Metadata field

As explained in Learn Docker in a Month of Lunches, Second Edition

A metadata field is a named attribute containing descriptive information about a log record, such as its application, service, or image.

A metadata field is a named attribute containing descriptive information about a log record, such as its application, service, or image. Adding these fields makes filtering in Kibana easier. section 19.4

Fluentd enriches records with metadata fields while processing container logs. The same records can then be routed to different targets, such as Elasticsearch or stdout, without changing the application. section 19.4

Figure 19.14 Fluentd uses the tag in the log to filter out records and to generate new fields.

The figure shows Fluentd using log tags to filter records and generate new metadata fields. section 19.4

Filtering and routing enriched logs

Access-log records can be filtered from Elasticsearch and echoed to stdout while retaining the same app, service, and image metadata. Changing the Fluentd configuration later sends them back to Elasticsearch without application changes. section 19.4

How Learn Docker in a Month of Lunches, Second Edition covers it

How deep it goes

Defines fields through app, service, and image examples, then demonstrates their use in Fluentd filtering and routing.

Examples

Uses app, service, and image fields, plus access-log filtering between stdout and Elasticsearch.

What you can do after

Operate/configure Fluentd to enrich records, filter access logs, and change destinations without modifying the application.

How it connects

Connects metadata fields with log records, Fluentd, Docker, tags, Kibana, Elasticsearch, stdout, and log routing.

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Related concepts

• operationpart of · An operation is an action or computation performed by or through a system, object, or interface, often producing a result or effect.
• schemacontrasts with · A data schema is a formal specification of the structure, fields, types, relationships, and constraints of data.
• attributekind of · An attribute is a named property, value, or piece of information associated with an entity, object, or program element.
• Kibanauses · Kibana is an open-source web interface for searching, analyzing, visualizing, monitoring, and dashboarding data stored in Elasticsearch.
• referenceuses · A reference is an indirect value or relationship that identifies or provides access to another value, object, resource, or source.
• metadata interfaceused by · A metadata interface is an interface that defines the information associated with an operation independently of the operation's result.

This explainer was generated by Manning's knowledge graph from the text of Learn Docker in a Month of Lunches, Second Edition. The section links point to the parts of the book it draws on.