Elastic stack (ELK) on Docker

Run the latest version of the Elastic stack with Docker and Docker Compose.

It will give you the ability to analyze any data set by using the searching/aggregation capabilities of Elasticsearch and the visualization power of Kibana.

Based on the official Docker images from Elastic:

• elasticsearch
• logstash
• kibana

Contents

1. Requirements
   • Host setup
   • SELinux
   • Docker for Windows
2. Getting started
   • Bringing up the stack
   • Initial setup
3. Configuration
   • How can I tune the Kibana configuration?
   • How can I tune the Logstash configuration?
   • How can I tune the Elasticsearch configuration?
   • How can I scale out the Elasticsearch cluster?
4. Storage
   • How can I persist Elasticsearch data?
5. Extensibility
   • How can I add plugins?
6. JVM tuning
   • How can I specify the amount of memory used by a service?
7. Going further
   • Using a newer stack version
   • Plugins and integrations

Requirements

Host setup

1. Install Docker version 17.05+
2. Install Docker Compose version 1.6.0+
3. Clone this repository

SELinux

On distributions which have SELinux enabled out-of-the-box you will need to either re-context the files or set SELinux into Permissive mode in order for docker-elk to start properly. For example on Redhat and CentOS, the following will apply the proper context:

$ chcon -R system_u:object_r:admin_home_t:s0 docker-elk/

Docker for Windows

If you're using Docker for Windows, ensure the "Shared Drives" feature is enabled for the C: drive (Docker for Windows > Settings > Shared Drives). See Configuring Docker for Windows Shared Drives (MSDN Blog).

Usage

Bringing up the stack

Note: In case you switched branch or updated a base image - you may need to run docker-compose build first

Start the stack using docker-compose:

$ docker-compose up

You can also run all services in the background (detached mode) by adding the -d flag to the above command.

Give Kibana a few seconds to initialize, then access the Kibana web UI by hitting http://localhost:5601 with a web browser.

By default, the stack exposes the following ports:

• 5044: Logstash TCP input.
• 9200: Elasticsearch HTTP
• 9300: Elasticsearch TCP transport(Internal)
• 5601: Kibana

Filebeat monitors the log file which can be indexed and visualized through Kibana.

Initial setup

Default Kibana index pattern creation

When Kibana launches for the first time, it is not configured with any index pattern.

Via the Kibana web UI

NOTE: You need to inject data into Logstash before being able to configure a Logstash index pattern via the Kibana web UI. Then all you have to do is hit the Create button.

Refer to Connect Kibana with Elasticsearch for detailed instructions about the index pattern configuration.

On the command line

Create an index pattern via the Kibana API:

$ curl -XPOST -D- 'http://localhost:5601/api/saved_objects/index-pattern' \
    -H 'Content-Type: application/json' \
    -H 'kbn-version: 6.4.0' \
    -d '{"attributes":{"title":"logstash-*","timeFieldName":"@timestamp"}}'

The created pattern will automatically be marked as the default index pattern as soon as the Kibana UI is opened for the first time.

Configuration

NOTE: Configuration is not dynamically reloaded, you will need to restart the stack after any change in the configuration of a component.

How can I tune the Kibana configuration?

The Kibana default configuration is stored in kibana/config/kibana.yml.

It is also possible to map the entire config directory instead of a single file.

How can I tune the Logstash configuration?

The Logstash configuration is stored in logstash/config/logstash.yml. For example, you can specify pipeline settings, the location of configuration files, logging options, and other settings. However, for our purpose we do not need to modify this file. Another file stored in logstash/pipeline/logstash.conf is required to handle the logstash event pipeline based on configuration. The Logstash event processing pipeline has three stages: inputs → filters → outputs. Inputs generate events, filters modify them, and outputs ship them elsewhere.

It is also possible to map the entire config directory instead of a single file, however you must be aware that Logstash will be expecting a log4j2.properties file for its own logging.

How can I tune the Elasticsearch configuration?

The Elasticsearch configuration is stored in elasticsearch/config/elasticsearch.yml.

You can also specify the options you want to override directly via environment variables:

elasticsearch:

  environment:
    network.host: "_non_loopback_"
    cluster.name: "my-cluster"

How can I scale out the Elasticsearch cluster?

Follow the instructions from the Wiki: Scaling out Elasticsearch

Storage

How can I persist Elasticsearch data?

The data stored in Elasticsearch will be persisted after container reboot but not after container removal.

In order to persist Elasticsearch data even after removing the Elasticsearch container, you'll have to mount a volume on your Docker host. Update the elasticsearch service declaration to:

elasticsearch:

  volumes:
    - /path/to/storage:/usr/share/elasticsearch/data

This will store Elasticsearch data inside /path/to/storage.

NOTE: beware of these OS-specific considerations:

• Linux: the unprivileged elasticsearch user is used within the Elasticsearch image, therefore the mounted data directory must be owned by the uid 1000.
• macOS: the default Docker for Mac configuration allows mounting files from /Users/, /Volumes/, /private/, and /tmp exclusively. Follow the instructions from the documentation to add more locations.

Extensibility

How can I add plugins?

To add plugins to any ELK component you have to:

1. Add a RUN statement to the corresponding Dockerfile (eg. RUN logstash-plugin install logstash-filter-json)
2. Add the associated plugin code configuration to the service configuration (eg. Logstash input/output)
3. Rebuild the images using the docker-compose build command

JVM tuning

How can I specify the amount of memory used by a service?

By default, both Elasticsearch and Logstash start with 1/4 of the total host memory allocated to the JVM Heap Size.

The startup scripts for Elasticsearch and Logstash can append extra JVM options from the value of an environment variable, allowing the user to adjust the amount of memory that can be used by each component:

Service	Environment variable
Elasticsearch	ES_JAVA_OPTS
Logstash	LS_JAVA_OPTS

To accomodate environments where memory is scarce (Docker for Mac has only 2 GB available by default), the Heap Size allocation is capped by default to 256MB per service in the docker-compose.yml file. If you want to override the default JVM configuration, edit the matching environment variable(s) in the docker-compose.yml file.

For example, to increase the maximum JVM Heap Size for Logstash:

logstash:

  environment:
    LS_JAVA_OPTS: "-Xmx1g -Xms1g"

Going further

Using a newer stack version

To use a different Elastic Stack version than the one currently available in the repository, simply change the version number inside the .env file, and rebuild the stack with:

$ docker-compose build
$ docker-compose up

NOTE: Always pay attention to the upgrade instructions for each individual component before performing a stack upgrade.

Plugins and integrations

See the following Wiki pages:

• External applications
• Popular integrations