minio/docs/sts/ldap.md

MinIO LDAP Integration

MinIO provides a custom STS API that allows integration with LDAP based corporate environments. The flow is as follows:

1. User provides their LDAP username and password to the STS API.
2. MinIO logs-in to the LDAP server as the user - if the login succeeds the user is authenticated.
3. MinIO then queries the LDAP server for a list of groups that the user is a member of.
   • This is done via a customizable LDAP search query.
4. MinIO then generates temporary credentials for the user storing the list of groups in a cryptographically secure session token. The temporary access key, secret key and session token are returned to the user.
5. The user can now use these credentials to make requests to the MinIO server.

The administrator will associate IAM access policies with each group and if required with the user too. The MinIO server then evaluates applicable policies on a user (these are the policies associated with the groups along with the policy on the user if any) to check if the request should be allowed or denied.

Configuring LDAP on MinIO

LDAP configuration is designed to be simple for the MinIO administrator.

The full path of a user DN (Distinguished Name) (e.g. uid=johnwick,cn=users,cn=accounts,dc=minio,dc=io) is configured as a format string in the MINIO_IDENTITY_LDAP_USERNAME_FORMAT environment variable. This allows an LDAP user to not specify this whole string in the LDAP STS API. Instead the user only needs to specify the username portion (i.e. johnwick in this example) that will be substituted into the format string configured on the server.

MinIO can be configured to find the groups of a user from LDAP by specifying the MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER and MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE environment variables. When a user logs in via the STS API, the MinIO server queries the LDAP server with the given search filter and extracts the given attribute from the search results. These values represent the groups that the user is a member of. On each access MinIO applies the IAM policies attached to these groups in MinIO.

LDAP is configured via the following environment variables:

Variable	Required?	Purpose
MINIO_IDENTITY_LDAP_SERVER_ADDR	YES	LDAP server address
MINIO_IDENTITY_LDAP_USERNAME_FORMAT	YES	Format of full username DN
MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN	NO	Base DN in LDAP hierarchy to use in search requests
MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER	NO	Search filter to find groups of a user
MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE	NO	Attribute of search results to use as group name
MINIO_IDENTITY_LDAP_STS_EXPIRY_DURATION	NO (default: "1h")	STS credentials validity duration
MINIO_IDENTITY_LDAP_TLS_SKIP_VERIFY	NO (default: "false")	Disable TLS certificate verification

Please note that MinIO will only access the LDAP server over TLS.

An example setup for development or experimentation:

export MINIO_IDENTITY_LDAP_SERVER_ADDR=myldapserver.com:636
export MINIO_IDENTITY_LDAP_USERNAME_FORMAT="uid=${username},cn=accounts,dc=myldapserver,dc=com"
export MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN="dc=myldapserver,dc=com"
export MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER="(&(objectclass=groupOfNames)(member=${usernamedn}))"
export MINIO_IDENTITY_LDAP_GROUP_NAME_ATTRIBUTE="cn"
export MINIO_IDENTITY_LDAP_STS_EXPIRY_DURATION=60
export MINIO_IDENTITY_LDAP_TLS_SKIP_VERIFY=true

Variable substitution in LDAP configuration strings

In the configuration values described above, some values support runtime substitutions. The substitution syntax is simply ${variable} - this substring is replaced with the (string) value of variable. The following substitutions will be available:

Variable	Example Runtime Value	Description
username	"james"	The LDAP username of a user.
usernamedn	"uid=james,cn=accounts,dc=myldapserver,dc=com"	The LDAP username DN of a user. This is constructed from the LDAP user DN format string provided to the server and the actual LDAP username.

The MINIO_IDENTITY_LDAP_USERNAME_FORMAT environment variable supports substitution of the username variable only.

The MINIO_IDENTITY_LDAP_GROUP_SEARCH_FILTER and MINIO_IDENTITY_LDAP_GROUP_SEARCH_BASE_DN environment variables support substitution of the username and usernamedn variables only.