Docker and Infrastructure Dependencies

In KillrVideo, we offer microservice implementations in multiple programming languages, but each of these implementations have a base common set of dependencies they need in order to be a functional reference application. Those base dependencies are:

  • DataStax Enterprise: we need at least one node of DSE / Cassandra running that the microservices implementations can use to store data.
  • KillrVideo Web Tier: we need the Web Tier in order to provide a working UI and application that drives calls to the microservices.

For a developer looking to learn about Cassandra and DSE it would be impractical (and kind of ridiculous) to ask them to install all of these things locally in addition to the code for the microservices implementation they are interested in. Instead, we've chosen to use Docker to run these dependencies. Docker has become an increasingly popular way for developers to run infrastructure on their local dev machines. This way, the only thing a developer needs to install is Docker for Mac or Windows in order to try out KillrVideo (and chances are they may already have it installed).

Docker Compose for Starting Dependencies

The Docker project offers a nice tool called Docker Compose which allows you to run multiple Docker containers that are defined in a .yaml file.

For a very simple way to get the application running using Docker Compose, see the Getting Started page.

We created the killrvideo-docker-common repository to house a flexible configuration that can be used to swap between the various microservice tier implementations and enable additional configurations.

To accomplish this flexible configuration, we take advantage of a feature of Docker Compose that lets us define additional .yaml files that we layer on top of the base docker-compose.yaml file and provide overrides and additions.

Other Docker Compose Examples

You may be interested in other configuration options for running KillrVideo in Docker, such as:

  • Starting a copy of OpsCenter, the web-based visual management and monitoring tool, to monitor your KillrVideo DSE node(s).
  • Starting a copy of Studio, an interactive web-based developer tool for interacting with Cassandra data using CQL and Graph data using Gremlin.
  • Storing DSE / Cassandra data on a volume mounted from the host machine, so that your data can survive beyond the lifespan of a single container.

These alternate configurations are available as part of the killrvideo-docker-common repository. See the README.md file for a detailed description of how to use these configurations; we provide a quick summary here.

To use one of these alternate configurations, you'll want to concatenate additional .yaml files when calling docker-compose, for example:

> docker-compose -f docker-compose.yaml -f docker-compose-volumes.yaml up -d

Alternatively, you can create a .env file in the directory where you want to run docker-compose and provide a value for the COMPOSE_FILE variable:

For example, you might change the default configuration to: 

COMPOSE_FILE=./docker-compose.yaml:./docker-compose-volumes.yaml:

in order to use the docker-compose-volumes.yaml file which starts a DSE instance with the data drive mounted from the host machine.

Running KillrVideo with an external DSE cluster

While the default configuration we provide for running KillrVideo in Docker includes running a single DSE node in a docker container, it is also possible to configure KillrVideo to run against an external cluster (that is, a cluster not running in Docker). We use this configuration option to run the publicly accessible version of KillrVideo you can find at www.killrvideo.com.

To configure KillrVideo to run with an external cluster, you'll want to take a look at the configuration options supported by the killrvideo-dse-config container. You'll want to edit the docker-compose configuration so that DSE is not started in a docker container, and you'll want to edit the environment variables in your local .env file in the directory where you run docker-compose to configure:

  • any desired security roles that you have set in the cluster for administrative and application roles
  • replication strategies to use for Cassandra and Graph data

See the Service Discovery page for more information. for more information on the environment variables you can set in order to configure these options.

Next: Service Discovery