REC-195: recommend -store=file when keyring is not available

cmd/engflow_auth/main.go

@@ -191,6 +191,11 @@ func (r *appState) import_(cliCtx *cli.Context) error {
 		storeURLs = append(storeURLs, clusterURL)
 	}
 
+	// Check early if the keyring works.
+	if err := r.testKeyringBeforeStore(storeURLs[0].Host); err != nil {
+		return err
+	}
+
 	var storeErrs []error
 	for _, storeURL := range storeURLs {
 		if err := r.storeToken(storeURL.Host, token.Token); err != nil {
@@ -228,6 +233,11 @@ func (r *appState) login(cliCtx *cli.Context) error {
 	}
 	oauthURL := oauthEndpoint(clusterURL)
 
+	// Check early if the keyring works.
+	if err := r.testKeyringBeforeStore(clusterURL.Host); err != nil {
+		return err
+	}
+
 	// Tokens fetched during the process will be associated with each URL in
 	// storeURLs in the token store
 	storeURLs := []*url.URL{clusterURL}

cmd/engflow_auth/main_test.go

@@ -372,6 +372,20 @@ func TestRun(t *testing.T) {
 			wantCode: autherr.CodeAuthFailure,
 			wantErr:  "fetch_token_fail",
 		},
+		{
+			desc: "login token load failure",
+			args: []string{"login", "cluster.example.com"},
+			authenticator: &fakeAuth{
+				deviceResponse: &oauth2.DeviceAuthResponse{
+					VerificationURIComplete: "https://cluster.example.com/with/auth/code",
+				},
+			},
+			keyringStore: &oauthtoken.FakeTokenStore{
+				LoadErr: errors.New("token_load_fail"),
+			},
+			wantCode: autherr.CodeTokenStoreFailure,
+			wantErr:  "-store=file", // error message recommends -store=file
+		},
 		{
 			desc: "login token store failure",
 			args: []string{"login", "cluster.example.com"},
@@ -628,6 +642,15 @@ func TestRun(t *testing.T) {
 			machineInput: strings.NewReader(`{"token":{"access_token":"token_data"},"cluster_host":"cluster.example.com"}`),
 			keyringStore: oauthtoken.NewFakeTokenStore().WithPanic("do not call"),
 		},
+		{
+			desc: "import with keyring load failure",
+			args: []string{"login", "cluster.example.com"},
+			keyringStore: &oauthtoken.FakeTokenStore{
+				LoadErr: errors.New("token_load_fail"),
+			},
+			wantCode: autherr.CodeTokenStoreFailure,
+			wantErr:  "-store=file", // error message recommends -store=file
+		},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {

cmd/engflow_auth/tokens.go

@@ -20,11 +20,34 @@ import (
 	"io/fs"
 	"os"
 
+	"github.com/EngFlow/auth/internal/autherr"
 	"github.com/EngFlow/auth/internal/oauthtoken"
 	"github.com/golang-jwt/jwt/v5"
 	"golang.org/x/oauth2"
 )
 
+// testKeyringBeforeStore attempts to load a token for the given hostname from
+// the encrypted keyring.
+//
+// If the file store is being used (-store=file) or if the token is missing or
+// is returned successfully, this method returns nil.
+//
+// If there's an error loading the token, this method returns an actionable
+// error, suggesting the user try -store=file.
+//
+// This should be called by commands that write the token store, before
+// the user goes through the web login flow.
+func (r *appState) testKeyringBeforeStore(hostname string) error {
+	if r.writeFileStore {
+		// Not using keyring.
+		return nil
+	}
+	if _, err := r.keyringStore.Load(hostname); err != nil && !errors.Is(err, fs.ErrNotExist) {
+		return autherr.CodedErrorf(autherr.CodeTokenStoreFailure, "failed to initialize encrypted keyring: %w\n\tNon-interactive environments typically don't support encrypted keyrings.\n\tUse -store=file to use unencrypted storage instead.", err)
+	}
+	return nil
+}
+
 // loadToken loads a token for the given cluster or returns an error equivalent
 // to fs.ErrNotExist if the token is not found in any store.
 //

internal/oauthtoken/fake.go

@@ -15,6 +15,7 @@
 package oauthtoken
 
 import (
+	"errors"
 	"fmt"
 	"io/fs"
 	"time"
@@ -53,7 +54,7 @@ func (f *FakeTokenStore) Load(cluster string) (*oauth2.Token, error) {
 	}
 	token, ok := f.Tokens[cluster]
 	if !ok {
-		return nil, fmt.Errorf("%s: token not found", cluster)
+		return nil, &tokenNotFoundError{cluster: cluster}
 	}
 	return token, nil
 }
@@ -133,3 +134,15 @@ func NewFakeTokenForSubject(subject string) *oauth2.Token {
 		Expiry:      expiry,
 	}
 }
+
+type tokenNotFoundError struct {
+	cluster string
+}
+
+func (e *tokenNotFoundError) Error() string {
+	return fmt.Sprintf("%s: token not found", e.cluster)
+}
+
+func (e *tokenNotFoundError) Is(err error) bool {
+	return errors.Is(err, fs.ErrNotExist)
+}