The MinIO Security Token Service (STS) AssumeRoleWithWebIdentity API endpoint generates temporary access credentials using a JSON Web Token (JWT) returned from a configured OpenID IDentity Provider (IDP). This page documents the MinIO server AssumeRoleWithWebIdentity endpoint. For instructions on implementing STS using an S3-compatible SDK, defer to the documentation for that SDK.

The MinIO STS AssumeRoleWithWebIdentity API endpoint is modeled after the AWS AssumeRoleWithWebIdentity endpoint and shares certain request/response elements. This page documents the MinIO-specific syntax and links out to the AWS reference for all shared elements.

Request Endpoint

The AssumeRoleWithWebIdentity endpoint has the following form:


The following example uses all supported arguments. Replace the hostname with the appropriate URL for your MinIO cluster:


Request Query Parameters

This endpoint supports the following query parameters:







Specify the JSON Web Token (JWT) returned by the configured OpenID IDentity Provider.




Specify 2011-06-15.




Specify the number of seconds after which the temporary credentials expire. Defaults to 3600.

  • The minimum value is 900 or 15 minutes.

  • The maximum value is 604800 or 7 days.

If DurationSeconds is omitted, MinIO checks the JWT token for an exp claim before using the default duration. See RFC 7519 4.1.4: Expiration Time Claim for more information on JSON web token expiration.




Specify the URL-encoded JSON-formatted policy to use as an inline session policy.

  • The minimum string length is 1.

  • The maximum string length is 2048.

The resulting permissions for the temporary credentials are the intersection between the policy specified as part of the JWT claim and the specified inline policy. Applications can only perform those operations for which they are explicitly authorized.

The inline policy can specify a subset of permissions allowed by the policy specified in the JWT claim. Applications can never assume more privileges than those specified in the JWT claim policy.

Omit to use only the JWT claim policy.

See Access Management for more information on MinIO authentication and authorization.




The role Amazon Resource Number (ARN) to use for all user authentication requests. If used, there must be a matching OIDC RolePolicy defined for the RoleArn’s provider by the role_policy configuration parameter or the MINIO_IDENTITY_OPENID_ROLE_POLICY environment variable.

When used, all valid authorization requests assume the same set of permissions provided by the RolePolicy. You can use OpenID Policy Variables to create policies that programmatically manage what each individual user has access to.

If you do not supply a RoleArn, MinIO attempts to authorize through a JWT-based claim.

Response Elements

The XML response for this API endpoint is similar to the AWS AssumeRoleWithWebIdentity response. Specifically, MinIO returns an AssumeRoleWithWebIdentityResult object, where the AssumedRoleUser.Credentials object contains the temporary credentials generated by MinIO:

  • AccessKeyId - The access key applications use for authentication.

  • SecretKeyId - The secret key applications use for authentication.

  • Expiration - The ISO-8601 date-time after which the credentials expire.

  • SessionToken - The session token applications use for authentication. Some SDKs may require this field when using temporary credentials.

The following example is similar to the response returned by the MinIO STS AssumeRoleWithWebIdentity endpoint:

<?xml version="1.0" encoding="UTF-8"?>
<AssumeRoleWithWebIdentityResponse xmlns="">

Error Elements

The XML error response for this API endpoint is similar to the AWS AssumeRoleWithWebIdentity response.