pg_keytool — derive cluster encryption key and/or send it to the PostgreSQL server
pg_keytool [option...]
pg_keytool reads either an encryption key or a
password (if the -w was specified) from standard input. If
it receives a password, it runs
the key
derivation function (KDF) on it in
order to derive the key.
The encryption key is written either to standard output (the default
behavior) or, if any of the -s, -h
or -p options is specified, sent via a frontend/backend
protocol to the PostgreSQL server during start
up.
One common use case is that pg_keytool is used
with the -K option of initdb or
pg_ctl, see the examples in
Chapter 32. In this case it sends the encryption key to
standard output.
The other use case is that PostgreSQL is started in another way than using pg_ctl, typically using systemd or a custom script. In this case, pg_keytool can be used to send the key to the server. (pg_keytool should connect to the same port or Unix-domain socket to which applications will eventually connect.)
If in the latter case you provide pg_keytool with an encryption key (as opposed to with a password), the utility only ensures transmission of the key to the database server.
-D directory
Specifies the directory where the database cluster is stored. In
particular, pg_keytool looks for
the global/kdf_params file here, see
kdf_params file.
If this option is not passed, pg_keytool
tries to get the data directory from the PGDATA
environment variable.
-h hostname--host=hostnameSpecifies the host name of the machine on which the server is running. If the value begins with a slash, it is used as the directory for the Unix-domain socket.
-p portSpecifies the TCP port or the local Unix-domain socket file extension on which the server is listening for connections. Defaults to the port specified at compile time, usually 5432.
-s
Send the key to the PostgreSQL server
rather than to standard output. This option does not have to be
specified explicitly if the
--host or --port option is
passed.
-wIf this option is given, the data read from the standard input is the password, otherwise it is the encryption key itself.