MinIO supports multiple long term users in addition to default user created during server startup. New users can be added after server starts up, and server can be configured to deny or allow access to buckets and resources to each of these users. This document explains how to add/remove users and modify their access rights.
Use [`mc admin policy`](https://min.io/docs/minio/linux/reference/minio-mc-admin/mc-admin-policy.html) to create canned policies. Server provides a default set of canned policies namely `writeonly`, `readonly` and `readwrite`*(these policies apply to all resources on the server)*. These can be overridden by custom policies using `mc admin policy` command.
You can use policy variables in the *Resource* element and in string comparisons in the *Condition* element.
You can use a policy variable in the Resource element, but only in the resource portion of the ARN. This portion of the ARN appears after the 5th colon (:). You can't use a variable to replace parts of the ARN before the 5th colon, such as the service or account. The following policy might be attached to a group. It gives each of the users in the group full programmatic access to a user-specific object (their own "home directory") in MinIO.
If the user is authenticating using an STS credential which was authorized from OpenID connect we allow all `jwt:*` variables specified in the JWT specification, custom `jwt:*` or extensions are not supported. List of policy variables for OpenID based STS.
-`aws:CurrentTime` - This can be used for conditions that check the date and time.
-`aws:EpochTime` - This is the date in epoch or Unix time, for use with date/time conditions.
-`aws:PrincipalType` - This value indicates whether the principal is an account (Root credential), user (MinIO user), or assumed role (STS)
-`aws:SecureTransport` - This is a Boolean value that represents whether the request was sent over TLS.
-`aws:SourceIp` - This is the requester's IP address, for use with IP address conditions. If running behind Nginx like proxies, MinIO preserve's the source IP.
-`aws:UserAgent` - This value is a string that contains information about the requester's client application. This string is generated by the client and can be unreliable. You can only use this context key from `mc` or other MinIO SDKs which standardize the User-Agent string.
-`aws:username` - This is a string containing the friendly name of the current user, this value would point to STS temporary credential in `AssumeRole`ed requests, use `jwt:preferred_username` in case of OpenID connect and `ldap:username` in case of AD/LDAP. *aws:userid* is an alias to *aws:username* in MinIO.
-`aws:groups` - This is an array containing the group names, this value would point to group mappings for the user, use `jwt:groups` in case of OpenID connect and `ldap:groups` in case of AD/LDAP.