• kubernetes services: externalName

  2 min read

  
  

  One of kind of Service objects on kubernetes is extenalName. It creates a CNAME DNS entry to point to an external DNS service. For exemple:

  kind: Service
  apiVersion: v1
  metadata:
    name: ensvc
  spec:
    type: ExternalName
    externalName: pet2cattle.com
  

  29/01/2021

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• Getting a terraform plan in json format

  2 min read

  
  

  Starting terraform v0.12 we can get the terraform plan in json format. To do so, first we will need to save the plan to a file:

  $ terraform plan -out demo.plan
  

  28/01/2021

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• How to conditionally include a resource in terraform

  1 min read

  
  

  On terraform modules sometimes it make sense to completely get rid of some resources using some condition. Since we don't have an if statement, we can use count instead

  27/01/2021

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• Ansible: Test a task by applying it locally

  2 min read

  If you need to test a set of ansible tasks without having to go into much trouble, you can use ansible-playbook to do a quick local test. To do so you just need ansible installed and create a yaml file with the playbook to execute using the following format:

  ---
  - hosts: 127.0.0.1
    tasks:
    - name: mkdir /tmp/test
      command: 
        cmd: mkdir -p /tmp/test
  

  26/01/2021

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• kubectl: set a given namespace as your default

  2 min read

  
  

  When you need to work on some specific namespace it is quite annoying yo have to specify at each kubectl command the same namespace over and over again. It's much easier to change the current context to use another namespace by default.

  25/01/2021

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• mkdit: Yet another cure for your mistyping

  3 min read

  
  

  It is quite anoying when you keep typing mkdit instead of mkdir for creating a directory just as it is to type sl instead of ls. At least, for sl there's an actual Debian package that, the Steam Locomotive. Having this in mind I created another tool called mkdir:

  https://github.com/jordiprats/bash-mkdit

  Using this as an example we will configure a github action to build .deb and .rpm packages for this tool.

  22/01/2021

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• How to trigger a Kubernetes cronjob

  2 min read

  
  

  If you deploy a Cronjob on Kubernetes it can be useful to test it out by manually triggering a run rather than to wait until it is run according by it's schedule.

  Let's assume we have the following Cronjob that we want to run:

  $ kubectl get cronjob
  NAME                    SCHEDULE    SUSPEND   ACTIVE   LAST SCHEDULE   AGE
  pet2cattle-sitemapgen   0 5 * * *   False     0        <none>          13m
  

  21/01/2021

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• Create a cronjob on a kubernetes cluster

  3 min read

  
  

  The cronjob object haven't been GA until Kubernetes v1.21, even though the Job object have been GA for a long time. Let's take a look how it works:

  $ kubectl create job demo --image nginx --dry-run=client -o yaml  | head -n1
  apiVersion: batch/v1
  $ kubectl create cronjob demo --image nginx --schedule="*/1 * * * *" -o yaml --dry-run=client | head -n1
  apiVersion: batch/v1beta1
  

  20/01/2021

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• Creating a kubernetes cluster with multiple nodes using minkube

  6 min read

  
  

  Minikube is very useful for creating mockup environments for testing purposes, but it can be also use for studying yout CKA certification. Some topics, like node affinity or node failure will require you to have a multinode cluster but you can still use minikube

  19/01/2021

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• Rollback an upgrade using helm

  3 min read

  
  

  When we upgrade an application using helm it can always go something wrong so instead of upgrading to another version or uninstall / install the application, we can rollback to a previous version that we know it is working

  Previously we already talked about the helm history command

  $ helm history pet2cattle
  REVISION  UPDATED                   STATUS      CHART           APP VERSION DESCRIPTION     
  60        Wed Dec 30 16:17:58 2020  superseded  pet2cattle-1.7  2.8         Upgrade complete
  61        Fri Jan  1 21:45:07 2021  superseded  pet2cattle-2    3           Upgrade complete
  62        Sat Jan  2 11:57:26 2021  superseded  pet2cattle-2    3.1         Upgrade complete
  63        Sat Jan  2 22:09:24 2021  superseded  pet2cattle-2    3.2         Upgrade complete
  64        Mon Jan  4 09:33:53 2021  superseded  pet2cattle-2    3.3         Upgrade complete
  65        Tue Jan  5 07:57:53 2021  superseded  pet2cattle-2    3.4         Upgrade complete
  66        Wed Jan  6 15:25:30 2021  superseded  pet2cattle-2    3.5         Upgrade complete
  67        Thu Jan  7 09:10:07 2021  superseded  pet2cattle-2    3.6         Upgrade complete
  68        Fri Jan  8 08:17:56 2021  superseded  pet2cattle-2    3.7         Upgrade complete
  69        Sat Jan  9 19:23:25 2021  deployed    pet2cattle-2    3.8         Upgrade complete
  

  Let's assume that the latest deployed versions is not working.

  18/01/2021

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