Docker Kafka

This project provides a Dockerized Kafka for running on EC2 instances using Cloud Compose.

Quick Start

To use this project do the following:

1. Create a new Github repo for your configuration (e.g. my-configs)
2. Create a directory for kafka (e.g. mkdir my-configs/kafka)
3. Create a sub-directory for your cluster (e.g. mkdir my-configs/kafka/foobar)
4. Clone this project into your Github repo using subtree merge
5. Copy the docker-kafka/cloud-compose/cloud-compose.yml.example to your cluster sub-directory
6. Modify the cloud-compose.yml to fit your needs
7. Create a new cluster using the Cloud Compose cluster plugin.

pip install cloud-compose cloud-compose-cluster
pip freeze -r > requirements.txt
cloud-compose cluster up

FAQ

How is kafka configured?

See cloud-compose/templates/docker-compose.override.yml for a list of environment variables that can alter the default Kafka configuration properties.

How do I safely upgrade the cluster?

If you use the default replication factor of 3 and run the cluster across 3 availability zones, you can safely upgrade one zone at a time. Start by checking that under replicated partitions is zero, then terminate all the servers in one availability zone. Wait fot the under replicated partitions to return to zero before continuing with the next zone.

How do I manage secrets?

Secrets can be configured using environment variables. Envdir is highly recommended as a tool for switching between sets of environment variables in case you need to manage multiple clusters. At a minimum you will need AWS_ACCESS_KEY_ID, AWS_REGION, and AWS_SECRET_ACCESS_KEY.

How do I share config files?

Since most of the config files are common between clusters, it is desirable to directly share the configuration between projects. The recommend directory structure is to have docker-kafka sub-directory and then a sub-directory for each cluster. For example if I had a test and prod mongodb cluster my directory structure would be:

kafka/
  docker-kafka/cloud-compose/templates/
  test/cloud-compose.yml
  prod/cloud-compose.yml
  templates/

The docker-kafka directory would be a subtree merge of this Git project, the templates directory would be any common templates that only apply to your mongodb clusters, the the test and prod directories have the cloud-compose.yml files for your two clusters. Regardless of the directory structure, make sure the search_paths in your cloud-compose.yml reflect all the config directories and the order that you want to load the config files.

How do I create a subtree merge of this project?

A subtree merge is an alternative to a Git submodules for copying the contents of one Github repo into another. It is easier to use once it is setup and does not require any special commands (unlike submodules) for others using your repo.

Initial subtree merge

To do the initial merge you will need to create a git remote, then merge it into your project as a subtree and commit the changes

# change to the cluster sub-directory
cd my-configs/kafka
# add the git remote
git remote add -f docker-kafka git@github.com:washingtonpost/docker-kafka.git
# pull in the git remote, but don't commit it
git merge -s ours --no-commit docker-kafka/master
# make a directory to merge the changes into
mkdir docker-kafka
# actually do the merge
git read-tree --prefix=kafka/docker-kafka/ -u docker-kafka/master
# commit the changes
git commit -m 'Added docker-kafka subtree'

Updating the subtree merge

When you want to update the docker-kafka subtree use the git pull with the subtree merge strategy

# Add the remote if you don't already have it
git remote add -f docker-kafka git@github.com:washingtonpost/docker-kafka.git
# do the subtree merge again
git pull -s subtree docker-kafka master