Bash Script to Update /etc/hosts for Docker Containers

update_hosts_for_docker_containers.sh

#!/bin/bash

#Example Usage: bash update_hosts_for_docker_containers.sh --containers="my_container_id_1,my_container_id_2" --urls="example1.com,example2.com"

#Author: https://github.com/faiyazalam

containers=""
urls=""

# Parse arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        --containers=*)
            containers="${1#*=}"
            shift
            ;;
        --urls=*)
            urls="${1#*=}"
            shift
            ;;
        *)
            echo "Unknown parameter passed: $1"
            exit 1
            ;;
    esac
done

# Convert comma-separated values to arrays
IFS=',' read -r -a containers_array <<< "$containers"
IFS=',' read -r -a urls_array <<< "$urls"

# Check if the number of containers and URLs match
if [ ${#containers_array[@]} -ne ${#urls_array[@]} ]; then
    echo "The number of containers and URLs should match."
    exit 1
fi

# Loop through arrays to update /etc/hosts
for ((i=0; i<${#containers_array[@]}; i++)); do
    ip_address=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "${containers_array[i]}")
    hostname="${urls_array[i]}"

    # Check if the entry exists in /etc/hosts
    if grep -q "$hostname" /etc/hosts; then
        sudo sed -i "s/.*$hostname.*/$ip_address $hostname/" /etc/hosts
        echo "$hostname entry updated in /etc/hosts"
    else
        # Add the entry to /etc/hosts
        echo "$ip_address $hostname" | sudo tee -a /etc/hosts
        echo "$hostname entry added to /etc/hosts"
    fi
done

This Bash script facilitates the mapping of Docker container IP addresses to specific URLs in the /etc/hosts file. By providing a list of Docker container names and their corresponding URLs, this script updates the host file, ensuring the containers are accessible via their designated URLs. Usage example: bash update_hosts_for_docker_containers.sh --containers="container1,container2" --urls="url1,url2".