As your mobile users get accustomed to advanced features that require Cloud support, it becomes increasingly hard to protect their privacy while staying up to date with data protection regulations such as the GDPR. We would like to show you how you can continue to use cloud-based SDKs and employ Firebase to create an experience that pleases both your users and your newly hired data stewardship team.

1. How to go serverless and
not violate the GDPR
Sebastian Schmidt and Rachel Myers
Berlin | November 20 - 21, 2018

3. GDPR
11 Chapters that regulate:
● Rights of data subjects
● Responsibilities for data controllers/processors
● Data transfers
● Penalties

4. GDPR
11 Chapters that regulate:
● Rights of data subjects
● Responsibilities for data controllers/processors
● Data transfers
● Penalties
Your users!
You!

5. Not giving
legal advice

6. Global Privacy Regulations

7. Global Privacy Regulations

8. Global Privacy Regulations

11. Develop
Grow
Realtime
Database
Authentication
Cloud Storage
Cloud
Firestore
Hosting
Cloud
Functions
Crashlytics
Performance
Test Lab
Analytics
Dynamic Links
Invites
App Indexing
Cloud
Messaging
Remote
Config
AdMob
AdWords
Predictions

12. Serverless
Concerns

13. Privacy
Concerns

14. Serverless
Concerns
Privacy
Concerns

16. User privacy
built on Serverless

17. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

18. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

19. Read your Horoscope!
(You have to be an EU citizen and 18+)
Username
Birthday
Country
sebastian
April 28th, 1990
Czech Republic

20. Read your Horoscope!
(You have to be an EU citizen and 18+)
Username
Birthday
Country
sebastian
April 28th, 1990
Czech Republic

21. ← Open source

22. 1. Account
information

23. 1. Account
information
2. Photos

24. 1. Account
information
2. Photos
3. Social data

25. Save only what you need.
Only as long as you
need.

26. SELECT COUNT(*)
FROM users
WHERE age BETWEEN (18, 25)
Keep the count. Don’t keep the data!

27. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

28. Delete user data
● When your app no longer needs the data
● When a user deletes their account

30. Not in
your
control

31. Not in
your
control

32. Cloud Functions for Firebase
programmatically connect
Firebase and Cloud

33. How does it work?
Event
emitted
Your code
executed
Function
triggered

34. How does it work?
Event
emitted
Your code
executed
Function
triggered
firestore.document(‘posts/a’).delete(
)
deleteData() function

35. We only
display the
top five!
No need to
save the
rest!

36. Delete the
rest!

37. Manage User Data
Privacy with Cloud
Functions
link.firebase.events/h1

38. App Engine lets you
invoke Cloud Functions
periodically!
link.firebase.events/h2

39. Remove user data
● When your app no longer needs the data
● When a user deletes their account

40. link.firebase.events/h
3

41. // functions/index.js
// Paths to user data to export or delete
exports.clearData = functions.auth.user().onDelete((event) => {
const uid = event.data.uid;
const dbPromise = clearDatabaseData(uid);
const storagePromise = clearStorageData(uid);
const firestorePromise = clearFirestoreData(uid);
const promises = [dbPromise, storagePromise, firestorePromise];
return Promise.all(promises).then(() =>
console.log(`Successfully removed data for user ${uid}.`)
);
});
link.firebase.events/h4

42. // functions/index.js
// Paths to user data to export or delete
exports.clearData = functions.auth.user().onDelete((event) => {
const uid = event.data.uid;
const dbPromise = clearDatabaseData(uid);
const storagePromise = clearStorageData(uid);
const firestorePromise = clearFirestoreData(uid);
const promises = [dbPromise, storagePromise, firestorePromise];
return Promise.all(promises).then(() =>
console.log(`Successfully removed data for user ${uid}.`)
);
});
link.firebase.events/h4

43. // functions/user_privacy.json
// Paths to user data to export or delete
{
"storage": {
"clearData": [
["myproject.appspot.com", "UID/sample_data.json"],
["myproject.appspot.com", "UID/avatar"]
],
},
"firestore": {
"clearData": [
{"collection": "users", "doc": "UID", "field": "last_name"},
{"collection": "admins", "doc": "UID"}
]
}
}
link.firebase.events/h4

44. // functions/index.js
// Paths to user data to export or delete
exports.clearData = functions.auth.user().onDelete((event) => {
const uid = event.data.uid;
const dbPromise = clearDatabaseData(uid);
const storagePromise = clearStorageData(uid);
const firestorePromise = clearFirestoreData(uid);
const promises = [dbPromise, storagePromise, firestorePromise];
return Promise.all(promises).then(() =>
console.log(`Successfully removed data for user ${uid}.`)
);
});
link.firebase.events/h4

45. // functions/user_privacy.json
// Paths to user data to export or delete
exports.clearData = functions.auth.user().onDelete((event) => {
const uid = event.data.uid;
const dbPromise = clearDatabaseData(uid);
const storagePromise = clearStorageData(uid);
const firestorePromise = clearFirestoreData(uid);
const promises = [dbPromise, storagePromise, firestorePromise];
return Promise.all(promises).then(() =>
console.log(`Successfully removed data for user ${uid}.`)
);
});
link.firebase.events/h4

46. // functions/index.js
// Deletes user data from the RealTime Database
const clearDatabaseData = (uid) => {
const paths = userPrivacyPaths.database.clearData;
const promises = [];
for (let i = 0; i < paths.length; i++) {
const path = replaceUID(paths[i], uid);
promises.push(db.ref(path).remove().catch((error) => {
// Avoid execution interuption.
console.error('Error deleting data at ', path, error);
}));
}
return Promise.all(promises).then(() => uid);
};
link.firebase.events/h4

47. // functions/index.js
// Deletes user data from the RealTime Database
const clearDatabaseData = (uid) => {
const paths = userPrivacyPaths.database.clearData;
const promises = [];
for (let i = 0; i < paths.length; i++) {
const path = replaceUID(paths[i], uid);
promises.push(db.ref(path).remove().catch((error) => {
// Avoid execution interuption.
console.error('Error deleting data at ', path, error);
}));
}
return Promise.all(promises).then(() => uid);
};
link.firebase.events/h4

48. // functions/index.js
// Deletes user data from the RealTime Database
const clearDatabaseData = (uid) => {
const paths = userPrivacyPaths.database.clearData;
const promises = [];
for (let i = 0; i < paths.length; i++) {
const path = replaceUID(paths[i], uid);
promises.push(db.ref(path).remove().catch((error) => {
// Avoid execution interuption.
console.error('Error deleting data at ', path, error);
}));
}
return Promise.all(promises).then(() => uid);
};
link.firebase.events/h4

49. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

50. // functions/index.js
// Exports user data
exports.exportData = functions.https.onRequest((req, res) => {
const uid = JSON.parse(req.body).uid;
const exportData = {};
const dbProm = exportDatabaseData(uid).then((dbData) => {
exportData.database = dbData;
});
const fsProm = exportFirestoreData(uid).then((fsData) => {
exportData.firestore = fsData;
});
const storageProm = exportStorageData(uid).then((storageRefs) => {
exportData.storage = storageRefs;
});
return Promise.all([dbProm, fsProm, storageProm]).then(() => {
console.log(`Success! Completed export for user ${uid}.`);
return uploadToStorage(uid, exportData);
}).then(() => res.json({exportComplete: true}));
});
link.firebase.events/h4

51. // functions/index.js
// Exports user data
exports.exportData = functions.https.onRequest((req, res) => {
const uid = JSON.parse(req.body).uid;
const exportData = {};
const dbProm = exportDatabaseData(uid).then((dbData) => {
exportData.database = dbData;
});
const fsProm = exportFirestoreData(uid).then((fsData) => {
exportData.firestore = fsData;
});
const storageProm = exportStorageData(uid).then((storageRefs) => {
exportData.storage = storageRefs;
});
return Promise.all([dbProm, fsProm, storageProm]).then(() => {
console.log(`Success! Completed export for user ${uid}.`);
return uploadToStorage(uid, exportData);
}).then(() => res.json({exportComplete: true}));
});
link.firebase.events/h4

52. // functions/index.js
// Exports user data
exports.exportData = functions.https.onRequest((req, res) => {
const uid = JSON.parse(req.body).uid;
const exportData = {};
const dbProm = exportDatabaseData(uid).then((dbData) => {
exportData.database = dbData;
});
const fsProm = exportFirestoreData(uid).then((fsData) => {
exportData.firestore = fsData;
});
const storageProm = exportStorageData(uid).then((storageRefs) => {
exportData.storage = storageRefs;
});
return Promise.all([dbProm, fsProm, storageProm]).then(() => {
console.log(`Success! Completed export for user ${uid}.`);
return uploadToStorage(uid, exportData);
}).then(() => res.json({exportComplete: true}));
});
link.firebase.events/h4

53. // functions/index.js
// Helper function that exports user data from RealTime Database.
const exportDatabaseData = (uid) => {
const paths = userPrivacyPaths.database.exportData;
const promises = [];
const exportData = {};
for (let i = 0; i < paths.length; i++) {
const path = replaceUID(paths[i], uid);
promises.push(db.ref(path).once('value').then((snapshot) => {
const read = snapshot.val();
if (read !== null) {
exportData[snapshot.key] = read;
}
}).catch((err) => {
console.error('Error exporting data: ', err);
}));
};
return Promise.all(promises).then(() => exportData);
};
link.firebase.events/h4

54. // functions/index.js
// Helper function that exports user data from RealTime Database.
const exportDatabaseData = (uid) => {
const paths = userPrivacyPaths.database.exportData;
const promises = [];
const exportData = {};
for (let i = 0; i < paths.length; i++) {
const path = replaceUID(paths[i], uid);
promises.push(db.ref(path).once('value').then((snapshot) => {
const read = snapshot.val();
if (read !== null) {
exportData[snapshot.key] = read;
}
}).catch((err) => {
console.error('Error exporting data: ', err);
}));
};
return Promise.all(promises).then(() => exportData);
};
firebase.events/q4

55. // functions/index.js
// Exports user data
exports.exportData = functions.https.onRequest((req, res) => {
const uid = JSON.parse(req.body).uid;
const exportData = {};
const dbProm = exportDatabaseData(uid).then((dbData) => {
exportData.database = dbData;
});
const fsProm = exportFirestoreData(uid).then((fsData) => {
exportData.firestore = fsData;
});
const storageProm = exportStorageData(uid).then((storageRefs) => {
exportData.storage = storageRefs;
});
return Promise.all([dbProm, fsProm, storageProm]).then(() => {
console.log(`Success! Completed export for user ${uid}.`);
return uploadToStorage(uid, exportData);
}).then(() => res.json({exportComplete: true}));
});
link.firebase.events/h4

56. service firebase.storage {
match /b/{bucket}/o {
match /exportData {
// Only allow access to exported data by the user
// who requested an export
match /{uid} {
allow read, write: if request.auth.uid == uid
}
match /{uid}/{path=**} {
allow read, write: if request.auth.uid == uid
}
}
}
}
firebase.events/q4

57. Remember that rules are ORed together.
✔
Simulated data access allowed

58. Delete and export are easier when
data’s nested under a user’s UID

59. $ firebase deploy ...
Done.

60. Manage User Data
Privacy with Cloud
Functions
link.firebase.events/h4

61. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

62. Client Application Storage

63. Client Application Storage

64. Client Storage

65. Client Storage

66. Security Rules

67. Security Rules Simulator

68. Security Rules
Emulators
link.firebase.events/h5

69. Security Rules Schema
Messages
PUBLIC
USER 2USER 1
Friends
Private
Messages
Friends
Private
ACTIVITY
USER 2USER 1
Log Log
Entry EntryEntry Entry
Messages

70. Rules Takeaways
● Never trust data from client apps
● Write rules with the Security Simulator
● Test rules with the Security Rules Emulator

71. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

72. Take a look at our data
retention policies
link.firebase.events/h6

73. Take a look at our data
retention policies
link.firebase.events/h7

74. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

75. Instance IDs
Unique for each app installation
123 234 345

76. Instance IDs
Same ID across restarts
123123 123
MON TUE
3rd 4th 5th
WED

77. Delete Instance ID data
with the Admin SDKs
link.firebase.events/h8

78. Backend stores data
for 2 weeks
Client keeps
data for 1 week

79. Backend keeps
backup for 2 weeks
Client keeps
data for 1 week
We will keep your data for 2 weeks.
AGREEDISAGREE

80. Unchecked
boxes

81. Comments
enabled
Comments
disabled

82. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

83. Separate Public
from
Private Dataservice cloud.firestore {
match /databases/{database}/documents {
match /users/{uid}/public {
allow read, write;
}
match /users/{uid}/private {
allow read, write:
if request.auth.uid == uid;
}
}
}

84. service cloud.firestore {
match /databases/{database}/documents {
match /public/{uid} {
allow read, write;
}
match /private/{uid} {
allow read, write:
if request.auth.uid == uid;
}
}
}
Separate Public
from
Private Data

87. Reduce the user data that you store
Manage user data with Cloud Functions:
Delete data you no longer need
Export data on request
Security Rules!
Inform users about data collection:
Storage Retention Policies
Firebase Instance IDs
Storing Privacy Settings
Keeping an Activity Log

88. const firestore = admin.firestore();
exports.activityLog = functions.firestore
.document('privacy/{uid}').onWrite(snap => {
const uid = context.params.uid;
const settings = snap.data();
settings['udpate_time'] =
admin.firestore.FieldValue.serverTimestamp();
firestore.collection(
`activity_log/${uid}/entries`
).add(settings);
});
link.firebase.events/h8

89. const firestore = admin.firestore();
exports.activityLog = functions.firestore
.document('privacy/{uid}').onWrite(snap => {
const uid = context.params.uid;
const settings = snap.data();
settings['udpate_time'] =
admin.firestore.FieldValue.serverTimestamp();
firestore.collection(
`activity_log/${uid}/entries`
).add(settings);
});
link.firebase.events/h8

90. match /activity_log/{uid} {
allow create: if request.auth.uid == uid;
allow update: if request.auth.uid == uid && resource == null;
allow delete: if false;
}
link.firebase.events/h9

91. Storing Privacy
Settings
with Firebaselink.firebase.events/h9

92. Let’s treat our users well!

93. ● Respect user data
● Offer clear data policies
● Limit data intake
● Let users decide how to handle data

94. Thank you!
Rachel Myers, Firebase
GitHub & Twitter: @rachelmyers
Sebastian Schmidt, Firebase
GitHub: @schmidt-sebastian