Logstash Comprehensive Tutorial

Introduction to Logstash

Logstash is an open-source, server-side data processing pipeline that ingests data from multiple sources simultaneously, transforms it, and then sends it to a "stash" like Elasticsearch. It is a core component of the Elastic Stack, which also includes Elasticsearch, Kibana, and Beats.

Installation

To install Logstash, follow these steps:

After extracting the Logstash package, you can run Logstash from the command line.

Basic Configuration

Logstash uses configuration files to specify the pipeline. A configuration file consists of three sections: input, filter, and output.

input {
    stdin {}
}

filter {
    grok {
        match => { "message" => "%{WORD:word} %{NUMBER:number}" }
    }
}

output {
    stdout { codec => rubydebug }
}
                

In this example, the input is taken from the standard input (stdin), a grok filter is applied to parse the input, and the output is sent to the standard output (stdout) in a readable format.

Running Logstash

To run Logstash with the given configuration file, use the following command:

Logstash will read the configuration file and start processing data according to the defined pipeline.

Input Plugins

Logstash supports various input plugins to collect data from different sources. Common input plugins include:

• File
• Syslog
• Beats
• HTTP

Example configuration for file input:

input {
    file {
        path => "/path/to/your/logfile.log"
        start_position => "beginning"
    }
}
                

Filter Plugins

Filter plugins are used to transform and parse data. Some common filter plugins are:

• Grok
• Mutate
• Date
• GeoIP

Example configuration for grok filter:

filter {
    grok {
        match => { "message" => "%{COMBINEDAPACHELOG}" }
    }
}
                

Output Plugins

Output plugins send the processed data to various destinations. Common output plugins include:

• Elasticsearch
• File
• Stdout
• HTTP

Example configuration for Elasticsearch output:

output {
    elasticsearch {
        hosts => ["localhost:9200"]
        index => "logstash-%{+YYYY.MM.dd}"
    }
}
                

Advanced Configuration

Logstash allows for advanced configurations including conditionals, multiple pipelines, and use of environment variables.

Example of using conditionals:

filter {
    if [type] == "syslog" {
        grok {
            match => { "message" => "%{SYSLOGLINE}" }
        }
    } else if [type] == "apache" {
        grok {
            match => { "message" => "%{COMBINEDAPACHELOG}" }
        }
    }
}
                

Monitoring Logstash

Logstash provides various monitoring APIs and can be integrated with monitoring tools like Kibana to track the performance and health of the Logstash instance.

To enable monitoring, you can configure the monitoring settings in the logstash.yml file.

Conclusion

Logstash is a powerful tool for collecting, transforming, and forwarding data. By understanding its configuration syntax and utilizing its various plugins, you can effectively manage and process your data pipelines in an edge computing environment.