Have you ever wondered how your browser resolves a domain name when you hit Enter on a URL? Here’s how it works, at a high level.

1. Your browser first looks in its own cache for the address. If it doesn’t find it, it checks the OS cache, and finally the ISP’s cache.

2. If the name isn’t cached, the next step is the /etc/hosts file. If there’s an IP address there, the browser tries to load the page from that server.

Amazon’s Leadership Principles are used in everything from hiring to design reviews, and they’ve become hugely influential well beyond Amazon itself.

Watch a walkthrough of the principles on YouTube →

The fourteen principles:

1. Customer Obsession
2. Ownership
3. Invent and Simplify
4. Are Right, A Lot
5. Learn and Be Curious
6. Hire and Develop the Best
7. Insist on the Highest Standards
8. Think Big
9. Bias for Action
10. Frugality
11. Earn Trust
12. Dive Deep
13. Have Backbone; Disagree and Commit
14. Deliver Results

(Amazon has since added two more - “Strive to be Earth’s Best Employer” and “Success and Scale Bring Broad Responsibility” - bringing the total to sixteen.)

Arnold Schwarzenegger gave this commencement speech at the University of Southern California, and the six rules he lays out have stuck with me. They’re simple, but they apply just as much to a career in engineering as to anything else.

Watch Arnold’s full USC commencement speech on YouTube →

His six rules:

1. Trust yourself. Work out who you really are and what you want, rather than what others expect of you.
2. Break the rules. Not the laws - the conventions. You rarely do anything remarkable by following the well-worn path.
3. Don’t be afraid to fail. You can’t win without being willing to lose. Failure is the cost of trying anything worthwhile.
4. Don’t listen to the naysayers. “It can’t be done” usually means “I couldn’t do it.”
5. Work your butt off. There is no substitute for the hours. Talent without effort gets overtaken.
6. Give back. Reaching the top means nothing if you don’t reach back and help others up.

What I take from it for our work: most of the interesting problems in cloud and reliability engineering come from being willing to question how things are “normally” done, putting in the unglamorous hours to get the details right, and then sharing what you learn. That’s a big part of why this blog exists.

By default, the JVM’s maximum heap size is 1/4 of the physical memory available - you can read about this in the Oracle GC tuning guide. This means that if you don’t define -Xmx in your JVM parameters, the container will set 1/4 of the host memory as the maximum heap size.

On a recent enough JVM (8u191+ and 10+), the JVM is container-aware: if you set a Kubernetes resource limit, the JVM uses that limit rather than the host’s memory to size the heap. So your maximum heap size becomes 1/4 of your Kubernetes resource limit.

A Service Account provides an identity for processes that run in a pod. When processes inside a pod contact the API server, they are authenticated as a particular Service Account.

Create a Service Account using the YAML below.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: sa-app-name
  namespace: namespace-name

Once the Service Account is created, you can reference it in your pod spec:

apiVersion: v1
kind: Pod
metadata:
  name: app-name
spec:
  serviceAccountName: sa-app-name

Now on to Kubernetes Secrets. A Secret lets you store and manage sensitive information. Here we’ll create two secrets for our tests: mysecret1 and mysecret2. Note the --- separator - without it, the second document silently overwrites the first.

Bill Gates is famously a voracious reader, getting through dozens of books a year and publishing detailed recommendations on his blog, GatesNotes.

Watch a roundup of fifteen of his picks on YouTube →

What I like about his lists is how little of it is about technology. Gates reads widely - history, public health, psychology, science, biography - and that breadth clearly feeds into how he thinks about hard problems.