Script to get resources used and available in a K8s cluster

k8s_resources.sh

#!/bin/bash

# Variables to keep track of the total available CPU and memory
total_available_cpu=0
total_available_memory=0

for node in $(kubectl get nodes -o jsonpath='{.items[*].metadata.name}'); do
  echo "Node: $node"
  
  # Get the current usage
  current_usage=$(kubectl top node $node | tail -n 1 | awk '{print $2, $4}')
  current_cpu_usage=$(echo $current_usage | cut -d' ' -f1 | sed 's/m//') # remove 'm' from millicores
  current_memory_usage=$(echo $current_usage | cut -d' ' -f2 | sed 's/Mi//') # remove 'Mi' from mebibytes
  
  # Get the allocatable resources
  allocatable_resources=$(kubectl get node $node -o json | jq -r '.status.allocatable | "\(.cpu),\(.memory)"')
  allocatable_cpu=$(echo $allocatable_resources | cut -d',' -f1) # in cores or millicores
  allocatable_memory=$(echo $allocatable_resources | cut -d',' -f2 | sed 's/Ki//') # remove 'Ki' from kibibytes
  
  # Check if the allocatable CPU is in millicores or cores and convert to millicores if necessary
  if [[ $allocatable_cpu == *m ]]; then
    allocatable_cpu_millicores=$(echo "$allocatable_cpu" | sed 's/m//') # remove 'm' from millicores
  else
    allocatable_cpu_millicores=$(echo "$allocatable_cpu * 1000" | bc)
  fi
  
  # Get the allocated resources
  allocated_resources=$(kubectl describe node $node | grep -A 5 "Allocated resources:" | grep -E '(cpu|memory)' | awk '{print $2}')
  allocated_cpu=$(echo $allocated_resources | cut -d' ' -f1 | sed 's/[^0-9]*//g') # remove non-numeric characters
  allocated_memory=$(echo $allocated_resources | cut -d' ' -f2 | sed 's/[^0-9]*//g') # remove non-numeric characters
  
  # Calculate the available resources
  available_cpu=$(echo "$allocatable_cpu_millicores - $current_cpu_usage" | bc)
  available_memory=$(echo "$allocatable_memory - $current_memory_usage * 1024" | bc) # convert mebibytes to kibibytes
  
  # Update the total available CPU and memory
  total_available_cpu=$(echo "$total_available_cpu + $available_cpu" | bc)
  total_available_memory=$(echo "$total_available_memory + $available_memory" | bc)
  
  # Calculate the percentage of allocated resources vs allocatable resources
  cpu_percentage=$(echo "$allocated_cpu / $allocatable_cpu_millicores * 100" | bc -l)
  memory_percentage=$(echo "scale=2; ($allocated_memory * 1024 / $allocatable_memory) * 100" | bc -l)

  # Check if allocated resources are 80% or higher of the allocatable resources
  if (( $(echo "$cpu_percentage >= 80" | bc -l) )); then
    echo "WARNING: Node CPU workload requests reaching close to maximum resource available"
  fi
  if (( $(echo "$memory_percentage >= 80" | bc -l) )); then
    echo "WARNING: Node memory workload requests reaching close to maximum resource available"
  fi
  
  echo "Current CPU usage: $current_cpu_usage m"
  echo "Allocatable CPU: $allocatable_cpu_millicores m"
  echo "Allocated CPU: $allocated_cpu m"
  echo "Percentage of CPU allocated: $cpu_percentage%"
  echo "Available CPU: $available_cpu m"
  
  echo "Current memory usage: $current_memory_usage Mi"
  echo "Allocatable memory: $(echo "$allocatable_memory / 1024" | bc) Mi" # convert kibibytes to mebibytes
  echo "Allocated memory: $allocated_memory Mi"
  echo "Percentage of memory allocated: $memory_percentage%"
  echo "Available memory: $(echo "$available_memory / 1024" | bc) Mi" # convert kibibytes to mebibytes
  
  echo
done

# Print the total available CPU and memory across the cluster
echo "Total available CPU across the cluster: $total_available_cpu m"
echo "Total available memory across the cluster: $(echo "$total_available_memory / 1024" | bc) Mi" # convert kibibytes to mebibytes