docs: Add note about checking the contents of configuration

This command allows an admin to flush a specific server
from the resolver caches or flush the whole cache.

changelog.d/1349.feature

@@ -0,0 +1 @@
+Introduce a resolver command to allow flushing a server from the cache or to flush the complete cache. Contributed by @Omar007

docs/reference/admin/query.md

@@ -112,6 +112,19 @@ ### `!admin query resolver overrides-cache`
 
 Query the overrides cache
 
+### `!admin query resolver flush-cache`
+
+Flush a given server from the resolver caches or flush them completely
+
+* Examples:
+  * Flush a specific server:
+
+    `!admin query resolver flush-cache matrix.example.com`
+
+  * Flush all resolver caches completely:
+
+    `!admin query resolver flush-cache --all`
+
 ## `!admin query pusher`
 
 pusher service

docs/troubleshooting.mdx

@@ -20,6 +20,16 @@ ### Lost access to admin room
 
 ## General potential issues
 
+### Configuration not working as expected
+
+Sometimes you can make a mistake in your configuration that
+means things don't get passed to Continuwuity correctly.
+This is particularly easy to do with environment variables.
+To check what configuration Continuwuity actually sees, you can
+use the `!admin server show-config` command in your admin room.
+Beware that this prints out any secrets in your configuration,
+so you might want to delete the result afterwards!
+
 ### Potential DNS issues when using Docker
 
 Docker's DNS setup for containers in a non-default network intercepts queries to

src/admin/query/resolver.rs

@@ -1,5 +1,5 @@
 use clap::Subcommand;
-use conduwuit::{Result, utils::time};
+use conduwuit::{Err, Result, utils::time};
 use futures::StreamExt;
 use ruma::OwnedServerName;
 
@@ -7,6 +7,7 @@
 
 #[admin_command_dispatch]
 #[derive(Debug, Subcommand)]
+#[allow(clippy::enum_variant_names)]
 /// Resolver service and caches
 pub enum ResolverCommand {
 	/// Query the destinations cache
@@ -18,6 +19,14 @@ pub enum ResolverCommand {
 	OverridesCache {
 		name: Option<String>,
 	},
+
+	/// Flush a specific server from the resolver caches or everything
+	FlushCache {
+		name: Option<OwnedServerName>,
+
+		#[arg(short, long)]
+		all: bool,
+	},
 }
 
 #[admin_command]
@@ -69,3 +78,18 @@ async fn overrides_cache(&self, server_name: Option<String>) -> Result {
 
 	Ok(())
 }
+
+#[admin_command]
+async fn flush_cache(&self, name: Option<OwnedServerName>, all: bool) -> Result {
+	if all {
+		self.services.resolver.cache.clear().await;
+		writeln!(self, "Resolver caches cleared!").await
+	} else if let Some(name) = name {
+		self.services.resolver.cache.del_destination(&name);
+		self.services.resolver.cache.del_override(&name);
+		self.write_str(&format!("Cleared {name} from resolver caches!"))
+			.await
+	} else {
+		Err!("Missing name. Supply a name or use --all to flush the whole cache.")
+	}
+}

src/service/admin/mod.rs

@@ -406,6 +406,10 @@ pub async fn get_admins(&self) -> Vec<OwnedUserId> {
 
 	/// Checks whether a given user is an admin of this server
 	pub async fn user_is_admin(&self, user_id: &UserId) -> bool {
+		if self.services.globals.server_user == user_id {
+			return true;
+		}
+
 		if self
 			.services
 			.server