many: delay classic registration until first store interaction

overlord/auth/auth.go

@@ -28,8 +28,10 @@ import (
 	"os"
 	"sort"
 	"strconv"
+	"time"
 
 	"golang.org/x/net/context"
+
 	"gopkg.in/macaroon.v1"
 
 	"github.com/snapcore/snapd/asserts"
@@ -372,6 +374,11 @@ type DeviceAssertions interface {
 	// Serial returns the device serial assertion.
 	Serial() (*asserts.Serial, error)
 
+	// EnsureSerial does a best-effort of triggering and waiting
+	// up to timeout for registration to occur and returns the
+	// serial if now available, or ErrNoState otherwise.
+	EnsureSerial(context.Context, time.Duration) (*asserts.Serial, error)
+
 	// DeviceSessionRequestParams produces a device-session-request with the given nonce, together with other required parameters, the device serial and model assertions.
 	DeviceSessionRequestParams(nonce string) (*DeviceSessionRequestParams, error)
 	// ProxyStore returns the store assertion for the proxy store if one is set.
@@ -403,6 +410,8 @@ type AuthContext interface {
 
 	StoreID(fallback string) (string, error)
 
+	EnsureSerial(ctx context.Context, timeout time.Duration) (*asserts.Serial, error)
+
 	DeviceSessionRequestParams(nonce string) (*DeviceSessionRequestParams, error)
 	ProxyStoreParams(defaultURL *url.URL) (proxyStoreID string, proxySroreURL *url.URL, err error)
 
@@ -498,6 +507,20 @@ func (ac *authContext) StoreID(fallback string) (string, error) {
 	return fallback, nil
 }
 
+// EnsureSerial does a best-effort of triggering and waiting
+// up to timeout for registration to occur and returns the
+// serial if now available, or ErrNoSerial otherwise.
+func (ac *authContext) EnsureSerial(ctx context.Context, timeout time.Duration) (*asserts.Serial, error) {
+	if ac.deviceAsserts == nil {
+		return nil, ErrNoSerial
+	}
+	serial, err := ac.deviceAsserts.EnsureSerial(ctx, timeout)
+	if err == state.ErrNoState {
+		return nil, ErrNoSerial
+	}
+	return serial, err
+}
+
 // DeviceSessionRequestParams produces a device-session-request with the given nonce, together with other required parameters, the device serial and model assertions. It returns ErrNoSerial if the device serial is not yet initialized.
 func (ac *authContext) DeviceSessionRequestParams(nonce string) (*DeviceSessionRequestParams, error) {
 	if ac.deviceAsserts == nil {

overlord/auth/auth_test.go

@@ -1,7 +1,7 @@
 // -*- Mode: Go; indent-tabs-mode: t -*-
 
 /*
- * Copyright (C) 2016 Canonical Ltd
+ * Copyright (C) 2016-2018 Canonical Ltd
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
@@ -552,6 +552,13 @@ func (as *authSuite) TestAuthContextDeviceSessionRequestParamsNilDeviceAssertion
 	c.Check(err, Equals, auth.ErrNoSerial)
 }
 
+func (as *authSuite) TestAuthContextEnsureSerialNilDeviceAssertions(c *C) {
+	authContext := auth.NewAuthContext(as.state, nil)
+
+	_, err := authContext.EnsureSerial(context.TODO(), 5*time.Second)
+	c.Check(err, Equals, auth.ErrNoSerial)
+}
+
 func (as *authSuite) TestAuthContextCloudInfo(c *C) {
 	authContext := auth.NewAuthContext(as.state, nil)
 
@@ -661,6 +668,13 @@ func (da *testDeviceAssertions) Serial() (*asserts.Serial, error) {
 	return a.(*asserts.Serial), nil
 }
 
+func (da *testDeviceAssertions) EnsureSerial(ctx context.Context, timeout time.Duration) (*asserts.Serial, error) {
+	if ctx == nil {
+		panic("context required")
+	}
+	return da.Serial()
+}
+
 func (da *testDeviceAssertions) DeviceSessionRequestParams(nonce string) (*auth.DeviceSessionRequestParams, error) {
 	if da.nothing {
 		return nil, state.ErrNoState
@@ -704,7 +718,10 @@ func (as *authSuite) TestAuthContextMissingDeviceAssertions(c *C) {
 	// no assertions in state
 	authContext := auth.NewAuthContext(as.state, &testDeviceAssertions{nothing: true})
 
-	_, err := authContext.DeviceSessionRequestParams("NONCE")
+	_, err := authContext.EnsureSerial(context.TODO(), 0)
+	c.Check(err, Equals, auth.ErrNoSerial)
+
+	_, err = authContext.DeviceSessionRequestParams("NONCE")
 	c.Check(err, Equals, auth.ErrNoSerial)
 
 	storeID, err := authContext.StoreID("fallback")
@@ -721,6 +738,10 @@ func (as *authSuite) TestAuthContextWithDeviceAssertions(c *C) {
 	// having assertions in state
 	authContext := auth.NewAuthContext(as.state, &testDeviceAssertions{})
 
+	serialAssert, err := authContext.EnsureSerial(context.TODO(), 0)
+	c.Check(err, IsNil)
+	c.Check(serialAssert.Serial(), Equals, "9999")
+
 	params, err := authContext.DeviceSessionRequestParams("NONCE-1")
 	c.Assert(err, IsNil)