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Application manifest

An application manifest defines the various attributes of an application.

The available attributes are listed in the following table:

Name Value type Description Status
name string Verbose name of the application. The following special characters are not allowed: < > : " / \ | ? *, as well as space Supported
version string Version to encode with the application. Maximum length is 50 characters. Supported
instance-type string Instance type that all instances created for the application will use. Jump to details Deprecated since 1.20
required-permissions array of strings List of permissions to automatically grant to the application. See Android Permissions for a list of available permissions. If [*] was given, all required runtime permissions for the application will be granted on application installation. Supported
image (optional) string Name or ID of an image to be used for the application. The default image is used if empty. Jump to details Supported
addons (optional) array List of addons to be installed during the application bootstrap process. Supported
tags (optional) array List of tags to be associated with the application. Supported
boot-package (optional) string Package to launch once the system has booted (default: package name retrieved from the APK if APK file is present). Supported on AOSP only
boot-activity (optional) string Activity of boot package to launch once the system has booted (default: main activity as defined in the application manifest). Supported on AOSP only
video-encoder (optional) string Video encoder to be used by an instance launched from the application (default: gpu-preferred). Possible values are: gpu, gpu-preferred, software. Jump to details Supported
watchdog (optional) map Watchdog settings to be configured on application installation. Jump to details Supported
services (optional) array Services to be provided from the installed application. Jump to details Supported
resources (optional) map Resources to be allocated on application installation. Jump to details Supported
extra-data (optional) array List of additional data to be installed on application installation. Jump to details Supported
hooks (optional) object Hooks settings to be configured on application installation. Jump to details Supported
bootstrap (optional) object Application bootstrap settings to be configured on application installation. Jump to details Supported
features (optional) array List of feature flags to be defined for instances created from the application. Supported
node-selector (optional) array List of selectors which will limit what node an instance for the application can be scheduled on. Jump to details Supported

Instance type

The instance-type attribute is deprecated since 1.20. For any application, a default set of resources will be chosen. If you wish to set specific resources to your application, use the resources attribute to do so.

Similar to other clouds, Anbox Cloud describes the amount of resources that are available to a single instance with an instance type. An instance type is a name that is mapped to a set of resources. This allows to have an easy abstraction when referring to resource requirements of instances or particular applications.

Anbox Cloud offers the following instance types:

Name vCPU cores RAM Disk size GPU slots
a2.3 2 3 GB 3 GB 0
a4.3 4 3 GB 3 GB 0
a6.3 6 3 GB 3 GB 0
a8.3 8 3 GB 3 GB 0
a10.3 10 3 GB 3 GB 0
g2.3 2 3 GB 3 GB 1
g4.3 4 3 GB 3 GB 1
g6.3 6 3 GB 3 GB 1
g8.3 8 3 GB 3 GB 1
g10.3 10 3 GB 3 GB 1

Image

The image attribute defines which image the application is based on. If left empty, your application is based on the default image. See How to manage images for more details on this. Available images on your installation can be listed with the following command:

amc image list

Node selector

The node-selector attribute allows specifying a list of selectors to limit the LXD nodes on which an instance for the application can be scheduled. AMS will match the selector against the tags specified for each node.

The following manifest specifies a node selector that instructs the AMS to schedule only those instances having the tags foo and bar, onto a node:

name: candy
instance-type: a4.3
node-selector: [foo, bar]

Video encoder

A video encoder type can be specified through the video-encoder field in the manifest file when creating an application, so that an instance launched from the application can use a GPU or software video encoder according to different scenarios. Virtual machines do not have GPU support and hence will use software video encoding.

Name Description
gpu A GPU-based video encoder
gpu-preferred A GPU-based video encoder if GPU slots are not used up, otherwise, fall back to use a software-based video encoder
software A software-based video encoder

When gpu video encoder is specified in the manifest, AMS can fail to create an application if:

  • All GPU slots are used up by running instances.
  • There is no GPU support across the entire LXD cluster.

Watchdog

The watchdog attribute includes the following field definitions:

Name Value type Description
disabled Boolean Toggle application watchdog on or off (default: false)
allowed-packages array of strings Besides the boot package, list of packages to be allowed to display in the foreground

When an instance is launched, Anbox enables an application watchdog by default for the installed package unless it’s disabled explicitly with:

name: candy
instance-type: a4.3
image: default
watchdog:
  disabled: true

If one of the following scenarios occurs, the watchdog will be triggered. The instance will be terminated and ends up with error status.

  • The application crashes or an ANR is triggered.
  • The application is not in the foreground when an application which is not listed in allowed-packages was brought to the foreground and gained the focus.
  • The boot package or activity is invalid.
  • One of the allowed-packages is invalid.

The rules forbid launching another activity, not part of the installed package or listed allowed packages. Launching activities of the same package is allowed.

Supplying ['*'] to the allowed-packages when the watchdog is enabled allows any application to be displayed in the foreground without triggering a watchdog.

Services

An instance launched from the installed application can expose services you want to make accessible from outside the instance. You must define the following properties for each service:

Name Value type Description
name string Name of service
port integer Port number to be exposed by the service
protocols array of strings Protocols to be used by the service (Possible values are: tcp, udp)
expose Boolean Expose service to be accessible externally or internally

Resources

Anbox Cloud provides a set of instance types that define the resources available to an instance. For example, if you start an instance for an application that uses the instance type a4.3, the instance is assigned 4 vCPU cores, 3 GB of RAM and 3 GB of disk space.

If your application requires resources that do not correspond to any of the provided instance types, you can use the resources directive to override some or all of the predefined resources.

Name Value type Minimum value Description
cpus integer 1 Number of vCPU cores
memory string 3 GB Memory to be assigned to the application
disk-size string 3 GB Disk size to be assigned to the application
gpu-slots(optional) integer 0 Number of GPU slots to be assigned to the application

If all required fields (cpus/memory/disk-size) of resources are supplied in the application manifest, the instance-type field is no longer needed. Even if the instance-type field is provided, it will be overridden by the requirements in the resources fields upon application installation.

See How to configure available resources for more information.

Extra data

Some Android applications which contain large program assets such as graphics or media files use so-called OBB files to store additional data. These data files are separated from the APK and saved onto the external or internal SD card of an Android device. The extra-data field can be used in this case to install an APK with separated OBB files or any other additional data into the Android system.

Each item of extra-data should be declared as follows:

<name>:
    target: <target-path>
    owner:  <uid>:<gid> # optional
    permissions: <file-permission> # optional

The fields have the following purpose:

Name Value type Description
name string Name of file or directory to be installed into the Android file system
target-path string Target location for the file or directory
owner (optional) string Owner assigned to the target file or directory in the Android file system
permissions (optional) string Permissions assigned to the target file or directory in the Android file system

permissions represents Linux file permissions in octal notation.

It’s recommended to let Anbox choose the right values for owner and permissions instead of manually providing them. If owner and permissions are not specified, the following default values will be used:

Name App data installation directory Type Value
owner SD card File package_uid:sdcard_rw
SD card Dir package_uid:sdcard_rw
system data File package_uid:package_gid
system data Dir package_uid:package_gid
permissions SD card File 0660
SD card Dir 0771
system data File 0660
system data Dir boot package folder → 0700, nested folders of boot package folder → 0770

Each item (file or folder) declared in the extra-data field of the manifest YAML file should be placed in a directory called extra-data.

For security reasons, the target location of the files and directories listed in the extra-data section is restricted to a few specific locations in the Android file system. These are:

  • /sdcard/Android/obb/<apk-package-name>
  • /sdcard/Android/data/<apk-package-name>
  • /data/app/<apk-package-name>
  • /data/data/<apk-package-name>

The manifest and extra data in our example are placed next to the application package, which must be named app.apk:

.
├── app.apk
├── extra-data
│   ├── com.canonical.candy.obb
│   └── game-data-folder
│       └── data.bin
└── manifest.yaml

Hooks

Hooks allow you to run custom scripts when a certain event is triggered in the life cycle of an instance. See Hooks for more details about the usage of hooks in an application.

Bootstrap

An application bootstrap can be fine-tuned through the bootstrap field.

The bootstrap attribute includes the following field definitions:

Name Value type Description
keep array Contents under the APP_DIR directory to be preserved in the application image after the bootstrap is finished. Wildcard patterns are supported. See pattern syntax for more details.

To minimise the application size, most contents under the APP_DIR directory are removed when the application bootstrap is finished. By default, only the metadata content is preserved. If a hook requires any other files under the APP_DIR directory during the regular instance runtime, you must include them in the application image.

name: my-application
instance-type: a4.3
bootstrap:
  keep:
    - 'apks/*.apk'
    - 'scripts'

This will include the scripts folder and all APK files under the apks folder in the application image when the bootstrap is done, so that they are available to use during the regular instance runtime.

Because it contains metadata, the manifest.yaml file and the hooks directory (if present) are not removed when the application bootstrap is finished and are always kept in the application image even if they are not explicitly defined in the keep list under the bootstrap attribute.

Last updated 15 days ago. Help improve this document in the forum.