feat(Slack): Added better messages to Slack channel

cmd/main.go

@@ -5,6 +5,7 @@ import (
 	"elasticsearch-vm-autoscaler/internal/google"
 	"elasticsearch-vm-autoscaler/internal/prometheus"
 	"elasticsearch-vm-autoscaler/internal/slack"
+	"fmt"
 
 	"log"
 	"os"
@@ -79,27 +80,29 @@ func main() {
 		// If the up condition is met, add a node to the MIG
 		if upCondition {
 			log.Printf("Up condition %s met: Trying to create a new node!", prometheusUpCondition)
-			err = google.AddNodeToMIG(projectID, zone, migName, debugMode)
+			currentSize, maxSize, err := google.AddNodeToMIG(projectID, zone, migName, debugMode)
 			if err != nil {
 				log.Printf("Error adding node to MIG: %v", err)
 				time.Sleep(time.Duration(retryIntervalSeconds) * time.Second)
 				continue
 			}
 			// Notify via Slack that a node has been added
 			if slackWebhookURL != "" {
-				slack.NotifySlack("New node created succesfully in MIG", slackWebhookURL)
+				message := fmt.Sprintf("Added new node to MIG %s. Current size is %d nodes and the maximum nodes to create are %d", migName, currentSize, maxSize)
+				slack.NotifySlack(message, slackWebhookURL)
 			}
 		} else if downCondition { // If the down condition is met, remove a node from the MIG
 			log.Printf("Down condition %s met. Trying to remove one node!", prometheusDownCondition)
-			err = google.RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasticPassword, debugMode)
+			currentSize, minSize, nodeRemoved, err := google.RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasticPassword, debugMode)
 			if err != nil {
 				log.Printf("Error draining node from MIG: %v", err)
 				time.Sleep(time.Duration(retryIntervalSeconds) * time.Second)
 				continue
 			}
 			// Notify via Slack that a node has been removed
 			if slackWebhookURL != "" {
-				slack.NotifySlack("Removed node from MIG", slackWebhookURL)
+				message := fmt.Sprintf("Removed node %s from MIG %s. Current size is %d nodes and the minimum nodes to exist are %d", nodeRemoved, migName, currentSize, minSize)
+				slack.NotifySlack(message, slackWebhookURL)
 			}
 		} else {
 			// No scaling conditions met, so no changes to the MIG

internal/google/mig.go

@@ -18,32 +18,32 @@ import (
 )
 
 // AddNodeToMIG increases the size of the Managed Instance Group (MIG) by 1, if it has not reached the maximum limit.
-func AddNodeToMIG(projectID, zone, migName string, debugMode bool) error {
+func AddNodeToMIG(projectID, zone, migName string, debugMode bool) (int32, int32, error) {
 	ctx := context.Background()
 
 	// Create a new Compute client for managing the MIG
 	client, err := createComputeClient(ctx, compute.NewInstanceGroupManagersRESTClient)
 	if err != nil {
-		return fmt.Errorf("failed to create Instance Group Managers client: %v", err)
+		return 0, 0, fmt.Errorf("failed to create Instance Group Managers client: %v", err)
 	}
 	defer client.Close()
 
 	// Get the current target size of the MIG
 	targetSize, err := getMIGTargetSize(ctx, client, projectID, zone, migName)
 	if err != nil {
-		return fmt.Errorf("failed to get MIG target size: %v", err)
+		return 0, 0, fmt.Errorf("failed to get MIG target size: %v", err)
 	}
 	log.Printf("Current size of MIG is %d nodes", targetSize)
 
 	// Get the scaling limits (minimum and maximum)
 	_, maxSize, err := getMIGScalingLimits()
 	if err != nil {
-		return fmt.Errorf("failed to get MIG scaling limits: %v", err)
+		return 0, 0, fmt.Errorf("failed to get MIG scaling limits: %v", err)
 	}
 
 	// Check if the MIG has reached its maximum size
 	if targetSize >= maxSize {
-		return fmt.Errorf("MIG has reached its maximum size (%d/%d), no further scaling is possible", targetSize, maxSize)
+		return 0, 0, fmt.Errorf("MIG has reached its maximum size (%d/%d), no further scaling is possible", targetSize, maxSize)
 	}
 
 	// Create a request to resize the MIG by increasing the target size by 1
@@ -58,55 +58,55 @@ func AddNodeToMIG(projectID, zone, migName string, debugMode bool) error {
 	if !debugMode {
 		_, err = client.Resize(ctx, req)
 		if err != nil {
-			return err
+			return 0, 0, err
 		} else {
 			log.Printf("Scaled up MIG successfully %d/%d", targetSize+1, maxSize)
 		}
 	}
-	return nil
+	return targetSize + 1, maxSize, nil
 }
 
 // RemoveNodeFromMIG decreases the size of the Managed Instance Group (MIG) by 1, if it has not reached the minimum limit.
-func RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasticPassword string, debugMode bool) error {
+func RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasticPassword string, debugMode bool) (int32, int32, string, error) {
 	ctx := context.Background()
 
 	// Create a new Compute client for managing the MIG
 	client, err := createComputeClient(ctx, compute.NewInstanceGroupManagersRESTClient)
 	if err != nil {
-		return fmt.Errorf("failed to create Instance Group Managers client: %v", err)
+		return 0, 0, "", fmt.Errorf("failed to create Instance Group Managers client: %v", err)
 	}
 	defer client.Close()
 
 	// Get the current target size of the MIG
 	targetSize, err := getMIGTargetSize(ctx, client, projectID, zone, migName)
 	if err != nil {
-		return fmt.Errorf("failed to get MIG target size: %v", err)
+		return 0, 0, "", fmt.Errorf("failed to get MIG target size: %v", err)
 	}
 	log.Printf("Current size of MIG is %d nodes", targetSize)
 
 	// Get the scaling limits (minimum and maximum)
 	minSize, _, err := getMIGScalingLimits()
 	if err != nil {
-		return fmt.Errorf("failed to get MIG scaling limits: %v", err)
+		return 0, 0, "", fmt.Errorf("failed to get MIG scaling limits: %v", err)
 	}
 
 	// Check if the MIG has reached its minimum size
 	if targetSize <= minSize {
-		return fmt.Errorf("MIG has reached its minimum size (%d/%d), no further scaling down is possible", targetSize, minSize)
+		return 0, 0, "", fmt.Errorf("MIG has reached its minimum size (%d/%d), no further scaling down is possible", targetSize, minSize)
 	}
 
 	// Get a random instance from the MIG to remove
 	instanceToRemove, err := GetInstanceToRemove(ctx, client, projectID, zone, migName)
 	if err != nil {
-		return fmt.Errorf("error draining Elasticsearch node: %v", err)
+		return 0, 0, "", fmt.Errorf("error draining Elasticsearch node: %v", err)
 	}
 
 	// If not in debug mode, drain the node from Elasticsearch before removal
 	if !debugMode {
 		log.Printf("Instance to remove: %s. Draining from elasticsearch cluster", instanceToRemove)
 		err = elasticsearch.DrainElasticsearchNode(elasticURL, instanceToRemove, elasticUser, elasticPassword)
 		if err != nil {
-			return fmt.Errorf("error draining Elasticsearch node: %v", err)
+			return 0, 0, "", fmt.Errorf("error draining Elasticsearch node: %v", err)
 		}
 		log.Printf("Instance drained successfully from elasticsearch cluster")
 	}
@@ -126,7 +126,7 @@ func RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasti
 	if !debugMode {
 		_, err = client.DeleteInstances(ctx, deleteReq)
 		if err != nil {
-			return fmt.Errorf("error deleting instance: %v", err)
+			return 0, 0, "", fmt.Errorf("error deleting instance: %v", err)
 		} else {
 			log.Printf("Scaled down MIG successfully %d/%d", targetSize-1, minSize)
 		}
@@ -139,12 +139,12 @@ func RemoveNodeFromMIG(projectID, zone, migName, elasticURL, elasticUser, elasti
 	if !debugMode {
 		err = elasticsearch.ClearElasticsearchClusterSettings(elasticURL, elasticUser, elasticPassword)
 		if err != nil {
-			return fmt.Errorf("error clearing Elasticsearch cluster settings: %v", err)
+			return 0, 0, "", fmt.Errorf("error clearing Elasticsearch cluster settings: %v", err)
 		}
 		log.Printf("Cleared up elasticsearch settings for draining node")
 	}
 
-	return nil
+	return targetSize - 1, minSize, instanceToRemove, nil
 }
 
 // getMIGScalingLimits retrieves the minimum and maximum scaling limits for a Managed Instance Group (MIG).