Ask HN: How do you prevent downtime from dev machine problems?

So here I sit, with my computer in the shop for some (not-entirely-essential) repairs, and hoping I'll get my computer back in time to get a good workday in tomorrow. Which gets me to thinking about how to deal with situations like this in the future.

I could keep a second computer lying around, with separate SSH keys for login to all the relevant servers, but that feels a but risky in terms of security. Maybe better, I could keep one around with an identical hardware setup to my primary machine, so I can just swap out the hard drive when a non-storage device on one fails.

What are some other strategies? What's your preferred trade-off between convenience and security?