camunda-feel

Camunda FEEL Expressions

Write, debug, and evaluate FEEL expressions used in Camunda 8 BPMN processes, DMN decisions, and forms.

Prerequisites

• c8ctl CLI installed and configured (c8ctl add profile) — provides c8ctl feel evaluate
• Camunda 8.9+ cluster for default cluster-engine evaluation (uses POST /v2/expression/evaluation)

Cross-References

• camunda-bpmn: Use when FEEL expressions are part of BPMN conditions or I/O mappings
• camunda-dmn: Use when FEEL appears inside DMN — input expressions, input entries (unary tests), output entries, literal expressions
• camunda-forms: Use when FEEL expressions control form validation or conditional visibility
• camunda-ai-agents: Use when FEEL expressions are prompts, fromAi() parameter declarations, or toolCallResult shaping in an AI Agent process

Instructions

FEEL in Camunda

FEEL is used for:

• Gateway conditions: Route process flow based on variable values
• Input/output mappings: Transform variables between process scopes
• Timer definitions: Define durations, dates, and cycles
• DMN decision tables: Define input/output rules
• Form validation: Validate user input

All FEEL expressions in BPMN XML must be prefixed with =:

<bpmn:conditionExpression xsi:type="bpmn:tFormalExpression">=amount &gt; 1000</bpmn:conditionExpression>

Expression Evaluation

To validate and debug FEEL expressions, use c8ctl feel evaluate. By default this runs against the configured cluster's Scala FEEL engine — the same engine that Zeebe uses at runtime, so results match production behavior exactly.

# Simple expression
c8ctl feel evaluate '1 + 2'

# Expression with individual variables (leading = optional)
c8ctl feel evaluate '=amount * 1.15' --var amount=100

# Multiple variables
c8ctl feel evaluate 'a + b' --var a=1 --var b=2

# JSON values for complex types
c8ctl feel evaluate 'sum(items)' --var 'items=[1,2,3]'

# Bulk variables as a single JSON object
c8ctl feel evaluate 'orderTotal > 1000 and customer.tier = "premium"' \
  --vars '{"orderTotal": 1500, "customer": {"tier": "premium"}}'

# Dot-path nesting on the CLI
c8ctl feel evaluate 'customer.name' --var customer.name=Alice