Astro Runtime architecture
Astro Runtime is a production ready, data orchestration tool based on Apache Airflow that is distributed as a Docker image and is required by all Astronomer products. It is intended to provide organizations with improved functionality, reliability, efficiency, and performance.
Deploying Astro Runtime is a requirement if your organization is using Astro. Astro Runtime includes the following features:
- Timely support for new patch, minor, and major versions of Apache Airflow. This includes bug fixes that have not been released by the open source project but are backported to Astro Runtime and available to users earlier.
- Exclusive features to enrich the task execution experience, including smart task concurrency defaults and high availability configurations.
- The
openlineage-airflowpackage. OpenLineage standardizes the definition of data lineage, the metadata that forms lineage metadata, and how data lineage metadata is collected from external systems. This package enables data lineage on Astro. See OpenLineage and Airflow. - A custom Airflow UI that includes links to Astronomer resources and exposes the currently running Docker image tag in the footer of all UI pages.
- A custom logging module that ensures Airflow task logs are reliably available to the Astro data plane. (Astro only).
- A custom security manager that enforces user roles and permissions as defined by Astro. (Astro only).
- A monitoring DAG that the Astronomer team uses to monitor the health of Astro Deployments. (Astro only)
For more information about the features that are available in Astro Runtime releases, see the Astro Runtime release notes.
Runtime versioning
Astro Runtime versions are released regularly and use semantic versioning. Astronomer ships major, minor, and patch releases of Astro Runtime in the format of major.minor.patch.
- Major versions are released for significant feature additions. This includes new major or minor versions of Apache Airflow, as well as API or DAG specification changes that are not backward compatible.
- Minor versions are released for functional changes. This includes API or DAG specification changes that are backward compatible, which might include new minor versions of
astronomer-providersandopenlineage-airflow. - Patch versions are released for bug and security fixes that resolve unwanted behavior. This includes new patch versions of Apache Airflow,
astronomer-providers, andopenlineage-airflow.
Every version of Astro Runtime correlates to an Apache Airflow version. All Deployments must run only one version of Astro Runtime, but you can run different versions of Astro Runtime on different Deployments within a given cluster or Workspace.
For a list of supported Astro Runtime versions and more information on the Astro Runtime maintenance policy, see Astro Runtime versioning and lifecycle policy.
Astro Runtime and Apache Airflow parity
This table lists Astro Runtime releases and their associated Apache Airflow versions.
| Astro Runtime | Apache Airflow version |
|---|---|
| 4 | 2.2 |
| 5 | 2.3 |
| 6 | 2.4 |
| 7 | 2.5 |
| 8 | 2.6 |
| 9 | 2.7 |
| 10 | 2.8 |
| 11 | 2.9 |
| 12 | 2.10 |
For version compatibility information, see the Runtime release notes.
Default environment variables
The following table lists the Airflow environment variables that have different default values on Astro Runtime as of version 12.5.0. Unlike global environment variables set on the Astro data plane, you can override the values of these variables for specific use cases.
| Environment Variable | Description | Value |
|---|---|---|
AIRFLOW__SCHEDULER__DAG_DIR_LIST_INTERVAL | The time in seconds that Airflow waits before re-scanning the dags directory for new files. Note that this environment variable is set for all Deployments regardless of Runtime version. | 30 |
AIRFLOW__CELERY__STALLED_TASK_TIMEOUT | The maximum time in seconds that tasks running with the Celery executor can remain in a queued state before they are automatically rescheduled. | 600 |
AIRFLOW_CORE_PARALLELISM | The maximum number of task instances that can run concurrently for each scheduler in your Deployment. | [number-of-running-workers-for-all-worker-queues] * [max-tasks-per-worker] |
AIRFLOW__SCHEDULER__MAX_TIS_PER_QUERY | The batch size of queries to the metadata database in the main scheduling loop. | 512 |
AIRFLOW__KUBERNETES_EXECUTOR__WORKER_PODS_CREATION_BATCH_SIZE | The number of worker Pods that can be created each time the scheduler parses DAGs. This setting limits the number of tasks that can be scheduled at one time. | 16 |
Astro monitoring DAG (Astro Hybrid only)
Astro Runtime includes a monitoring DAG that is pre-installed in the Docker image and enabled for all Deployments on Astro Hybrid. In addition to generating Deployment health and metrics functionality, this DAG allows the Astronomer team to monitor the health of your data plane by enabling real-time visibility into whether your workers are healthy and tasks are running.
The astronomer_monitoring_dag runs a simple bash task every 5 minutes to ensure that your Airflow scheduler and workers are functioning as expected. If the task fails twice in a row or is not scheduled within a 10-minute interval, Astronomer support receives an alert and will work with you to troubleshoot. The DAG runs and appears in the Airflow UI only on Astro Deployments.
Because this DAG is essential to Astro's managed service, you are not charged for its task runs. For the same reasons, this DAG can't be modified or disabled through the Airflow UI. To modify when this DAG runs on a Deployment, set the following Deployment environment variable:
- Key:
AIRFLOW_MONITORING_DAG_SCHEDULE_INTERVAL - Value: An alternative schedule defined as a cron expression
Provider packages
Astro Runtime 12.5.0 includes the following pre-installed open source provider packages. Providers marked with an asterisk (*) are also installed by default on open source Apache Airflow.
- Common IO
apache-airflow-providers-common-io* - Common SQL
apache-airflow-providers-common-sql* - FAB
apache-airflow-providers-fab* - FTP
apache-airflow-providers-ftp* - HTTP
apache-airflow-providers-http* - IMAP
apache-airflow-providers-imap* - SMTP
apache-airflow-providers-smtp* - SQLite
apache-airflow-providers-sqlite* - Amazon
apache-airflow-providers-amazon - Astronomer Providers
astronomer-providers - Astro Python SDK
astro-sdk-python - Celery
apache-airflow-providers-celery - Cloud Native Computing Foundation (CNCF) Kubernetes
apache-airflow-providers-cncf-kubernetes - Datadog
apache-airflow-providers-datadog - Elasticsearch
apache-airflow-providers-elasticsearch - Google
apache-airflow-providers-google - Microsoft Azure
apache-airflow-providers-microsoft-azure - MySQL
apache-airflow-providers-mysql - OpenLineage
apache-airflow-providers-openlineage - PostgreSQL (Postgres)
apache-airflow-providers-postgres - Redis
apache-airflow-providers-redis
Provider package versioning
Astronomer users specific provider package versions in each release of Astro Runtime. See Astro Runtime provider package reference for a list of all providers installed in each release of Astro Runtime.
Python versioning
| Astro Runtime | Apache Airflow version | Python version |
|---|---|---|
| 4 | 2.2 | 3.9 |
| 5 | 2.3 | 3.9 |
| 6 | 2.4 | 3.9 |
| 7 | 2.5 | 3.9 |
| 8 | 2.6 | 3.10 |
| 9 | 2.7 | 3.11 |
| 10 | 2.8 | 3.11 |
| 11 | 2.9 | 3.11 |
| 12 | 2.10 | 3.12 |
Starting with Astro Runtime 9, if you require a different version of Python than what's included in the base image, you can use a Python versions of Astro Runtime. See Image types.
If you're running Astro Runtime 6.0 (based on Airflow 2.4) to Runtime 8, Astronomer recommends that you use the ExternalPythonOperator to run different Python versions in Airflow. See ExternalPythonOperator.
If you're currently using the KubernetesPodOperator or the PythonVirtualenvOperator in your DAGs, you can continue to use them to create virtual or isolated environments that can run tasks with different versions of Python.
Python version considerations
Starting with Python version 3.12, Python has removed the module imp. This can cause errors for your DAGs if you Astro Runtime version 12 or higher, which supports Python Version 3.12 or higher.
See How do I migrate from imp guidance from Python for remediation steps.
If you're currently using the KubernetesPodOperator or the PythonVirtualenvOperator in your DAGs, you can continue to use them to create virtual or isolated environments that can run tasks with different versions of Python.
Postgres version compatibility
The following table shows which versions Postgres are compatible with each version of Astro Runtime. Note that Postgres versioning is handled automatically on Astro Hosted and Hybrid.
| Astro Runtime | Apache Airflow version | Postgres versions |
|---|---|---|
| 5 | 2.3 | 10-13 |
| 6 | 2.4 | 10-13 |
| 7 | 2.5 | 11-15 |
| 8 | 2.6 | 11-15 |
| 9 | 2.7 | 11-15 |
| 10 | 2.8 | 12-16 |
| 11 | 2.9 | 12-16 |
| 12 | 2.10 | 12-16 |
Executors
In Airflow, the executor is responsible for determining how and where a task is completed.
In all local environments created with the Astro CLI, Astro Runtime runs the Local executor. On Astro and Astronomer Software, you can use either the Celery executor or the Kubernetes executor.
Image types
Astro Runtime is distributed as a Debian-based Docker image. An Astro Runtime image must be specified in the Dockerfile of your Astro project. The default image tag is:
quay.io/astronomer/astro-runtime:<version>
You can modify this image tag in your Astro project Dockerfile to use different versions of Astro Runtime. The following sections explain each image type and how to specify them. For a list of all Astro Runtime Docker images, see Quay.io.
Base images
The base Astro Runtime Docker image has the following format:
quay.io/astronomer/astro-runtime:<version>-base
A base Astro Runtime image is recommended for complex use cases that require additional customization, such as installing Python packages from private sources.
For all other cases, Astronomer recommends using non-base images, which incorporate ONBUILD commands that copy and scaffold your Astro project directory so you can more easily pass those files to the images running each core Airflow component.
Python version images
Starting with Astro Runtime 9, Astronomer maintains different Astro Runtime images for each supported Python version.
Python version images have the following format:
quay.io/astronomer/astro-runtime:<runtime-version>-python-<python-version>
Starting with Astro Runtime 11.13.0 and 12.3.0, RHEL version images are also available for Python versions 3.11 and 3.12. To select a particular Python and RHEL version combination, use the following format:
quay.io/astronomer/astro-runtime:<runtime-version>-ubi9-python-<python_version>-base
Slim images
Starting with Astro Runtime 11, Astronomer maintains a slim Astro Runtime image. Slim Astro Runtime images only include the dependencies required for the basic functionality of Astro. Providers marked with an asterisk (*) are also installed by default on open source Apache Airflow. The providers installed in the slim image are:
- Common IO
apache-airflow-providers-common-io* - Common SQL
apache-airflow-providers-common-sql* - FAB
apache-airflow-providers-fab* - FTP
apache-airflow-providers-ftp* - HTTP
apache-airflow-providers-http* - IMAP
apache-airflow-providers-imap* - SMTP
apache-airflow-providers-smtp* - SQLite
apache-airflow-providers-sqlite* - Celery
apache-airflow-providers-celery - Elasticsearch
apache-airflow-providers-elasticsearch - MySQL
apache-airflow-providers-mysql - PostgreSQL (Postgres)
apache-airflow-providers-postgres astronomer-kubernetes-executor
Use the slim Astro Runtime image if you want faster local builds and deploys, smaller footprint for security vulnerabilities and dependency conflicts, or you don't require the packages included in the default Astro Runtime distribution.
Combine image types
Image types are additive, meaning that you can combine multiple types in your image tag to specify an image with multiple variations.
Types must be specified in a specific order in your image tag. The order and format multi-type image tag is:
quay.io/astronomer/astro-runtime:<astro-runtime-version>-<python-version-type>-<slim-type>-<base-type>
You can add or remove any types as needed. For example, to use the base, slim Astro Runtime image with Python 3.11, your image tag would be:
quay.io/astronomer/astro-runtime:11.0.0-python-3.11-slim-base
If you wanted the same base image using Python 3.11, but you didn't want it to be slim, you would remove the -slim- from the image tag like in the following example:
quay.io/astronomer/astro-runtime:11.0.0-python-3.11-base
Operating system support
The following table lists the operating systems and architectures supported by each Astro Runtime version. If you're using a Mac computer with an M1 chip, Astronomer recommends using Astro Runtime 6.0.4 or later.
| Astro Runtime | Apache Airflow version | Operating System (OS) | Architecture |
|---|---|---|---|
| 4 | 2.2 | Debian 11.1 (bullseye) | AMD64 |
| 5 | 2.3 | Debian 11.3 (bullseye) | AMD64 |
| 6 | 2.4 | Debian 11.5 (bullseye) | AMD64 and ARM64 |
| 7 | 2.5 | Debian 11.5 (bullseye) | AMD64 and ARM64 |
| 8 | 2.6 | Debian 11.7 (bullseye) | AMD64 and ARM64 |
| 9 | 2.7 | Debian 11.7 (bullseye) | AMD64 and ARM64 |
| 10 | 2.8 | Debian 11.8 (bullseye) | AMD64 and ARM64 |
| 11 | 2.9 | Debian 11.8 (bullseye), RHEL UBI 9¹² | AMD64 and ARM64 |
| 12 | 2.10 | Debian 12.6 (bookworm), RHEL UBI 9¹³ | AMD64 and ARM64 |
¹ RHEL UBI 9 support is currently experimental and any breaking changes between versions will be announced in the Astro Runtime release notes.
² Astro Runtime 11.13.0 and later support RHEL UBI 9.
³ Astro Runtime 12.3.0 and later support RHEL UBI 9.
Astro Runtime 6.0.4 and later images are multi-arch and support AMD64 and ARM64 processor architectures for local development. Docker automatically uses the correct processor architecture based on the computer you are using.