Apache Accumulo Docker Image

This is the first release of this project. Eventually, this project will create an apache/accumulo image at DockerHub. Until then, you will need to build your own image. The main branch of this repo creates a Docker image for Accumulo 2.0+. If you want to create a Docker image for Accumulo 1.9, there is a 1.9 branch for that.

Obtain the Docker image

To obtain the docker image created by this project, you can either pull it from DockerHub at apache/accumulo or build it yourself. To pull the image from DockerHub, run the command below:

docker pull apache/accumulo

While it is easier to pull from DockerHub, the image will default to the software versions below:

Software	Version
Accumulo	2.1.2
Hadoop	3.3.6
ZooKeeper	3.8.2

If these versions do not match what is running on your cluster, you should consider building your own image with matching versions. However, Accumulo must be 2.0.0+. Below are instructions for building an image:

Clone the Accumulo docker repo

 git clone git@github.com:apache/accumulo-docker.git

Build the default Accumulo docker image using the command below.
```
 cd /path/to/accumulo-docker
 docker build -t accumulo .
```
Or build the Accumulo docker image with specific released versions of Hadoop, Zookeeper, etc that will downloaded from Apache using the command below:
```
 docker build --build-arg ZOOKEEPER_VERSION=3.4.8 --build-arg HADOOP_VERSION=2.7.0 -t accumulo .
```
Or build with an Accumulo tarball (located in same directory as DockerFile) using the command below:
```
 docker build --build-arg ACCUMULO_FILE=accumulo-<version>-bin.tar.gz -t accumulo .
```

Image basics

The entrypoint for the Accumulo docker image is the accumulo script. While the primary use case for this image is to start Accumulo processes (i.e tserver, master, etc), you can run other commands in the accumulo script to test out the image:

# No arguments prints Accumulo command usage
docker run accumulo
# Print Accumulo version
docker run accumulo version
# Print Accumulo classpath
docker run accumulo classpath

Run Accumulo using Docker

Before you can run Accumulo services in Docker, you will need to install Accumulo, configure accumulo.properties, and initialize your instance with --upload-accumulo-props. This will upload configuration to Zookeeper and limit how much configuration needs to be set on the command line.

$ accumulo init --upload-accumulo-props
...
Uploading properties in accumulo.properties to Zookeeper. Properties that cannot be set in Zookeeper will be skipped:
Skipped - instance.secret = <hidden>
Skipped - instance.volumes = hdfs://localhost:8020/accumulo
Skipped - instance.zookeeper.host = localhost:2181
Uploaded - table.durability = flush
Uploaded - tserver.memory.maps.native.enabled = false
Uploaded - tserver.readahead.concurrent.max = 64
Uploaded - tserver.server.threads.minimum = 64
Uploaded - tserver.walog.max.size = 512M

Any configuration that is skipped above will need to be passed in as a command line option to Accumulo services running in Docker containers. These options can be set in an environment variable which is used in later commands.

export ACCUMULO_CL_OPTS="-o instance.secret=mysecret -o instance.volumes=hdfs://localhost:8020/accumulo -o instance.zookeeper.host=localhost:2181"

The Accumulo docker image expects that the HDFS path set by instance.volumes is owned by the accumulo user. This can be accomplished by running the command below (replace the HDFS path with yours):

hdfs dfs -chown -R accumulo hdfs://localhost:8020/accumulo

Docker engine

Use the docker command to start local docker containers. The commands below will start a local Accumulo cluster with two tablet servers.

docker run -d --network="host" accumulo monitor $ACCUMULO_CL_OPTS
docker run -d --network="host" accumulo tserver $ACCUMULO_CL_OPTS
docker run -d --network="host" accumulo tserver $ACCUMULO_CL_OPTS
docker run -d --network="host" accumulo master $ACCUMULO_CL_OPTS
docker run -d --network="host" accumulo gc $ACCUMULO_CL_OPTS

If you would like to set Java heap size inside the Docker container, start the local docker container using the command below:

docker run -e ACCUMULO_JAVA_OPTS='-Xmx1g' -d --network="host" accumulo tserver $ACCUMULO_CL_OPTS

Marathon

Using the Marathon UI, you can start Accumulo services using the following JSON configuration template. The template is configured to start an Accumulo monitor but it can be modified to start other Accumulo services such as master, tserver and gc. For tablet servers, set instances to the number of tablet servers that you want to run.