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Setting up a GTFS Realtime Validator app

The GTFS Realtime Validator is a open-source tool that allows validating a GTFS Realtime feed given a matching GTFS Schedule file. By using both datasets, the validator can not only check the realtime feed's format, but also the quality of its data. It looks like this:

image

The run the validator on your machine, either fork our ready-made repository or follow this tutorial to build your own setup from scratch.

FYI the tool is maintained in MobilityData's gtfs-realtime-validator repository but it was originally created by an independent team. See their article Introducing the GTFS-realtime Validator.

Prerequisites

For this project, as for all projects here at MobilityDataDev, you'll need:

That's it!

Creating the app

The official documentation provides two installation guides:

  • The first consists in installing Java and the webapp package, then running the command java -jar {JAR file name}.

  • The second uses Docker commands to either pull or build an image, then run it.

However, we're using a third approach: Docker Compose. This enables putting all the configuration in one file, including complimentary services that we'll get to in a second, then run it all in one single, simple command.

Docker Compose is a tool for defining and running multi-container applications. [It] simplifies the control of your entire application stack, making it easy to manage services, networks, and volumes in a single, comprehensible YAML configuration file. Then, with a single command, you create and start all the services from your configuration file. – Source

Here goes:

  1. Create a ./docker-compose.yml file at the root of your repository, containing the service definition for the validator:
services:
  gtfs-rt-validator-service:
    container_name: gtfs-rt-validator-container
    image: ghcr.io/mobilitydata/gtfs-realtime-validator
    ports:
      - "8081:8080"
    environment:
      JAVA_OPTS: "-Xmx5g -XX:MaxMetaspaceSize5g"

  1. Run docker compose up.

  2. Open http://localhost:8081.

And just like that, the validator tool is now available! It looks like this:

!image

Using the app

Using the GTFS RT Validator is incredibly simple. All you need to know is right there on that web page:

What is the GTFS-Realtime Validator?

The upper-left box tells us what the tool does in one sentence, and provides a link to exact list of test rules.

Getting Started

The upper-right box provides a short, 5-step guide to create your very first validation report.

Step 1: Add the URL for your GTFS zip file

The lower-left box has three form inputs:

  1. The "GTFS feed" input box requires a direct URL to a valid GTFS Schedule ZIP file.

That URL must be a direct download link! Test it in your browser first to make sure it doesn't redirect or responds with an HTML page.

"Oh no, I only have a local ZIP file and can't upload it to the web".

No worries! Create a new ./gtfs-schedule-files folder then add a service to ./docker-compose.yml to expose that directly on localhost:

services:
  # ...

  server-service:
    container_name: server-container
    image: python:3.9-slim
    command: python3 -m http.server 8000 --directory /shared
    ports:
      - "8082:80"
    volumes:
      - ./gtfs-schedule-files:/shared

Run docker compose up again to restart both services, then open http://localhost:8082/my-file.zip. If all went well, your browser will download the file.

Now you can access your local file in the validator tool from inside the container, using the URL http://server-container/my-file.zip.

  1. The "Run GTFS validation" checkbox is optional. If selected, the tool also validates the GTFS Schedule data alone. This takes longer though.

  2. The "Use shapes.txt for GTFS-realtime rules" checkbox is also optional. It .... TODO

Step 1: Add the URL for your GTFS zip file

WIP

Understanding reports