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Version: 8.10 (unreleased)

Evaluate an expressionAdded in 8.9

POST 
/expression/evaluation

Strongly Consistent About endpoint data consistency

Evaluates a FEEL expression and returns the result. Supports references to tenant scoped cluster variables when a tenant ID is provided. Optionally, provide a scopeKey to make the variables of a specific process instance or element instance visible while evaluating the expression.

When the expression references a secret (camunda.secrets.<name>), the endpoint never returns the resolved secret value. Instead, each reference resolves to its own literal placeholder text camunda.secrets.<name>, which composes like any other string. This changed in 8.10; previously such references evaluated to null and logged a warning:

  • =camunda.secrets.TEST now returns "camunda.secrets.TEST".
  • ="Bearer " + camunda.secrets.TEST now returns "Bearer camunda.secrets.TEST".

This placeholder mechanism is bypassed if the request-body variables include a variable literally named camunda. In that case the request-body variable takes precedence, so camunda.secrets.<name> resolves against it instead of producing a placeholder (typically evaluating to null).

Every secret reference the evaluation encountered from a trusted source is listed in the referencedSecrets array of the response. That array reports every camunda.secrets.<name> name that was referenced, whether or not a matching secret is configured: a misspelled or unconfigured name is still listed here and only surfaces as an error later, in the errors array of the follow-up POST /v2/secrets/resolve call. To obtain the actual secret values, resolve those references yourself with that endpoint (POST /v2/secrets/resolve).

For background on how the cluster resolves secret references in other contexts, such as during job activation, see Secret resolution and job activation. That page describes a different mechanism than this endpoint uses.

Required permissions​

When authorization is enabled, this endpoint requires all of the following permissions. See resources and permissions to learn more.

Resource typePermission
EXPRESSIONEVALUATE
Determined at runtimeWhen the expression is evaluated in the scope of a process instance (scopeKey resolves to an instance), additionally requires READ_PROCESS_INSTANCE on PROCESS_DEFINITION for that process. Skipped when unscoped.

Request​

Responses​

Expression evaluated successfully