This article still uses the Helm charts to deploy the Elastic Stack. It is now archived and read-only. A later version of this article will be published using the recommended ECK Kubernetes operator. Stay tuned 🤓
- Introduction
- Architecture
- Prerequisites
- 1. Observability database and frontend
- 2. Logs
- 3. Technical metrics
- 4. Business metrics
- 5. Traces
- Conclusion
- Further reading
Introduction
The Elastic Stack is a group of open-source products from Elastic designed to help users extract data from any type of source and in any format, enabling them to search, analyze, and visualize that data in real-time.
Observability refers to the ability to understand a system's internal state by examining its external outputs, particularly its data.
To efficiently administer a web application deployed to a Kubernetes cluster, we need to make the invisible visible across multiple complementary aspects, employing the three pillars of observability: logs, metrics, and traces. These pillars are essential for gaining insights into the application's performance and health.
From a tooling perspective, a paid approach would involve using tools like Datadog, New Relic, and App Dynamics, following the latest Magic Quadrant for Application Performance Monitoring and Observability:
On the open-source side, a popular stack is Prometheus/Grafana/Loki/Tempo.
However, in this article, we will explore an alternative route that we have successfully experimented with on multiple projects over the past few years: The Elastic Stack. One of the great advantages of this collection of tools is how seamlessly they integrate with each other.
By following the guidance in this article, you will be able to observe the following with the Elastic Stack:
- Logs:
- Kubernetes technical logs
- Application logs
- Metrics:
- Kubernetes generic health indicators
- Application technical KPIs
- Application business KPIs
- Traces:
- End-to-end traces of application user requests
- Traces of application internal routines
Architecture
Below, you'll discover the architecture that emerged from our careful considerations:
- Efficiency: A design that strikes a balance between minimalism and robustness suitable for production environments.
- Unified Cluster Approach: While best practices often suggest separate clusters for applications and observability data, our recommended architecture proposes a unified cluster. We've chosen this approach to begin with, opting for simplicity and cost-effectiveness, reserving the split-cluster strategy for when the application experiences significant growth and reaches a critical scale.
Prerequisites
To follow this guide, you need the following prerequisites in place:
A Kubernetes cluster (of course). If you are familiar with Terraform, you can refer to our guide for AWS or our guide for the OVHcloud equivalent to set up the cluster.
An Ingress controller. We recommend using the NGINX Ingress controller due to its comprehensive functionalities, listed for web applications in Kubernetes NGINX Ingress Controller: 10+ Complementary Configurations for Web Applications.
Helm installed on your machine. The Elastic modules will be installed using the official Elastic Helm repo. Although the repo is now read-only, it is still fully functional, and the community is expected to maintain it.
To add the official Elastic Helm repo as a remote, execute the following command in your shell:
helm repo add elastic https://helm.elastic.co
1. Observability database and frontend
Install Elasticsearch
Elasticsearch is a distributed, free and open search and analytics engine for all types of data. We will use it as the centralized database of the stack.
Create a configuration file overriding some of the default values:
elasticsearch.helm.values.yml
replicas: 3 # default
minimumMasterNodes: 2 # default
esJavaOpts: "-Xmx4g -Xms4g"
ingress:
enabled: false
resources:
requests:
cpu: 500m
memory: 5Gi
limits:
cpu: 4
memory: 10Gi
volumeClaimTemplate:
resources:
requests:
storage: 100Gi # default 30Gi
Replace the elasticsearch password with one of our choice in below command, then use it to install or upgrade Elasticsearch to the cluster in elk namespace:
helm -n elk upgrade --install es elastic/elasticsearch --create-namespace --version 8.5.1 -f elasticsearch.helm.values.yml --set secret.password=XXX
Install Kibana
Kibana is a free and open frontend application that sits on top of the Elastic Stack. All observability data will be presented through it. It is also to administration tool for the whole stack.
Create a configuration file overriding some of the default values:
kibana.helm.values.yml
imageTag: 8.5.1
resources:
requests:
cpu: 10m
memory: 768Mi
limits:
cpu: 1900m
memory: 1024Mi
ingress:
enabled: false
# Allows you to add any config files in /usr/share/kibana/config/
kibanaConfig:
kibana.yml: |
### default
server.host: "0.0.0.0"
server.shutdownTimeout: "5s"
elasticsearch.hosts: ["http://elasticsearch:9200"]
monitoring.ui.container.elasticsearch.enabled: true
### custom
# from https://github.com/elastic/apm-server/issues/10361
xpack.fleet.packages:
- name: apm
version: 8.5.1
NOTE: notice the disabled ingress. You can enable it depending on your architecture. Notice also the custom configuration to enable Elastic APM automatically. This module itself will be installed in a below paragraph.
Install Kibana with this commands (the deletion handle edge cases):
kubectl -n elk delete secret kib-kibana-es-token || true
helm -n elk upgrade --install kib elastic/kibana --version 8.5.1 -f kibana.helm.values.yml
2. Logs
Logs are a fundamental component of observability, providing a chronological record of events and activities within a system or application. These records typically contain textual information, including error messages, status updates, and user actions. Logs play a crucial role in diagnosing issues, monitoring system behavior, and troubleshooting problems. They are essential for understanding the historical context of events and are commonly used for auditing, compliance, and debugging purposes. Logs are often collected and aggregated in centralized systems, making it easier for developers and operators to analyze and gain insights into the health and performance of complex systems.
Logs are handled by Filebeat, stored by the Elasticsearch cluster, and presented by Kibana.
Display logs data with Kibana
Once logs will be collected using next paragraph, we will be able to create visualizations of our choice in Kibana. Here are some examples.
- Log level heatmaps and log volume per container:
- Generic logs:
- Tokenized logs:
- Log volume per level per namespace:
Collect logs with Filebeat
Filebeat is a log shipping tool that efficiently collects logs from a device and sends them to an external storage.
When installed in a Kubernetes cluster, Filebeat will automatically fetch container logs and ship them directly to Elasticsearch. While it's possible to use a Logstash instance in between, we chose not to for the sake of simplicity (and lack of need at the moment).
Filebeat also boasts the capability to split logs on the fly, which we'll leverage to separate logs produced by our developed application modules. However, all other logs will remain raw, including the generic Kubernetes-added fields.
To create a configuration file resembling this setup, you can use the following YAML file:
filebeat.helm.values.yml
resources:
requests:
cpu: 10m
memory: 250Mi
# from https://stackoverflow.com/questions/73788395/elasticsearch-filebeat-how-to-define-multiline-in-filebeat-inputs-with-condi
filebeatConfig:
filebeat.yml: |
max_procs: 1 # default = virtual CPU count (8 in production, too much for OVH API servers)
filebeat.autodiscover:
providers:
- type: kubernetes
resource: pod # pod / service / node
scope: node # node / cluster
add_resource_metadata: # add labels and annotations from these resources
node.enabled: false
namespace.enabled: false
kube_client_options:
qps: 1
burst: 10
templates:
- condition:
or:
- equals.kubernetes.container.name: server # all our app containers have this name
- equals.kubernetes.container.name: teleport # same message start
config:
- type: container
paths:
- /var/log/containers/*-${data.kubernetes.container.id}.log
multiline:
pattern: "^[0-9]{4}-[0-9]{2}-[0-9]{2}" # starts with our date pattern
negate: true
match: after
processors:
- add_kubernetes_metadata:
host: ${NODE_NAME}
matchers:
- logs_path:
logs_path: "/var/log/containers/"
- dissect:
# searchable fields are defined here: https://www.elastic.co/guide/en/ecs/8.7/ecs-field-reference.html
# 2023-04-13T09:44:59.013Z INFO user[1f4ba76d-c76f-4d4f-bd91-453b5313708d] 1 --- [io-8080-exec-10] c.p.b.m.t.a.LyraMessageBuilder: Start LyraMessageBuilder.build(..)
tokenizer: "%{event.start} %{log.level} user[%{process.real_user.id}] %{log.syslog.msgid} --- [%{log.syslog.procid}] %{log.origin.function}: %{event.reason}"
field: "message"
target_prefix: ""
ignore_failure: true
overwrite_keys: true
trim_values: "all" # values are trimmed for leading and trailing
- condition: # other non app pods
and:
- not.equals.kubernetes.container.name: apm-server
- not.equals.kubernetes.container.name: autoscaler # kube-dns-autoscaler
- not.equals.kubernetes.container.name: aws-cluster-autoscaler
- not.equals.kubernetes.container.name: calico-node
- not.equals.kubernetes.container.name: cert-manager-webhook-ovh
- not.equals.kubernetes.container.name: coredns
- not.equals.kubernetes.container.name: csi-snapshotter
- not.equals.kubernetes.container.name: filebeat
- not.equals.kubernetes.container.name: ingress-nginx-default-backend
- not.equals.kubernetes.container.name: logstash
- not.equals.kubernetes.container.name: metricbeat
- not.equals.kubernetes.container.name: pgadmin4
- not.equals.kubernetes.container.name: server # <-- above condition
- not.equals.kubernetes.container.name: teleport # <-- above condition
- not.equals.kubernetes.container.name: wormhole
config:
- type: container
paths:
- /var/log/containers/*-${data.kubernetes.container.id}.log
processors:
- add_kubernetes_metadata:
host: ${NODE_NAME}
matchers:
- logs_path:
logs_path: "/var/log/containers/"
output.elasticsearch:
hosts: '["https://${ELASTICSEARCH_HOSTS:elasticsearch-master:9200}"]'
username: '${ELASTICSEARCH_USERNAME}'
password: '${ELASTICSEARCH_PASSWORD}'
protocol: https
ssl.certificate_authorities: ["/usr/share/filebeat/certs/ca.crt"]
A few notes on the above configuration:
- The
scope: nodeconfiguration of the Kubernetes provider is mandatory for master nodes with limited performance. While there's no difference on AWS, it becomes crucial on OVH managed clusters to ensure optimal performance. - There are two template blocks defined: one for our application and another for logs from all other applications (excluding the ones we choose to ignore).
- Multiline logs are handled using
config[0].multiline. Thenegate: truesolution proves to be the most reliable approach to address edge case issues effectively. - The tokenizer plays a crucial role in populating known Filebeat fields, enabling them to be searchable in Kibana.
Once your configuration file is ready, install Filebeat:
helm -n elk upgrade --install fb elastic/filebeat --version 8.5.1 -f filebeat.helm.values.yml
Handle logs retention in Kibana
Sooner or later, you will need to configure data retention in Elasticsearch. Elasticsearch offers a well-structured data lifecycle, ranging from Hot to Warm to Cold phases, to balance performance and CPU usage effectively.
To configure Filebeat lifecycle policies in Kibana, run this command in the Dev Tools:
PUT _ilm/policy/filebeat
{
"policy": {
"phases": {
"hot": { "actions": { "rollover": { "max_primary_shard_size": "10GB", "max_age": "7d" } } },
"delete": { "min_age": "30d", "actions": { "delete": {} } }
}
}
}
3. Technical metrics
Metrics are quantitative measurements that provide valuable numerical data about the performance and behavior of a system or application. These measurements are usually collected at regular intervals, representing various aspects such as resource utilization, response times, throughput, and error rates. Metrics enable monitoring and alerting systems to detect anomalies and deviations from expected behavior, facilitating proactive problem identification and mitigation. By visualizing metrics over time, teams can identify trends and patterns, optimize resource allocation, and make informed decisions to improve the overall system performance and user experience.
Technical metrics are handled by Metricbeat, stored by the Elasticsearch cluster, and presented by Kibana.
Display technical metrics in Kibana
Once technical metrics will be collected using next paragraph, we will be able to access default Metricbeat dashboards in Kibana, and/or create some custom ones.
Here are examples from official documentation:
Collect technical metrics with Metricbeat
Metricbeat is a lightweight shipper that you can install to periodically collect metrics.
When installed in a Kubernetes cluster, Metricbeat will automatically fetch metrics and statistics and ship them directly to Elasticsearch.
Create a configuration file resembling this:
metricbeat.helm.values.yml
daemonset:
resources:
requests:
cpu: 10m
memory: 250Mi
limits: # re-definition of chart default values
memory: 500Mi
metricbeatConfig:
metricbeat.yml:
| # test connection in pod with command 'apm-server test output'
metricbeat.modules:
- module: kubernetes
metricsets:
- node
- pod
- system
period: 1m
hosts: ["https://${HOSTNAME}:10250"]
bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
ssl.verification_mode: "none"
processors:
- add_kubernetes_metadata: ~
- module: kubernetes
enabled: true
metricsets:
- event
period: 1m
output.elasticsearch:
hosts: '["https://${ELASTICSEARCH_HOSTS:elasticsearch-master:9200}"]'
ssl.enabled: true
ssl.certificate_authorities: ["/usr/share/metricbeat/certs/ca.crt"]
username: '${ELASTICSEARCH_USERNAME}'
password: '${ELASTICSEARCH_PASSWORD}'
deployment:
enabled: true
resources:
requests:
cpu: 10m
memory: 250Mi
limits: # re-definition of chart default values
memory: 500Mi
metricbeatConfig:
metricbeat.yml: |
metricbeat.modules:
- module: kubernetes
enabled: true
metricsets:
- state_node
- state_deployment
- state_pod
period: 30s
hosts: ["${KUBE_STATE_METRICS_HOSTS}"]
output.elasticsearch:
hosts: '["https://${ELASTICSEARCH_HOSTS:elasticsearch-master:9200}"]'
ssl.enabled: true
ssl.certificate_authorities: ["/usr/share/metricbeat/certs/ca.crt"]
username: '${ELASTICSEARCH_USERNAME}'
password: '${ELASTICSEARCH_PASSWORD}'
Once your configuration file is ready, install Metricbeat:
helm -n elk upgrade --install fb elastic/metricbeat --version 8.5.1 -f metricbeat.helm.values.yml
Handle technical metrics retention in Kibana
To configure Metricbeat lifecycle policies in Kibana, you can run a command like this in the Dev Tools:
PUT _ilm/policy/metricbeat
{
"policy": {
"phases": {
"hot": { "actions": { "rollover": { "max_primary_shard_size": "10GB", "max_age": "7d" } } },
"delete": { "min_age": "30d", "actions": { "delete": {} } }
}
}
}
4. Business metrics
Business metrics, distinct from technical metrics, are key performance indicators (KPIs) that provide insights into the overall health and success of a business. These metrics focus on measuring the business's performance, growth, revenue, and customer engagement. Unlike technical metrics, which primarily assess the performance and efficiency of systems and processes, business metrics are tied directly to the organization's strategic goals and objectives. Examples of business metrics include customer acquisition cost (CAC), customer lifetime value (CLV), conversion rates, revenue growth, and customer satisfaction scores. Analyzing and tracking business metrics is essential for making informed decisions, identifying areas of improvement, and aligning business efforts to achieve long-term success and profitability.
Business metrics could be collected from data added to traces by additional development. Or they can be collected automatically from your databases.
In this section, business metrics will indeed be harvested from the application's database by Logstash, stored by the Elasticsearch cluster, and presented by Kibana.
Display business metrics in Kibana
Once business metrics will be collected using next paragraph, we will be able to create visualizations of our choice in Kibana.
Here are is an example:
Collect business metrics with Logstash
Logstash is a data processing pipeline that ingests data from a multitude of sources, transforms it, and then sends it to elasticsearch.
Logstash is capable of getting data directly from a PostGreSQL server. It is probably capable of handling multiple PostGreSQL database requests, but we decided to have on logstash process per request.
To create a configuration file resembling this setup, you can use the following YAML file:
logstash.helm.values.yml
fullnameOverride: ls-finance
logstashConfig:
logstash.yml: |
http.host: 0.0.0.0
xpack.monitoring.enabled: false
# Allows you to add any pipeline files in /usr/share/logstash/pipeline/logstash.conf
### ***warn*** there is a hardcoded logstash.conf in the image, override it first
logstashPipeline:
logstash.conf: |
input {
jdbc {
jdbc_connection_string => "jdbc:postgresql://${BACKEND_DB_HOST_PORT}/backend"
jdbc_user => "${BACKEND_DB_USER}"
jdbc_password => "${BACKEND_DB_PASSWORD}"
jdbc_driver_class => "org.postgresql.Driver"
jdbc_driver_library => "/usr/share/logstash/drivers/postgresql-42.6.0.jar"
schedule => "* * * * *"
statement => "WITH balance_aggregation as ( select id AS movement_id FROM wallet_movement)
SELECT '${NAMESPACE}' AS namespace, date_time, wm.id as movement_id, wallet_movement_type as movement_type, amount, current_balance, wallet_type, pf.email AS user_email, w.user_id, mp.name AS marketplace, pay.local_ref, w.id AS wallet_id
FROM wallet_movement wm
LEFT JOIN balance_aggregation b ON wm.id = b.movement_id
WHERE amount <> 0"
}
}
filter {
mutate {
add_field => { "kubernetes.namespace" => "%{namespace}" }
}
if [user_id] =~ /.+/ {
mutate {
add_field => { "process.real_user.id" => "%{user_id}" }
}
}
}
output {
elasticsearch {
hosts => ["https://elasticsearch-master.elk.svc.cluster.local:9200"]
user => '${ELASTICSEARCH_USERNAME}'
password => '${ELASTICSEARCH_PASSWORD}'
index => 'my-logstash-index'
document_id => '%{movement_id}'
doc_as_upsert => true
ssl_certificate_verification => false
}
}
extraEnvs:
- name: "ELASTICSEARCH_USERNAME"
valueFrom:
secretKeyRef:
name: elasticsearch-master-credentials
key: username
- name: "ELASTICSEARCH_PASSWORD"
valueFrom:
secretKeyRef:
name: elasticsearch-master-credentials
key: password
- name: BACKEND_DB_HOST_PORT
valueFrom:
secretKeyRef:
name: app-backend
key: BACKEND_DB_HOST_PORT
- name: BACKEND_DB_USER
valueFrom:
secretKeyRef:
name: app-backend
key: BACKEND_DB_USER
- name: BACKEND_DB_PASSWORD
valueFrom:
secretKeyRef:
name: app-backend
key: BACKEND_DB_PASSWORD
- name: NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
### init container and volume to be able to do:
# curl --location https://jdbc.postgresql.org/download/postgresql-42.6.0.jar --output /usr/share/logstash/lib/postgresql-42.6.0.jar
extraVolumes:
- name: postgres-driver
emptyDir: {}
extraInitContainers:
- name: init-script-downloader
image: curlimages/curl:8.00.1
args:
- --location
- --insecure
- https://jdbc.postgresql.org/download/postgresql-42.6.0.jar
- --output
- /tmp/drivers/postgresql-42.6.0.jar
volumeMounts:
- name: postgres-driver
mountPath: /tmp/drivers/
extraVolumeMounts:
- name: postgres-driver
mountPath: /usr/share/logstash/drivers/
A few notes on the above configuration:
- The
fullnameOverrideparameter let you install multiple instances, one per request - The mutation filters lets us ship fields with
.in the name, something we did not manage to do directly in the request - The default logstash image does not contain any JDBC adapter,
extraVolumes,extraVolumeMountsandextraInitContainershelps us get around that limitation
Once your configuration file is ready, install Logstash:
helm -n elk upgrade --install fb elastic/logstash --version 8.5.1 -f logstash.helm.values.yml
It will then send data every minute to Elasticsearch, overriding obsolete rows in associated index.
By default, Elasticsearch create 2 versions of a field, with and without keyword. We do not need both, we do not use searchable text in Logstash fields. For this purpose, apply this in Dev Tools / Console in Kibana:
DELETE my-logstash-index
PUT my-logstash-index
{
"mappings": {
"dynamic": "runtime"
}
}
5. Traces
Traces are detailed records of the end-to-end flow of a specific user request or transaction as it traverses through various components and services within a distributed system. These traces provide a holistic view of the entire request's journey, capturing information about service interactions, latency, and potential bottlenecks. Traces are vital for understanding the complexities of microservices architecture and identifying performance issues in distributed systems. They help in pinpointing the root cause of problems and optimizing the flow of requests, leading to better system reliability and user satisfaction. Traces are particularly valuable in environments with high interconnectivity, enabling teams to visualize and comprehend the flow of data across a vast network of services.
Traces are collected by APM Agents (depending of the technology)[https://www.elastic.co/guide/en/apm/agent/index.html]. If no agent is provided for a given technology, we can still send data using OpenTelemetry. These agents send data to the APM Server, which populate Elasticsearch. As usual, data is presented through Kibana. There are traces displayed, but also metrics, improving the observability capabilities.
Display traces and metrics in Kibana
There is a whole APM section in Kibana. You can inspect user requests with great details.
Notably, we can see trace details:
And also lots of metrics, for example:
Collect traces with APM agents and APM Server
Traces are harvested by an agent in each application module, sending data to a specific APM server, that store data in Elasticsearch.
Observing a web application, with client side rendering, the APM server has to be exposed by an ingress for the frontend part.
To create a configuration file resembling this setup, you can use the following YAML file:
apm-server.helm.values.yml
ingress:
enabled: true
annotations:
nginx.ingress.kubernetes.io/enable-access-log: "false" # too many NGINX logs
# hosts:
# - TODO # in command line
apmConfig:
apm-server.yml:
| # test connection in pod with command 'apm-server test output'
### default
queue: {}
output.elasticsearch:
hosts: ["https://elasticsearch-master:9200"] # http=>https else does not work (even with 'protocol: https')
username: "${ELASTICSEARCH_USERNAME}"
password: "${ELASTICSEARCH_PASSWORD}"
### custom
protocol: https
ssl.verification_mode: none
apm-server:
host: "0.0.0.0:8200" # default
rum.enabled: true
kibana:
enabled: true
host: http://kib-kibana:5601
protocol: "http"
username: "${ELASTICSEARCH_USERNAME}"
password: "${ELASTICSEARCH_PASSWORD}"
Note the Kibana configuration triggered directly by APM server at startup with apm-server:kibana:enabled. Note also the enable-access-log to avoid polluting NGINX ingress controller logs.
Once your configuration file is ready, install APM Server with this command, configuring the right ingress.hosts for the right environment:
helm -n elk upgrade --install apm elastic/apm-server --version 8.5.1 -f devops/k8s/apm-server.helm.values.yml --set "ingress.hosts[0]=apm.my-app.com"
Reduce traces footprint in Kibana
You will experiment a lot of space taken by APM documents. If you want to avoid unnecessary data, you can drop some documents from ingestion pipelines.
We found that data stored in metrics-apm.internal and metrics-apm.app grow very fast and are not much of use to us. You can completely ignore them by running those commands in the Kibana's Dev Tools:
PUT _ingest/pipeline/metrics-apm.internal@custom
{
"description": "remove unused internal live data",
"processors": [ { "drop": { "if" : "ctx.processor?.event == 'metric'" } } ]
}
PUT _ingest/pipeline/metrics-apm.app@custom
{
"description": "remove unused app live data",
"processors": [ { "drop": { "if" : "ctx.processor?.event == 'metric'" } } ]
}
Another optimization can be dropping some specific traces/spans. For example, if Kubernetes liveness and readiness probes have /health/ in their URL for each application modules, and you want to get rid of them, you can completely filter them out at ingestion with this command:
PUT _ingest/pipeline/traces-apm@custom
{
"description": "remove kubernetes liveness and readiness spans",
"processors": [ { "drop": { "if" : "ctx.url?.path?.contains('/health/')" } } ]
}
Handle traces retention in Kibana
PUT _ilm/policy/custom-30d
{
"policy": {
"phases": {
"hot": { "actions": { "rollover": { "max_primary_shard_size": "10GB", "max_age": "7d" } } },
"delete": { "min_age": "30d", "actions": { "delete": {} } }
}
}
}
And use it for traces-apm:
PUT _component_template/traces-apm@custom
{
"template": {
"settings": {
"lifecycle": {
"name": "custom-30d"
}
}
},
"_meta": {
"package": {
"name": "apm"
},
"managed_by": "fleet",
"managed": true
}
}
Conclusion
With this tutorial, we managed to implement the three pillars of observability for a web application on Kubernetes: logs, metrics, and traces. All using a single open-source, free integrated stack, Yet having infinite display customization at hand.
You struggle with the instruction provided ? You managed to obtain better result with another free efficient stack ? You are satisfied with your custom dashboard and want to share ? Feel free to engage discussion in below comment section 🤓.
Illustrations generated locally by Automatic1111 using MajicMixFantasy model with TeslapunkAI LoRA
Further reading
This article was enhanced with the assistance of an AI language model to ensure clarity and accuracy in the content, as English is not my native language.
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