printer

Hyperion - Printer Plugin

This package provides a printer pipeline plugin that can be used to print all messages passing through a part of the pipeline. This plugin may be useful for debugging purposes.

Note: The printer plugin works as both a passthrough plugin (forwarding all received messages to the next stage) and as a final step in the pipeline.

Usage

For full details on the supported configuration format, please see the configuration section of this document.

The printer plugin simply takes whatever input it gets, prints it, and forwards it. Because this behaviour is static, only the configuration for the abstract pipeline plugin is needed.

Building & Running

To build the library, run gradle pipeline:printer:shadowJar. The result will be located in build/printer-all.jar.

To execute the tests and linting, run gradle pipeline:printer:check.

To run a compiled version of the printer plugin, simply launch it using Java:

java -jar build/printer-all.jar [path to config]

Docker

The printer plugin can be easily built and run using Docker.

Running the pre-built Docker image

A pre-built image is available at the Docker hub repository. The plugin image is tagged as sergdelft/hyperion:pipeline-plugins-printer-<version>. Please consult the root README for the latest published version. To run this image with printer_config.yml as its configuration execute:

docker run -it -rm -v ${PWD}/printer_config.yml:/root/config.yml sergdelft/hyperion:pipeline-plugins-printer-0.1.0

Building the Docker image yourself

The included Dockerfile compiles and bundles the plugin. To build it, navigate to the repository root and run the following command:

docker build . -f pipeline/plugins/printer/Dockerfile -t hyperion-printer:latest

Once building completes, the plugin can be ran using the following command, assuming that the configuration file is located at printer_config.yml:

docker run -it -rm -v ${PWD}/printer_config.yml:/root/config.yml hyperion-printer:latest

Configuration

This plugin accepts configuration in a YAML file supplied as a command line argument. The following options are accepted:

# Various settings needed for the plugin to interact with the pipeline,
# such as it's unique ID and the hostname and port of the Hyperion plugin manager.
# 
# Please note that the plugin must also be able to talk to any of its previous
# and next steps in the pipeline. As such, it is recommended that all of the 
# plugins are contained on a single networking setup.
pipeline:
    # The host and port pair that can be used to contact the Hyperion plugin manager.
    # Please note that this machine must be able to talk over TCP to the manager and
    # that the manager must be aware of this plugin/aggregator.
    manager-host: "manager:8000"
  
    # The unique ID of this pipeline step that matches the configuration of the plugin
    # manager. Used to identify which plugins are inputs/outputs of this step. Please
    # note that the plugin will crash at launch if the plugin manager does not recognize
    # this plugin ID.
    plugin-id: "Printer"
  
    # The size of the internal buffer used for storing data that has not yet been processed
    # locally. Increasing this will allow for more messages to be buffered, at the cost of
    # more memory usage. Messages incoming while the buffer is full will be thrown away. If
    # this happens often, consider using the load balancer plugin to shard this plugin across
    # multiple instances. Defaults to 20,000.
    buffer-size: 20000

Input Format

This plugin will accept essentially any string at all.

{
    "message": "[Apr 10] INFO com.foo.Bar:10 - Message"
}

Output Format

The plugin will simply forward whatever input it got after printing it.

{
    "message": "[Apr 10] INFO com.foo.Bar:10 - Message",
}