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Monitor Pod Health in Kubernetes

In this guide, we will create a Bash script to monitor the health of Kubernetes pods across all namespaces. This script will automate the retrieval of pod statuses, display their health conditions, and generate a report for easy review. It also includes icons for enhanced readability in the terminal.

Script Overview

The script will:

• Check prerequisites (ensure kubectl is installed and configured).
• List all namespaces in the cluster.
• Retrieve pod statuses for each namespace.
• Categorize pod health into statuses like Running, Pending, or Failed.
• Optionally generate a report or take action if unhealthy pods are detected.

Script

Here’s the complete script:

#!/bin/bash

# Kubernetes Pod Health Monitor Script
# Author: [Your Name]
# Date: [Date]
# Version: 1.0

# Icons for display
CHECK="\u2714" # ✔
CROSS="\u274C" # ✘
INFO="\u2139"  # ℹ
WARNING="\u26A0" # ⚠

# Function: Check if kubectl is installed
function check_kubectl() {
    if ! command -v kubectl &> /dev/null; then
        echo -e "${CROSS} Error: kubectl is not installed. Please install kubectl and configure access to the cluster."
        exit 1
    else
        echo -e "${CHECK} kubectl is installed."
    fi
}

# Function: Check cluster connectivity
function check_cluster_access() {
    if ! kubectl cluster-info > /dev/null 2>&1; then
        echo -e "${CROSS} Error: Unable to connect to the Kubernetes cluster. Please check your kubeconfig."
        exit 1
    else
        echo -e "${CHECK} Connected to the Kubernetes cluster."
    fi
}

# Function: Get all namespaces
function get_namespaces() {
    echo -e "${INFO} Retrieving namespaces..."
    kubectl get namespaces -o custom-columns=NAME:.metadata.name --no-headers
}

# Function: Monitor pod health across namespaces
function monitor_pods() {
    echo -e "${INFO} Monitoring pod health across all namespaces..."
    namespaces=$(get_namespaces)

    echo -e "${INFO} Found the following namespaces:"
    echo "$namespaces"

    # Initialize counters
    total_pods=0
    healthy_pods=0
    unhealthy_pods=0

    echo -e "\n${INFO} Pod health report:"
    echo -e "Namespace\tPod Name\t\tStatus"

    # Iterate through each namespace
    for ns in $namespaces; do
        pods=$(kubectl get pods -n "$ns" -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.phase}{"\n"}{end}')
        while read -r pod status; do
            total_pods=$((total_pods + 1))
            if [[ $status == "Running" ]]; then
                healthy_pods=$((healthy_pods + 1))
                echo -e "$ns\t$pod\t\t${CHECK} $status"
            else
                unhealthy_pods=$((unhealthy_pods + 1))
                echo -e "$ns\t$pod\t\t${CROSS} $status"
            fi
        done <<< "$pods"
    done

    echo -e "\n${INFO} Summary:"
    echo -e "Total Pods: $total_pods"
    echo -e "Healthy Pods: ${CHECK} $healthy_pods"
    echo -e "Unhealthy Pods: ${CROSS} $unhealthy_pods"
}

# Function: Generate a report
function generate_report() {
    echo -e "${INFO} Generating pod health report..."
    report_file="pod_health_report_$(date +%F).txt"
    kubectl get pods --all-namespaces -o wide > "$report_file"
    echo -e "${CHECK} Report saved to $report_file"
}

# Main script starts here
echo "=== Kubernetes Pod Health Monitor ==="

# Step 1: Check prerequisites
check_kubectl
check_cluster_access

# Step 2: Monitor pod health
monitor_pods

# Step 3: Generate optional report
read -p "Do you want to generate a detailed report? (yes/no): " generate
if [[ $generate == "yes" ]]; then
    generate_report
fi

echo -e "${CHECK} Script execution completed."

Monitor Pod Health in Kubernetes

1. Checking Prerequisites

The script first ensures that kubectl is installed and accessible. This is done using:

if ! command -v kubectl &> /dev/null; then

If kubectl is unavailable, the script terminates with an error.

It also verifies connectivity to the Kubernetes cluster:

if ! kubectl cluster-info > /dev/null 2>&1; then

2. Listing All Namespaces in Kubernetes

The script retrieves a list of namespaces using:

kubectl get namespaces -o custom-columns=NAME:.metadata.name --no-headers

For more details on namespaces, see Kubernetes Namespaces.

3. Monitoring Pod Health

For each namespace, the script retrieves pod names and their statuses:

pods=$(kubectl get pods -n "$ns" -o jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.phase}{"\n"}{end}')

Pod statuses are categorized into healthy (Running) and unhealthy (any other status). For details on pod statuses, see Pod Lifecycle.

4. Generating a Summary

The script provides a summary of total, healthy, and unhealthy pods:

echo -e "Total Pods: $total_pods"
echo -e "Healthy Pods: ${CHECK} $healthy_pods"
echo -e "Unhealthy Pods: ${CROSS} $unhealthy_pods"

5. Generating a Detailed Report

If the user opts to generate a report, the script saves detailed pod information to a file:

kubectl get pods --all-namespaces -o wide > "$report_file"

For more options with kubectl get, visit the kubectl Cheat Sheet.

Possible Enhancements

• Alerting System: Integrate notifications via Slack or email for unhealthy pods.
• Threshold-Based Actions: Automatically restart pods using kubectl commands if a threshold of unhealthy pods is crossed.
• Expanded Reporting: Include pod events or logs for debugging.

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