If libpq has been compiled with LDAP support (option
   --with-ldapconfigure)
   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 32.17).  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=*)