remove show-config admin room command

Just `cat` the config file. Also this code would be very annoying to
maintain. Getting rid of this also revealed that another config option
is specific to RocksDB, so `cfg`s for that have been added.

src/config.rs

@@ -1,8 +1,4 @@
-use std::{
-    fmt,
-    fmt::Write,
-    net::{IpAddr, Ipv4Addr},
-};
+use std::net::{IpAddr, Ipv4Addr};
 
 use ruma::{OwnedServerName, RoomVersionId};
 use serde::Deserialize;
@@ -25,6 +21,7 @@ pub(crate) struct Config {
     pub(crate) server_name: OwnedServerName,
     pub(crate) database_backend: String,
     pub(crate) database_path: String,
+    #[cfg(feature = "rocksdb")]
     #[serde(default = "default_db_cache_capacity_mb")]
     pub(crate) db_cache_capacity_mb: f64,
     #[serde(default = "default_cache_capacity_modifier")]
@@ -88,98 +85,6 @@ pub(crate) struct TlsConfig {
     pub(crate) key: String,
 }
 
-impl fmt::Display for Config {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // Prepare a list of config values to show
-        let lines = [
-            ("Server name", self.server_name.host()),
-            ("Database backend", &self.database_backend),
-            ("Database path", &self.database_path),
-            (
-                "Database cache capacity (MB)",
-                &self.db_cache_capacity_mb.to_string(),
-            ),
-            (
-                "Cache capacity modifier",
-                &self.cache_capacity_modifier.to_string(),
-            ),
-            #[cfg(feature = "rocksdb")]
-            (
-                "Maximum open files for RocksDB",
-                &self.rocksdb_max_open_files.to_string(),
-            ),
-            ("PDU cache capacity", &self.pdu_cache_capacity.to_string()),
-            (
-                "Cleanup interval in seconds",
-                &self.cleanup_second_interval.to_string(),
-            ),
-            ("Maximum request size", &self.max_request_size.to_string()),
-            (
-                "Maximum concurrent requests",
-                &self.max_concurrent_requests.to_string(),
-            ),
-            ("Allow registration", &self.allow_registration.to_string()),
-            ("Allow encryption", &self.allow_encryption.to_string()),
-            ("Allow federation", &self.allow_federation.to_string()),
-            ("Allow room creation", &self.allow_room_creation.to_string()),
-            (
-                "JWT secret",
-                match self.jwt_secret {
-                    Some(_) => "set",
-                    None => "not set",
-                },
-            ),
-            ("Trusted servers", {
-                let mut lst = vec![];
-                for server in &self.trusted_servers {
-                    lst.push(server.host());
-                }
-                &lst.join(", ")
-            }),
-            (
-                "TURN username",
-                if self.turn_username.is_empty() {
-                    "not set"
-                } else {
-                    &self.turn_username
-                },
-            ),
-            ("TURN password", {
-                if self.turn_password.is_empty() {
-                    "not set"
-                } else {
-                    "set"
-                }
-            }),
-            ("TURN secret", {
-                if self.turn_secret.is_empty() {
-                    "not set"
-                } else {
-                    "set"
-                }
-            }),
-            ("Turn TTL", &self.turn_ttl.to_string()),
-            ("Turn URIs", {
-                let mut lst = vec![];
-                for item in self.turn_uris.iter().cloned().enumerate() {
-                    let (_, uri): (usize, String) = item;
-                    lst.push(uri);
-                }
-                &lst.join(", ")
-            }),
-        ];
-
-        let mut msg: String = "Active config values:\n\n".to_owned();
-
-        for line in lines.into_iter().enumerate() {
-            writeln!(msg, "{}: {}", line.1 .0, line.1 .1)
-                .expect("write to in-memory buffer should succeed");
-        }
-
-        write!(f, "{msg}")
-    }
-}
-
 fn false_fn() -> bool {
     false
 }
@@ -196,6 +101,7 @@ fn default_port() -> u16 {
     6167
 }
 
+#[cfg(feature = "rocksdb")]
 fn default_db_cache_capacity_mb() -> f64 {
     300.0
 }

src/service/admin.rs

@@ -156,9 +156,6 @@ enum AdminCommand {
         amount: u32,
     },
 
-    /// Show configuration values
-    ShowConfig,
-
     /// Reset user password
     ResetPassword {
         /// Username of the user for whom the password should be reset
@@ -659,13 +656,6 @@ impl Service {
 
                 RoomMessageEventContent::text_plain("Done.")
             }
-            AdminCommand::ShowConfig => {
-                // Construct and send the response
-                RoomMessageEventContent::text_plain(format!(
-                    "{}",
-                    services().globals.config
-                ))
-            }
             AdminCommand::ResetPassword {
                 username,
             } => {