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latestOpenAPI 3.0.0Apache 2.0 License2026-07-1737274251.5 KB

Starts a state machine execution.

A qualified state machine ARN can either refer to a Distributed Map state defined within a state machine, a version ARN, or an alias ARN.

The following are some examples of qualified and unqualified state machine ARNs:

  • The following qualified state machine ARN refers to a Distributed Map state with a label mapStateLabel in a state machine named myStateMachine.

    arn:partition:states:region:account-id:stateMachine:myStateMachine/mapStateLabel

    If you provide a qualified state machine ARN that refers to a Distributed Map state, the request fails with ValidationException.

  • The following qualified state machine ARN refers to an alias named PROD.

    arn:<partition>:states:<region>:<account-id>:stateMachine:<myStateMachine:PROD>

    If you provide a qualified state machine ARN that refers to a version ARN or an alias ARN, the request starts execution for that version or alias.

  • The following unqualified state machine ARN refers to a state machine named myStateMachine.

    arn:<partition>:states:<region>:<account-id>:stateMachine:<myStateMachine>

If you start an execution with an unqualified state machine ARN, Step Functions uses the latest revision of the state machine for the execution.

To start executions of a state machine version, call StartExecution and provide the version ARN or the ARN of an alias that points to the version.

StartExecution is idempotent for STANDARD workflows. For a STANDARD workflow, if you call StartExecution with the same name and input as a running execution, the call succeeds and return the same response as the original request. If the execution is closed or if the input is different, it returns a 400 ExecutionAlreadyExists error. You can reuse names after 90 days.

StartExecution isn't idempotent for EXPRESS workflows.

post/#X-Amz-Target=AWSStepFunctions.StartExecution

Headers

X-Amz-Target'AWSStepFunctions.StartExecution' required

Request body

stateMachineArnstring required
<p>The Amazon Resource Name (ARN) of the state machine to execute.</p> <p>The <code>stateMachineArn</code> parameter accepts one of the following inputs:</p> <ul> <li> <p> <b>An unqualified state machine ARN</b> – Refers to a state machine ARN that isn't qualified with a version or alias ARN. The following is an example of an unqualified state machine ARN.</p> <p> <code>arn:&lt;partition&gt;:states:&lt;region&gt;:&lt;account-id&gt;:stateMachine:&lt;myStateMachine&gt;</code> </p> <p>Step Functions doesn't associate state machine executions that you start with an unqualified ARN with a version. This is true even if that version uses the same revision that the execution used.</p> </li> <li> <p> <b>A state machine version ARN</b> – Refers to a version ARN, which is a combination of state machine ARN and the version number separated by a colon (:). The following is an example of the ARN for version 10. </p> <p> <code>arn:&lt;partition&gt;:states:&lt;region&gt;:&lt;account-id&gt;:stateMachine:&lt;myStateMachine&gt;:10</code> </p> <p>Step Functions doesn't associate executions that you start with a version ARN with any aliases that point to that version.</p> </li> <li> <p> <b>A state machine alias ARN</b> – Refers to an alias ARN, which is a combination of state machine ARN and the alias name separated by a colon (:). The following is an example of the ARN for an alias named <code>PROD</code>.</p> <p> <code>arn:&lt;partition&gt;:states:&lt;region&gt;:&lt;account-id&gt;:stateMachine:&lt;myStateMachine:PROD&gt;</code> </p> <p>Step Functions associates executions that you start with an alias ARN with that alias and the state machine version used for that execution.</p> </li> </ul>
namestring
<p>Optional name of the execution. This name must be unique for your Amazon Web Services account, Region, and state machine for 90 days. For more information, see <a href="https://docs.aws.amazon.com/step-functions/latest/dg/limits.html#service-limits-state-machine-executions"> Limits Related to State Machine Executions</a> in the <i>Step Functions Developer Guide</i>.</p> <p>If you don't provide a name for the execution, Step Functions automatically generates a universally unique identifier (UUID) as the execution name.</p> <p>A name must <i>not</i> contain:</p> <ul> <li> <p>white space</p> </li> <li> <p>brackets <code>&lt; &gt; { } [ ]</code> </p> </li> <li> <p>wildcard characters <code>? *</code> </p> </li> <li> <p>special characters <code>" # % \ ^ | ~ ` $ &amp; , ; : /</code> </p> </li> <li> <p>control characters (<code>U+0000-001F</code>, <code>U+007F-009F</code>, <code>U+FFFE-FFFF</code>)</p> </li> <li> <p>surrogates (<code>U+D800-DFFF</code>)</p> </li> <li> <p>invalid characters (<code> U+10FFFF</code>)</p> </li> </ul> <p>To enable logging with CloudWatch Logs, the name should only contain 0-9, A-Z, a-z, - and _.</p>
inputstring password
<p>The string that contains the JSON input data for the execution, for example:</p> <p> <code>"{\"first_name\" : \"Alejandro\"}"</code> </p> <note> <p>If you don't include any JSON input data, you still must include the two braces, for example: <code>"{}"</code> </p> </note> <p>Length constraints apply to the payload size, and are expressed as bytes in UTF-8 encoding.</p>
traceHeaderstring
<p>Passes the X-Ray trace header. The trace header can also be passed in the request payload.</p> <note> <p> For X-Ray traces, all Amazon Web Services services use the <code>X-Amzn-Trace-Id</code> header from the HTTP request. Using the header is the preferred mechanism to identify a trace. <code>StartExecution</code> and <code>StartSyncExecution</code> API operations can also use <code>traceHeader</code> from the body of the request payload. If <b>both</b> sources are provided, Step Functions will use the <b>header value</b> (preferred) over the value in the request body. </p> </note>

Response

Success

executionArnstring required

The Amazon Resource Name (ARN) that identifies the execution.

startDatestring date-time required

The date the execution is started.