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v0.2.0

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Lariat

Lariat is a powerful command-line tool designed to streamline the execution of commands and running of executables on remote Android devices. It achieves this by leveraging DeviceFarmer's API and the Android Debug Bridge (ADB). With Lariat, the cumbersome process of manually connecting to devices, pushing files, running commands, and retrieving results is simplified and made more efficient. It is an ideal solution for automating tasks in continuous integration (CI) pipelines.

Prerequisites

Python 3.8 or higher
ADB installed and added to the system's PATH
DeviceFarmer Access Token
JSON configuration file containing the Swagger spec URL and DeviceFarmer API token

Installation

Lariat is available on PyPI:

python -m pip install lariat

Lariat officially supports Python 3.8+.

Configuration File

Lariat utilizes a JSON configuration file. The default location for this config file is in the .lariat directory within the user's home directory (~/.lariat/config.json). The configuration file is used to specify the following:

device_farmer_url: The URL of the DeviceFarmer instance to connect to.
- NOTE: Lariat will append the standard API JSON spec to the base url. If using a custom path for your spec file, specify a full url ending in .json or .yaml.
access_token: Your DeviceFarmer access token.
- This can be obtained by logging into your DeviceFarmer UI, and going to Settings->Keys->Access Tokens
adb_private_key_path: (Optional) Path to a non-default adb private key. Defaults to ~/.android/adbkey if not specified
adb_shell_default_read_timeout_s: (Optional) Default total timeout (in seconds) for reading data from a device. This value may need to be increased from the default value of 10s for certain device operations.

{
   "access_token": "ef02da4fb3884395af4cf011061a2318ca5e9a04abd04de59c5c99afcce0b7fz",
   "device_farmer_url": "https://my.device-farmer-instance.com/",
   "adb_private_key_path": "/custom/path/adb.key",
   "adb_shell_default_read_timeout_s": 32.5
}

All config options can be specified on the command line to override any defaults set in the config file. For example, the command line option --device_farmer_url can be used to override the DeviceFarmer URL set in the config file.

Usage

usage: lariat [-h] [-g | -e EXEC_FILE | -c COMMAND] [--config CONFIG] [-s SELECT [SELECT ...]] [-f FILTER [FILTER ...]]
                [-p PUSH_FILES]

DeviceFarmer automation tool

optional arguments:
  -h, --help            show this help message and exit
  -g, --get-devices     Enumerate devices on DeviceFarmer instance. Does not execute any commands on devices. Prints JSON results
                        to stdout.
  -e EXEC_FILE, --exec-file EXEC_FILE
                        Push a file and execute it. Pushes to /data/local/tmp/.
  -c COMMAND, --command COMMAND
                        Run a command.
  --config CONFIG       Override the default path to the configuration file. Default:/home/larry.espenshade/.lariat/config.json
  -s SELECT [SELECT ...], --select SELECT [SELECT ...]
                        Select the fields to be returned by --get-devices (-g). If not specified, all fields are returned.
  -f FILTER [FILTER ...], --filter FILTER [FILTER ...]
                        Filter devices via a list of key-value pairs (e.g., sdk=27 manufacturer=SAMSUNG). Non boolean values are
                        regex matched
  -p PUSH_FILES, --push-files PUSH_FILES
                        Specify the path to the file or directory to be pushed to the device. Pushes to /data/local/tmp/.
  -v, --verbose         Increase log level. Can be supplied multiple times to further increase log verbosity (e.g. -vv)

Device Fields

The --select and --filter options both use "field names" to perform their respective actions. These field names are JSON keys as defined by DeviceFarmer as part of its REST API. You can view supported fields for your DeviceFarmer installation by navigating to the following URL: https://<device_farmer_url>/api/v1/devices/<serial> where device_farmer_url is the URL to your DeviceFarmer installation and serial is the serial number of one of your devices. The /<serial> component can be omitted to view all fields of all devices.

Field names support dot notation to access nested keys. For example, battery.health can be used to access the nested health key within battery.

Note that specifying a --filter along with a --select will automatically include any field names specified in the filter in the resulting JSON.

Commonly Used Fields

abi - Device Application Binary Interface (eg. armeabi-v7a)
manufacturer - Device Manufacturer
marketName - Device Marketing Name
model - Device Model Name
provider.name - STF Provider hosting this device
version - Android version

Examples

Enumerate all devices on a DeviceFarmer instance:

lariat --get-devices

Limit the fields returned by --get-devices:

lariat --get-devices --select serial model status

Filter devices based on specific fields and values (e.g. all Samsung devices with SDK level 25-27):

lariat --get-devices --filter manufacturer=SAMSUNG sdk=2[5-7]

Filter devices based on JSON sub-key using dot notation:

lariat --get-devices --filter provider.name=my.devicefarmer.com

Push a local file to the device and execute it:

lariat --exec-file path/to/hello

Run a command on all arm64 devices:

lariat --command "echo hello" --filter abi=arm64-v8a

Push files to the device:

lariat --push-files path/to/files

Results

Lariat returns results for each device that met the filtering criteria.

The following is sample output for an echo command:

lariat --command "echo hello" --filter abi=arm64-v8a

"A12345": {
    "output": "hello",
    "exitcode": 0,
},
"B54321": {
    "output": "hello",
    "exitcode": 0,
},
"C678910": {
    "reason": "Device is currently in use",
}

Each result contains different fields depending on the device's availability:

If a device is unavailable, the result will have a single field:
- reason: Specifies why the device was not available for use, such as it being currently in use, not present on the range, etc.
If a device is available and an operation was performed on it, the result will include two fields:
- output: Contains the ADB shell output of the command executed, or details about the action performed.
- exitcode: The return code of the command or action executed on the device.

Remember that a device will either have a 'reason' field (if it was unavailable) or 'output' and 'exitcode' fields

Docker Image

For convenience, an official Lariat Docker image is available.

To use the docker image, simply run

docker run --rm -v ~/.android:/root/.android:ro -v ~/.lariat:/root/.lariat:ro ghcr.io/zetier/lariat:latest -c 'echo hello'

This docker run command creates and runs a Docker container based on the ghcr.io/zetier/lariat:latest image. It performs the following actions:

Creates a read-only volume mount for the .android directory on the host machine, which contains ADB keys, to the /root/.android directory inside the container.
Creates a read-only volume mount for the .lariat directory on the host machine, which contains the lariat configuration file, to the /root/.lariat directory inside the container.
The --rm flag ensures that the container is automatically removed after it exits.
Inside the container, the command lariat -c 'echo hello' is executed, which prints "hello" as the output on every lockable device on your DeviceFarmer range.

Please note that if your ADB keys and configuration file are located in different directories on the host machine, you may need to modify the docker run command accordingly to provide the correct paths for volume mounting.

CI Integration

Lariat was designed for simple integration into CI pipelines. Below is an example of a GitLab job that tests a binary built in the pipeline on a DeviceFarmer range:

.lariat-test:
  image:
    name: ghcr.io/zetier/lariat:latest
    entrypoint: [""]
  stage: test
  before_script:
    # Copy keys and configs from private CI variables
    - mkdir -p ~/.android
    - echo "$CI_ADB_PUB_KEY" > ~/.android/adbkey.pub
    - echo "$CI_ADB_PRI_KEY" > ~/.android/adbkey
    - echo "$CI_FARMHAND_CONFIG" -> ~/.lariat/config.json
  script:
    - lariat --file $BINARY > test_results.json
  artifacts:
    paths:
      - test_results.json

# Assumes a `build-android-binary` job that produces `android_binary`
# as an artifact.
android-range-test:
  extends: .lariat-test
  variables:
    BINARY: android_binary
  needs:
    - build-android-binary

Notes

Lariat will lock devices before performing any operations to ensure exclusive access. After the operations have been completed, the devices will be unlocked.
Make sure to provide the correct path to the ADB private key file via ~/.lariat/config.json if it is different from the default location (~/.android/adbkey)
By default, Lariat will enumerate ~~every~~ device on the DeviceFarmer range, including ones not present or ready. You can modify this as needed by specifying --filter ready=true present=true if needed.

Development Install

NOTE: Lariat is developed on and regularly tested with Ubuntu 18.04 with Python 3.8. Other distributions and versions may work, but are currently untested.

Clone the repository

Install dependencies along with the Lariat python package

sudo apt-get update
sudo apt-get install python3-venv python3.8-venv -y
python3.8 -m venv venv
source venv/bin/activate
(venv) pip install --upgrade pip
(venv) pip install .