brokerd: config, [gateway] socket for Mattermost approvals

crates/brokerd/src/config.rs

@@ -45,6 +45,14 @@ impl Default for Approvals {
     }
 }
 
+/// `[gateway]`: where `gatewayd` takes approvals to post in Mattermost. Without the section,
+/// Mattermost approvals are off and only `bxctl` answers. An empty path means the default.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Default)]
+#[serde(deny_unknown_fields, default)]
+pub struct Gateway {
+    pub socket: PathBuf,
+}
+
 fn default_podman() -> PathBuf {
     PathBuf::from("podman")
 }
@@ -129,6 +137,8 @@ pub struct Config {
     pub approvals: Approvals,
     #[serde(default)]
     pub runner: Option<Runner>,
+    #[serde(default)]
+    pub gateway: Option<Gateway>,
 }
 
 /// The longest an approval may wait: a day, the longest `loopd` waits after a pending frame.
@@ -262,6 +272,15 @@ impl Config {
             self.sockets.admin.clone()
         }
     }
+    /// `gateway.sock`, when `[gateway]` is set.
+    pub fn gateway_socket(&self) -> Option<PathBuf> {
+        let gateway = self.gateway.as_ref()?;
+        if gateway.socket.as_os_str().is_empty() {
+            Some(self.paths.home.join("run/gateway/gateway.sock"))
+        } else {
+            Some(gateway.socket.clone())
+        }
+    }
     pub fn audit_dir(&self) -> PathBuf {
         self.paths.home.join("audit")
     }