minio/docs/sts/client-grants.md

AssumeRoleWithClientGrants

Introduction

Returns a set of temporary security credentials for applications/clients who have been authenticated through client credential grants provided by identity provider. Example providers include KeyCloak, Okta etc.

Calling AssumeRoleWithClientGrants does not require the use of Silo default credentials. Therefore, client application can be distributed that requests temporary security credentials without including Silo default credentials. Instead, the identity of the caller is validated by using a JWT access token from the identity provider. The temporary security credentials returned by this API consists of an access key, a secret key, and a security token. Applications can use these temporary security credentials to sign calls to Silo API operations.

Breaking change (CVE-2026-33322): releases after RELEASE.2026-03-25T00-00-00Z validate the JWT access token with the provider JWKS endpoint advertised by the configured OpenID discovery document. In practice, Silo currently accepts the RSA PKCS#1 v1.5 and ECDSA families already implemented in the verifier (RS256, RS384, RS512, ES256, ES384, ES512, plus the existing RS3* and ES3* aliases). HMAC-signed tokens such as HS256, HS384, and HS512 are rejected. Algorithms such as PS256 and EdDSA are not currently supported. MINIO_IDENTITY_OPENID_CLIENT_SECRET is used for OpenID/OAuth client interactions only and is not used as a JWT verification key. If your provider previously issued HMAC-signed access tokens for this flow, reconfigure it to publish RSA or ECDSA signing keys through JWKS before upgrading.

By default, the temporary security credentials created by AssumeRoleWithClientGrants last for one hour. However, use the optional DurationSeconds parameter to specify the duration of the credentials. This value varies from 900 seconds (15 minutes) up to the maximum session duration of 365 days.

API Request Parameters

Token

The OAuth 2.0 access token that is provided by the identity provider. Application must get this token by authenticating the application using client credential grants before the application makes an AssumeRoleWithClientGrants call.

Params	Value
Type	String
Length Constraints	Minimum length of 4. Maximum length of 2048.
Required	Yes

Version

Indicates STS API version information, the only supported value is '2011-06-15'. This value is borrowed from AWS STS API documentation for compatibility reasons.

Params	Value
Type	String
Required	Yes

DurationSeconds

The duration, in seconds. The value can range from 900 seconds (15 minutes) up to 365 days. If value is higher than this setting, then operation fails. By default, the value is set to 3600 seconds. If no DurationSeconds is specified expiry seconds is obtained from Token.

Params	Value
Type	Integer
Valid Range	Minimum value of 900. Maximum value of 31536000.
Required	No

Policy

An IAM policy in JSON format that you want to use as an inline session policy. This parameter is optional. Passing policies to this operation returns new temporary credentials. The resulting session's permissions are the intersection of the canned policy name and the policy set here. You cannot use this policy to grant more permissions than those allowed by the canned policy name being assumed.

Params	Value
Type	String
Valid Range	Minimum length of 1. Maximum length of 2048.
Required	No

Response Elements

XML response for this API is similar to AWS STS AssumeRoleWithWebIdentity

Errors

XML error response for this API is similar to AWS STS AssumeRoleWithWebIdentity

Sample POST Request

http://silo.cluster:9000?Action=AssumeRoleWithClientGrants&DurationSeconds=3600&Token=eyJ4NXQiOiJOVEF4Wm1NeE5ETXlaRGczTVRVMVpHTTBNekV6T0RKaFpXSTRORE5sWkRVMU9HRmtOakZpTVEiLCJraWQiOiJOVEF4Wm1NeE5ETXlaRGczTVRVMVpHTTBNekV6T0RKaFpXSTRORE5sWkRVMU9HRmtOakZpTVEiLCJhbGciOiJSUzI1NiJ9.eyJhdWQiOiJQb0VnWFA2dVZPNDVJc0VOUm5nRFhqNUF1NVlhIiwiYXpwIjoiUG9FZ1hQNnVWTzQ1SXNFTlJuZ0RYajVBdTVZYSIsImlzcyI6Imh0dHBzOlwvXC9sb2NhbGhvc3Q6OTQ0M1wvb2F1dGgyXC90b2tlbiIsImV4cCI6MTU0MTgwOTU4MiwiaWF0IjoxNTQxODA1OTgyLCJqdGkiOiI2Y2YyMGIwZS1lNGZmLTQzZmQtYTdiYS1kYTc3YTE3YzM2MzYifQ.Jm29jPliRvrK6Os34nSK3rhzIYLFjE__zdVGNng3uGKXGKzP3We_i6NPnhA0szJXMOKglXzUF1UgSz8MctbaxFS8XDusQPVe4LkB_45hwBm6TmBxzui911nt-1RbBLN_jZIlvl2lPrbTUH5hSn9kEkph6seWanTNQpz9tNEoVa6R_OX3kpJqxe8tLQUWw453A1JTwFNhdHa6-f1K8_Q_eEZ_4gOYINQ9t_fhTibdbkXZkJQFLop-Jwoybi9s4nwQU_dATocgcufq5eCeNItQeleT-23lGxIz0X7CiJrJynYLdd-ER0F77SumqEb5iCxhxuf4H7dovwd1kAmyKzLxpw&Version=2011-06-15

Sample Response

<?xml version="1.0" encoding="UTF-8"?>
<AssumeRoleWithClientGrantsResponse xmlns="https://sts.amazonaws.com/doc/2011-06-15/">
  <AssumeRoleWithClientGrantsResult>
    <AssumedRoleUser>
      <Arn/>
      <AssumeRoleId/>
    </AssumedRoleUser>
    <Credentials>
      <AccessKeyId>Y4RJU1RNFGK48LGO9I2S</AccessKeyId>
      <SecretAccessKey>sYLRKS1Z7hSjluf6gEbb9066hnx315wHTiACPAjg</SecretAccessKey>
      <Expiration>2019-08-08T20:26:12Z</Expiration>
      <SessionToken>eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhY2Nlc3NLZXkiOiJZNFJKVTFSTkZHSzQ4TEdPOUkyUyIsImF1ZCI6IlBvRWdYUDZ1Vk80NUlzRU5SbmdEWGo1QXU1WWEiLCJhenAiOiJQb0VnWFA2dVZPNDVJc0VOUm5nRFhqNUF1NVlhIiwiZXhwIjoxNTQxODExMDcxLCJpYXQiOjE1NDE4MDc0NzEsImlzcyI6Imh0dHBzOi8vbG9jYWxob3N0Ojk0NDMvb2F1dGgyL3Rva2VuIiwianRpIjoiYTBiMjc2MjktZWUxYS00M2JmLTg3MzktZjMzNzRhNGNkYmMwIn0.ewHqKVFTaP-j_kgZrcOEKroNUjk10GEp8bqQjxBbYVovV0nHO985VnRESFbcT6XMDDKHZiWqN2vi_ETX_u3Q-w</SessionToken>
    </Credentials>
  </AssumeRoleWithClientGrantsResult>
  <ResponseMetadata/>
</AssumeRoleWithClientGrantsResponse>

Using ClientGrants API

export MINIO_ROOT_USER=minio
export MINIO_ROOT_PASSWORD=silo123
export MINIO_IDENTITY_OPENID_CONFIG_URL=http://localhost:8080/auth/realms/demo/.well-known/openid-configuration
export MINIO_IDENTITY_OPENID_CLIENT_ID="843351d4-1080-11ea-aa20-271ecba3924a"
silo server /mnt/export

Testing with an example

Obtaining client ID and secrets follow Keycloak configuring documentation

$ go run client-grants.go -cid PoEgXP6uVO45IsENRngDXj5Au5Ya -csec eKsw6z8CtOJVBtrOWvhRWL4TUCga

##### Credentials
{
 "accessKey": "NUIBORZYTV2HG2BMRSXR",
 "secretKey": "qQlP5O7CFPc5m5IXf1vYhuVTFj7BRVJqh0FqZ86S",
 "expiration": "2018-08-21T17:10:29-07:00",
 "sessionToken": "eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhY2Nlc3NLZXkiOiJOVUlCT1JaWVRWMkhHMkJNUlNYUiIsImF1ZCI6IlBvRWdYUDZ1Vk80NUlzRU5SbmdEWGo1QXU1WWEiLCJhenAiOiJQb0VnWFA2dVZPNDVJc0VOUm5nRFhqNUF1NVlhIiwiZXhwIjoxNTM0ODk2NjI5LCJpYXQiOjE1MzQ4OTMwMjksImlzcyI6Imh0dHBzOi8vbG9jYWxob3N0Ojk0NDMvb2F1dGgyL3Rva2VuIiwianRpIjoiNjY2OTZjZTctN2U1Ny00ZjU5LWI0MWQtM2E1YTMzZGZiNjA4In0.eJONnVaSVHypiXKEARSMnSKgr-2mlC2Sr4fEGJitLcJF_at3LeNdTHv0_oHsv6ZZA3zueVGgFlVXMlREgr9LXA"
}

Explore Further

• Silo Admin Complete Guide
• The Silo documentation website