• Enable access logs for an AWS ALB using terraform

  2 min read

  To be able to collect access logs it might be just more convenient to be able to enable them at the load balancer level rather than having to aggregate logs from all the backend services. If we are using an AWS ALB we can configure it to push it's logs to an S3 bucket

  29/04/2022

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• Kubernetes: volume node affinity conflict

  4 min read

  While trying to deploy Pods we might notice the on the Events section that Pod cannot be scheduled due to a volume node affinity conflict:

  $ kubectl describe pod website-365-flask-ampa2-ha-member-1 -n website-365 
  Name:           website-365-flask-ampa2-ha-member-1
  Namespace:      website-365
  Priority:       0
  Node:           <none>
  Labels:         (...)
  Annotations:    (...)
  Status:         Pending
  IP:             
  IPs:            <none>
  Controlled By:  StatefulSet/website-365-flask-ampa2-ha-member
  Init Containers:
  (...)
  Containers:
  (...)
  Conditions:
    Type           Status
    PodScheduled   False 
  Volumes:
    volume:
      Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
      ClaimName:  volume-website-365-flask-ampa2-ha-member-1
      ReadOnly:   false
  (...)
  Events:
    Type     Reason             Age                      From                Message
    ----     ------             ----                     ----                -------
    Normal   NotTriggerScaleUp  31m (x20835 over 7d19h)  cluster-autoscaler  pod didn't trigger scale-up: 2 node(s) had taint {pti/role: system}, that the pod didn't tolerate, 1 node(s) had volume node affinity conflict
    Normal   NotTriggerScaleUp  95s (x46144 over 7d19h)  cluster-autoscaler  pod didn't trigger scale-up: 1 node(s) had volume node affinity conflict, 2 node(s) had taint {pti/role: system}, that the pod didn't tolerate
    Warning  FailedScheduling   64s (x2401 over 43h)     default-scheduler   0/4 nodes are available: 2 node(s) had taint {pti/role: system}, that the pod didn't tolerate, 2 node(s) had volume node affinity conflict.
  

  27/04/2022

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• terraform: How to calculate subnets using the cidrsubnet function

  3 min read

  If we are using terraform for creating subnets on AWS we are going to need to split the VPC's network range into several pieces, one for each AZ. We can let terraform handle all the details by using the cidrsubnet() function

  20/04/2022

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• terraform: Get the latest AMI id

  2 min read

  
  

  Hard coding values is never a good idea, using the aws_ami datasource we can query AWS to fetch the latest AMI available, or any AMI really, as long as we properly set the filters so than just one AMI is selected.

  06/04/2022

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• terraform: Update a Lambda function when the code changes

  2 min read

  
  

  If we are using the archive_file datasource to zip some Lambda function to be able to push it to AWS, we need to se the source_code_hash with it's hash to make sure the function gets updated when it changes:

  01/04/2022

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