I’m setting up a Hadoop cluster using Docker containers and facing an issue with the /etc/hosts
file. Here’s a detailed description of my setup and the problem:
Setup:
I’m using Docker to create multiple containers running Ubuntu 22.4.
Each container runs an instance of Hadoop (version 3.3.2).
I need to configure static IP addresses for the containers and update the /etc/hosts
file accordingly to ensure proper hostname resolution within the cluster.
Problem:
After exporting and running the containers, the /etc/hosts
file gets reset, removing my custom entries. Despite this, I notice that I can still start the Hadoop cluster successfully using the start-dfs.sh
script, and the nodes seem to communicate correctly. However, I want to ensure that my custom /etc/hosts
entries persist to avoid potential issues.
Steps Taken:
- Created the containers and assigned static IPs:
docker run -itd --name hadoop01 --network mynet --ip 192.168.88.101 my_hadoop_image
docker run -itd --name hadoop02 --network mynet --ip 192.168.88.102 my_hadoop_image
docker run -itd --name hadoop03 --network mynet --ip 192.168.88.103 my_hadoop_image
- Manually edited the
/etc/hosts
file in each container to include:
192.168.88.101 hadoop01
192.168.88.102 hadoop02
192.168.88.103 hadoop03
- Exported and re-ran the containers:
docker export hadoop01 > hadoop01.tar
docker import hadoop01.tar new_hadoop01_image
docker run -itd --name new_hadoop01 --network mynet --ip 192.168.88.101 new_hadoop01_image
- Observed that the
/etc/hosts
entries were missing, yet the Hadoop cluster still started successfully.
Questions:
- Why does the Hadoop cluster start successfully even after the
/etc/hosts
entries are reset? - What is the best practice for persisting
/etc/hosts
entries in
Docker containers to ensure reliable hostname resolution in a
Hadoop cluster? - Are there alternative methods or configurations within Docker or
Hadoop that can achieve the same goal without manually editing the
/etc/hosts
file?
Additional Information:
- The Docker network is set up as a custom bridge network.
- I’m using Hadoop’s default configuration files for
core-site.xml
andhdfs-site.xml
.
Any insights or suggestions to ensure persistent hostname resolution in this setup would be greatly appreciated.
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