Monitor and analyze logs of applications running on Azure Kubernetes Service (AKS).

[Lalit_Waghulkar]

The Elastic Stack, commonly known as ELK (Elasticsearch, Logstash, and Kibana), is a powerful set of tools for collecting, analyzing, and visualizing log data in real-time. It's widely used for monitoring and observability, providing deep insights into the performance and health of your Kubernetes clusters on Azure.

Problem: Monitoring and analyzing logs from multiple sources in a Kubernetes environment can be challenging. Traditional tools may not provide the necessary granularity and flexibility to handle the dynamic nature of Kubernetes clusters.

Solution: Deploying the Elastic Stack (ELK) on your Kubernetes cluster can help address these challenges by providing a robust and scalable solution for log aggregation, search, and visualization.

Step-by-Step Guide to Deploying ELK on Kubernetes

1. Setting Up Elasticsearch
Elasticsearch is a distributed, RESTful search and analytics engine capable of storing and searching large volumes of data in near real-time.

Steps:

• Deploy Elasticsearch using Helm, a package manager for Kubernetes.
  

  helm repo add elastic https://helm.elastic.co
  	helm repo update
  	helm install elasticsearch elastic/elasticsearch --namespace monitoring​

2. Setting Up Logstash
Logstash is a server-side data processing pipeline that ingests data from multiple sources, transforms it, and then sends it to Elasticsearch.

Steps:

• Create a Kubernetes ConfigMap to store the Logstash configuration
  

  kubectl create configmap logstash-config --from-file=logstash.conf --namespace monitoring​

• Deploy Logstash using the ConfigMap.
  

  kubectl apply -f - <<EOF
  	apiVersion: apps/v1
  	kind: Deployment
  	metadata:
  	name: logstash
  	namespace: monitoring
  	spec:
  	replicas: 1
  	selector:
  	matchLabels:
  	app: logstash
  	template:
  	metadata:
  	labels:
  	app: logstash
  	spec:
  	containers:
  	- name: logstash
  	image: docker.elastic.co/logstash/logstash:7.10.0
  	volumeMounts:
  	- name: logstash-config
  	mountPath: /usr/share/logstash/pipeline/logstash.conf
  	subPath: logstash.conf
  	volumes:
  	- name: logstash-config
  	configMap:
  	name: logstash-config
  	EOF​

3.Setting Up Kibana
Kibana is a data visualization and exploration tool used for log and time-series analytics applications.

Steps:

• Deploy Kibana using Helm.
  

  helm install kibana elastic/kibana --namespace monitoring​

4. Configuring Fluentd for Log Forwarding
Fluentd is an open-source data collector that helps you unify your logging infrastructure. It's commonly used to forward logs from Kubernetes to Elasticsearch.

Steps:

• Deploy Fluentd as a DaemonSet to ensure that it runs on all nodes in the Kubernetes cluster.
  

  kubectl apply -f - <<EOF
  	apiVersion: apps/v1
  	kind: DaemonSet
  	metadata:
  	name: fluentd
  	namespace: monitoring
  	spec:
  	selector:
  	matchLabels:
  	app: fluentd
  	template:
  	metadata:
  	labels:
  	app: fluentd
  	spec:
  	containers:
  	- name: fluentd
  	image: fluent/fluentd-kubernetes-daemonset:v1.11-debian-elasticsearch7-1.0
  	env:
  	- name: FLUENT_ELASTICSEARCH_HOST
  	value: "elasticsearch.monitoring.svc.cluster.local"
  	- name: FLUENT_ELASTICSEARCH_PORT
  	value: "9200"
  	volumeMounts:
  	- name: varlog
  	mountPath: /var/log
  	- name: varlibdockercontainers
  	mountPath: /var/lib/docker/containers
  	readOnly: true
  	volumes:
  	- name: varlog
  	hostPath:
  	path: /var/log
  	- name: varlibdockercontainers
  	hostPath:
  	path: /var/lib/docker/containers
  	EOF​

Common Issues and Solutions


Issue 1: Elasticsearch Cluster Health is Yellow or Red

• Solution:
  • Check the status of Elasticsearch nodes and ensure they are running.
  • Increase the number of master-eligible nodes to improve cluster resilience.
  • Check for any shard allocation issues and resolve them using the Elasticsearch API.

Issue 2: Logstash Not Ingesting Data

• Solution:
  • Verify Logstash configuration for any syntax errors.
  • Check Logstash logs for any errors or warnings.
  • Ensure that Logstash has network connectivity to Elasticsearch.

Issue 3: Kibana Not Loading Dashboards

• Solution:
  • Ensure Kibana is correctly configured to connect to Elasticsearch.
  • Check Kibana logs for any errors or warnings.
  • Verify network connectivity between Kibana and Elasticsearch.

By deploying the Elastic Stack on your Kubernetes cluster, you can effectively monitor and analyze logs, ensuring better visibility and performance for your applications running on Azure Kubernetes Service (AKS).