token retrieved by auth code grant
+func GetOIDCToken(issuer string, clientID string, clientSecret string) (*OIDCToken, error) {
+	port := 8000
+	provider, err := oidc.NewProvider(oauth2.NoContext, issuer)
+	if err != nil {
+		return nil, err
+	}
+
+	state, err := generateState()
+	if err != nil {
+		return nil, err
+	}
+
+	webBrowserConfig := oauth2.Config{
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		RedirectURL:  fmt.Sprintf("http://localhost:%d/", port),
+		Endpoint:     provider.Endpoint(),
+		Scopes:       []string{oidc.ScopeOpenID, "email"},
+	}
+
+	cliConfig := oauth2.Config{
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		RedirectURL:  "urn:ietf:wg:oauth:2.0:oob",
+		Endpoint:     provider.Endpoint(),
+		Scopes:       []string{oidc.ScopeOpenID, "email"},
+	}
+
+	showInstructionToGetToken(webBrowserConfig.RedirectURL, cliConfig.AuthCodeURL(state))
+	token, err := getTokenByWebBrowserOrCLI(webBrowserConfig, cliConfig, state)
+	if err != nil {
+		return nil, err
+	}
+
+	rawIDToken, ok := token.Extra("id_token").(string)
+	if !ok {
+		return nil, fmt.Errorf("id_token is missing in the token response: %s", token)
+	}
+
+	log.Printf("Verifying ID token...")
+	verifier := provider.Verifier(&oidc.Config{ClientID: clientID})
+	idToken, err := verifier.Verify(oauth2.NoContext, rawIDToken)
+	if err != nil {
+		return nil, err
+	}
+
+	idTokenClaim := struct {
+		Email string `json:"email"`
+	}{}
+	if err := idToken.Claims(&idTokenClaim); err != nil {
+		return nil, err
+	}
+
+	log.Printf("You are logged in as %s (%s)", idTokenClaim.Email, idToken.Subject)
+	return &OIDCToken{
+		IDToken:      rawIDToken,
+		RefreshToken: token.RefreshToken,
+	}, nil
+}
+
+func getTokenByWebBrowserOrCLI(webBrowserConfig oauth2.Config, cliConfig oauth2.Config, state string) (*oauth2.Token, error) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	webBrowserAuthCodeCh := make(chan string)
+	cliAuthCodeCh := make(chan string)
+	errCh := make(chan error)
+
+	go ReceiveAuthCodeFromWebBrowser(ctx, webBrowserConfig.AuthCodeURL(state), state, webBrowserAuthCodeCh, errCh)
+	go ReceiveAuthCodeFromCLI(ctx, cliAuthCodeCh, errCh)
+
+	select {
+	case err := <-errCh:
+		return nil, err
+
+	case authCode := <-webBrowserAuthCodeCh:
+		log.Printf("Exchanging code and token...")
+		return webBrowserConfig.Exchange(ctx, authCode)
+
+	case authCode := <-cliAuthCodeCh:
+		log.Printf("Exchanging code and token...")
+		return cliConfig.Exchange(ctx, authCode)
+	}
+}
+
+func showInstructionToGetToken(localhostURL string, cliAuthCodeURL string) {
+	log.Printf("Starting OpenID Connect authentication:")
+	fmt.Printf(`
+## Automatic (recommended)
+
+Open the following URL in the web browser:
+
+%s
+
+## Manual
+
+If you cannot access to localhost, instead open the following URL:
+
+%s
+
+Enter the code: `, localhostURL, cliAuthCodeURL)
+}
+
+func generateState() (string, error) {
+	var n uint64
+	if err := binary.Read(rand.Reader, binary.LittleEndian, &n); err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("%x", n), nil
+}
--- a/oidc_cli.go
+++ b/oidc_cli.go
@@ -0,0 +1,16 @@
+package main
+
+import (
+	"context"
+	"fmt"
+)
+
+// ReceiveAuthCodeFromCLI receives an auth code from CLI
+func ReceiveAuthCodeFromCLI(ctx context.Context, authCodeCh chan<- string, errCh chan<- error) {
+	var authCode string
+	if _, err := fmt.Scanln(&authCode); err != nil {
+		errCh <- err
+	} else {
+		authCodeCh <- authCode
+	}
+}
--- a/oidc_http.go
+++ b/oidc_http.go
@@ -0,0 +1,70 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+)
+
+// ReceiveAuthCodeFromWebBrowser starts a server and receives an auth code
+func ReceiveAuthCodeFromWebBrowser(ctx context.Context, authCodeURL string, state string, authCodeCh chan<- string, errCh chan<- error) {
+	server := http.Server{
+		Addr: ":8000",
+		Handler: &AuthCodeGrantHandler{
+			AuthCodeURL: authCodeURL,
+			State:       state,
+			Resolve:     func(authCode string) { authCodeCh <- authCode },
+			Reject:      func(err error) { errCh <- err },
+		},
+	}
+
+	go func() {
+		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			errCh <- err
+		}
+	}()
+
+	select {
+	case <-ctx.Done():
+		server.Shutdown(context.Background())
+	}
+}
+
+// AuthCodeGrantHandler handles requests for OIDC auth code grant
+type AuthCodeGrantHandler struct {
+	AuthCodeURL string
+	State       string
+	Resolve     func(string)
+	Reject      func(error)
+}
+
+func (s *AuthCodeGrantHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	log.Printf("%s %s", r.Method, r.RequestURI)
+	switch r.URL.Path {
+	case "/":
+		code := r.URL.Query().Get("code")
+		state := r.URL.Query().Get("state")
+		errorCode := r.URL.Query().Get("error")
+		errorDescription := r.URL.Query().Get("error_description")
+		switch {
+		case code != "" && state == s.State:
+			s.Resolve(code)
+			fmt.Fprintf(w, "Please back to the command line.")
+
+		case code != "" && state != s.State:
+			s.Reject(fmt.Errorf("OIDC state did not match. expected=%s, actual=%s", s.State, state))
+			fmt.Fprintf(w, "Please back to the command line.")
+
+		case errorCode != "":
+			s.Reject(fmt.Errorf("OIDC error: %s %s", errorCode, errorDescription))
+			fmt.Fprintf(w, "Please back to the command line.")
+
+		default:
+			http.Redirect(w, r, s.AuthCodeURL, 302)
+		}
+
+	default:
+		http.Error(w, "Not Found", 404)
+	}
+}