Data is the new gold in today’s world. With businesses relying more and more on data-driven decisions, understanding where data comes from and how it flows is essential. Data is constantly moving from raw ingestion, to transformation, to analytics, and finally to end consumers like dashboards or machine learning models.
While data navigates and transforms into many other data points, the more pressing need is transparency: knowing where your data came from, how it was transformed, and where it will flow next.
That’s where OpenLineage comes in. Data lineage can be built in several ways and on of the most popular approaches is using OpenLineage.
Most definitions says that OpenLineage is a “open standard for metadata and lineage collection.” That’s helpful, but what does it mean at the core level? In this blog post, I’ll explore the foundation of OpenLineage, how it is structured and where the lineage information is gathered.
OpenLineage – A Specification
OpenLineage is a vendor-neutral, open specification designed to model an capture data lineage in a consistent, interoperable format. It is defines a formal JSON schema that represents a core lineage entities such as Job, Run, Dataset and their associated metadata. This specification is supported by suite of languages specific client libraries and instrumentation APIs(e.g., in Python, Java and Scala) that allow orchestration frameworks like Apache Airflow, dbt , Apache Spark to emit lineage events at runtime. These events are typically serialized to JSON and transmitted over HTTP or Kafka to a lineage. OpenLineage also includes a reference implementation, with Marquez serving as the primary open-source backend that ingests and visualizes these lineage events. backend.
Anatomy of a Lineage Event
At the core of OpenLineage is the event, a JSON document that represents what a pipeline/job did at a specific moment.
Each event typically include
eventType– START, COMPLETE, FAILeventTime– When the job ranrun– A specific execution of the job (UUID)job– The logical job (name + namespace)inputsandoutputs– Dependent datasets
This JSON is the heart of OpenLineage, and emitting this structure is what it means to be “OpenLineage-compliant.”
Emit OpenLineage Events
A jobs that is instrumented with OpenLineage config, constructs and emits event objects (like above), and sends it configured backend (like Marquez) over HTTP or Kafka.
This is how a job tells OpenLineage what happened, by manually creating and emitting the event.
Although, one thing to note is that, the event construction and emit is not done manually through code. The Tools such as Airflow, DBT, Apache Spark etc, which are OpenLineage compliant emit lineage events automatically using appropriate client SDK under the hood. We can configure then to point to OpenLineage backend and they start emitting the events as the jobs runs.
OpenLineage Backend – Marquez
There are several tools that acts a collectors or backend for OpenLineage events. These tools are responsible for receiving, storing, and sometimes visualizing the lineage metadata emitted by data processing tools. OpenLineage itself defines a standard for lineage event schemas and how those events should be emitted, but it relies on external systems to collect and utilize this data effectively.
One of the most prominent backend for OpenLinage is Marquez which is an open source metadata service that stores and serves OpenLineage events and it’s also the reference backend for OpenLineage. Marquez uses a relational database (PostgreSQL) as its primary datastore. It provides a centralized metadata service that listens for OpenLineage events and stores them in a queryable format. It also exposes APIs for retrieving lineage information, which can then be visualized through its built-in UI or consumed by other systems.
In addition to Marquez, organizations can implement custom collectors or integrate OpenLineage with their existing data catalogs, such as DataHub, Amundsen, or OpenMetadata. These platforms can be extended to receive OpenLineage events via Kafka, HTTP, or other transports, allowing lineage metadata to be integrated into a broader data governance and observability strategy.
Final Thoughts
OpenLineage is not a product, and not a vendor, it’s a specification plus tooling that enables interoperable, automated lineage tracking. It is a comprehensive effort to standardize and simplify the capture of data lineage across diverse tools and platforms.
There is thorough documentation and a wealth of resources available on the OpenLineage website, including comprehensive kickstart guides. https://openlineage.io/