• Configure an AWS Load Balancer to target an Autoscaling Group using terraform

  3 min read

  
  

  It's quite convenient to be able to configure a AWS Load Balancer to target an Auto Scaling Group so we don't have to handle how instances are getting in and out of this load balancer. This can be done easily using terraform as follows

  04/05/2022

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• How to use aws s3 sync command

  2 min read

  Similarly on how we use the rsync command to copy content across the filesystem and even across servers, we can use aws s3 sync to not only sync files between the computer we are running it and an S3 bucket but also between S3 buckets

  03/05/2022

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• 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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