Rename original_url to default for subgraph url overrides (#589)

Rename it to `default` to follow the same pattern as for timeout
expressions

Author: kamilkisiela

.changeset/rename_original_url_variable_to_default_in_subgraph_url_override_expressions.md

@@ -0,0 +1,23 @@
+---
+config: minor
+router: minor
+executor: minor
+---
+
+# Rename `original_url` variable to `default` in subgraph URL override expressions.
+
+This change aligns the variable naming with other configuration expressions, such as timeout configuration.
+
+When using expressions to override subgraph URLs, use `.default` to refer to the original URL defined in the subgraph definition.
+
+Example:
+
+```yaml
+url:
+  expression: |
+    if .request.headers."x-region" == "us-east" {
+      "https://products-us-east.example.com/graphql"
+    } else {
+      .default
+    }
+```

docs/README.md

@@ -105,7 +105,7 @@ override_subgraph_urls:
                 } else if .request.headers."x-region" == "eu-west" {
                     "https://products-eu-west.example.com/graphql"
                 } else {
-                  .original_url
+                  .default
                 }
             
 query_planner:
@@ -1691,7 +1691,7 @@ products:
               } else if .request.headers."x-region" == "eu-west" {
                   "https://products-eu-west.example.com/graphql"
               } else {
-                .original_url
+                .default
               }
           
 
@@ -1704,7 +1704,7 @@ products:
 
 |Name|Type|Description|Required|
 |----|----|-----------|--------|
-|**url**||Overrides for the URL of the subgraph.<br/><br/>For convenience, a plain string in your configuration will be treated as a static URL.<br/><br/>### Static URL Example<br/>```yaml<br/>url: "https://api.example.com/graphql"<br/>```<br/><br/>### Dynamic Expression Example<br/><br/>The expression has access to the following variables:<br/>- `request`: The incoming HTTP request, including headers and other metadata.<br/>- `original_url`: The original URL of the subgraph (from supergraph sdl).<br/><br/>```yaml<br/>url:<br/>  expression: \|<br/>    if .request.headers."x-region" == "us-east" {<br/>      "https://products-us-east.example.com/graphql"<br/>    } else if .request.headers."x-region" == "eu-west" {<br/>      "https://products-eu-west.example.com/graphql"<br/>    } else {<br/>      .original_url<br/>    }<br/>|yes|
+|**url**||Overrides for the URL of the subgraph.<br/><br/>For convenience, a plain string in your configuration will be treated as a static URL.<br/><br/>### Static URL Example<br/>```yaml<br/>url: "https://api.example.com/graphql"<br/>```<br/><br/>### Dynamic Expression Example<br/><br/>The expression has access to the following variables:<br/>- `request`: The incoming HTTP request, including headers and other metadata.<br/>- `default`: The original URL of the subgraph (from supergraph sdl).<br/><br/>```yaml<br/>url:<br/>  expression: \|<br/>    if .request.headers."x-region" == "us-east" {<br/>      "https://products-us-east.example.com/graphql"<br/>    } else if .request.headers."x-region" == "eu-west" {<br/>      "https://products-eu-west.example.com/graphql"<br/>    } else {<br/>      .default<br/>    }<br/>|yes|
 
 <a name="query_planner"></a>
 ## query\_planner: object

e2e/configs/override_subgraph_urls/override_dynamic_header.router.yaml

@@ -9,5 +9,5 @@ override_subgraph_urls:
         if .request.headers."x-accounts-port" == "4100" {
           "http://0.0.0.0:4100/accounts"
         } else {
-          .original_url
+          .default
         }

e2e/src/override_subgraph_urls.rs

@@ -43,7 +43,7 @@ mod override_subgraph_urls_e2e_tests {
     /// The router config overrides the URL for the "accounts" subgraph to point to 4100
     /// when a specific header is present.
     /// This way we can verify that the override is applied correctly.
-    /// Without the header, the request goes to 4200 and fail (thanks to `.original_url`).
+    /// Without the header, the request goes to 4200 and fail (thanks to `.default`).
     async fn should_override_subgraph_url_based_on_header_value() {
         let subgraphs_server = SubgraphsServer::start_with_port(4100).await;
         let app = init_router_from_config_file(
@@ -68,7 +68,7 @@ mod override_subgraph_urls_e2e_tests {
             "expected 1 request to accounts subgraph"
         );
 
-        // Makes the expression to evaluate to port 4200 (value of .original_url)
+        // Makes the expression to evaluate to port 4200 (value of .default)
         // which is not running, so the request fails
         let req = init_graphql_request("{ users { id } }", None);
         let resp = test::call_service(&app.app, req.to_request()).await;

lib/executor/src/executors/map.rs

@@ -237,7 +237,7 @@ impl SubgraphExecutorMap {
 
         let value = VrlValue::Object(BTreeMap::from([
             ("request".into(), client_request.into()),
-            ("original_url".into(), original_url_value),
+            ("default".into(), original_url_value),
         ]));
 
         // Resolve the expression to get an endpoint URL.

lib/router-config/src/override_subgraph_urls.rs

@@ -32,7 +32,7 @@ pub struct PerSubgraphConfig {
     ///
     /// The expression has access to the following variables:
     /// - `request`: The incoming HTTP request, including headers and other metadata.
-    /// - `original_url`: The original URL of the subgraph (from supergraph sdl).
+    /// - `default`: The original URL of the subgraph (from supergraph sdl).
     ///
     /// ```yaml
     /// url:
@@ -42,7 +42,7 @@ pub struct PerSubgraphConfig {
     ///     } else if .request.headers."x-region" == "eu-west" {
     ///       "https://products-eu-west.example.com/graphql"
     ///     } else {
-    ///       .original_url
+    ///       .default
     ///     }
     pub url: UrlOrExpression,
 }
@@ -62,7 +62,7 @@ fn override_subgraph_urls_example_1() -> OverrideSubgraphUrlsConfig {
         } else if .request.headers."x-region" == "eu-west" {
             "https://products-eu-west.example.com/graphql"
         } else {
-          .original_url
+          .default
         }
     "#;
     let mut subgraphs = HashMap::new();