• kubernetes: Pods can be composed of multiple containers

  2 min read

  
  

  One common misunderstanding with kubernetes is mistakenly assume "a pod" really means "a container".

  A pod is the minimal unit we take into account in kubernetes but this does not mean that a pod is a container: A pod can be composed of several containers working together. We can easily see this on the READY column that are going to tell us for a given pod from how many containers it is composed:

  $ kubectl  get pods
  NAME                                     READY   STATUS      RESTARTS   AGE
  ampa-7dcbfd689f-59ghw                    2/2     Running     0          5d1h
  

  12/03/2021

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• Using terraform_remote_state for getting data from another terraform state

  2 min read

  
  

  On terraform, besides returning some information to the user, returning data as output can be used as an input for terraform code that needs to use a resource created by another team.

  On the terraform code that creates the resource, we will have to set the variable and it's value:

  output endpoint {
      vpc_id = aws_vpc.databases.id
  }
  

  Then, on the code that uses this resource we will have to declare the tfstate as a data source using terraform_remote_state

  11/03/2021

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• The selector option can help us to select a subset of pods with kubectl

  2 min read

  
  

  On most kubectl command we will find the selector option for filtering pods based on it's labels. To use we just need to set the filter using the key=value format:

  $ kubectl get pods -l "app=spin"
  NAME                               READY   STATUS    RESTARTS   AGE
  spin-clouddriver-9899c9b54-nbjp6   1/1     Running   0          29h
  spin-deck-56ff48c587-lc75g         1/1     Running   0          29h
  spin-echo-7ccf545b48-b5n9l         1/1     Running   0          29h
  spin-front50-59bff89745-2f65h      1/1     Running   0          29h
  spin-gate-644c968b68-2q8nj         1/1     Running   0          29h
  spin-igor-6669794575-2cnb4         1/1     Running   0          29h
  spin-orca-795789b678-nqrk7         1/1     Running   0          29h
  spin-rosco-6c9879b69f-gdrfl        1/1     Running   0          29h
  

  10/03/2021

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• Enabling debug information on terraform using TF_LOG

  2 min read

  
  

  Sometimes with terraform you might end up with some meaningless error that does not provide any clue what's going on. So instead or just trying to guess that have changed; we can enable some traces in terraform to try to make sense what's going on

  Error: AccessDenied: Access Denied
    status code: 403, request id: 8FCD12996B11F5F8, host id: xMF1Gs+VIEpxpk+1Og6UtchyT10K+mRWFe2IUZ8gqG13KbsRm0L8nRw8udzkqEVJagg8+RMpY3M=
  

  09/03/2021

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• terraform: Refresh null_resource when a variable changes

  2 min read

  
  

  When using local-exec with the null_resource we might need to be able to update the resources that gets created like this. Let's assume we have the following terraform code to apply Kustomize to a kubernetes cluster:

  resource "null_resource" "metrics-server" {
    provisioner "local-exec" {
      command = "kubectl apply -k 'https://github.com/jordiprats/django-ampa/deploy-${var.version}/'"
    }
  }
  

  Given this setup even though the var.version changed, the resource won't be updated if it was already applied

  08/03/2021

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