Installing Apache Airflow

This section provides a step-by-step guide to installing Apache Airflow.

Apache Airflow (or simply Airflow) is a platform to programmatically author, schedule, and monitor workflows. In Airflow, workflows are defined as code, and they are more maintainable, versionable, testable, and collaborative.

You can use Airflow to author workflows as directed acyclic graphs (DAGs) of tasks. The Airflow scheduler executes tasks on an array of workers while following the specified dependencies. Availability of a rich set of command line utilities help performing complex surgeries on DAGs. The user interface makes it easy to visualize pipelines running in production, monitor progress, and troubleshoot issues when needed.

To install the Apache Airflow, follow the steps below:

Add Apache Airflow repositories to helm configuration.

helm repo add apache-airflow https://airflow.apache.org
helm repo update

Download the Helm charts to local.

mkdir -p /home/user/airflow-chart-download
cd /home/user/airflow-chart-download
# Download the chart locally,
# it should download a tarball in the same directory
helm pull apache-airflow/airflow
# untar the downloaded tarball
tar -zxvf airflow-1.14.0.tgz

Update the airflow image with the HCL provided airflow image details in the helm chart inside the values.yaml as below.
```
vi /home/user/airflow-chart-download/airflow/values.yaml
```
Edit below properties
```
defaultAirflowRepository: hclcr.io/unica/airflow-custom
defaultAirflowTag: "1"
airflowVersion: "2.8.3"
```
The properties will look like below:
Update the security context in PostgreSQL values.yaml as below to disable seccompProfile.
```
vi /home/user/airflow-chart-download/airflow/charts/postgresql/values.yaml
```

Update the OpenShift SCC and grant necessary permissions to all the below listed service accounts to deploy the pods.

<your airflow deployment namespace>-create-user-job
if your namespace is airflow, the below all service accounts will be created when you deploy the helm chart.
so grant the necessary permission in the SCC for all the service accounts.
airflow-create-user-job
airflow-migrate-database-job
airflow-redis
airflow-scheduler
airflow-statsd
airflow-triggerer
airflow-webserver
airflow-worker
default

Deploy the Apache Airflow using Helm.

helm upgrade --install airflow /home/user/airflow-chart-download/airflow --namespace airflow --create-namespace --debug --timeout 15m

After deploying Apache Airflow, verify the deployed pods.
```
kubectl get pods --namespace airflow
```
As a result, the output will be as shown below:

Configuring Apache Airflow

Expose the Airflow web server service, which will create the route to access the Airflow UI.

oc expose svc airflow-webserver -n airflow
oc get routes -n airflow

Access the airflow UI application using the HOST/PORT URL.