[Mateusz Herych] How can Android Backup break your app

Presentation from GDG DevFest Ukraine 2015 - the biggest Google related event in the country. October 23-24, Lviv. Learn more at http://devfest.gdg.org.ua/

Transcript

1. Auto Backup
2. Auto Backup Quick story on how it can break your app
3. +MateuszHerych GDG Kraków Android GDE Engineer @ Base
4. Basic facts
5. Automatic backups are enabled for all apps installed on devices running Marshmallow. No additional app code is required.
6. Automatic backups are enabled for all apps by default.
7. What does it mean?
8. Android now backups Databases
9. Android now backups Databases SharedPreferences
10. Android now backups Databases SharedPreferences Basically everything in your /data (-cache -nobackupfiles)
11. Android won’t backup Context.getCacheDir
12. Android won’t backup Context.getCacheDir Context.getNoBackupFilesDir
13. Once in 24h
14. WIFI, overnight/idle, charging
15. Backup is restored during the installation
16. targetSdkVersion 23
17. EASY!
18. Q & A
21. Titanium Backup
22. Backup is not a new concept on Android.
23. And you can face exact same problems.
26. Or just follow good practices and use common sense.
27. Practice #1
28. Practice #1 Don’t backup data that’s synchronized with your backend anyway.
29. Tables.CONTACTS first_name TEXT, last_name TEXT, modified INTEGER NOT NULL DEFAULT 0
30. Tables.CONTACTS INSERT INTO contacts VALUES (‘Jan’, ‘Kowalski’, 1)
31. Tables.CONTACTS INSERT INTO contacts VALUES (‘Jan’, ‘Kowalski’, 1) … and then Android decides to backup your data.
32. ????
33. Every device that receives a backup will post an update to the server.
34. = Duplicates
36. If your database is a “syncable database”
37. Consider removing it from the backup list.
38. AndroidManifest.xml <application android:fullBackupContent=” @xml/scheme” … />
39. res/xml/scheme.xml <?xml version="1.0" encoding="utf-8"?> <full-backup-content> <exclude domain="database" path="my. db"/> </full-backup-content>
40. res/xml/scheme.xml <?xml version="1.0" encoding="utf-8"?> <full-backup-content> <include domain="database" path="my. db"/> </full-backup-content>
41. res/xml/scheme.xml <?xml version="1.0" encoding="utf-8"?> <full-backup-content> <exclude domain="database" path="my. db"/> </full-backup-content>
42. Domain database, sharedpref, file, external, root
43. DON’T HARDCODE ABSOLUTE PATHS!
44. Practice #2
45. Practice #2 Take care of data migrations.
46. Data migrations mean
47. Data migrations mean Database schema migrations
48. Data migrations mean Database schema migrations SharedPreferences
49. Data migrations mean Database schema migrations SharedPreferences Any serialized data (binary, json, etc)
50. Beware, you may receive data from the older version.*
51. Practice #3
52. Practice #3 GCM anyone?
53. Keep your GCM registration_id out of your backup.
54. It may break GCM on that device.
55. It may break GCM on another device, too.
56. Same for other, per- device unique tokens/keys.
57. Same for other, per- device unique tokens/keys. PS: Check if InstanceId fits your needs
58. How?
59. How? Separate SharedPreferences
60. How? Separate SharedPreferences Separate database
61. Practice #4
62. Practice #4 Consider legal issues.
63. Practice #4 Quick story on how it can break your app
64. Practice #4 Quick story on how it can put you in jail
65. Practice #4 Quick story on how it can put you in jail
66. Technically speaking...
67. Android Backup sends your users’ data to Google
68. Android Backup sends your users’ data to another company
69. Ask yourself - do you backup user’s confidential data?
70. Then if (and only if) you REALLY think it’s necessary
71. Encrypt it.
72. Backup is cool
73. Recovery is cool
74. Use it wisely.
75. Leaving its settings as defaults isn’t wise.*
76. *For most apps.
77. Ah, one more thing.
78. 25 MB
79. After which your backup doesn’t work anymore.
80. So decide what exactly to backup and have a strategy
81. NO STRATEGY =
82. NO STRATEGY = OPTING OUT
83. Even worse
84. It makes your user think there’s some backup
85. But suddenly there is not
86. Thanks!
87. Q & A
88. Q & A Really. https://developer.android.com/preview/backup/index.html https://commonsware.com/blog/2015/06/04/random- musings-m-developer-preview-bad-part-two.html