Metadata can enrich your events and make application performance monitoring even more useful. Let’s explore the different types of metadata that Elastic APM offers.

Labelsedit

Labels are used to add indexed information to transactions, spans, and errors. Indexed means the data is searchable and aggregatable in Elasticsearch. Multiple labels can be defined with different key-value pairs.

Label values can be a string, boolean, or number in APM Server 6.7+. Using this API in combination with an older APM Server version leads to validation errors. In addition, some agents only support string values at this time. Because labels for a given key, regardless of agent used, are stored in the same place in Elasticsearch, all label values of a given key must have the same data type. Multiple data types per key will throw an exception, e.g. {foo: bar} and {foo: 42}

Custom contextedit

Custom context is used to add non-indexed, custom contextual information to transactions and errors. Non-indexed means the data is not searchable or aggregatable in Elasticsearch, and you cannot build dashboards on top of the data. This also means you do not have to worry about mapping explosions, as these fields are not added to the mapping.

Non-indexed information is useful for providing contextual information to help you quickly debug performance issues or errors.

User contextedit

User context is used to add indexed user information to transactions and errors. Indexed means the data is searchable and aggregatable in Elasticsearch.