Coalesce

The Coalesce processor consolidates fields that arrive under different names into one standard field. You give it an ordered list of places a value might live, and the first non-empty source populates the target.

Supported Telemetry Types

Logs	Metrics	Traces
✓	✓	✓

The processor runs only on the signals you select in Choose Telemetry Type. Each selected signal is configured independently in its own section.

Configuration

Basic Configuration

You give the processor an ordered list of source fields and a single field to write the first non-empty value to.

Parameter	Type	Required	Default	Description
Choose Telemetry Type	Telemetry Selector	No	(none)	The signals (Logs, Metrics, Traces) this processor applies to. Each selected signal is configured in its own section.
Condition	OTTL Condition	No	(empty)	An OTTL condition that must be true for the processor to run. Empty applies it to every record of the selected signal.
Coalesce From (priority order)	Source rows	Yes	—	The ordered list of source fields. At least one is required. Each row picks a context and a field key; the first non-empty source populates the target. Drag to reorder.
Coalesce To	Enum	Yes	Attributes	Where the result is written: Attributes or Body. Logs only; Metrics and Traces always write to attributes.
Attributes Field / Body Field	OTTL Field	Yes	(empty)	The single field that receives the coalesced value. Which one shows depends on Coalesce To.

Source Contexts by Signal

Signal	Available source contexts
Logs	body, attributes, resource
Metrics	attributes, resource
Traces	attributes, resource

body is offered for Logs only. Metrics and Traces have no body, and they always write the result to attributes (no Coalesce To choice).

Examples

Normalizing a timestamp that arrives under several names

A timestamp may show up as attributes["time"], body["ts"], or resource.attributes["event.time"] depending on the source. Listing all three in priority order coalesces them into a single attributes["timestamp"]: the processor checks each in order and writes the first non-empty one, leaving the target untouched once it is set.

Normalize severity fields on logs

Severity may arrive as body["sev"], body["severity"], or body["level"]. Listing them in priority order coalesces the first non-empty one into attributes["severity"], only on records whose body is a map.

apiVersion: bindplane.observiq.com/v1
kind: Processor
metadata:
  name: coalesce-severity
spec:
  type: coalesce_v2
  parameters:
    - name: telemetry_types
      value:
        - Logs
    - name: log_condition
      value: IsMap(body)
    - name: log_sources
      value:
        - context: body
          key: sev
        - context: body
          key: severity
        - context: body
          key: level
    - name: to_log_base
      value: Attributes
    - name: to_log_attributes
      value: severity

Configuration Tips

Order is priority

• The list is evaluated top to bottom and the first non-empty source wins, so put the most authoritative source first. Once the target is populated, later sources are ignored for that record.
• An empty Coalesce From list is rejected; add at least one source.

Troubleshooting

The target field isn't being populated

Symptoms: Records pass through and the target field stays empty.

Solutions:

1. Confirm at least one source in the list actually resolves on the record (right context, exact key).
2. Check that the target field isn't already set upstream; coalesce only writes when the target is empty.
3. If a Condition is set, confirm it evaluates true for the records you expect to transform.

Standalone Processor

apiVersion: bindplane.observiq.com/v1
kind: Processor
metadata:
  name: coalesce-timestamp
spec:
  type: coalesce_v2
  parameters:
    - name: telemetry_types
      value:
        - Logs
    - name: log_sources
      value:
        - context: attributes
          key: time
        - context: body
          key: ts
        - context: resource
          key: event.time
    - name: to_log_base
      value: Attributes
    - name: to_log_attributes
      value: timestamp

What Changed in This Version

This replaces the original Coalesce processor, which is now deprecated. Existing configurations keep using the deprecated processor until you migrate.

• First non-empty wins. The original applied each source in order with an action that defaulted to upsert, so the last non-empty source overwrote the target (last-wins). The v2 writes the first non-empty source instead (SQL COALESCE semantics) and leaves the target untouched once set.
• Multiple locations in one list. Sources can mix body, attributes, and resource in a single priority-ordered list, instead of coalescing from a single base.
• Reorderable. Sources can be dragged to set priority order.

Related Resources

• OTTL set function

Bindplane Resources

• Concat processor