Add ability to configure the number of max concurrent reconciles (#154)

* Add MAX_CONCURRENT_RUN_RECONCILES to yaml

config/default/manager_image_patch.yaml

@@ -20,3 +20,5 @@ spec:
               secretKeyRef:
                 name: dbrickssettings
                 key: DatabricksToken
+          - name: MAX_CONCURRENT_RUN_RECONCILES
+            value: "1"

controllers/run_controller.go

@@ -19,6 +19,8 @@ package controllers
 import (
 	"context"
 	"fmt"
+	"os"
+	"strconv"
 	"time"
 
 	"github.com/go-logr/logr"
@@ -31,8 +33,11 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	databricksv1alpha1 "github.com/microsoft/azure-databricks-operator/api/v1alpha1"
+	ctrl_controller "sigs.k8s.io/controller-runtime/pkg/controller"
 )
 
+const maxConcurrentReconcilesEnvName = "MAX_CONCURRENT_RUN_RECONCILES"
+
 // RunReconciler reconciles a Run object
 type RunReconciler struct {
 	client.Client
@@ -110,5 +115,18 @@ func (r *RunReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
 func (r *RunReconciler) SetupWithManager(mgr ctrl.Manager) error {
 	return ctrl.NewControllerManagedBy(mgr).
 		For(&databricksv1alpha1.Run{}).
+		WithOptions(ctrl_controller.Options{
+			MaxConcurrentReconciles: getMaxConcurrentReconciles(),
+		}).
 		Complete(r)
 }
+
+func getMaxConcurrentReconciles() int {
+	concurrentReconciles, err := strconv.Atoi(os.Getenv(maxConcurrentReconcilesEnvName))
+
+	if err != nil || concurrentReconciles < 1 {
+		return 1
+	}
+
+	return concurrentReconciles
+}

docs/deploy.md

@@ -19,6 +19,8 @@ wget https://github.com/microsoft/azure-databricks-operator/releases/latest/down
 unzip release.zip
 ```
 
+> (optional) [Configure maximum number of run reconcilers](##configure-maximum-number-of-run-reconcilers)
+
 2. Create the `azure-databricks-operator-system` namespace:
 
 ```sh
@@ -40,6 +42,16 @@ kubectl --namespace azure-databricks-operator-system \
 kubectl apply -f release/config
 ```
 
+## Configure maximum number of run reconcilers
+
+1. Change the `MAX_CONCURRENT_RUN_RECONCILES` value in `config/default/manager_image_patch.yaml` under the `env` section with the desired number of reconcilers
+```yaml
+          - name: MAX_CONCURRENT_RUN_RECONCILES
+            value: "1"
+```
+
+> By default `MAX_CONCURRENT_RUN_RECONCILES` is set to 1 
+
 ## Use kustomize to customise your deployment
 
 1. Clone the source code: