app: Move the admin server into a subcrate (#1028)

The proxy's admin server is split across `linkerd/app` and
`linkerd/app/core/` -- with the former implementing the stack and the
latter implementing the HTTP server.

This change unifies these modules into `linkerd/app/admin`, which is no
longer needed to compile the inbound and outbound proxies. The admin
crate has a dependency on the inbound crate, as they currently share
target types.

Author: olix0r

Cargo.lock

@@ -629,6 +629,7 @@ dependencies = [
  "futures",
  "indexmap",
  "ipnet",
+ "linkerd-app-admin",
  "linkerd-app-core",
  "linkerd-app-gateway",
  "linkerd-app-inbound",
@@ -644,14 +645,30 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "linkerd-app-admin"
+version = "0.1.0"
+dependencies = [
+ "futures",
+ "html-escape",
+ "http",
+ "hyper",
+ "linkerd-app-core",
+ "linkerd-app-inbound",
+ "serde_json",
+ "thiserror",
+ "tokio",
+ "tower",
+ "tracing",
+]
+
 [[package]]
 name = "linkerd-app-core"
 version = "0.1.0"
 dependencies = [
  "bytes",
  "drain",
  "futures",
- "html-escape",
  "http",
  "http-body",
  "hyper",

Cargo.toml

@@ -6,6 +6,7 @@ resolver = "2"
 members = [
     "hyper-balance",
     "linkerd/addr",
+    "linkerd/app/admin",
     "linkerd/app/core",
     "linkerd/app/gateway",
     "linkerd/app/inbound",

linkerd/app/Cargo.toml

@@ -18,6 +18,7 @@ allow-loopback = ["linkerd-app-outbound/allow-loopback"]
 futures = "0.3.15"
 indexmap = "1.0"
 ipnet = "2.0"
+linkerd-app-admin = { path = "./admin" }
 linkerd-app-core = { path = "./core" }
 linkerd-app-gateway = { path = "./gateway" }
 linkerd-app-inbound = { path = "./inbound" }

linkerd/app/admin/Cargo.toml

@@ -0,0 +1,34 @@
+[package]
+name = "linkerd-app-admin"
+version = "0.1.0"
+authors = ["Linkerd Developers <cncf-linkerd-dev@lists.cncf.io>"]
+license = "Apache-2.0"
+edition = "2018"
+publish = false
+description = """
+The linkerd proxy's admin server.
+"""
+
+[dependencies]
+html-escape = "0.2"
+http = "0.2"
+hyper = { version = "0.14", features = ["http1", "http2"] }
+futures = "0.3"
+linkerd-app-core = { path = "../core" }
+linkerd-app-inbound = { path = "../inbound" }
+serde_json = "1"
+thiserror = "1"
+tokio = { version = "1", features = ["macros", "sync", "parking_lot"]}
+tracing = "0.1"
+
+[dependencies.tower]
+version = "0.4"
+default-features = false
+features = [
+    "buffer",
+    "make",
+    "spawn-ready",
+    "timeout",
+    "util",
+]
+

linkerd/app/admin/src/lib.rs

@@ -0,0 +1,8 @@
+#![deny(warnings, rust_2018_idioms)]
+#![forbid(unsafe_code)]
+
+mod server;
+mod stack;
+
+pub use self::server::{Admin, Latch, Readiness};
+pub use self::stack::{Config, Task};

linkerd/app/core/src/admin/level.rs renamed to linkerd/app/admin/src/server/level.rs

@@ -2,8 +2,7 @@ use hyper::{
     body::{Buf, HttpBody},
     Body,
 };
-use linkerd_error::Error;
-use linkerd_tracing::level::Handle;
+use linkerd_app_core::{trace::level::Handle, Error};
 use std::io;
 
 pub(super) async fn serve<B>(

linkerd/app/core/src/admin/mod.rs renamed to linkerd/app/admin/src/server/mod.rs

@@ -10,15 +10,17 @@
 //!   tracing configuration).
 //! * `POST /shutdown` -- shuts down the proxy.
 
-use crate::{proxy::http::ClientHandle, svc, trace};
 use futures::future;
 use http::StatusCode;
 use hyper::{
     body::{Body, HttpBody},
     Request, Response,
 };
-use linkerd_error::Error;
-use linkerd_metrics::{self as metrics, FmtMetrics};
+use linkerd_app_core::{
+    metrics::{self as metrics, FmtMetrics},
+    proxy::http::ClientHandle,
+    svc, trace, Error,
+};
 use std::{
     future::Future,
     net::SocketAddr,

linkerd/app/core/src/admin/readiness.rs renamed to linkerd/app/admin/src/server/readiness.rs

@@ -1,6 +1,5 @@
 use hyper::Body;
-use linkerd_error::Error;
-use linkerd_tracing::TaskList;
+use linkerd_app_core::{trace::TaskList, Error};
 use std::fmt::Write;
 
 pub(super) fn serve<B>(

linkerd/app/core/src/admin/tasks.rs renamed to linkerd/app/admin/src/server/tasks.rs

@@ -1,19 +1,16 @@
-use crate::core::{
-    admin, classify,
+use linkerd_app_core::{
+    classify,
     config::ServerConfig,
     detect, drain, errors,
     metrics::{self, FmtMetrics},
+    proxy::{http, identity::LocalCrtKey},
     serve,
     svc::{self, Param},
     tls, trace,
     transport::{listen::Bind, ClientAddr, Local, Remote, ServerAddr},
     Error,
 };
-use crate::{
-    http,
-    identity::LocalCrtKey,
-    inbound::target::{HttpAccept, Target, TcpAccept},
-};
+use linkerd_app_inbound::target::{HttpAccept, Target, TcpAccept};
 use std::{pin::Pin, time::Duration};
 use thiserror::Error;
 use tokio::sync::mpsc;
@@ -25,9 +22,9 @@ pub struct Config {
     pub metrics_retain_idle: Duration,
 }
 
-pub struct Admin {
+pub struct Task {
     pub listen_addr: Local<ServerAddr>,
-    pub latch: admin::Latch,
+    pub latch: crate::Latch,
     pub serve: Pin<Box<dyn std::future::Future<Output = ()> + Send + 'static>>,
 }
 
@@ -42,7 +39,7 @@ struct UnexpectedSni(tls::ServerId, Remote<ClientAddr>);
 // === impl Config ===
 
 impl Config {
-    #[allow(clippy::clippy::too_many_arguments)]
+    #[allow(clippy::too_many_arguments)]
     pub fn build<B, R>(
         self,
         bind: B,
@@ -52,7 +49,7 @@ impl Config {
         trace: trace::Handle,
         drain: drain::Watch,
         shutdown: mpsc::UnboundedSender<()>,
-    ) -> Result<Admin, Error>
+    ) -> Result<Task, Error>
     where
         R: FmtMetrics + Clone + Send + Sync + Unpin + 'static,
         B: Bind<ServerConfig>,
@@ -62,8 +59,8 @@ impl Config {
 
         let (listen_addr, listen) = bind.bind(&self.server)?;
 
-        let (ready, latch) = admin::Readiness::new();
-        let admin = admin::Admin::new(report, ready, shutdown, trace);
+        let (ready, latch) = crate::server::Readiness::new();
+        let admin = crate::server::Admin::new(report, ready, shutdown, trace);
         let admin = svc::stack(admin)
             .push(metrics.http_endpoint.to_layer::<classify::Response, _>())
             .push_on_response(
@@ -137,7 +134,7 @@ impl Config {
             .into_inner();
 
         let serve = Box::pin(serve::serve(listen, admin, drain.signaled()));
-        Ok(Admin {
+        Ok(Task {
             listen_addr,
             latch,
             serve,