add sha256 support to rhai

.changesets/feat_feat_sha256_in_rhai.md

@@ -0,0 +1,17 @@
+### Add support for SHA256 hashing in Rhai ([Issue #4939](https://github.com/apollographql/router/issues/4939))
+
+This adds a new `sha256` module to create SHA256 hashes within Rhai scripts. An example looks like: 
+
+```rs
+fn supergraph_service(service){
+    service.map_request(|request|{
+        log_info("hello world");
+        let sha = sha256::digest("hello world");
+        log_info(sha);
+    });
+}
+```
+
+The only function currently is `digest`. 
+
+By [@lleadbet](https://github.com/lleadbet) in https://github.com/apollographql/router/pull/4940

apollo-router/src/plugins/rhai/engine.rs

@@ -173,6 +173,17 @@ mod router_json {
     }
 }
 
+#[export_module]
+mod router_sha256 {
+    use sha2::Digest;
+
+    #[rhai_fn(pure)]
+    pub(crate) fn digest(input: &mut ImmutableString) -> String {
+        let hash = sha2::Sha256::digest(input.as_bytes());
+        hex::encode(hash)
+    }
+}
+
 #[export_module]
 mod router_expansion {
     pub(crate) type Expansion = expansion::Expansion;
@@ -1625,6 +1636,7 @@ impl Rhai {
 
         let base64_module = exported_module!(router_base64);
         let json_module = exported_module!(router_json);
+        let sha256_module = exported_module!(router_sha256);
 
         let expansion_module = exported_module!(router_expansion);
 
@@ -1651,6 +1663,8 @@ impl Rhai {
             .register_static_module("base64", base64_module.into())
             // Register our json module (not global)
             .register_static_module("json", json_module.into())
+            // Register our SHA256 module (not global)
+            .register_static_module("sha256", sha256_module.into())
             // Register our expansion module (not global)
             // Hide the fact that it is an expansion module by calling it "env"
             .register_static_module("env", expansion_module.into())

apollo-router/src/plugins/rhai/tests.rs

@@ -11,6 +11,7 @@ use http::StatusCode;
 use rhai::Engine;
 use rhai::EvalAltResult;
 use serde_json::Value;
+use sha2::Digest;
 use tower::util::BoxService;
 use tower::BoxError;
 use tower::Service;
@@ -584,6 +585,16 @@ fn it_can_generate_uuid() {
     assert_eq!(uuid_v4_rhai, uuid_parsed.to_string());
 }
 
+#[test]
+fn it_can_sha256_string() {
+    let engine = new_rhai_test_engine();
+    let hash = sha2::Sha256::digest("hello world".as_bytes());
+    let hash_rhai: String = engine
+        .eval(r#"sha256::digest("hello world")"#)
+        .expect("can decode string");
+    assert_eq!(hash_rhai, hex::encode(hash));
+}
+
 async fn base_globals_function(fn_name: &str) -> Result<bool, Box<rhai::EvalAltResult>> {
     let dyn_plugin: Box<dyn DynPlugin> = crate::plugin::plugins()
         .find(|factory| factory.name == "apollo.rhai")

docs/source/customizations/rhai-api.mdx

@@ -242,6 +242,24 @@ You don't need to import the "base64" module. It is imported in the router.
 
 </Note>
 
+## sha256 hash strings
+
+Your Rhai customization can use the function `sha256::digest()` to hash strings using the SHA256 hashing algorithm.
+
+```rhai
+fn supergraph_service(service){
+    service.map_request(|request|{
+        let sha = sha256::digest("hello world");
+        log_info(sha);
+    });
+}
+```
+<Note>
+
+You don't need to import the "sha256" module. It is imported in the router.
+
+</Note>
+
 ### Different alphabets
 
 Base64 supports multiple alphabets to encode data, depending on the supported characters where it is used. The router supports the following alphabets: