## 34.17. LDAP Lookup of Connection Parameters

If libpq has been compiled with LDAP support (option ``--with-ldap`` for `configure`) it is possible to retrieve connection options like `host` or `dbname` via LDAP from a central server. The advantage is that if the connection parameters for a database change, the connection information doesn't have to be updated on all client machines.

LDAP connection parameter lookup uses the connection service file `pg_service.conf` (see Section 34.16). A line in a `pg_service.conf` stanza that starts with `ldap://` will be recognized as an LDAP URL and an LDAP query will be performed. The result must be a list of `keyword = value` pairs which will be used to set connection options. The URL must conform to RFC 1959 and be of the form

    ldap://[hostname[:port]]/search_base?attribute?search_scope?filter

where `hostname` defaults to `localhost` and `port` defaults to 389.

Processing of `pg_service.conf` is terminated after a successful LDAP lookup, but is continued if the LDAP server cannot be contacted. This is to provide a fallback with further LDAP URL lines that point to different LDAP servers, classical `keyword = value` pairs, or default connection options. If you would rather get an error message in this case, add a syntactically incorrect line after the LDAP URL.

A sample LDAP entry that has been created with the LDIF file

    version:1
    dn:cn=mydatabase,dc=mycompany,dc=com
    changetype:add
    objectclass:top
    objectclass:device
    cn:mydatabase
    description:host=dbserver.mycompany.com
    description:port=5439
    description:dbname=mydb
    description:user=mydb_user
    description:sslmode=require

might be queried with the following LDAP URL:

    ldap://ldap.mycompany.com/dc=mycompany,dc=com?description?one?(cn=mydatabase)

You can also mix regular service file entries with LDAP lookups. A complete example for a stanza in `pg_service.conf` would be:

    # only host and port are stored in LDAP, specify dbname and user explicitly
    [customerdb]
    dbname=customer
    user=appuser
    ldap://ldap.acme.com/cn=dbserver,cn=hosts?pgconnectinfo?base?(objectclass=*)