DataWeave 2.2 is compatible and bundled with Mule 4.2. Standard Support for Mule 4.2 ended on May 2, 2021, and this version of Mule will reach its End of Life on May 2, 2023, when Extended Support ends.

Deployments of new applications to CloudHub that use this version of Mule are no longer allowed. Only in-place updates to applications are permitted.

MuleSoft recommends that you upgrade to the latest version of Mule 4 that is in Standard Support so that your applications run with the latest fixes and security enhancements.

envVar(String): String | Null

Returns an environment variable with the specified name or null if the environment variable is not defined.


Name Description


Provides the name of the environment variable.


This example returns a Mac command console (SHELL) path and returns null on FAKE_ENV_VAR (an undefined environment variable). SHELL is one of the standard Mac environment variables. Also notice that the import command enables you to call the function without prepending the module name to it.


%dw 2.0
import * from dw::System
output application/json
    "envVars" : [
       "real" : envVar("SHELL"),
       "fake" : envVar("FAKE_ENV_VAR")


"envVars": [
    "real": "/bin/bash"
    "fake": null

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