Pair Program! The Bruce Campbell Way

This is a small set of tools designed to provide a baseline environment for doing remote pair programming via SSH. The toolkit consists of:

• Wemux, a wrapper around tmux to simplify multi-user access
• A common baseline configuration for tmux and vim (none of us use emacs; PRs welcome)
• An install script to facilitate setup

While it can be cool to do remote screen-sharing, the sad fact is that pushing bitmaps across the wire takes a lot of bandwidth, and the user experience for the guest is... suboptimal. So, this project bundles up a reasonably usable set of terminal-based tools. Just think of it as retrocomputing and you'll be fine. :D

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NEW TO (REMOTE) PAIRING?

There's an excellent list of resources at pairprogramwith.me.

NEW TO TMUX?

You may find this 10-minute tmux Quick Start screencast helpful.

A QUICK NOTE ABOUT TMUX COMMANDS

When you're using tmux, it passes your keystrokes through to the programs it's managing for you. In order to send commands to tmux, you first have to get its attention by sending it the PREFIX key. By default, tmux uses Control-b as its PREFIX key, but the tmux.conf file included in this repository changes it to Control-\ (that's control-backslash).

This can be confusing to first-time users, so just to be clear, here's what you do:

1. Hold down the Control key.
2. Press the \ or backslash key.
3. Release the Control key.
4. Press the 'c' key. (This should create a new window.)

Most tmux references will use the notation C-\ for Control-backslash. This document borrows the notation (( PREFIX x )) to represent the sequence "PREFIX combo, followed by x" from Brian Hogan's book about tmux: http://pragprog.com/book/bhtmux/tmux

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HOWTO: Join a Session on Someone Else's Computer

Preflight Checklist:

• You're able to reach your host's computer over at least one Internets:
  • If using Hamachi, make sure it's running, and that you can see your host's machine on at least one of your networks.

Takeoff:

• Make sure your host has your SSH public key.
• Open a terminal window, make the font as small as you can tolerate, and make the window as big as you can tolerate (bonus points for using full-screen mode).
• Start an audio and/or video chat session (FaceTime, G+ Hangout, iChat, Skype) with your host.
• On your computer, run: ssh username@hosts_ip_address
• On your host's computer, run: wemux pair
  • Troubleshooting:
    • "No wemux server to pair with on 'wemux'": This indicates that the host has not yet run wemux start. Either you're very fast, or they forgot? :)
    • You can see the other session, but cannot type: You may have joined wemux in mirror mode instead of pair mode. Detach from the wemux session using (( PREFIX d )) (see the section on tmux commands if you're not sure what this means) and then type wemux pair.

In flight:

• Pair as usual. Air traffic control suggests using the "mine/yours" protocol to negotiate control of the keyboard.
  (Protip: either word can be inflected as a question or a statement.)

Landing:

• Use (( PREFIX d )) to Detach from tmux on your host's computer. (See the section on tmux commands if you're not sure what this means.)
• Type 'exit' to end the SSH session and return to your local computer.

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HOWTO: Host a Session on Your Computer

Preflight Checklist:

• You've completed basic setup (see Setting Up, below).
• You have SSH keys for all of your intended guests, and you've created accounts (see bin/create_all_pair_accounts) for them to use.
• In System Preferences, Sharing: "Remote Login" (aka SSH) is enabled, and your guest accounts are allowed to use it. (The easiest way to ensure this is to enable it for all users; if you're using a whitelist approach, you'll have to visit this screen every time you pair with someone new.)
• Your computer is reachable over at least one Internets:
  • If using Hamachi, make sure it's running, and that you've added your guest's machine to at least one of your networks.

Takeoff:

• Open a terminal window, make the font as small as you can tolerate, and make the window as big as you can tolerate (bonus points for using full-screen mode).
• Run: wemux start
• Start an audio and/or video chat session (FaceTime, G+ Hangout, iChat, Skype) with your guest(s). If necessary, give them the IP address they can SSH to.
• If your terminal dimensions are larger than those of your guest(s), you'll see a border appear on the right and/or bottom edge of your terminal window as soon as they run wemux pair.
• Within tmux's "status-interval" setting (5 seconds as of this writing), you'll see the tmux status bar update with the usernames of all users currently in the tmux session.

In flight:

• Pair as usual. Air traffic control suggests using the "mine/yours" protocol to negotiate control of the keyboard.
  (Protip: either word can be inflected as a question or a statement.)

Landing:

• If you're done with your tmux session, just exit all of the shells running inside it; it'll shut down once its last hosted process exits.
• If you'd like to leave your state hanging around for later, use (( PREFIX d )) to Detach. It'll stick around as long as your computer stays on.
  (To come back later, just run wemux start again; wemux will figure out that there's a session already running and reattach you to it.)

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Audio

Having a high-quality audio channel is critical to remote pairing. Strictly speaking, this is not something the ls-pair toolkit can set up for you, but here are some things to keep in mind:

• Background Noise: Shared offices are loud. Grab a private room if you can.

• External Speakers: Please don't use them unless you're certain that the sound won't feed back into your mic and bounce back to your partner. It's incredibly distracting.

• Microphone: The mics built in to your Apple laptop or external display are tolerable if you're in a quiet environment. In big open-plan offices, though, they're useless. Please use a microphone that's close to your mouth, designed for use in noisy environments, or both.

  • If you already have a Skype-friendly headset, dig it out of your drawer. These can usually be purchased for under $20 on Amazon or from many big-box retailers.

  • If you have a pair of iPhone earbuds, the mic works reasonably well. They can be a bit uncomfortable for extended wear -- YMMV.

• Bandwidth: Mics are the first step, but then your voice has to go through a series of tubes. Sometimes packets get dropped. There may not be much you can do about this in any given pairing session, but in the long term, try to avoid wifi networks with a lot of contention.

• Software: I've had decent results with both iChat and Skype. Both are significantly better than the "voice chat" option built into, for example, join.me.

If it's an option, you might try working from home on days when you know you'll spend a significant amount of time doing remote pairing -- you may have a quieter environment and a better Internet connection, and you'll feel more comfortable speaking up when you aren't worried about distracting your coworkers with one half of an ongoing conversation.

Video

If you have the hardware and bandwidth to support it, it can be surprisingly beneficial to have video while pairing. As social primates, our brains have dedicated significant resources to decoding body language. It can be helpful to run the A/V processing on a completely separate box so that your primary development machine is not slowed down. Also, having a dedicated screen for your partner's video feed makes it harder to cover them up with another window, which contributes to a telepresence effect.

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Setting Up

All Participants

VPN

LogMeIn's Hamachi is a reliable way of creating ad-hoc VPNs, but it's a bit annoying to admin. The set up process is described in this wiki page.

Hosts

The rest of this section applies only to hosts. Guests only need to SSH to their host's machine.

SSH

Please enable SSH on your machine. In Lion, go to System Preferences --> Sharing and click on "Remote Login". Make sure the box is checked, and under "Allow access for:", check "All users". (If you want to whitelist only certain users, you will need to revisit this preference pane each time you add an account for a new pair-partner.)

You must add your pair partner's SSH public key to the 'public_keys' subdirectory. The file should be named '{desired_username}.pub', where 'desired_username' is the username your pair partner will use to log in to your machine.

Creating Guest Accounts

You need to create a new account on your machine for each person with whom you wish to pair. First, make sure you know which username they will be using and verify that there is a matching public key in the 'public_keys' directory (see SSH above).

This repo includes a script, bin/create_pair_account, that will prompt you for a username, create the account on your system, and set up the account's '.ssh/authorized_keys' to include the key file in 'public_keys'. No need to worry about setting a password; OSX won't allow password-based login for this account.

There is also a bin/create_all_pair_accounts command that will provision a pair account for each SSH key in 'public_keys'.

Other Configuration

• Clone this repository and cd into its directory
• Run bin/install
• If you have an existing ~/.vimrc or ~/.vim directory, the install script will not overwrite it. See the "Standard Vim Configuration" section, below.

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Other Considerations

iTerm2

As of Lion, Mac OS X's Terminal.app finally supports 256-color terminal emulation. However, iTerm2 has a number of other niceties that you may prefer. I've included a copy of my preferences file, with a few different color schemes, in com.googlecode.iterm2.plist; feel free to copy this somewhere. (You can point iTerm2 at this file by going to Preferences, General, "Load preferences from a user-defined folder or URL". I suggest copying the file elsewhere so that any changes you make don't accidentally get pushed back up into this repository. I have mine in Dropbox.)

Text Editors

The use of SSH and tmux basically limits your choices to terminal-friendly editors. (Unless you have some crazy GUI editor with a sharing protocol you can tunnel across SSH -- in which case, I'd like to see it!)

This project is just about getting two (or more) developers to share access to the same environment. It is editor-agnostic; each pair can negotiate whatever editor(s) they're comfortable using. (Note: as long as you make sure to reload your buffers, it's quite feasible to have vim in one tmux window and emacs in another.)

Standard Vim Configuration

If you don't want to pull your hair out while fumbling through your pair's custom Vim bindings, you can toggle your Vim configuration with the provided set of configs:

bin/toggle_vim_config

This script creates a backup of your Vim config and symlinks the ls-pair vimrc and vim directory. To toggle back to your configuration, simply run the command again:

bin/toggle_vim_config

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License

The MIT License

Copyright (C) 2012 LivingSocial

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.