• zoe agents are started and stopped via zoe.sh but this agent also launches and stops installed agents. In order not to duplicate work, here are some suggestions:

A) add per-agent start/stop in zoe.sh script (trivial) and remove launch/stop from the manager, or...

B) make this agent responsible of all other agents (make it the equivalent of 'init')

• add this agent to zoe-startup-kit and have it as an integral part of the project
• you can assume there is an environment variable ZOE_HOME pointing to the zoe installation dir. Configuration files can be simplified under this assumption

Please let me know what do you think and if I can help in any way

These functions should be implemented in the zoe.sh script to in order to improve usability and not duplicate code. Needed functions would be:

• A launch function that launchs a single agent rather than the whole lot (used when installing or updating agents)
• A stop function that stops a single agent (used when installing or updating agents)
• A restart function that stops and launches a single agent. This one would be very important if we want to be able to update the manager like the rest of the agents.

The manager would still have these functions available, but calling to the zoe.sh script instead.

Message received: {'dst': 'zam', 'tag': 'install', 'name': 'dhl'}
Candidate found: <bound method AgentManager.install of <main.AgentManager object at 0x24c3e10>>
Calling method <bound method AgentManager.install of <main.AgentManager object at 0x24c3e10>> with parameters {'dst': 'zam', 'tag': 'install', 'name': 'dhl'}
Cloning into '/home/pi/zoe-startup-kit/var/zam/dhl'...
Traceback (most recent call last):
File "/home/pi/zoe-startup-kit/lib/python/zoe/listener.py", line 130, in connection
self._delegate.receive(parser)
File "/home/pi/zoe-startup-kit/lib/python/zoe/deco/deco.py", line 109, in receive
tags = parser.tags()
File "/home/pi/zoe-startup-kit/lib/python/zoe/deco/deco.py", line 131, in dispatch
print("Too many candidates found")
File "/home/pi/zoe-startup-kit/lib/python/zoe/deco/deco.py", line 169, in docall
elif arg in defaults:
File "./zam.py", line 126, in install
file_list = self.move_files(name)
File "./zam.py", line 541, in move_files
new_path = new_path.replace(env["ZOE_HOME"], "")
AttributeError: 'NoneType' object has no attribute 'replace'

There may be times where an agent requires an additional library or component installed in the machine. In order to prevent Zoe (and the agents) from touching system files, these additional components could be placed in the ZOE_HOME/lib directory, under their corresponding subdirectory.

This would mean that is up to the agent's developer to provide the installation of the dependencies. The preinst and postinst scripts could be used for this matter.

For instance, if an agent written in Python requires the SQLAlchemy module, it could be installed with the pip tool like so:

#!/bin/bash
# zam/preinst
# This script is executed before the installation of the agent takes place.

# Define the user directory
export PYTHONUSERBASE=${ZOE_HOME}/lib/python

# Install SQLAlchemy into that directory
pip install --user SQLAlchemy

The dependencies could also be included in the agent's repository and installed by the manager normally, but that would depend on the license of the code involved.

Any thoughts on this @voiser?

Dependency handling is quite limited right now in some points:

• Agent developer must manage dependency installation
• Libraries may have conflicting versions
• If an agent is uninstalled, dependencies remain

In the long term, it would be nice to have a different way of handling external dependencies for agents (or improve the current one).