Check if storage is working when returning the response to a faucet healthcheck request.

contracts/rust/src/bin/gen-vk-libraries.rs

@@ -18,7 +18,7 @@ use std::{fs::OpenOptions, io::prelude::*, path::PathBuf};
 
 // depth of the record merkle tree
 const TREE_DEPTH: u8 = 24;
-// list of supported tranaction types, each would result in a different verifying key
+// list of supported transaction types, each would result in a different verifying key
 const SUPPORTED_VKS: [(NoteType, u8, u8, u8); 7] = [
     (NoteType::Transfer, 1, 2, TREE_DEPTH),
     (NoteType::Transfer, 2, 2, TREE_DEPTH),

faucet/src/faucet.rs

@@ -478,6 +478,28 @@ pub struct HealthCheck {
 /// normally, a response with status 503 and payload {"status":
 /// "unavailable"} should be added.
 async fn healthcheck(req: tide::Request<FaucetState>) -> Result<tide::Response, tide::Error> {
+    // Ensure we can write to storage.
+    let mut index = req.state().queue.index.lock().await;
+    let default_user_pub_key = UserPubKey::default();
+    let res = index.insert(default_user_pub_key.clone());
+    if res.is_err() {
+        tracing::error!(
+            "Insertion of dummy public key into faucet queue index failed. {:?}",
+            res
+        );
+        return Err(faucet_server_error(res.err().unwrap()));
+    }
+
+    let res = index.remove(&default_user_pub_key);
+    if res.is_err() {
+        tracing::error!(
+            "Removal of dummy public key from faucet queue index failed. {:?}",
+            res
+        );
+        return Err(faucet_server_error(res.err().unwrap()));
+    }
+
+    // Return healthcheck response
     response(
         &req,
         &HealthCheck {