Recently, my workflow with Bazaar has adapted to use bzr-pipeline, because much of the work I'm doing is based upon prerequisite branches. This means I find myself doing a lot of switching between pipes, sending pipes to Launchpad for review, etc. I have added the following aliases to ~/.bazaar/bazaar.conf in order to make my life easier.

next = switch-pipe :next
prev = switch-pipe :prev
send-pipe = send -r branch::prev..
diff-pipe = diff -r branch::prev
pipes = show-pipeline

Also, if you haven't used bzr-pipeline yet, try it out next time you're trying to break your work up into many smaller branches.

So while I've spent my fair share of time hacking with Bazaar, I'm ashamed to say I hadn't done a lot of hacking on Bazaar. I've fixed small issues in Bazaar plugins, and even written a few of my own (although Jono Lange actually released his implementation before I could get mine done). However, during Christmastime, I had the opportunity to hack on some Bazaar plugins that I will be releasing shortly. In this process, I learned a bunch about the bzrlib API, and its great ease of use. I thought I'd compile a bit of what I've found into a blog post or two.

I'd like to start the examples off with some relatively easy exercises. In order to do some of these examples, it's best to have a local bzr branch of any kind. I'll start by demonstrating how to do some of the tasks you do from the command line (or GUI of your choice) programmatically.

from bzrlib.branch import Branch

my_branch = Branch.open('/path/to/branch')

my_branch_config = my_branch.get_config()
print my_branch_config.username()

from bzrlib.branch import Branch

remote_branch_url = 'bzr+ssh://bzr.eventuallyanyway.com/code/foo-bar-baz'

remote_branch = Branch.open(remote_branch_url)
local_branch = remote_branch.bzrdir.sprout(
    '/code/foo-bar-baz').open_branch()

from bzrlib.workingtree import WorkingTree

tree = WorkingTree.open('/code/foo-bar-baz')

delta = tree.changes_from(tree.basis_tree())
if delta.has_changes:
    tree.commit('Committed changes')

I do a lot of code review in Launchpad, use a lot of the code features, and have worked out some pretty good methods of making this simple and easy to work with. I thought, in lieu of my last post, and the ones I'm planning for the near future, it'd be good to detail some of the things that I do to make my workflow.

Launchpad's web UI is slow. I'll admit it. We're working on doing some really great things to speed it up, but frankly, all web applications are. You've got to load pages, parse javascript, etc. In fact, most things you shouldn't even have to wait around for. They are things that should require minimal attention for much of the time, and often things that are "fire and forget."

So let's build off the config settings I've already blogged about. If you haven't read that article yet, I highly suggest you go back and read it, or you're gonna get really confused really quick.

[/home/rockstar/Projects/repos]
push_location = lp:~rockstar/
push_location:policy = appendpath
public_branch = lp:~rockstar/
public_branch:policy = appendpath
submit_to = merge@code.launchpad.net

# Entertainer
[/home/rockstar/Projects/repos/entertainer]
submit_branch = lp:entertainer

mail_client = evolution

vote needs_fixing

vote approve
status approved

Many of Bazaar's dirty little secrets are hidden away in options you can set in ~/.bazaar/bazaar.conf and ~/.bazaar/locations.conf. Here are some fun things to configure to streamline your hacking with Launchpad and with other projects.

First, some background. I have a rather detailed and involved setup and workflow (which I'll detail later), so I'm going to do my best to make this as simple as possible. For the sake of this example, I'm going to lay out my folders this way:

~/
~/Projects
~/Projects/bzr
~/Projects/bzr/bzr.dev
~/Projects/bzr/foo
~/Projects/bzr/bar
~/Projects/bzr/baz
~/Projects/entertainer
~/Projects/entertainer/entertainer
~/Projects/+junk
~/Projects/private
~/Projects/private/ironlion

So I have put all my branches into a ~/Projects directory, inside a dir each for various projects I work on that are hosted on Launchpad(bzr and Entertainer for the sake of this example). I also have two other folders, one called +junk (for junk branches), a folder called private which, as you may have guessed, will be for things I don't push to Launchpad (like, say, for instance, the source for this blog, which contains db passwords all sorts of fun info... :)

To start out, let's look at my ~/.bazaar/bazaar.conf:

[DEFAULT]
email = Paul Hummer <paul@myemaildomain.com>
create_signatures = always
gpg_signing_command = /usr/bin/gpg
launchpad_username = rockstar

This where you put all the things about your general use of bzr. The email line will usually get set by doing bzr whoami which you should generally run the first time you run bzr, so that bzr knows your name and your email address. If you've ever seen your revisions on Launchpad saying something like rockstar <rockstar@megatron> it's probably because you haven't set your email config line, and so it's taking your user name and host name of the system you're working on (in this case, my system's name is megatron). I've also set my launchpad username. This is also important, and would get set when doing bzr launchpad-login rockstar Confused yet? If so, just skip down to the next block. create_signatures and gpg_signing_command are both to allow me to sign my revisions.

[ALIASES]
cbranch = cbranch --lightweight
ci = commit --strict
diff = diff --diff-options -p
diff-thread = cdiff -r thread:
ll = log --line -r-10..-1
lpsend = send --no-bundle
recentlog = log -r-20..-1 --short
sdiff = cdiff -r submit:
st = status --short
unpushed = missing --mine-only :push

These are my aliases. Think of them like shell aliases. The details you don't have to worry about too much, but when find yourself running the same commands over and over, add them to your aliases.

locations.conf is where all the fun happens. It's what tells bzr, based on the location of the branch, where to push, where to submit, etc. So let's start with a generic blanket statement that'll be used for all projects pushed to Launchpad. So let's start with:

[/home/rockstar/Projects]
push_location = lp:~rockstar/
push_location:policy = appendpath
public_branch = lp:~rockstar/
public_branch:policy = appendpath

The secret here is in the appendpath. Basically, bzr looks at the relationship of the current branch, say ~/Projects/entertainer/entertainer to this config section, and, using the appendpath policy, decides it needs to be pushed to lp:/~rockstar/entertainer/entertainer Hooray! Now, if I create a new branch at ~/Projects/entertainer/fix-bug-123465 and just call bzr push, bzr is smart enough to push it to lp:~rockstar/entertainer/fix-bug-123456 This even works with junk branches (branches that aren't attached to a project), provided you just put your branch in the +junk folder.

But wait! What if I don't want to push to Launchpad? I first ask "Why don't you? It's so great!" :) As locations.conf stands now, if you put something in your private area, Launchpad is going to tell you there is no project named private when yo utry to push. Well, let's fix that.

[/home/rockstar/Projects/private]
push_location = bzr+ssh://bzr.eventuallyanyway.com/code/
push_location:policy = appendpath
public_branch = bzr+ssh://bzr.eventuallyanyway.com/code/
public_branch:policy = appendpath

As you can see, I push my private branches to bzr.eventuallyanyway.com/code. It uses the same tricks as I showed before, so the same idea can be assumed.

It's important that I point out that there's no order required in how these config sections get put into locations.conf because bzr is smart enough to find the most specific config and use it.

This concludes this session of bzr-lp hackery. Comments welcome.