[jira] [Created] (DRILL-7563) Docker & Kubernetes Drill server container

["Paul Rogers (Jira)" <ji...@apache.org>]

Paul Rogers created DRILL-7563:
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             Summary: Docker & Kubernetes Drill server container
                 Key: DRILL-7563
                 URL: https://issues.apache.org/jira/browse/DRILL-7563
             Project: Apache Drill
          Issue Type: Improvement
    Affects Versions: 1.17.0
            Reporter: Paul Rogers
            Assignee: Paul Rogers


Drill provides two Docker containers:

* [Build Drill from sources|https://github.com/apache/drill/blob/master/Dockerfile]
* [Run Drill in interactive embedded mode|https://github.com/apache/drill/blob/master/distribution/Dockerfile]

User feedback suggests that these are not quite the right solutions to run Drill in a K8s (or OpenShift) cluster. In addition, we need a container to run a Drill server. This ticket summarizes the tasks involved.

h4. Container Image

The container image should:

* Start with the OpenJDK base image with minimal extra packages.
* Download and install an official Drill release.

We may then want to provide two derived images:

The Drillbit image which:

* Configures Drill for production and as needed in the following steps.
* Provides entry points for the Drillbit and for Sqlline
* Exposes Drill's four ports
* Accept as parameters things like the ZK host IP(s).

The Sqlline image, meant to be run in interactive mode (like the current embedded image) and which:

* Accept as parameters the ZK host IP(s).

h4. Runtime Environment

Drill has very few dependencies, but it must have a running ZK.

* Start a [ZK container|https://hub.docker.com/_/zookeeper/].
* A place to store logs, which can be in the container by default, stored on the host file system via a volume mount.
* Access to a data source, which can be configured via a storage plugin stored in ZK.
* Ensure graceful shutdown integration with the Docker shutdown mechanism.

h4. Running Drill in Docker

Users must run at least one Drillbit, and may run more. Users may want to run Sqlline.

* The Drillbit container requires, at a minimum, the IP address of the ZK instance(s).
* The Sqlline container requires only the ZK instances, from which it can find the Drillbit.

Uses will want to customize some parts of Drill: at least memory, perhaps any of the other options. Provide a way to pass this information into the container to avoid the need to rebuild the container to change configuration.

h4. Running Drill in K8s

The containers should be usable in "plain" Docker. Today, however, many people use K8s to orchestrate Docker. Thus, the Drillbit (but probably not the Sqlline) container should be designed to work with K8s. An example set of K8s YAML files should illustrate:

* Create a host-mount file system to capture Drill logs and query profiles.
* Optionally write Drill logs to stdout, to be captured by {{fluentd}} or similar tools.
* Pass Drill configuration (both HOCON and envrironment) as config maps.
* Pass ZK as an environment variable (the value of which would, one presumes, come from some kind of service discovery system.)

The result is that the user should be able to manually tinker with the YAML files, then use {{kubeadm}} to launch, monitor and stop Drill. The user sets cluster size manually by launching the desired number of Drill pods.

h4. Helm Chart for Drill

The next step is to wrap the YAML files in a Helm chart, with parameters exposed for the config options noted above.

h4. Drill Operator for K8s
 
Full K8s integration will require an operator to manage the Drill cluster. K8s operators are often written in Go, though doing so is not necessary. Drill already includes Drill-on-YARN which is, essential a "YARN operator." Repurpose this code to work with K8s as the target cluster manager rather than YARN. Reuse the same operations from DoY: configure, start, resize and stop a cluster.

 



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