As mentioned in the previous chapter, the CIMI server also handles all of the user authentication for the cloud. The server supports the use of internal or external databases of users.

The internal database, with user records stored in Couchbase, is convenient because all information is contained within the cloud infrastructure and user records can be managed in the same way as other configuration files.

Using an external database, such as LDAP, allows the user information to be exported to other system or allows better integration of the cloud with other services in the data center. In the case of VOMS proxies, this also delegates some authority to third parties to manage the users associated with a particular Virtual Organization.


There are two aspects to the authentication configuration for a StratusLab cloud: defining the methods to be used and managing the users.

To define the authentication mechanisms for the cloud infrastructure, you must create the document “ServiceConfiguration/authn” in the Couchbase database. You can use the same web interface shown earlier to browse to the “ServiceConfiguration” collection and then to add the new document.

The document must follow the defined schema:

  "service": "authn",
      "password-enabled": true,
      "cert-enabled": false
      "password-enabled": false,
      "cert-enabled": false,
      "enabled": false

where the “service” and “localdb” fields are required (and the value for the “service” field must be “authn”!). The fields “ldap” and “voms” are optional. The details of the “ldap” map are given below.

If the configuration document does not exist, then the default is to only use the local user database with password credentials. It is recommended to always keep this method active along with at least one administrative account defined in the database.

NOTE: Enabling or disabling authentication methods requires that the CIMI service be restarted.

Adding or removing users from the system, requires changes to the local or external user databases. The details on this are given in the following sections.

NOTE: Adding, removing, or modifying users does not require restarting the CIMI service. These changes will be taken into account immediately for all future authentication actions.

You can also define “roles” for the users to either indicate group membership or rights to perform particular actions. There are three special roles ”::ADMIN”, ”::USER”, and ”::ANON”. The first confers administrative rights to the user; users with this role will have complete control over the cloud configuration. The ”::USER” role is given to anyone who has been authenticated. The ”::ANON” role is used for users that have not been authenticated.

Couchbase User Entries

You can manage users directly in the Couchbase database via the CIMI interface. There is a “User” collection and you can add, modify, and remove entries from the system with the same web browser interface you’ve used for the other resources.

The schema for user records is:

  "last-name": "required",
  "first-name": "required",
  "username": "required, must be unique",
  "password": "optional, value is bcrypt hash",
  "enabled": true,
  "roles": [ "list", "of", "roles" ],
  "altnames": {
    "x500dn": "DN of user in RFC2253 format"

If the “enabled” field is not supplied, the default value is “false”. The “password” is used only for password authentication; similarly, the “x500dn” field is only used for certificate authentication.

The schema is a “loose” one, meaning that other fields may be added if you want to track additional information. One example would be an “email” field.

Using Passwords

To use password authentication, the “localdb/password-enabled” flag must be true in the “ServiceConfiguration/authn” document. The user record for the given username must exist, must be enabled, and must have a password set.

The value of the password field is the bcrypt hash of the clear text password. See the preceeding text for generating the bcrypt hash.

Using Certificates

To use certificate authentication, the “localdb/cert-enabled” flag must be true. The field “x500dn” must exist and have the RFC2253-formatted DN of the user’s certificate. The user can use the raw certificate or a proxy generated from that certificate. The user will be identified with the value of the “username” field in the user record.

For certificate authentication to work, the SSL configuration for the Jetty server must be done. By default, the configuration for trusting the EGI Certificate Authorities is done by the stratus-install command. If you want to trust different Certificate Authorities, you must adjust the SSL configuration. See the previous chapter for what needs to be done.

LDAP User Database

To authenticate users against an LDAP database, you must have deployed and populated an LDAP server. The authentication configuration for using LDAP is quite flexible, so nearly any standard layout for the information should work.

The “ldap” field in the “ServiceConfiguration/authn” document must follow the schema:

"ldap": {
  "password-enabled": true,
  "cert-enabled": false,

  "connection": {
    "host": {
      "address": "localhost",
      "port": 389
    "ssl?": false

  "user-object-class": "inetOrgPerson",
  "user-base-dn": "ou=users,o=cloud"
  "user-id-attr": "uid",

  "role-object-class": "groupOfUniqueNames",
  "role-base-dn": "ou=groups,o=cloud",
  "role-member-attr": "uniqueMember",
  "role-name-attr": "cn",

  "skip-bind?": false,

All of the fields are required. The “connection” values provide the location of the server. The “user-” fields indicate what objects in the LDAP database are user records and the “role-” fields indicate the groups that are mapped to roles.

Using Passwords

The “skip-bind?” field indicates whether to try to bind to the database with the given user password to authenticate the user. Normally, for password authentication this should be false and the LDAP server should be setup to allow only the user to view her user record.

Using Certificates

This is not supported in the current version, but is planned for a future version.

VOMS Proxy Authentication

VOMS proxies are a mechanism by which users can delegate some rights to a third party such as a service. These proxies also convey certain rights associated with a user who belongs to a Virtual Organization. The Virtual Organization itself manages its membership, defines the rights, and allocates those rights to members.

By default, the SSL configuration of the server will be setup to allow validation of VOMS proxies according to the policies of the European Grid Infrastructure. You must use this configuration (or a similar one if you are an expert) to use VOMS proxy authentication.

To enable this, set the “voms/enabled” flag to true in the authentication configuration. You must then add a pseudo-user entry in the local database for each Virtual Organization you want to support.

An example pseudo-user entry for the “” Virtual Organization is:

  "last-name": "Virtual Organization",
  "first-name": "LAL",
  "username": "",
  "enabled": true

It is important that the username contain the “vo:” prefix to the name of the Virtual Organization that is being authorized. The entry should not have a password associated with it.

The “username” associated with users identified via VOMS proxies is the DN of their certificate. The FQANs (fully-qualified attribute names) of the VOMS certificate are mapped to roles in the StratusLab authentication.

Future Authentication Methods

The authentication framework used by StratusLab is extensible allowing different mechanisms to be incorporated fairly easily. Candidates for additional mechansims to support in the future include OAUTH2 and Shibboleth. Feedback on the desire for these (or other) mechanisms is welcome.