In modern cloud environments, load balancers are critical for distributing traffic, improving availability, and scaling applications. But beyond traffic management, load balancer logs provide valuable insights into system performance, user behavior, and security threats.
To make the most of this data, organizations often stream these logs to Splunk—a powerful platform for searching, analyzing, and visualizing machine data in real time.
This post walks through how to send load balancer logs to Splunk from the three major cloud providers: AWS, Azure, and Google Cloud Platform (GCP).
AWS: Send Elastic Load Balancer (ELB) Logs to Splunk
1. Enable Access Logs
- Navigate to the EC2 > Load Balancers section.
- Select your Application Load Balancer (ALB).
- Under the Attributes tab, enable Access Logs.
- Specify an S3 bucket for storing the logs.
2. Set Up S3 to Splunk Ingestion
There are a couple of ways to ingest logs from S3 to Splunk:
- Use Splunk Add-on for AWS (requires a Heavy Forwarder).
- Or use Splunk Data Manager with AWS integration.
3. Configure the Splunk Add-on for AWS
- Install the Splunk Add-on for AWS on a Heavy Forwarder or Indexer.
- Go to Inputs > Create New Input:
- Choose S3 as the input type.
- Configure your AWS credentials (access key/secret or IAM role).
- Set the bucket and prefix used for the ALB logs.
- Define the sourcetype (e.g.,
aws:elb:accesslogs).
🔹 Tip: Make sure your S3 bucket policy allows read access for the IAM role used by Splunk.
Azure: Send Application Gateway Logs to Splunk
1. Enable Diagnostics on Azure Application Gateway
- Go to your Application Gateway in the Azure portal.
- Under Monitoring > Diagnostic Settings, add a new setting:
- Enable AccessLogs, PerformanceLogs, and FirewallLogs.
- Choose Log Analytics, Event Hub, or Storage Account as the destination.
2. Stream Logs to Splunk
You have multiple integration options:
Option A: Azure Event Hub → Splunk HEC
- Stream diagnostic logs to Azure Event Hub.
- Use the Splunk Add-on for Microsoft Cloud Services to connect to Event Hub.
- Configure the add-on to listen for events and send them to your Splunk index.
Option B: Azure Monitor + Azure Functions → Splunk
- Use an Azure Function to pick up logs from Log Analytics or Blob Storage.
- Send logs to Splunk HTTP Event Collector (HEC).
🔹 Tip: If using Event Hub, ensure proper partition access policies are configured and checkpointing is handled.
GCP: Send Cloud Load Balancing Logs to Splunk
1. Enable Load Balancer Logging
- Go to the Cloud Logging page in GCP.
- Enable logging on your HTTP(S) Load Balancer backend service.
- Logs will appear in Cloud Logging (formerly Stackdriver).
2. Export Logs to Pub/Sub
- Go to Logging > Log Router.
- Create a sink:
- Set the destination as Pub/Sub topic.
- Use a filter like: iniCopyEdit
resource.type="http_load_balancer"
3. Ingest from Pub/Sub to Splunk
- Deploy the Splunk Dataflow connector for GCP (a ready-made pipeline).
- It reads messages from Pub/Sub and sends them to Splunk HEC.
Tip: GCP’s Pub/Sub → Dataflow → Splunk setup is ideal for real-time log ingestion with minimal management overhead.
Summary Table
| Cloud | Log Source | Integration Method | Recommended Tool |
|---|---|---|---|
| AWS | ALB / NLB Logs | S3 → Splunk Add-on for AWS | Splunk Add-on for AWS |
| Azure | App Gateway Logs | Event Hub / Function → HEC | Splunk Add-on for Microsoft Cloud |
| GCP | HTTP(S) LB Logs | Pub/Sub → Dataflow → HEC | GCP Dataflow Template for Splunk |
Best Practices
- Normalize sourcetypes for consistent searches across platforms.
- Use indexing rules in Splunk to separate logs by cloud or service.
- Monitor for log ingestion failures or latencies with alerts.
- Ensure IAM permissions are scoped properly to reduce security risks.
- Apply retention and filtering policies to control costs.
Conclusion
Sending load balancer logs to Splunk across AWS, Azure, and GCP helps unify observability in a multi-cloud world. By setting up these pipelines, you gain powerful insights into performance, security, and user behavior—all in one place.
With the right configurations, Splunk becomes a real-time, centralized dashboard for troubleshooting and performance analytics across your load-balanced applications.
