feat: single connection to either mqtt service or core mqtt and not both

Connecting to Cumulocity now establishes a single MQTT connection
either to the the core MQTT endpoint or the MQTT service, but not both.
Connecting to MQTT service requires SmartREST proxy to be enabled on it,
so that messaging over SmartREST and JSON over MQTT still works.

Author: albinsuresh

Cargo.lock

@@ -0,0 +1,2 @@
+pub const MQTT_CORE_TLS_PORT: u16 = 8883;
+pub const MQTT_SVC_TLS_PORT: u16 = 9883;

crates/common/tedge_config/src/tedge_toml/models/c8y.rs

@@ -1,6 +1,7 @@
 pub mod apt_config;
 pub mod auth_method;
 pub mod auto;
+pub mod c8y;
 pub mod c8y_software_management;
 pub mod connect_url;
 pub mod cryptoki;
@@ -24,10 +25,10 @@ use strum::Display;
 
 pub const HTTPS_PORT: u16 = 443;
 pub const MQTT_TLS_PORT: u16 = 8883;
-pub const MQTT_SVC_TLS_PORT: u16 = 9883;
 
 pub use self::apt_config::*;
 pub use self::auto::*;
+pub use self::c8y::*;
 pub use self::c8y_software_management::*;
 pub use self::connect_url::*;
 pub use self::cryptoki::Cryptoki;

crates/common/tedge_config/src/tedge_toml/models/mod.rs

@@ -20,7 +20,6 @@ use super::models::SoftwareManagementApiFlag;
 use super::models::TemplatesSet;
 use super::models::TopicPrefix;
 use super::models::HTTPS_PORT;
-use super::models::MQTT_SVC_TLS_PORT;
 use super::models::MQTT_TLS_PORT;
 use super::tedge_config_location::TEdgeConfigLocation;
 use crate::models::AbsolutePath;
@@ -474,20 +473,9 @@ define_tedge_config! {
             #[tedge_config(example = "true", default(value = false))]
             enabled: bool,
 
-            /// MQTT service endpoint for the Cumulocity tenant, with optional port.
-            #[tedge_config(example = "mqtt.your-tenant.cumulocity.com:9883")]
-            #[tedge_config(default(from_optional_key = "c8y.mqtt"))]
-            url: HostPort<MQTT_SVC_TLS_PORT>,
-
-            /// The topic prefix that will be used for the Cumulocity MQTT service endpoint connection.
-            /// For instance, if set to "c8y-mqtt", then messages published to `c8y-mqtt/xyz`
-            /// will be forwarded to the MQTT service endpoint on the `xyz` topic
-            #[tedge_config(example = "c8y-mqtt", default(function = "c8y_mqtt_service_topic_prefix"))]
-            topic_prefix: TopicPrefix,
-
             /// Set of MQTT topics the bridge should subscribe to on the Cumulocity MQTT service endpoint
             #[tedge_config(example = "incoming/topic,another/topic,test/topic")]
-            #[tedge_config(default(value = "$demo/$error"))]
+            #[tedge_config(default(function = "TemplatesSet::default"))]
             topics: TemplatesSet,
         }
     },
@@ -1218,16 +1206,6 @@ fn c8y_topic_prefix() -> TopicPrefix {
     TopicPrefix::try_new("c8y").unwrap()
 }
 
-fn c8y_mqtt_service_topic_prefix() -> TopicPrefix {
-    TopicPrefix::try_new("c8y-mqtt").unwrap()
-}
-
-impl From<HostPort<MQTT_TLS_PORT>> for HostPort<MQTT_SVC_TLS_PORT> {
-    fn from(value: HostPort<MQTT_TLS_PORT>) -> Self {
-        HostPort::try_from(value.host().to_string()).expect("Source hostname must have been valid")
-    }
-}
-
 fn az_topic_prefix() -> TopicPrefix {
     TopicPrefix::try_new("az").unwrap()
 }

crates/common/tedge_config/src/tedge_toml/tedge_config.rs

@@ -40,7 +40,6 @@ impl_append_remove_for_single_value!(
     ConnectUrl,
     HostPort<HTTPS_PORT>,
     HostPort<MQTT_TLS_PORT>,
-    HostPort<MQTT_SVC_TLS_PORT>,
     bool,
     IpAddr,
     u16,

crates/common/tedge_config/src/tedge_toml/tedge_config/append_remove.rs

@@ -77,6 +77,7 @@ mockall = { workspace = true }
 mockito = { workspace = true }
 mqtt_tests = { workspace = true }
 predicates = { workspace = true }
+pretty_assertions = { workspace = true }
 rcgen = { workspace = true }
 tedge_config = { workspace = true, features = ["test"] }
 tedge_test_utils = { workspace = true }