• Kubernetes: Configuring Topology Spread Constraints to tune Pod scheduling

  2 min read

  
  

  Ensuring high availability and fault tolerance in a Kubernetes cluster is a complex task: One important feature that allows us to addresses this challenge is Topology Spread Constraints.

  10/07/2023

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• OpenShift 3.11 - custom default route certificate failing with certificate has expired or is not yet valid

  2 min read

  
  

  After trying to set a custom default certificate for the OpenShift routes we might see how it's Pods starts crashing:

  $ kubectl get pods
  NAME                          READY   STATUS             RESTARTS   AGE
  router-10-rh8vf               1/1     Running            0          32m
  router-10-f2dt2               0/1     CrashLoopBackOff   6          7m
  router-10-m45b7               1/1     Running            0          31m
  

  Checking it's logs we'll get a quite misleading message:

  $ kubectl logs router-10-f2dt2 -n default
  Error from server: Get https://some.openshift.cluster:10250/containerLogs/default/router-10-f2dt2/router: x509: certificate has expired or is not yet valid
  

  04/07/2023

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• Using Abbreviated Commits in Git

  1 min read

  
  

  To pin some code to a specific version we can use a commit ID instead of a tag but using such a long string might feel a tad cumbersome:

  $ git log
  commit fb944d599d5487229463478928834cac20963f75 (HEAD -> main)
  Author: Eric <some@thing.com>
  Date:   Wed Jun 7 20:27:17 2023 +0100
  
      Fix exit with no error when cert violates lookahead (#2395)
  
  (...)
  

  22/06/2023

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• ExternalSecret: Partially load a secret

  2 min read

  
  

  Sometimes we might have a secret stored in the AWS Secrets Manager with multiple properties but we don't really need all the data stored in the secret. We can tell External Secrets Operator to use just a specific key instead of using the whole secret.

  13/06/2023

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• Add new line when printing data using jsonpath

  2 min read

  
  

  When we print values using jsonpath we'll get all the values in a single line (actually, it won't even bother adding the newline character at the end of the list):

  $ kubectl get ns -o jsonpath='{ .items[*].metadata.name }'
  default dynamodb-operator ec2-operator iam-operator kube-node-lease kube-public kube-system local-path-storage testvault
  

  06/06/2023

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