juniorz

kubectl logs has quirks due to log-rotation

kubectl logs does not take into account container log rotation (kubelet config containerLogMaxSize and containerLogMaxFiles). You can still find the latest rotated logs in /var/log/pods/<namespace>_<pod-name>_<pod-uid>/ though.

Don’t assume --since=0s will have all logs since the container started because it won't look into previous log files. Don't assume a long-running --follow will always give you latest logs, because it will not switch over to the new log after current is rotated.

See: kubernetes/kubernetes#59902

KUBECONFIG is not portable

juniorz

1.16

• Deprecation of kubernetes.io/role label.

  • Action: Replace with role.node.kubernetes.io/role.
  • Consequence: kubectl get node won't show the ROLE column. See: kubernetes/kubernetes#84912 (comment)

• Deprecation of API versions.

  • Action: Use https://github.com/rikatz/kubepug to find problematic API versions in your cluster.
  • Action: Change all manifests to the new API version.

• Action: Make sure helm charts release state also have the manifests with the new API version.

juniorz

Software development hard truths

• Continuous Integration is a software development discipline, not your orchestrator tool.
• Branch-by-abstraction and trunk-based development is the right superior answer for adopting CI (https://twitter.com/jezhumble/status/1220036153488756736)
• Feature branches and PR features goes against the grain with adopting CI.
• Pair programming is hard and works (https://martinfowler.com/articles/on-pair-programming.html).
• "Success creates its own truth" (https://longreads.com/2020/08/20/how-to-learn-everything-the-masterclass-diaries/). Be wary of the gospel preached on a famous/pupular/successful person/company's blog post. Can their life lessons be applied to your (or someone else's) reality?

juniorz

Termos

• the one stop shop for: Posto Ipiranga
• ballpark figure: chute
• inside baseball: panelinha

Pronuncia

• silent: https://www.merriam-webster.com/video/why-is-there-a-c-in-indict
• affect / effect

juniorz

computer programs are the tangible output of a thought process - the conversion of a thought process into a product.

Edward H. Bersoff, "Elements of Software Configuration Management"

software testing alone does not produce or ensure good software -- it only gives an indication of error frequency that can be expected and [...] verification only shows correspondence to functional requirements.

Joseph P. Cavano and James A. McCall, "A Framework for the Measurement of Software Quality"

juniorz

• Dead Space development struggling to integrate changes from multiple teams/experts: https://youtu.be/BQ3iqq49Ew8?t=655
• Desktop apps: once in a while you kill a process eating all you RAM. Web apps: once in a while you kill the Google Chrome GPU task eating all your RAM after you open a GIF.
• Today's browser wars: migrating a customer's 100s open tab from Chrome to Firefox/Edge/Opera/Safari.
• Why it is important to make experimention cheap.
  • If it is hard to experiment (time and space) and it requires coordination and help, people willl be reluctant to throw bad experiments away.
  • https://youtu.be/WFu1utKAZ18?t=916
  • https://youtu.be/WFu1utKAZ18?t=1778
• The origin of Control Plane vs Data Plane and how the concept influenced UNIX design

juniorz

"Those that know, do. Those that understand, teach."

Aristoteles (supposedly)

Scope: Building and running web-scale distributed cloud systems with container technologies :P

Learning goals

• Establish the challenges for engineering cloud-native systems (the problem space).
• Establish the approaches to address those challenges (the solution space).

juniorz

(not always bizarre, sometimes just backfiring daily design)

Kubernetes

• HorizontalPodAutoscaler takes into account Terminating pods when calculating the metrics. The consequence is if a pod has a bug on its termination procedure, terminating pods as part of a scale down triggers a scale up.
  • It once did the same for Pending pods.
• Can't omit clusterIP if you ever set it (even if to "") https://gitlab.com/gitlab-org/charts/gitlab/issues/1710#note_262760589
• How do you force HTTPS redirection on Ambassador: you use a nginx sidecar
• How do you force static HTTP responses (401, for example) on Ambassador: you use a nginx sidecar

juniorz

Tecnology and Society

• http://appropriatingtechnology.org/?q=node/296

Kubernetes autoscaling

• kubernetes/kubernetes#1629
• https://github.com/kubernetes/community/blob/master/contributors/design-proposals/autoscaling/horizontal-pod-autoscaler.md
• https://github.com/kubernetes/community/blob/master/contributors/design-proposals/autoscaling/vertical-pod-autoscaler.md
• Scale to/from zero

juniorz

1. Install Envoy (and Istio proxy) dependencies
   1. https://github.com/envoyproxy/envoy/blob/master/bazel/README.md
   2. https://github.com/istio/proxy/blob/3781be0e624470a4ee613c4ffc9816976f5dd701/.circleci/config.yml#L95
      1. Install XCode
      2. sudo xcode-select -s /Applications/Xcode.app/Contents/Developer; sudo xcodebuild -license; bazel clean --expunge; See: bazelbuild/bazel#6056 (comment)
   3. https://www.envoyproxy.io/docs/envoy/latest/install/building#requirements
2. Configure the dev environment
   1. https://github.com/istio/istio/wiki/Preparing-for-Development#setting-up-environment-variables
3. https://medium.com/@nadundesilva/building-istio-from-source-on-linux-be860d660aa7