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https://github.com/Screenly/Anthias.git
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d01eda0e9a
This change implements a mechanism for executing a restricted set of commands on the host from within the screenly Docker containers by using a very simple host agent process, which requires only 2 packaged dependencies (python3 and python3-redis) from the standard Raspbian repositories. Initially, this functionality is used to implement the previously disabled reboot and shutdown features. However, this could fairly easily be expanded to re-implement the USB asset loading functionality. Furthermore, this change removes the reinstallation of build-essential, as /usr/lib/gcc/arm-linux-gnueabihf/4.9/cc1plus does not exist after reinstalling such and screenly builds without error. Signed-off-by: Nash Kaminski <nashkaminski@kaminski.io>
53 lines
1.8 KiB
Python
Executable File
53 lines
1.8 KiB
Python
Executable File
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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__author__ = "Nash Kaminski"
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__license__ = "Dual License: GPLv2 and Commercial License"
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import logging
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import os
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import redis
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import subprocess
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# Name of redis channel to listen to
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CHANNEL_NAME = b'hostcmd'
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# Explicit command whitelist for security reasons, keys as bytes objects
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CMD_TO_ARGV = {b'reboot': ['/usr/bin/sudo', '-n', '/usr/bin/systemctl', 'reboot'],
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b'shutdown': ['/usr/bin/sudo', '-n', '/usr/bin/systemctl', 'poweroff']}
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def execute_host_command(cmd_name):
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cmd = CMD_TO_ARGV.get(cmd_name, None)
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if cmd is None:
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logging.warning("Unable to perform host command %s: no such command!", cmd_name)
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elif os.getenv('TESTING'):
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logging.warning("Would have executed %s but not doing so as TESTING is defined", cmd)
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else:
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logging.info("Executing host command %s", cmd_name)
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phandle = subprocess.run(cmd)
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logging.info("Host command %s (%s) returned %s", cmd_name, cmd, phandle.returncode)
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def process_message(message):
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if (message.get('type', '') == 'message' and message.get('channel', b'') == CHANNEL_NAME):
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execute_host_command(message.get('data', b''))
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else:
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logging.info("Received unsolicited message: %s", message)
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def subscriber_loop():
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# Connect to redis on localhost and wait for messages
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logging.info("Connecting to redis...")
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rdb = redis.Redis(host="127.0.0.1", port=6379, db=0)
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pubsub = rdb.pubsub(ignore_subscribe_messages=True)
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pubsub.subscribe(CHANNEL_NAME)
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logging.info("Subscribed to channel %s, ready to process messages", CHANNEL_NAME)
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for message in pubsub.listen():
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process_message(message)
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if __name__ == '__main__':
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# Init logging
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logging.basicConfig()
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logging.getLogger().setLevel(logging.INFO)
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# Loop forever processing messages
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subscriber_loop()
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