pkg/oauth2: consider session cancellation

cmd/telemeter-server/main.go

@@ -23,6 +23,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
+
 	oidc "github.com/coreos/go-oidc"
 	"github.com/oklog/run"
 	"github.com/spf13/cobra"
@@ -250,8 +252,17 @@ func (o *Options) Run() error {
 				Endpoint: provider.Endpoint(),
 			}
 
+			grantsTotal := prometheus.NewCounter(
+				prometheus.CounterOpts{
+					Name: "telemeter_password_credentials_grants_total",
+					Help: "Tracks the number of resource owner password credential grants.",
+				},
+			)
+
+			prometheus.MustRegister(grantsTotal)
+
 			src := telemeter_oauth2.NewPasswordCredentialsTokenSource(
-				ctx, &cfg,
+				ctx, &cfg, grantsTotal.Inc,
 				o.AuthorizeUsername, o.AuthorizePassword,
 			)
 

pkg/oauth2/token_source.go

@@ -3,6 +3,7 @@ package oauth2
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"sync"
 	"time"
 
@@ -13,6 +14,7 @@ type passwordCredentialsTokenSource struct {
 	ctx                context.Context
 	cfg                *oauth2.Config
 	username, password string
+	grantsCounter      func()
 
 	mu                sync.Mutex // protects the fields below
 	refreshToken      *oauth2.Token
@@ -32,20 +34,17 @@ type passwordCredentialsTokenSource struct {
 // using the given resource owner and password.
 //
 // It is safe for concurrent use.
-func NewPasswordCredentialsTokenSource(ctx context.Context, cfg *oauth2.Config, username, password string) *passwordCredentialsTokenSource {
+func NewPasswordCredentialsTokenSource(ctx context.Context, cfg *oauth2.Config, grantsCounter func(), username, password string) *passwordCredentialsTokenSource {
 	return &passwordCredentialsTokenSource{
-		ctx:      ctx,
-		username: username,
-		password: password,
-		cfg:      cfg,
+		ctx:           ctx,
+		username:      username,
+		password:      password,
+		cfg:           cfg,
+		grantsCounter: grantsCounter,
 	}
 }
 
 func (c *passwordCredentialsTokenSource) Token() (*oauth2.Token, error) {
-	return c.token(time.Now)
-}
-
-func (c *passwordCredentialsTokenSource) token(now func() time.Time) (*oauth2.Token, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -56,6 +55,12 @@ func (c *passwordCredentialsTokenSource) token(now func() time.Time) (*oauth2.To
 
 	if c.refreshToken.Valid() {
 		tok, err = c.accessTokenSource.Token()
+
+		rerr, ok := err.(*oauth2.RetrieveError)
+		if ok && rerr.Response != nil && rerr.Response.StatusCode == http.StatusBadRequest {
+			return c.passwordCredentialsToken()
+		}
+
 		if err != nil {
 			return nil, fmt.Errorf("access token source failed: %v", err)
 		}
@@ -65,26 +70,48 @@ func (c *passwordCredentialsTokenSource) token(now func() time.Time) (*oauth2.To
 		if tok.RefreshToken == c.refreshToken.RefreshToken {
 			return tok, nil
 		}
-	} else {
-		tok, err = c.cfg.PasswordCredentialsToken(c.ctx, c.username, c.password)
+
+		err = c.setRefreshToken(tok)
 		if err != nil {
-			return nil, fmt.Errorf("password credentials token source failed: %v", err)
+			return nil, err
 		}
 
-		c.accessTokenSource = c.cfg.TokenSource(c.ctx, tok)
+		return tok, nil
+	}
+
+	return c.passwordCredentialsToken()
+}
+
+func (c *passwordCredentialsTokenSource) passwordCredentialsToken() (*oauth2.Token, error) {
+	c.grantsCounter()
+
+	tok, err := c.cfg.PasswordCredentialsToken(c.ctx, c.username, c.password)
+	if err != nil {
+		return nil, fmt.Errorf("password credentials token source failed: %v", err)
+	}
+
+	c.accessTokenSource = c.cfg.TokenSource(c.ctx, tok)
+
+	err = c.setRefreshToken(tok)
+	if err != nil {
+		return nil, err
 	}
 
+	return tok, nil
+}
+
+func (c *passwordCredentialsTokenSource) setRefreshToken(tok *oauth2.Token) error {
 	expires, ok := tok.Extra("refresh_expires_in").(float64)
 	if !ok {
-		return nil, fmt.Errorf("refresh_expires_in is not a float64, but %T", tok.Extra("refresh_expires_in"))
+		return fmt.Errorf("refresh_expires_in is not a float64, but %T", tok.Extra("refresh_expires_in"))
 	}
 
 	// create a dummy access token to reuse calculation logic for the Valid() method
 	c.refreshToken = &oauth2.Token{
 		AccessToken:  tok.RefreshToken,
 		RefreshToken: tok.RefreshToken,
-		Expiry:       now().Add(time.Duration(int64(expires)) * time.Second),
+		Expiry:       time.Now().Add(time.Duration(int64(expires)) * time.Second),
 	}
 
-	return tok, nil
+	return nil
 }