From af214078fd067f578d393665c451ae3f9af2401e Mon Sep 17 00:00:00 2001
From: Amaury Chamayou <amchamay@microsoft.com>
Date: Fri, 27 Oct 2023 14:35:00 +0100
Subject: [PATCH] Add a GET /node/primary (#5793)

---
 CHANGELOG.md                  |  1 +
 doc/schemas/node_openapi.json | 15 ++++++++++++++-
 src/node/rpc/node_frontend.h  | 26 +++++++++++++++++++++++---
 tests/e2e_common_endpoints.py |  6 ++++++
 4 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a902d5817451..1cff406895ac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 - In governance contexts, JS runtimes now only use runtime limits from the [public:ccf.gov.js_runtime_options map](https://microsoft.github.io/CCF/main/audit/builtin_maps.html#js-runtime-options) if they are strictly higher than the defaults (#5730).
 - Fixed an issue where a JS runtime limit could be hit out of user code execution, leading to an incorrectly constructed JS runtime or a crash (#5730).
+- Added a GET /node/primary endpoint, returning 200 when primary and 404 when not, for load balancers to use (#5789).
 
 ## [5.0.0-dev4]
 
diff --git a/doc/schemas/node_openapi.json b/doc/schemas/node_openapi.json
index a16c6d677bbe..b55e5a87c82f 100644
--- a/doc/schemas/node_openapi.json
+++ b/doc/schemas/node_openapi.json
@@ -905,7 +905,7 @@
   "info": {
     "description": "This API provides public, uncredentialed access to service and node state.",
     "title": "CCF Public Node API",
-    "version": "4.6.0"
+    "version": "4.7.0"
   },
   "openapi": "3.0.0",
   "paths": {
@@ -1365,6 +1365,19 @@
       }
     },
     "/node/primary": {
+      "get": {
+        "responses": {
+          "200": {
+            "description": "Default response description"
+          },
+          "default": {
+            "$ref": "#/components/responses/default"
+          }
+        },
+        "x-ccf-forwarding": {
+          "$ref": "#/components/x-ccf-forwarding/never"
+        }
+      },
       "head": {
         "responses": {
           "200": {
diff --git a/src/node/rpc/node_frontend.h b/src/node/rpc/node_frontend.h
index 4bd2de5577c4..7324792227be 100644
--- a/src/node/rpc/node_frontend.h
+++ b/src/node/rpc/node_frontend.h
@@ -383,7 +383,7 @@ namespace ccf
       openapi_info.description =
         "This API provides public, uncredentialed access to service and node "
         "state.";
-      openapi_info.document_version = "4.6.0";
+      openapi_info.document_version = "4.7.0";
     }
 
     void init_handlers() override
@@ -1232,7 +1232,7 @@ namespace ccf
         .set_auto_schema<void, GetNode::Out>()
         .install();
 
-      auto is_primary = [this](auto& args) {
+      auto head_primary = [this](auto& args) {
         if (this->node_operation.can_replicate())
         {
           args.rpc_ctx->set_response_status(HTTP_STATUS_OK);
@@ -1276,7 +1276,27 @@ namespace ccf
         }
       };
       make_read_only_endpoint(
-        "/primary", HTTP_HEAD, is_primary, no_auth_required)
+        "/primary", HTTP_HEAD, head_primary, no_auth_required)
+        .set_forwarding_required(endpoints::ForwardingRequired::Never)
+        .install();
+
+      auto get_primary = [this](auto& args) {
+        if (this->node_operation.can_replicate())
+        {
+          args.rpc_ctx->set_response_status(HTTP_STATUS_OK);
+          return;
+        }
+        else
+        {
+          args.rpc_ctx->set_error(
+            HTTP_STATUS_NOT_FOUND,
+            ccf::errors::ResourceNotFound,
+            "Node is not primary");
+          return;
+        }
+      };
+      make_read_only_endpoint(
+        "/primary", HTTP_GET, get_primary, no_auth_required)
         .set_forwarding_required(endpoints::ForwardingRequired::Never)
         .install();
 
diff --git a/tests/e2e_common_endpoints.py b/tests/e2e_common_endpoints.py
index 7272a61ba4f4..ceda583b1f6c 100644
--- a/tests/e2e_common_endpoints.py
+++ b/tests/e2e_common_endpoints.py
@@ -17,6 +17,8 @@ def test_primary(network, args):
     with primary.client() as c:
         r = c.head("/node/primary")
         assert r.status_code == http.HTTPStatus.OK.value
+        r = c.get("/node/primary")
+        assert r.status_code == http.HTTPStatus.OK.value
 
     backup = network.find_any_backup()
     for interface_name in backup.host.rpc_interfaces.keys():
@@ -31,6 +33,10 @@ def test_primary(network, args):
             LOG.info(
                 f'Successfully redirected to {r.headers["location"]} on primary {primary.local_node_id}'
             )
+            r = c.get("/node/primary", allow_redirects=False)
+            assert r.status_code == http.HTTPStatus.NOT_FOUND.value, r
+            assert r.body.json()["error"]["code"] == "ResourceNotFound"
+            assert r.body.json()["error"]["message"] == "Node is not primary"
     return network