This project is a showcase of the LGTM stack to demonstrate the topic Observability.

The tle-fetcher retrieves TLE (two-line element set) data for calculating satellites trajectories from a NASA related API. You can learn more information on the TLE format here, on orbital mechanics here and while playing some rounds of Kerbal Space Program.

The sky-map service retrieves the data from tle-fetcher and outputs it as JSON.

This project uses Quarkus. If you want to learn more about Quarkus, please visit its website: https://quarkus.io/ .

To build and run this application, you will need the following dependencies on your system:

You can build the application using Gradle:

$ ./gradlew build

This will build the Java applications and two docker images. The docker image will be registered as qaware/tle-fetcher:1.0.0 and qaware/sky-map:1.0.0 within your Docker daemon:

$ docker images

REPOSITORY           TAG     IMAGE ID       CREATED         SIZE
qaware/sky-map       1.0.0   5f4a5695cc8f   7 seconds ago   438MB
qaware/tle-fetcher   1.0.0   55bd6d637c77   7 seconds ago   438MB

All relevant configuration can be found in each service src/main/resources/application.properties.

The Grafana stack is configured in the directories grafana, loki, promtail, mimir,grafana-agent and tempo.

NOTE: It is important to change the permissions on the configuration files for the Grafana stack. Run the following command:

$ chmod -R o+rX grafana loki mimir grafana-agent promtail tempo

Grafana is the visualization engine of the Grafana stack.

The main configuration is done in grafana.ini.

You can provision several other things automatically, like dashboards and datasources. All of this is stored in grafana/provisioning and deployed automatically on startup.

Loki is the log storage engine of the Grafana stack. In this repository, there is only the loki/loki.yaml with basic storage configuration.

Promtail is the logshipper of the Grafana stack. It periodically scrapes logfiles and sends them to Loki.

The configuration promtail/promtail.yaml scrapes the application logs from the services and pre-parses their JSON.

Mimir is a time series storage that can be connected to Grafana.

Grafana Agent periodically scrapes metrics from known endpoints and sends it to Grafana Mimir.

Tempo stores APM and tracing data from services. It can also be connected to Grafana.

Run the applications with docker compose:

$ docker compose up

• SmallRye OpenTracing (guide): Trace your services with SmallRye OpenTracing
• Micrometer Registry Prometheus (guide): Enable Prometheus support for Micrometer
• REST Client Classic (guide): Call REST services
• RESTEasy Classic JSON-B (guide): JSON-B serialization support for RESTEasy Classic
• RESTEasy Classic (guide): REST endpoint framework implementing JAX-RS and more
• Logging JSON (guide): Add JSON formatter for console logging
• SmallRye Health (guide): Monitor service health
• Micrometer metrics (guide): Instrument the runtime and your application with dimensional metrics using Micrometer.