lncfg: add postgres

docs/postgres.md

@@ -0,0 +1,31 @@
+# Postgres support in LND
+
+With the introduction of the `kvdb` interface, LND can support multiple database
+backends. One of the supported backends is Postgres. This document
+describes how it can be configured.
+
+## Building LND with postgres support
+
+To build LND with postgres support, include the following build tag:
+
+```shell
+⛰  make tags="kvdb_postgres"
+```
+
+## Configuring Postgres for LND
+
+In order for LND to run on Postgres, an empty database should already exist. A
+database can be created via the usual ways (psql, pgadmin, etc). A user with
+access to this database is also required.
+
+Creation of a schema and the tables is handled by LND automatically.
+
+## Configuring LND for Postgres
+
+LND is configured for Postgres through the following configuration options:
+
+* `db.backend=postgres` to select the Postgres backend.
+* `db.postgres.dsn=...` to set the database connection string that includes
+  database, user and password.
+* `db.postgres.timeout=...` to set the connection timeout. If not set, no
+  timeout applies.