Docker Hosts Update Script Using Container Names

readme.txt

Docker Hosts Update Script
This shell script updates the `/etc/hosts` file on a Docker host machine by mapping container IP addresses to specified hostnames or container names.

Author: 
https://github.com/faiyazalam

Parameters:
--containers: Comma-separated list of Docker container names.
--urls: Comma-separated list of corresponding hostnames. If not provided, defaults to container names.

Behavior:
Parses provided container names and URLs to update the /etc/hosts file.
Retrieves container IP addresses using Docker commands.
Checks for existing hostname entries and updates or appends to /etc/hosts.

Example usage:
bash script.sh --containers="container_name1,container_name2" --urls="example1.local,example2.local"

Note:
Ensure the script is run with appropriate permissions to modify the /etc/hosts file.
Container names and hostnames must correspond in order.

update-etc-hosts-mapping-using-container-names.sh

# Docker Hosts Update Script Using Container Names
## Description: This shell script updates the `/etc/hosts` file on a Docker host machine by mapping container IP addresses to specified hostnames or container names.
## Usage: bash script.sh --containers="container_name1,container_name2" --urls="hostname1,hostname2"
#Author: https://github.com/faiyazalam


#!/bin/bash

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"

# If URLs are not provided, set them to the same as containers
if [ -z "$urls" ]; then
    urls="${containers}"
fi

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<${#containers_array[@]}; i++)); do
    container_id=$(docker ps -aqf "name=${containers_array[i]}")
    
    # Check if the container ID exists
    if [ -z "$container_id" ]; then
        echo "Container ${containers_array[i]} not found."
        exit 1
    fi
    
    ip_address=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$container_id")
    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