Larry Price

And The Endless Cup Of Coffee

On Gender Bias and Home Improvement

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Instead of a highly technical guide, today I have a short anecdote of some recent electrical work we did in the master bathroom.

I met my wife when I joined my high school robotics team. I was a hammer: with no singular skill that I wanted to focus on, I was thrown into painting, cutting, drilling, electrical, lifting, sanding, building the website, and even marketing. Funnily enough, I never actually worked on programming the robot. As far as I knew at the time, my wife was doing similar work with more focus on marketing and operating the robot.

Fast-forward 10 years. I do most of the indoor home improvement work (electrical, dry walling, painting), and our yard work is fairly balanced. A few weekends ago, we were swapping out the light fixtures in the master bathroom. Well, she was mostly holding the flashlight while I cursed at the previous owner’s hackwork. As we’re wrapping up the first fixture, she starts asking really basic electrical questions. Beginner’s questions.

This struck me as a little odd. I answer with a bit of sarcasm, mentioning that it’s the absolute basic stuff she should remember from being on the robotics team. As it turns out, the (all-male) mentor staff never really encouraged the girls to work directly on the robot. The girls were pushed toward things like “marketing” and operating the robot, presumably because it reflected well on the team to have female drivers/operators. I started to think back on our overlapping time on the team and… Come to think of it, the girls really were pushed into a less-technical experience while I was pushed towards the greasy work.

This was 10 years ago, so I would hope things are a bit different now as more girls are influenced to get interested in STEM in high school. It’s a shame that she wasn’t encouraged to take on the same tasks as the boys, and it’s left an obvious effect on her into adulthood.

So I started thinking about my parents. My father would include me as much as possible in fixing up the house. My sister, on the other hand, would generally not be included. Granted, she’s 4 years younger than me, but I was forced to help my dad do things from a very young age when I would have rather been playing video games than learning life lessons. My wife is the eldest of three daughters, and they also were never really invited to help with home improvement outside of yard work.

We may not have grown up in the most forward-thinking town, but our parents are not sexists. Our robotics mentors may have lived a bit in the past, but they intended no malice while directing students towards work. In both of these cases, the adults were following the same pattern they’ve seen for generations. The trick now is to break that pattern.

For the second light fixture in the master bathroom, I held the flashlight. I instructed my wife in removing and replacing the fixture, only intervening on stubborn bolts. After we finished, she thanked me. I felt a bit guilty for not letting her take the wheel for so long. My assumption had always been she had the skills but no desire to get her hands dirty. Turns out she only needed the opportunity to break the pattern.

Using D-Bus Signals in Python

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This is the third in a series of blog posts on creating an asynchronous D-Bus service in python. For the inital entry, go here. For the previous entry, go here

Last time we transformed our base synchronous D-Bus service to include asynchronous calls in a rather naive way. In this post, we’ll refactor those asynchronous calls to include D-Bus signals; codewise, we’ll pick up right where we left off after part 2: https://github.com/larryprice/python-dbus-blog-series/tree/part2. Of course, all of today’s code can be found in the same project with the part3 tag: https://github.com/larryprice/python-dbus-blog-series/tree/part3.

Sending Signals

We can fire signals from within our D-Bus service to notify clients of tasks finishing, progress updates, or data availability. Clients subscribe to these signals and act accordingly. Let’s start by changing the signature of the slow_result method of RandomData to be a signal:

random_data.py
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# ...
@dbus.service.signal("com.larry_price.test.RandomData", signature='ss')
def slow_result(self, thread_id, result):
    pass

We’ve replaced the context decorator with a signal, and we’ve swapped out the guts of this method for a pass, meaning the method will call but doesn’t do anything else. We now need a way to call this signal, which we can do from the SlowThread class we were using before. When creating a SlowThread in the slow method, we can pass in this signal as a callback. At the same time, we can remove the threads list we used to use to keep track of existing SlowThread objects.

random_data.py
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class RandomData(dbus.service.Object):
    def __init__(self, bus_name):
        super().__init__(bus_name, "/com/larry_price/test/RandomData")

        random.seed()

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='i', out_signature='s')
    def slow(self, bits=8):
        thread = SlowThread(bits, self.slow_result)
        return thread.thread_id

    # ...

Now we can make some updates to SlowThread. The first thing we should do is add a new parameter callback and store it on the object. Because slow_result no longer checks the done property, we can remove that and the finished event. Instead of calling set on the event, we can now simply call the callback we stored with the current thread_id and result. We end up with a couple of unused variables here, so I’ve also gone ahead and refactored the work method on SlowThread to be a little cleaner.

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# ...

class SlowThread(object):
    def __init__(self, bits, callback):
        self._callback = callback
        self.result = ''

        self.thread = threading.Thread(target=self.work, args=(bits,))
        self.thread.start()
        self.thread_id = str(self.thread.ident)

    def work(self, bits):
        num = ''

        while True:
            num += str(random.randint(0, 1))
            bits -= 1
            time.sleep(1)

            if bits <= 0:
                break

        self._callback(self.thread_id, str(int(num, 2)))

And that’s it for the service-side. Any callers will need to subscribe to our slow_result method, call our slow method, and wait for the result to come in.

Receiving Signals

We need to make some major changes to our client program in order to receive signals. We’ll need to introduce a main loop, which we’ll spin up in a separate thread, for communicating on the bus. The way I like to do this is with a ContextManager so we can guarantee that the loop will be exited when the program exits. We’ll move the logic we previously used in client to get the RandomData object into a private member method called _setup_object, which we’ll call on context entry after creating the loop. On context exit, we’ll simply call quit on the loop.

client
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# Encapsulate calling the RandomData object on the session bus with a main loop
import dbus, dbus.exceptions, dbus.mainloop.glib
import threading
from gi.repository import GLib
class RandomDataClient(object):
    def __enter__(self):
        self._setup_dbus_loop()
        self._setup_object()

        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self._loop.quit()
        return True

    def _setup_dbus_loop(self):
        dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
        self._loop = GLib.MainLoop()

        self._thread = threading.Thread(target=self._loop.run)
        self._thread.start()

    def _setup_object(self):
        try:
            self._bus = dbus.SessionBus()
            self._random_data = self._bus.get_object("com.larry-price.test",
                                                     "/com/larry_price/test/RandomData")
        except dbus.exceptions.DBusException as e:
            print("Failed to initialize D-Bus object: '%s'" % str(e))
            sys.exit(2)

We can add methods on RandomDataClient to encapsulate quick and slow. quick is easy - we’ll just return self._random_data.quick(bits). slow, on the other hand, will take a bit of effort. We’ll need to subscribe to the slow_result signal, giving a callback for when the signal is received. Since we want to wait for the result here, we’ll create a threading.Event object and wait for it to be set, which we’ll do in our handler. The handler, which we’ll call _finished will validate that it has received the right result based on the current thread_id and then set the result on the RandomDataClient object. After all this, we’ll remove the signal listener from our bus connection and return the final result.

client
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class RandomDataClient(object):
    # ...

    def quick(self, bits):
        return self._random_data.quick(bits)

    def _finished(self, thread_id, result):
        if self._thread_id == self._thread_id:
            self._result = result
            self._done.set()

    def slow(self, bits):
        self._done = threading.Event()
        self._thread_id = None
        self._result = None

        signal = self._bus.add_signal_receiver(path="/com/larry_price/test/RandomData", handler_function=self._finished,
                                               dbus_interface="com.larry_price.test.RandomData", signal_name='slow_result')
        self._thread_id = self._random_data.slow(bits)
        self._done.wait()
        signal.remove()

        return self._result

Now we’re ready to actually call these methods. We’ll wrap our old calling code with the RandomDataClient context manager, and we’ll directly call the methods as we did before on the client:

client
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# ...

# Call the appropriate method with the given number of bits
with RandomDataClient() as client:
    if args.slow:
        print("Your random number is: %s" % client.slow(int(args.bits)))
    else:
        print("Your random number is: %s" % client.quick(int(args.bits)))

This should have feature-parity with our part 2 code, but now we don’t have to deal with an infinite loop waiting for the service to return.

Next time

We have a working asynchronous D-Bus service using signals. Next time I’d like to dive into forwarding command output from a D-Bus service to a client.

As a reminder, the end result of our code in this post is MIT Licensed and can be found on Github: https://github.com/larryprice/python-dbus-blog-series/tree/part3.

Creating an Asynchronous D-Bus Service With Python

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This is the second in a series of blog posts on creating an asynchronous D-Bus service in python. For part 1, go here.

Last time we created a base for our asynchronous D-Bus service with a simple synchronous server/client. In this post, we’ll start from that base which can be found on Github: https://github.com/larryprice/python-dbus-blog-series/tree/part1. Of course, all of today’s code can be found in the same project with the part2 tag: https://github.com/larryprice/python-dbus-blog-series/tree/part2.

Why Asynchronous?

Before we dive into making our service asynchronous, we need a reason to make our service asynchronous. Currently, our only d-bus object contains a single method, quick, which lives up to its namesake and is done very quickly. Let’s add another method to RandomData which takes a while to finish its job.

random_data.py
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import dbus.service
import random
import time

class RandomData(dbus.service.Object):
    def __init__(self, bus_name):
        super().__init__(bus_name, "/com/larry_price/test/RandomData")
        random.seed()

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='i', out_signature='s')
    def quick(self, bits=8):
        return str(random.getrandbits(bits))

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='i', out_signature='s')
    def slow(self, bits=8):
        num = str(random.randint(0, 1))
        while bits > 1:
            num += str(random.randint(0, 1))
            bits -= 1
            time.sleep(1)

        return str(int(num, 2))

Note the addition of the slow method on the RandomData object. slow is a contrived implementation of building an n-bit random number by concatenating 1s and 0s, sleeping for 1 second between each iteration. This will still go fairly quickly for a small number of bits, but could take quite some time for numbers as low as 16 bits.

In order to call the new method, we need to modify our client binary. Let’s add in the argparse module and take in a new argument: --slow. Of course, --slow will instruct the program to call slow instead of quick, which we’ll add to the bottom of the program.

client
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#!/usr/bin/env python3

# Take in a single optional integral argument
import sys
import argparse

arg_parser = argparse.ArgumentParser(description='Get random numbers')
arg_parser.add_argument('bits', nargs='?', default=16)
arg_parser.add_argument('-s', '--slow', action='store_true',
                        default=False, required=False,
                        help='Use the slow method')

args = arg_parser.parse_args()

# Create a reference to the RandomData object on the  session bus
import dbus, dbus.exceptions
try:
    bus = dbus.SessionBus()
    random_data = bus.get_object("com.larry-price.test", "/com/larry_price/test/RandomData")
except dbus.exceptions.DBusException as e:
    print("Failed to initialize D-Bus object: '%s'" % str(e))
    sys.exit(2)

# Call the appropriate method with the given number of bits
if args.slow:
    print("Your random number is: %s" % random_data.slow(int(args.bits)))
else:
    print("Your random number is: %s" % random_data.quick(int(args.bits)))

Now we can run our client a few times to see the result of running in slow mode. Make sure to start or restart the service binary before running these commands:

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$ ./client 4
Your random number is: 2
$ ./client 4 --slow
Your random number is: 15
$ ./client 16
Your random number is: 64992
$ ./client 16 --slow
Traceback (most recent call last):
  File "./client", line 26, in <module>
    print("Your random number is: %s" % random_data.slow(int(args.bits)))
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

Your mileage may vary (it is a random number generator, after all), but you should eventually see a similar crash which is caused by a timeout in the response of the D-Bus server. We know that this algorithm works; it just needs more time to run. Since a synchronous call won’t work here, we’ll have to switch over to more asynchronous methods…

An Asynchronous Service

At this point, we can go one of two ways. We can use the threading module to spin threads within our process, or we can use the multiprocessing module to create child processes. Child processes will be slightly pudgier, but will give us more functionality. Threads are a little simpler, so we’ll start there. We’ll create a class called SlowThread, which will do the work we used to do within the slow method. This class will spin up a thread that performs our work. When the work is finished, it will set a threading.Event that can be used to check that the work is completed. threading.Event is a cross-thread synchronization object; when the thread calls set on the Event, we know that the thread is ready for us to check the result. In our case, we call is_set on our event to tell a user whether or not our data is ready.

random_data.py
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# ...

import threading
class SlowThread(object):
    def __init__(self, bits):
        self.finished = threading.Event()
        self.result = ''

        self.thread = threading.Thread(target=self.work, args=(bits,))
        self.thread.start()
        self.thread_id = str(self.thread.ident)

    @property
    def done(self):
        return self.finished.wait(1)

    def work(self, bits):
        num = str(random.randint(0, 1))
        while bits > 1:
            num += str(random.randint(0, 1))
            bits -= 1
            time.sleep(1)

        self.result = str(num)
        self.finished.set()

# ...

On the RandomData object itself, we’ll initialize a new thread tracking list called threads. In slow, we’ll initialize a SlowThread object, append it to our threads list, and return the thread identifier from SlowThread. We’ll also want to add a method to try to get the result from a given SlowThread called slow_result, which will take in the thread identifier we returned earlier and try to find the appropriate thread. If the thread is finished (the event is set), we’ll remove the thread from our list and return the result to the caller.

random_data.py
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# ...

class RandomData(dbus.service.Object):
    def __init__(self, bus_name):
        super().__init__(bus_name, "/com/larry_price/test/RandomData")

        random.seed()
        self.threads = []

    # ...

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='i', out_signature='s')
    def slow(self, bits=8):
        thread = SlowThread(bits)
        self.threads.append(thread)
        return thread.thread_id

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='s', out_signature='s')
    def slow_result(self, thread_id):
        thread = [t for t in self.threads if t.thread_id == thread_id]
        if not thread:
            return 'No thread matching id %s' % thread_id

        thread = thread[-1]
        if thread.done:
            result = thread.result
            self.threads.remove(thread)
            return result

        return ''

Last thing we need to do is to update the client to use the new methods. We’ll call slow as we did before, but this time we’ll store the intermediate result as the thread identifier. Next we’ll use a while loop to spin forever until the result is ready.

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# ...

if args.slow:
    import time
    thread_id = random_data.slow(int(args.bits))
    while True:
        result = random_data.slow_result(thread_id)
        if result:
            print("Your random number is: %s" % result)
            break
        time.sleep(1)

# ...

Note that this is not the smartest way to do this; more on that in the next post. Let’s give it a try!

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$ ./client 4
Your random number is: 7
$ ./client 4 --slow
Your random number is: 12
$ ./client 16
Your random number is: 5192
$ ./client 16 --slow
27302

Next time

This polling method works as a naive approach, but we can do better. Next time we’ll look into using D-Bus signals to make our client more asynchronous and remove our current polling implementation.

As a reminder, the end result of our code in this post is MIT Licensed and can be found on Github: https://github.com/larryprice/python-dbus-blog-series/tree/part2.

Creating a D-Bus Service With Python

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I’ve been working on a d-bus service to replace some of the management guts of my project for a while now. We started out creating a simple service, but some of our management processes take a long time to run, causing a timeout error when calling these methods. I needed a way to run these tasks in the background and report status to any possible clients. I’d like to outline my approach to making this possible. This will be a multi-part blog series starting from the bottom: a very simple, synchronous d-bus service. By the end of this series, we’ll have a small codebase with asynchronous tasks which can be interacted with (input/output) from D-Bus clients.

All of this code is written with python3.5 on Ubuntu 17.04 (beta), is MIT licensed, and can be found on Github: https://github.com/larryprice/python-dbus-blog-series/tree/part1.

What is D-Bus?

From Wikipedia:

In computing, D-Bus or DBus (for “Desktop Bus”), a software bus, is an inter-process communication (IPC) and remote procedure call (RPC) mechanism that allows communication between multiple computer programs (that is, processes) concurrently running on the same machine.

D-Bus allows different processes to communicate indirectly through a known interface. The bus can be system-wide or user-specific (session-based). A D-Bus service will post a list of available objects with available methods which D-Bus clients can consume. It’s at the heart of much Linux desktop software, allowing processes to communicate with one another without forcing direct dependencies.

A synchronous service

Let’s start by building a base of a simple, synchronous service. We’re going to initialize a loop as a context to run our service within, claim a unique name for our service on the session bus, and then start the loop.

service
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#!/usr/bin/env python3

import dbus, dbus.service, dbus.exceptions
import sys

from dbus.mainloop.glib import DBusGMainLoop
from gi.repository import GLib

# Initialize a main loop
DBusGMainLoop(set_as_default=True)
loop = GLib.MainLoop()

# Declare a name where our service can be reached
try:
    bus_name = dbus.service.BusName("com.larry-price.test",
                                    bus=dbus.SessionBus(),
                                    do_not_queue=True)
except dbus.exceptions.NameExistsException:
    print("service is already running")
    sys.exit(1)

# Run the loop
try:
    loop.run()
except KeyboardInterrupt:
    print("keyboard interrupt received")
except Exception as e:
    print("Unexpected exception occurred: '{}'".format(str(e)))
finally:
    loop.quit()

Make this binary executable (chmod +x service) and run it. Your service should run indefinitely and do… nothing. Although we’ve already written a lot of code, we haven’t added any objects or methods which can be accessed on our service. Let’s fix that.

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import dbus.service
import random

class RandomData(dbus.service.Object):
    def __init__(self, bus_name):
        super().__init__(bus_name, "/com/larry_price/test/RandomData")
        random.seed()

    @dbus.service.method("com.larry_price.test.RandomData",
                         in_signature='i', out_signature='s')
    def quick(self, bits=8):
        return str(random.getrandbits(bits))

We’ve defined a D-Bus object RandomData which can be accessed using the path /com/larry_price/test/RandomData. This style of string is the general style of an object path. We’ve defined an interface implemented by RandomData called com.larry_price.test.RandomData with a single method quick as declared with the @dbus.service.method context decorator. quick will take in a single parameter, bits, which must be an integer as designated by the in_signature in our context decorator. quick will return a string as specified by the out_signature parameter. All that quick does is return a random string given a number of bits. It’s simple and it’s fast.

Now that we have an object, we need to declare an instance of that object in our service to attach it properly. Let’s assume that random_data.py is in a directory dbustest with an empty __init__.py, and our service binary is still sitting in the root directory. Just before we start the loop in the service binary, we can add the following code:

service
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# ...
# Run the loop
try:
    # Create our initial objects
    from dbustest.random_data import RandomData
    RandomData(bus_name)

    loop.run()
# ...

We don’t need to do anything with the object we’ve initialized; creating it is enough to attach it to our D-Bus service and prevent it from being garbage collected until the service exits. We pass in bus_name so that RandomData will connect to the right bus name.

A synchronous client

Now that you have an object with an available method on our service, you’re probably interested in calling that method. You can do this on the command line with something like dbus-send, or you could find the service using a GUI tool such as d-feet and call the method directly. But eventually we’ll want to do this with a custom program, so let’s build a very small program to get started.

client
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#!/usr/bin/env python3

# Take in a single optional integral argument
import sys
bits = 16
if len(sys.argv) == 2:
    try:
        bits = int(sys.argv[1])
    except ValueError:
        print("input argument must be integer")
        sys.exit(1)

# Create a reference to the RandomData object on the  session bus
import dbus, dbus.exceptions
try:
    bus = dbus.SessionBus()
    random_data = bus.get_object("com.larry-price.test", "/com/larry_price/test/RandomData")
except dbus.exceptions.DBusException as e:
    print("Failed to initialize D-Bus object: '%s'" % str(e))
    sys.exit(2)

# Call the quick method with the given number of bits
print("Your random number is: %s" % random_data.quick(bits))

A large chunk of this code is parsing an input argument as an integer. By default, client will request a 16-bit random number unless it gets a number as input from the command line. Next we spin up a reference to the session bus and attempt to find our RandomData object on the bus using our known service name and object path. Once that’s initialized, we can directly call the quick method over the bus with the specified number of bits and print the result.

Make this binary executable also. If you try to run client without running service, you should see an error message explaining that the com.larry-price.test D-Bus service is not running (which would be true). Start service, and then run client with a few different input options and observe the results:

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$ ./service & # to kill service later, be sure to note the pid here!
$ ./client
Your random number is: 41744
$ ./client 100
Your random number is: 401996322348922753881103222071
$ ./client 4
Your random number is: 14
$ ./client "new donk city"
input argument must be integer

That’s all there is to it. A simple, synchronous server and client. The server and client do not directly depend on each other but are able to communicate unidirectionally through simple method calls.

Next time

Next time, I’ll go into detail on how we can create an asynchronous service and client, and hopefully utilize signals to add a new direction to our communication.

Again, all the code can be found on Github: https://github.com/larryprice/python-dbus-blog-series/tree/part1.

Snappy Libertine

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Libertine is software suite for runnin X11 apps in non-X11 environments and installing deb-based applications on a system without dpkg. Snappy is a package management system to confine applications from one another. Wouldn’t it be cool to run libertine as a snap?

Yes. Yes it would.

snapd

The first thing to install is snapd itself. You can find installation instructions for many Linux distros at snapcraft.io, but here’s the simple command if you’re on a debian-based operating system:

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$ sudo apt install snapd

Ubuntu users may be surprised to find that snapd is already installed on their systems. snapd is the daemon for handling all things snappy: installing, removing, handling interface connections, etc.

lxd

We use lxd as our container backend for libertine in the snap. lxd is essentially a layer on top of lxc to give a better user experience. Fortunately for us, lxd has a snap all ready to go. Unfortunately, the snap version of lxd is incompatible with the deb-based version, so you’ll need to completely remove that before continuing. Skip this step if you never installed lxd:

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$ sudo apt remove --purge lxd lxd-client
$ sudo zpool destroy lxd                 # if you use zfs
$ sudo ip link set lxdbr0 down           # take down the bridge (lxdbr0 is the default)
$ sudo brctl delbr lxdbr0                # delete the bridge

For installing, in-depth instructions can be found in this blog post by one of the lxd devs. In short, we’re going to create a new group called lxd, add ourselves to it, and then add our own user ID and group ID to map to root within the container.

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$ sudo groupadd --system lxd                      # Create the group on your system
$ sudo usermod -G lxd -a $USER                    # Add the current user
$ newgrp lxd                                      # update current session with new group
$ echo root:`id --user ${USER}`:1 >> /etc/subuid  # Setup subuid to map correctly
$ echo root:`id --group ${USER}`:1 >> /etc/subgid # Setup subgid to map correctly
$ sudo snap install lxd                           # actually install the snap!

We also need to initialize lxd manually. For me, the defaults all work great. The important pieces here are setting up a new network bridge and a new filestore for lxd to use. You can optionally use zfs if you have it installed (zfsutils-linux should do it on Ubuntu). Generally, I just hit “return” as fast as the questions show up and everything turns out alright. If anything goes wrong, you may need to manually delete zpools, network bridges, or reinstall the lxd snap. No warranties here.

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$ sudo lxd init
Do you want to configure a new storage pool (yes/no) [default=yes]?
Name of the new storage pool [default=default]:
Name of the storage backend to use (dir or zfs) [default=zfs]:
Create a new ZFS pool (yes/no) [default=yes]?
Would you like to use an existing block device (yes/no) [default=no]?
Would you like LXD to be available over the network (yes/no) [default=no]?
Would you like stale cached images to be updated automatically (yes/no) [default=yes]?
Would you like to create a new network bridge (yes/no) [default=yes]?
What should the new bridge be called [default=lxdbr0]?
What IPv4 address should be used (CIDR subnet notation, “auto” or “none”) [default=auto]?

You should now be able to run lxd.lxc list without errors. It may warn you about running lxd init, but don’t worry about that if your initialization succeeded.

libertine

Now we’re onto the easy part. libertine is only available from edge channels in the app store, but we’re fairly close to having a version that we could push into more stable channels. For the latest and greatest libertine:

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$ sudo snap install --edge libertine
$ sudo snap connect libertine:libertined-client libertine:libertined

If we want libertine to work fully, we need to jump through a couple of hoops. For starters, dbus-activation is not fully functional at this time for snaps. Lucky for us, we can fake this by either running the d-bus service manually (/snap/bin/libertined), or by adding this file to /usr/share/dbus-1/services/com.canonical.libertine.Service.service

/usr/share/dbus-1/services/com.canonical.libertine.Service.service
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[D-BUS Service]
Name=com.canonical.libertine.Service
Exec=/snap/bin/libertine.libertined --cache-output

Personally, I always create the file, which will allow libertined to start automatically on the session bus whenever a user calls it. Hopefully d-bus activation will be fixed sooner rather than later, but this works fine for now.

Another issue is that existing deb-based libertine binaries may conflict with the snap binaries. We can fix this by adjusting PATH in our .bashrc file:

$HOME/.bashrc
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# ...
export PATH=/snap/bin:$PATH

This will give higher priority to snap binaries (which should be the default, IMO). One more thing to fix before running full-force is to add an environment variable to /etc/environment such that the correct libertine binary is picked up in Unity 8:

/etc/environment
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# ...
UBUNTU_APP_LAUNCH_LIBERTINE_LAUNCH=/snap/bin/libertine-launch

OK! Now we’re finally ready to start creating containers and installing packages:

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$ libertine-container-manager create -i my-container
# ... (this could take a few minutes)
$ libertine-container-manager install-package -i my-container -p xterm
# ... (and any other packages you may want)

If you want to launch your apps in Unity 7 (why not?):

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$ libertine-launch -i my-container xterm
# ... (lots of ourput, hopefully an open window!)

When running Unity 8, your apps should show up in the app drawer with all the other applications. This will all depend on libertined running, so make sure that it runs at startup!

I’ve been making a lot of improvements on the snap lately, especially as the ecosystem continues to mature. One day we plan for a much smoother experience, but this current setup will let us work out some of the kinks and find issues. If you want to switch back the deb-based libertine, you can just install it through apt and remove the change to /etc/environment.