The de_dot filter plugin is used in Logstash to replace dots in field names with underscores. This is particularly useful when working with Elasticsearch, as Elasticsearch doesn't allow dots in field names. The plugin helps ensure compatibility between your log data and Elasticsearch indexing.
Syntax
filter {
de_dot {}
}
For more details, refer to the official Logstash de_dot filter plugin documentation.
Example Use Case
Consider a scenario where you have log data with field names containing dots, which you want to index in Elasticsearch. You can use the de_dot filter to automatically convert these field names.
filter {
de_dot {
fields => ["field.with.dots", "another.dotted.field"]
nested => true
}
}
In this example, fields named "field.with.dots" and "another.dotted.field" will be renamed to "field_with_dots" and "another_dotted_field" respectively.
Common Issues and Best Practices
- Nested fields: By default, the plugin only processes top-level fields. To process nested fields, set
nested => true. - Field conflicts: Be cautious of potential field name conflicts after de-dotting. For example, "a.b" and "a_b" would both become "a_b".
- Performance: While generally lightweight, applying de_dot to a large number of fields might impact performance. Use the
fieldsoption to specify only the fields that need processing.
Frequently Asked Questions
Q: Why is the de_dot filter necessary?
A: Elasticsearch doesn't allow dots in field names. The de_dot filter ensures compatibility by replacing dots with underscores in field names before indexing in Elasticsearch.
Q: Can the de_dot filter process nested fields?
A: Yes, but you need to set nested => true in the filter configuration to process nested fields.
Q: Does the de_dot filter affect the original data?
A: The de_dot filter only changes field names within Logstash processing. It doesn't modify the original source data.
Q: Can I specify which fields to process with de_dot?
A: Yes, you can use the fields option to list specific fields you want to process, which can improve performance.
Q: Is there a way to use a different character instead of an underscore?
A: The de_dot filter specifically replaces dots with underscores. If you need a different replacement character, you might need to use a more flexible filter like the mutate filter with a rename operation.
