Runs an Exhibitor-managed ZooKeeper instance using S3 or GCS for backups and automatic node discovery.

Available on the Docker Index as simenduev/zookeeper-exhibitor:

docker pull simenduev/zookeeper-exhibitor

Why to Fork?

This is forked version of mbabineau/zookeeper-exhibitor

The fork add support for the following:

• Google Cloud Storage support (via gcsfuse), requires privileged mode, see below
• Updated Exhibitor and Zookeeper to their latest versions
• Using official Java container, based on Alpine flavor
• Allow to specify settling-period (ZK_SETTLING_PERIOD)

Versions

• Exhibitor 1.5.6
• ZooKeeper 3.4.8

Usage

The container expects the following environment variables to be passed in:

• HOSTNAME - addressable hostname for this node (Exhibitor will forward users of the UI to this address)
• GS_BUCKET - (optional) bucket used by Exhibitor for backups and coordination
• GS_PREFIX - (optional) key prefix within GS_BUCKET to use for this cluster
• S3_BUCKET - (optional) bucket used by Exhibitor for backups and coordination
• S3_PREFIX - (optional) key prefix within S3_BUCKET to use for this cluster
• AWS_ACCESS_KEY_ID - (optional) AWS access key ID with read/write permissions on S3_BUCKET
• AWS_SECRET_ACCESS_KEY - (optional) secret key for AWS_ACCESS_KEY_ID
• AWS_REGION - (optional) the AWS region of the S3 bucket (defaults to us-west-2)
• ZK_PASSWORD - (optional) the HTTP Basic Auth password for the "zk" user
• ZK_DATA_DIR - (optional) Zookeeper data directory
• ZK_LOG_DIR - (optional) Zookeeper log directory
• ZK_SETTLING_PERIOD - (optional) How long in ms to wait for the Ensemble to settle. Default 2 minutes
• HTTP_PROXY_HOST - (optional) HTTP Proxy hostname
• HTTP_PROXY_PORT - (optional) HTTP Proxy port
• HTTP_PROXY_USERNAME - (optional) HTTP Proxy username
• HTTP_PROXY_PASSWORD - (optional) HTTP Proxy password

Starting the container:

docker run -p 8181:8181 -p 2181:2181 -p 2888:2888 -p 3888:3888 \
    -e S3_BUCKET=<bucket> \
    -e S3_PREFIX=<key_prefix> \
    -e AWS_ACCESS_KEY_ID=<access_key> \
    -e AWS_SECRET_ACCESS_KEY=<secret_key> \
    -e HOSTNAME=<host> \
    simenduev/zookeeper-exhibitor:latest

Once the container is up, confirm Exhibitor is running:

$ curl -s localhost:8181/exhibitor/v1/cluster/status | python -m json.tool
[
    {
        "code": 3, 
        "description": "serving", 
        "hostname": "<host>", 
        "isLeader": true
    }
]

See Exhibitor's wiki for more details on its REST API.

You can also check Exhibitor's web UI at http://<host>:8181/exhibitor/v1/ui/index.html

Then confirm ZK is available:

$ echo ruok | nc <host> 2181
imok

AWS IAM Policy

Exhibitor can also use an IAM Role attached to an instance instead of passing access or secret keys. This is an example policy that would be needed for the instance:

{
    "Statement": [
        {
            "Resource": [
                "arn:aws:s3:::exhibitor-bucket/*",
                "arn:aws:s3:::exhibitor-bucket"
            ],
            "Action": [
                "s3:AbortMultipartUpload",
                "s3:DeleteObject",
                "s3:GetBucketAcl",
                "s3:GetBucketPolicy",
                "s3:GetObject",
                "s3:GetObject",
                "s3:GetObjectAcl",
                "s3:ListBucket",
                "s3:ListBucketMultipartUploads",
                "s3:ListMultipartUploadParts",
                "s3:PutObject",
                "s3:PutObjectAcl"
            ],
            "Effect": "Allow"
        }
    ]
}

Starting the container:

docker run -p 8181:8181 -p 2181:2181 -p 2888:2888 -p 3888:3888 \
    -e S3_BUCKET=<bucket> \
    -e S3_PREFIX=<key_prefix> \
    -e HOSTNAME=<host> \
    simenduev/zookeeper-exhibitor:latest

Google Cloud Storage

The most important note is that in order to be able to mount GS bucket (via gcsfuse), the container required to run in privileged mode. Credentials for use with GCS will automatically be loaded using Google application default credentials, unless you mount a JSON key file.

After everything is in place, this is how you start the container with GCS support:

docker run -p 8181:8181 -p 2181:2181 -p 2888:2888 -p 3888:3888 \
    --privileged \
    -e GS_BUCKET=<bucket> \
    -e GS_PREFIX=<key_prefix> \
    -e HOSTNAME=<host> \
    -v <path to json file>:/opt/exhibitor/key-file.json \
    simenduev/zookeeper-exhibitor