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Merge "Fix headings to be correct Markdown." am: abab751a70

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Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2284473

Change-Id: I8f084661b57142d61954676b698fa9471e330a2d
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2022-11-03 17:39:12 +00:00
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services/core/java/com/android/server/rollback/README.md
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@@ -1,4 +1,4 @@
#Rollback Manager # Rollback Manager
## Introduction ## Introduction
@@ -7,9 +7,9 @@ updatability efforts. RollbackManager adds support for rolling back an APK or
APEX update to the previous version installed on the device, and reverting any APEX update to the previous version installed on the device, and reverting any
APK or APEX data to the state it was in at the time of install. APK or APEX data to the state it was in at the time of install.
##Rollback Basics ## Rollback Basics
###How Rollbacks Work ### How Rollbacks Work
A new install parameter ENABLE_ROLLBACK can be specified to enable rollback when A new install parameter ENABLE_ROLLBACK can be specified to enable rollback when
updating an application. For example: updating an application. For example:
@@ -42,27 +42,27 @@ data taken when FooV2.apk was first installed.
See below for more details of shell commands for rollback. See below for more details of shell commands for rollback.
###Rollback Triggers ### Rollback Triggers
####Manually Triggered Rollback #### Manually Triggered Rollback
As mentioned above, it is possible to trigger rollback on device using a shell As mentioned above, it is possible to trigger rollback on device using a shell
command. This is for testing purposes only. We do not expect this mechanism to command. This is for testing purposes only. We do not expect this mechanism to
be used in production in practice. be used in production in practice.
####Watchdog Triggered Rollback #### Watchdog Triggered Rollback
Watchdog triggered rollback is intended to address severe issues with the Watchdog triggered rollback is intended to address severe issues with the
device. The platform provides several different watchdogs that can trigger device. The platform provides several different watchdogs that can trigger
rollback. rollback.
#####Package Watchdog ##### Package Watchdog
There is a package watchdog service running on device that will trigger rollback There is a package watchdog service running on device that will trigger rollback
of an update if there are 5 ANRs or process crashes within a 1 minute window for of an update if there are 5 ANRs or process crashes within a 1 minute window for
a package in the update. a package in the update.
#####Native Watchdog ##### Native Watchdog
If a native service crashes repeatedly after an update is installed, rollback If a native service crashes repeatedly after an update is installed, rollback
will be triggered. This particularly applies to updates that include APEXes will be triggered. This particularly applies to updates that include APEXes
@@ -70,25 +70,25 @@ that may update native services, but note that as it is difficult to tell which
native services have been affected by an update, *any* crashing native service native services have been affected by an update, *any* crashing native service
will cause the rollback to be triggered. will cause the rollback to be triggered.
#####Explicit Health Check ##### Explicit Health Check
There is an explicit check to verify the network stack is functional after an There is an explicit check to verify the network stack is functional after an
update. If there is no network connectivity within a certain time period after update. If there is no network connectivity within a certain time period after
an update, rollback is triggered. an update, rollback is triggered.
####Server Triggered Rollback #### Server Triggered Rollback
The RollbackManager API may be used by the installer to roll back an update The RollbackManager API may be used by the installer to roll back an update
based on a request from the server. based on a request from the server.
##Rollback Details ## Rollback Details
###RollbackManager API ### RollbackManager API
The RollbackManager API is an @SystemAPI guarded by the MANAGE_ROLLBACKS and The RollbackManager API is an @SystemAPI guarded by the MANAGE_ROLLBACKS and
TEST_MANAGE_ROLLBACKS permissions. See RollbackManager.java for details about TEST_MANAGE_ROLLBACKS permissions. See RollbackManager.java for details about
the RollbackManager API. the RollbackManager API.
###Rollback of APEX modules ### Rollback of APEX modules
Rollback is supported for APEX modules in addition to APK modules. In Q, there Rollback is supported for APEX modules in addition to APK modules. In Q, there
was no concept of data associated with an APEX, so only the APEX itself is was no concept of data associated with an APEX, so only the APEX itself is
@@ -100,7 +100,7 @@ terms of any state they persist on the system (outside of the APEX data
directories). For example, FooV2.apex must not change the file format of some directories). For example, FooV2.apex must not change the file format of some
state stored on the device in such a way that FooV1.apex cannot read the file. state stored on the device in such a way that FooV1.apex cannot read the file.
###Rollback of MultiPackage Installs ### Rollback of MultiPackage Installs
Rollback can be enabled for multi-package installs. This requires that all Rollback can be enabled for multi-package installs. This requires that all
packages in the install session, including the parent session, have the packages in the install session, including the parent session, have the
@@ -119,7 +119,7 @@ If there is a problem enabling rollback for any package in the multi-package
install session, rollback will not be enabled for any package in the install session, rollback will not be enabled for any package in the
multi-package install session. multi-package install session.
###Rollback of Staged Installs ### Rollback of Staged Installs
Rollback can be enabled for staged installs, which require reboot to take Rollback can be enabled for staged installs, which require reboot to take
effect. If reboot was required when the package was updated, then reboot is effect. If reboot was required when the package was updated, then reboot is
@@ -127,21 +127,21 @@ required when the package is rolled back. If no reboot was required when the
package was updated, then no reboot is required when the package is rolled back. package was updated, then no reboot is required when the package is rolled back.
###Rollbacks on Multi User Devices ### Rollbacks on Multi User Devices
Rollbacks should work properly on devices with multiple users. There is special Rollbacks should work properly on devices with multiple users. There is special
handling of user data backup to ensure app user data is properly backed up and handling of user data backup to ensure app user data is properly backed up and
restored for all users, even for credential encrypted users that have not been restored for all users, even for credential encrypted users that have not been
unlocked at various points during the flow. unlocked at various points during the flow.
###Rollback whitelist ### Rollback whitelist
Outside of testing, rollback may only be enabled for packages listed in the Outside of testing, rollback may only be enabled for packages listed in the
sysconfig rollback whitelist - see sysconfig rollback whitelist - see
`SystemConfig#getRollbackWhitelistedPackages`. Attempts to enable rollback for `SystemConfig#getRollbackWhitelistedPackages`. Attempts to enable rollback for
non-whitelisted packages will fail. non-whitelisted packages will fail.
###Failure to Enable Rollback ### Failure to Enable Rollback
There are a number of reasons why we may be unable to enable rollback for a There are a number of reasons why we may be unable to enable rollback for a
package, including: package, including:
@@ -158,13 +158,13 @@ If we are unable to enable rollback, the installation will proceed without
rollback enabled. Failing to enable rollback does not cause the installation to rollback enabled. Failing to enable rollback does not cause the installation to
fail. fail.
###Failure to Commit Rollback ### Failure to Commit Rollback
For the most part, a rollback will remain available after failure to commit it. For the most part, a rollback will remain available after failure to commit it.
This allows the caller to retry the rollback if they have reason to believe it This allows the caller to retry the rollback if they have reason to believe it
will not fail again the next time the commit of the rollback is attempted. will not fail again the next time the commit of the rollback is attempted.
###Installing Previously Rolled Back Packages ### Installing Previously Rolled Back Packages
There is no logic in the platform itself to prevent installing a version of a There is no logic in the platform itself to prevent installing a version of a
package that was previously rolled back. package that was previously rolled back.
@@ -175,7 +175,7 @@ package versions believed to be the main source of the bad update. The list of
installer to prevent reinstall of a previously rolled back package version if so installer to prevent reinstall of a previously rolled back package version if so
desired. desired.
###Rollback Expiration ### Rollback Expiration
An available rollback is expired if the rollback lifetime has been exceeded or An available rollback is expired if the rollback lifetime has been exceeded or
if there is a new update to package associated with the rollback. When an if there is a new update to package associated with the rollback. When an
@@ -183,9 +183,9 @@ available rollback is expired, the backed up apk and userdata associated with
the rollback are deleted. Once a rollback is expired, it can no longer be the rollback are deleted. Once a rollback is expired, it can no longer be
executed. executed.
##Shell Commands for Rollback ## Shell Commands for Rollback
###Installing an App with Rollback Enabled ### Installing an App with Rollback Enabled
The `adb install` command accepts the `--enable-rollback` flag to install an app The `adb install` command accepts the `--enable-rollback` flag to install an app
with rollback enabled. For example: with rollback enabled. For example:
@@ -194,7 +194,7 @@ with rollback enabled. For example:
$ adb install --enable-rollback FooV2.apk $ adb install --enable-rollback FooV2.apk
``` ```
###Triggering Rollback Manually ### Triggering Rollback Manually
If rollback is available for an application, the pm command can be used to If rollback is available for an application, the pm command can be used to
trigger rollback manually on device: trigger rollback manually on device:
@@ -206,7 +206,7 @@ $ adb shell pm rollback-app com.example.foo
For rollback of staged installs, you have to manually reboot the device for the For rollback of staged installs, you have to manually reboot the device for the
rollback to take effect after running the 'pm rollback-app' command. rollback to take effect after running the 'pm rollback-app' command.
###Listing the Status of Rollbacks on Device ### Listing the Status of Rollbacks on Device
You can get a list with details about available and recently committed rollbacks You can get a list with details about available and recently committed rollbacks
using dumpsys. For example: using dumpsys. For example:
@@ -246,9 +246,9 @@ committed.
The list of rollbacks is also included in bug reports. Search for "DUMP OF The list of rollbacks is also included in bug reports. Search for "DUMP OF
SERVICE rollback". SERVICE rollback".
##Configuration Properties ## Configuration Properties
###Rollback Lifetime ### Rollback Lifetime
Rollback lifetime refers to the maximum duration of time after the rollback is Rollback lifetime refers to the maximum duration of time after the rollback is
first enabled that it will be available. The default is for rollbacks to be first enabled that it will be available. The default is for rollbacks to be
@@ -263,7 +263,7 @@ $ adb shell device_config put rollback_boot rollback_lifetime_in_millis 17280000
The update will not take effect until after system server has been restarted. The update will not take effect until after system server has been restarted.
###Enable Rollback Timeout ### Enable Rollback Timeout
The enable rollback timeout is how long RollbackManager is allowed to take to The enable rollback timeout is how long RollbackManager is allowed to take to
enable rollback when performing an update. This includes the time needed to make enable rollback when performing an update. This includes the time needed to make
@@ -279,7 +279,7 @@ $ adb shell device_config put rollback enable_rollback_timeout 10000
The update will take effect for the next install with rollback enabled. The update will take effect for the next install with rollback enabled.
##Limitations ## Limitations
* You cannot enable rollback for the first version of an application installed * You cannot enable rollback for the first version of an application installed
on the device. Only updates to a package previously installed on the device can on the device. Only updates to a package previously installed on the device can