cli: Add command line option to specify the wallet location

Will be demuxed into starting the selected DB backend in one of the next
commits. Defaults to the old database location.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

doc/lightningd-config.5

@@ -149,6 +149,12 @@ is a relative path, it is relative to the starting directory, not
 readable (we allow missing files in the default case)\. Using this inside
 a configuration file is meaningless\.
 
+
+ \fBwallet\fR=\fIDSN\fR
+Identify the location of the wallet\. This is a fully qualified data source
+name, including a scheme such as \fBsqlite3\fR or \fBpostgres\fR followed by the
+connection parameters\.
+
 .SH Lightning node customization options
 
  \fBalias\fR=\fIRRGGBB\fR

doc/lightningd-config.5.md

@@ -128,6 +128,11 @@ is a relative path, it is relative to the starting directory, not
 readable (we allow missing files in the default case). Using this inside
 a configuration file is meaningless.
 
+ **wallet**=*DSN*
+Identify the location of the wallet. This is a fully qualified data source
+name, including a scheme such as `sqlite3` or `postgres` followed by the
+connection parameters.
+
 ### Lightning node customization options
 
  **alias**=*RRGGBB*

lightningd/lightningd.h

@@ -228,6 +228,8 @@ struct lightningd {
 	const char *original_directory;
 
 	struct plugins *plugins;
+
+	char *wallet_dsn;
 };
 
 /* Turning this on allows a tal allocation to return NULL, rather than aborting.

lightningd/options.c

@@ -808,6 +808,11 @@ static void handle_minimal_config_opts(struct lightningd *ld,
 			       opt_ignore_talstr, opt_show_charp,
 			       &ld->config_dir,
 			       "Set working directory. All other files are relative to this");
+
+	ld->wallet_dsn = tal_fmt(ld, "sqlite3://%s/lightningd.sqlite3", ld->config_dir);
+	opt_register_early_arg("--wallet", opt_set_talstr, NULL,
+			       &ld->wallet_dsn,
+			       "Location of the wallet database.");
 }
 
 static void register_opts(struct lightningd *ld)