My first task here was to set up a working Tripleo installation (which I did, using this, with some modifications). Next, add an LDAP backed domain to Keystone.

In general, I followed blog posts to add LDAP backing to a domain I created named freeipa. This is meant to document where I deviated from the posts I followed.

Quick one-liner on what Keystone is: Keystone is the OpenStack service that handles the authentication and authorization for the other services, like Glance, Nova, etc. By default, Keystone is backed by SQL. What if we want a specific domain in Keystone to be backed by a different driver, like LDAP?

Using Identity API v3 in Keystone

Before we start changing configuration values to tell Keystone to use LDAP, we must start by changing the API version. This is essential, because Identity v2 does not support multiple domains. To do that, use the script from this post. The script changes the environment variable OS_IDENTITY_API_VERSION in your rc files to be 3, instead of 2.

Enabling domain specific backends

Edit the values in the [identity] block indicated below to enable domain specific backends in /etc/keystone/keystone.conf.

domain_specific_drivers_enabled = true
domain_config_dir = /etc/keystone/domains

This is telling Keystone two things:
1. domains can have specific drivers (i.e., one domain backed by LDAP and another backed by SQL)
2. check under /etc/keystone/domains for any specific domain configuration files.

Now, make a directory domains under /etc/keystone. Note that this directory, and all files in it need to belong to the keystone user. Use chown to fix any issues.

Keystone will look in this directory for any domain specific config files, and they should be of the format keystone.x.conf, where x is the name of the domain we are configuring.

See the posts below in Resources for what the config file should look like. After you are finished editing your domain specific config file, we must restart httpd (instead of openstack-keystone) to pick up the changes. Use sudo systemctl restart httpd.service.


Adding an LDAP backed domain to a Packstack install
Getting service users out of LDAP
Kerberos and Devstack