Docker

Docker and Docker Compose will need to be installed in order to use the commands in this section.

Building Reaper Docker Image

Prerequisite

The generation of the Docker image requires that the JAR file be built and placed in the src/packages directory. If the JAR package is missing from the directory then it can built using either the steps in the Docker package build section (above), or in the Building from Source section.

Building Image

To build the Reaper Docker Image which is then added to the local image cache using the cassandra-reaper:latest tag, run the following command from the top level directory.

mvn -pl src/server/ docker:build -Ddocker.directory=src/server/src/main/docker

Docker Hub Image

A prebuilt Docker Image is available for download from Docker Hub. The image TAG can be specified when pulling the image from Docker Hub to pull a particular version. Set:

• TAG=master to run Reaper with the latest commits
• TAG=latest to run Reaper with the latest stable release

To pull the image from Docker Hub with a particular tag, run the following command.

docker pull thelastpickle/cassandra-reaper:${TAG}

Start Docker Environment

Using Docker

Reaper can be executed within a Docker container with either an ephemeral memory storage or persistent database.

In-Memory Backend

To launch a Reaper container backed by an In-Memory backend, use the following example with the appropriate JMX authentication settings for the cluster it will manage repairs for.

TAG=latest

REAPER_JMX_AUTH_USERNAME=reaperUser
REAPER_JMX_AUTH_PASSWORD=reaperPass

docker run \
    -p 8080:8080 \
    -p 8081:8081 \
    -e "REAPER_JMX_AUTH_USERNAME=${REAPER_JMX_AUTH_USERNAME}" \
    -e "REAPER_JMX_AUTH_PASSWORD=${REAPER_JMX_AUTH_PASSWORD}" \
    thelastpickle/cassandra-reaper:${TAG}

Then visit the the Reaper UI: http://localhost:8080/webui/.

Cassandra Backend

To launch a Reaper container backed by Cassandra, use the following example to connect to a Cassandra cluster that already has the reaper_db keyspace. Set the appropriate JMX authentication settings for the cluster that Reaper will manage repairs for.

TAG=latest

REAPER_JMX_AUTH_USERNAME=reaperUser
REAPER_JMX_AUTH_PASSWORD=reaperPass

REAPER_CASS_CLUSTER_NAME=reaper-cluster
REAPER_CASS_CONTACT_POINTS=["192.168.2.185"]

docker run \
    -p 8080:8080 \
    -p 8081:8081 \
    -e "REAPER_JMX_AUTH_USERNAME=${REAPER_JMX_AUTH_USERNAME}" \
    -e "REAPER_JMX_AUTH_PASSWORD=${REAPER_JMX_AUTH_PASSWORD}" \
    -e "REAPER_STORAGE_TYPE=cassandra" \
    -e "REAPER_CASS_CLUSTER_NAME=${REAPER_CASS_CLUSTER_NAME}" \
    -e "REAPER_CASS_CONTACT_POINTS=${REAPER_CASS_CONTACT_POINTS}" \
    -e "REAPER_CASS_KEYSPACE=reaper_db" \
    thelastpickle/cassandra-reaper:${TAG}

Then visit the the Reaper UI: http://localhost:8080/webui/.

Using Docker Compose

The Docker Compose services available allow for orchestration of an environment that uses Reaper’s default settings. This provides a quick way to start Reaper and become familiar with its usage without the need of additional infrastructure. The environment created using Docker Compose comprises a single containerised Apache Cassandra node and a single containerised Reaper service.

In addition to the environment using Reaper’s default settings, Docker Compose services are provided that allow orchestration of an environment in which the connections between Reaper and Cassandra are SSL encrypted. The services which create this environment contain a -ssl suffix in their name.

It is also possible to automate registering the Cassandra cluster with Reaper and making Reaper start repairing non-system keyspaces automatically. To register a cluster, run the Reaper image with the register-cluster command:

  register-clusters:
    image: cassandra-reaper:latest
    links:
      - cassandra
      - reaper-in-memory
    command: ["register-clusters", "cassandra:7199", "reaper-in-memory", "8080"]

The register-clusters arguments are:

• cassandra:7199 - host and (JMX) port of a node in the cluster we want to register.
• reaper-in-memory - hostname of the Reaper instance.
• 8080 - the port on which Reaper listens on.

To make Reaper automatically start repairs, make sure the following environment variables are set:

REAPER_AUTO_SCHEDULING_ENABLED="True"
REAPER_AUTO_SCHEDULING_TIME_BEFORE_FIRST_SCHEDULE="PT1M"
REAPER_AUTO_SCHEDULING_PERIOD_BETWEEN_POLLS="PT1M"

All available Docker Compose services can be found in the docker-compose.yml file.

Default Settings Environment

From the top level directory change to the src/packaging directory:

cd src/packaging

Start the Cassandra cluster:

docker-compose up cassandra

The nodetool Docker Compose service can be used to check on the Cassandra node’s status:

docker-compose run nodetool status

You can alternatively attach directly to the Cassandra container and run nodetool status from within it by running:

docker-compose exec cassandra /bin/bash

Now that you have a bash shell in the container, you can run nodetool -u reaperUser -pwf /etc/cassandra/jmxremote.password.

Once the Cassandra node is online and accepting CQL connections, create the required reaper_db Cassandra keyspace to allow Reaper to save its cluster and scheduling data.

By default, the reaper_db keyspace is created using a replication factor of 1. To change this replication factor, provide the intended replication factor as an optional argument:

docker-compose run cqlsh-initialize-reaper_db [$REPLICATION_FACTOR]

Wait a few moments for the reaper_db schema change to propagate, then start Reaper:

docker-compose up reaper

SSL Encrypted Connections Environment

From the top level directory change to the src/packaging directory:

cd src/packaging

Generate the SSL Keystore and Truststore which will be used to encrypt the connections between Reaper and Cassandra.

docker-compose run generate-ssl-stores

Start the Cassandra cluster which encrypts both the JMX and Native Protocol:

docker-compose up cassandra-ssl

The nodetool-ssl Docker Compose service can be used to check on the Cassandra node’s status:

docker-compose run nodetool-ssl status

Once the Cassandra node is online and accepting encrypted SSL connections via the Native Transport protocol, create the required reaper_db Cassandra keyspace to allow Reaper to save its cluster and scheduling data.

By default, the reaper_db keyspace is created using a replication factor of 1. To change this replication factor, provide the intended replication factor as an optional argument:

docker-compose run cqlsh-initialize-reaper_db-ssl [$REPLICATION_FACTOR]

Wait a few moments for the reaper_db schema change to propagate, then start the Reaper service that will establish encrypted connections to Cassandra:

docker-compose up reaper-ssl

Access The Environment

Once started, the UI can be accessed through:

http://127.0.0.1:8080/webui/

A nodetool Docker Compose service is included for both the default and SSL encrypted environments to allow nodetool commands to be performed on Cassandra.

For the default environment use:

docker-compose run nodetool status

For the SSL encrypted environment use:

docker-compose run nodetool-ssl status

When adding the Cassandra node to the Reaper UI with the IP address, the above commands can be used to find the node IP address. You can also add the Cassandra node to the Reaper UI by hostname. The container’s hostname is the docker-compose service name.

A cqlsh Docker Compose service is included as well for both the default and SSL encrypted environments to allow the creation of user tables in Cassandra.

For the default environment use:

docker-compose run cqlsh

For the SSL encrypted environment use:

docker-compose run cqlsh-ssl

Destroying the Docker Environment

When terminating the infrastructure, use the following command to stop all related Docker Compose services:

docker-compose down

To completely clean up all persistent data, delete the ./data/ directory:

rm -rf ./data/