The Environment filter plugin allows you to access environment variables within your Logstash configuration. This plugin is particularly useful when you need to incorporate dynamic values or sensitive information that shouldn't be hardcoded into your configuration files.
Syntax
filter {
environment {
add_field => { "field_name" => "${ENV_VARIABLE}" }
}
}
For more details, refer to the official Logstash Environment filter plugin documentation.
Example Use Case
Suppose you want to add a field to your events that contains the name of the environment (e.g., "production", "staging", "development") in which Logstash is running. You could set an environment variable DEPLOY_ENV on your system and use the Environment filter to add it to your events:
filter {
environment {
add_field => { "deployment_environment" => "${DEPLOY_ENV}" }
}
}
Common Issues and Best Practices
- Ensure that the environment variables you're trying to access are actually set in the environment where Logstash is running.
- Be cautious about using environment variables for sensitive information, as they might be visible to other processes or users on the same system.
- Remember that changes to environment variables require a restart of Logstash to take effect.
- Use meaningful names for your environment variables to maintain clarity in your configuration.
Frequently Asked Questions
Q: Can I use the Environment filter to access system-wide environment variables?
A: Yes, the Environment filter can access any environment variable that is available to the Logstash process, including system-wide variables.
Q: What happens if an environment variable I'm trying to access doesn't exist?
A: If the environment variable doesn't exist, the field will be created with an empty string as its value.
Q: Can I use the Environment filter to set environment variables?
A: No, the Environment filter can only read environment variables. It cannot set or modify them.
Q: Is it possible to use environment variables in other parts of the Logstash configuration?
A: Yes, you can use environment variables in other parts of your Logstash configuration using the ${VAR_NAME} syntax, without needing the Environment filter.
Q: How often does the Environment filter check for changes in environment variables?
A: The Environment filter reads environment variables when Logstash starts up. Changes to environment variables during runtime will not be reflected unless Logstash is restarted.
