Today I Learned

1. About clustering VMs in Hypervisor
2. A trick for using ssh keys with a personal and corporate GitHub account
3. To properly cycle

Hypervisor

So, in my spare time, I have a task for our Raleigh lab to cluster our DHCP server, which runs on a VM, so that if it goes down we have an easy backup already running. This was new technology to me, but a familiar concept (redundancy). The first step was the “R” in “R&D”: research.

So I spent today putting together a document on the basics of accomplishing the above, what questions I still had, and what challenges we might face. Unfortunately, I can’t share it with you.

So have IBM’s.

Keys and Locks

I’m really sorry about the emoji. I seem to be on a thing today. We’ll break up tomorrow.

Anyhoo, as I was saying, GitHub. ssh. Right, so I have this whole Dotfiles repository on GitHub. And it actually was really easy to set up the second time on my new Ubuntu machine. Only, (1) I configured git to use my Nuage name & email for git commits, leading to (2) I edited my Dotfiles internal .git/config to have my personal information, and (3) had to put in my GitHub password every time I pushed!

I suffered that for a whole day longer than I thought I would (Friday). Today, I had had enough.

As it turns out, ~/.ssh/config is your friend here. This is especially true in my case, where our corporate credentials are for a server Enterprise GitHub, so the hostname is completely different. But you can use the same trick for multiple regular accounts. Comments follow.

# change this if you want to use 'me.github.com' for a personal account in
# your `git clone` urls
# e.g., git clone git@me.github.com:benknoble/Dotfiles
Host github.com
  # HostName github.com
  # Uncomment the above line if the Host and HostName aren't the same
  # Think of Host as 'command line shortcut' and HostName as 'real URL'
  IdentityFile ~/.ssh/path/to/personal/public/key

# change this if you want to use 'corp.github.com' for an enterprise or
# secondary account in your `git clone` urls
# e.g., git clone git@corp.github.com:benknoble/Dotfiles
Host github.corp.domain.com
  # HostName github.fullurl.com
  # Uncomment the above line if the Host != HostName for corp
  IdentityFile ~/.ssh/path/to/enterprise/public/key

This assumes you have created and registered separate public keys with the appropriate accounts using ssh-keygen and GitHub settings.

You’ll note some of the comments about Host and HostName–this is why it’s easiest if one is a full on Enterprise GitHub. I can just use Host and my clone urls over ssh will work. If you needed multiple github.com profiles, you would have to set HostName to github.com in each one.

One final word on keys: you’ll need to update any remotes on current projects to use ssh urls.

Round and Round Again

I planned to do a whole thing here, but I’ve moved it to the feature. Expect it on Friday (or early, if I’m feeling generous).

Categories: Blog