Fix Admin Config model and documentation (#218)

Update the model and documentation for the Admin interface to match, and
provide defaulting.

Next will be the implementation of the `Admin` functionality, and pulling
it out of `Metrics`.

Work on #101

docs/proxy-configuration.md

@@ -29,18 +29,13 @@ properties:
   admin:
     type: object
     description: |
-      Configuration of operational proxy behavior.
+      Configuration of proxy admin HTTP interface.
     properties:
-      metrics:
-      type: object
+      address:
+      type: string
       description: |
-        Metrics related configuration.
-      properties:
-        port:
-          type: integer
-          description: |
-            Port on which to expose metrics.
-          default: 9091
+        Socket Address and port to bind the administration interface to.
+      default: [::]:9091
   static:
     type: object
     description: |

src/config/builder.rs

@@ -15,20 +15,22 @@
  */
 
 use super::{Config, Filter};
-use crate::config::{EndPoint, Proxy, Source, Version};
+use crate::config::{Admin, EndPoint, Proxy, Source, Version};
 
 /// Builder for a [`Config`]
 #[derive(Debug)]
 pub struct Builder {
     pub port: u16,
     pub source: Source,
+    pub admin: Admin,
 }
 
 impl Builder {
     /// Returns a [`Builder`] with empty values.
     pub fn empty() -> Self {
         Builder {
             port: 0,
+            admin: Admin::default(),
             source: Source::Static {
                 filters: vec![],
                 endpoints: vec![],
@@ -52,7 +54,7 @@ impl Builder {
                 id: "test".into(),
                 port: self.port,
             },
-            admin: None,
+            admin: self.admin,
             source: self.source,
             phantom: None,
         }

src/config/mod.rs

@@ -69,13 +69,16 @@ impl Default for Proxy {
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
-pub struct AdminAddress {
-    port: u16,
+pub struct Admin {
+    pub address: SocketAddr,
 }
 
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub struct Admin {
-    address: Option<AdminAddress>,
+impl Default for Admin {
+    fn default() -> Self {
+        Admin {
+            address: "[::]:9091".parse().unwrap(),
+        }
+    }
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
@@ -106,7 +109,8 @@ pub struct Config {
     #[serde(default)]
     pub proxy: Proxy,
 
-    pub admin: Option<Admin>,
+    #[serde(default)]
+    pub admin: Admin,
 
     #[serde(flatten)]
     pub source: Source,

src/proxy/builder.rs

@@ -45,7 +45,7 @@ pub(super) enum ValidatedSource {
 pub(super) struct ValidatedConfig {
     pub version: Version,
     pub proxy: Proxy,
-    pub admin: Option<Admin>,
+    pub admin: Admin,
     pub source: ValidatedSource,
     // Limit struct creation to the builder.
     pub phantom: PhantomData<()>,