Steps to Add Host-to-IP Mapping to Test Containers

Overview

This guide provides instructions on how to add host-to-IP mapping to test containers in Carrier. This is similar to the functionality provided by the /etc/hosts file in Linux-based systems.

Prerequisites

Before you begin, ensure that:

• You have Carrier installed and set up successfully.
• Docker is installed on the system where the interceptor is being run.
• You have access to the Carrier platform to configure the interceptor.

Step 1: Prepare the Host-to-IP Mapping

To map a hostname to a specific IP address in the test container, you’ll need to use the EXTRA_HOSTS parameter when running the interceptor.

1. Single Host Mapping:

   If you need to map a single host to an IP address, use the following format:

   -e EXTRA_HOSTS='{"HOST": "IP"}'
   

   Replace HOST with the desired hostname and IP with the corresponding IP address.

2. Multiple Host Mappings:

   To map multiple hosts to their respective IP addresses, use the following format:

   -e EXTRA_HOSTS='{"HOST1": "IP1", "HOST2": "IP2"}'
   

   Replace HOST1 and HOST2 with the desired hostnames, and IP1 and IP2 with the corresponding IP addresses.

   Note: This functionality has not yet been thoroughly tested with multiple hosts. Please proceed with caution and test configurations before full-scale deployment.

Step 2: Add the Host-to-IP Mapping to the Interceptor Command

To apply the host-to-IP mapping, modify the interceptor run command by adding the EXTRA_HOSTS parameter.

Example:

docker run -d --rm -v /var/run/docker.sock:/var/run/docker.sock \
  -e RAM_QUOTA=4g -e CPU_QUOTA=2 -e CPU_CORES=2 \
  -e RABBIT_HOST=${CARRIER_HOST} \
  -e RABBIT_USER=${RABBIT_USER} -e RABBIT_PASSWORD=${RABBIT_PWD} \
  -e VHOST=${PROJECT_VHOST} \
  -e QUEUE_NAME=my_new_QUEUE -e TOKEN=${AUTH_TOKEN} \
  -e EXTRA_HOSTS='{"my-service.local": "192.168.1.100"}' \
  -e LOKI_HOST=https://${CARRIER_HOST} getcarrier/interceptor:latest

In this example:

• The EXTRA_HOSTS parameter maps the hostname my-service.local to the IP address 192.168.1.100.

Step 3: Verify the Configuration

1. Run the Interceptor:

   Execute the interceptor command with the EXTRA_HOSTS parameter as configured.

2. Check the Container:

   After running the command, verify that the host-to-IP mapping is correctly applied inside the test container:

   docker inspect <container_name>
   

   Look for entries that match the mappings you specified.

Step 4: Test the Mapping

• For Single Host Mapping: Verify that the container correctly resolves the mapped hostnames to their corresponding IP addresses.
• For Multiple Host Mappings: If multiple mappings were configured, ensure that each hostname is correctly resolved to its respective IP address.

Next Steps

Once you have verified that the host-to-IP mapping works as expected, you can proceed with your performance testing or other container-based tasks, knowing that your custom hostname resolutions are correctly configured.

For any issues or advanced configurations, refer to the Carrier documentation or contact support.