Add -defaults program option to restore from broken configurations.

construct/construct.cc

@@ -38,6 +38,7 @@ bool write_avoid;
 bool soft_assert;
 bool nomatrix;
 bool matrix {true}; // matrix server by default.
+bool defaults;
 std::vector<std::string> execute;
 std::array<bool, 7> smoketest;
 
@@ -68,6 +69,7 @@ lgetopt opts[]
 	{ "sassert",    &soft_assert,   lgetopt::BOOL,    "Softens assertion effects in debug mode."},
 	{ "nomatrix",   &nomatrix,      lgetopt::BOOL,    "Prevent loading the matrix application module."},
 	{ "matrix",     &matrix,        lgetopt::BOOL,    "Allow loading the matrix application module."},
+	{ "defaults",   &defaults,      lgetopt::BOOL,    "Use configuration defaults without database load for this execution."},
 	{ nullptr,      nullptr,        lgetopt::STRING,  nullptr },
 };
 
@@ -455,6 +457,9 @@ applyargs()
 		cmdline = true;
 	}
 
+	if(defaults)
+		ircd::defaults.set("true");
+
 	if(read_only)
 		ircd::read_only.set("true");
 

doc/TROUBLESHOOTING.md

@@ -27,6 +27,13 @@ this simply replace the '.' characters with '_' in the name of the item when
 setting it in the environment. The name is otherwise the same, including its
 lower case.
 
+Otherwise, the program can be run with the option `-defaults`. This will
+prevent initial loading of the configuration from the database. It will
+not prevent environmental variable overrides (as mentioned above). Values
+will not be written back to the database unless they are explicitly set by
+the user in the console.
+
+
 ##### Recovering from database corruption
 
 In very rare cases after a hard crash the journal cannot completely restore

include/ircd/ircd.h

@@ -111,6 +111,7 @@ namespace ircd
 	extern conf::item<bool> read_only;
 	extern conf::item<bool> write_avoid;
 	extern conf::item<bool> soft_assert;
+	extern conf::item<bool> defaults;
 
 	// Informational
 	seconds uptime();

ircd/conf.cc

@@ -16,6 +16,14 @@ decltype(ircd::conf::on_init)
 ircd::conf::on_init
 {};
 
+decltype(ircd::defaults)
+ircd::defaults
+{
+	{ "name",     "ircd.defaults" },
+	{ "default",  false           },
+	{ "persist",  false           },
+};
+
 size_t
 ircd::conf::reset()
 {

matrix/homeserver.cc

@@ -256,7 +256,7 @@ ircd::m::homeserver::homeserver(const struct opts *const &opts)
 	if(primary == this)
 		vm = std::make_shared<vm::init>();
 
-	if(primary == this && conf)
+	if(primary == this && conf && !ircd::defaults)
 		conf->load();
 
 	if(primary == this && dbs::events && sequence(*dbs::events) == 0)