Merge pull request #41 from guardian/aa/chat-rate-limit

fix: Handle 429 responses from Chat API

src/google.rs

@@ -1,5 +1,7 @@
 use anyhow::{Context, Result};
+use log::info;
 use serde::{Deserialize, Serialize};
+use std::time;
 use url::Url;
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -32,23 +34,49 @@ impl GoogleChatMessage {
         Ok(updated_url.as_str().to_string())
     }
 
-    pub async fn send(self, webhook_url: &str, thread_key: &str) -> Result<GoogleChatMessage> {
+    pub async fn send(
+        self,
+        webhook_url: &str,
+        thread_key: &str,
+        attempt: i32,
+    ) -> Result<GoogleChatMessage> {
+        let max_attempts = 3;
         let url = GoogleChatMessage::build_webhook_url(webhook_url, thread_key)?;
 
         let response = reqwest::Client::new()
             .post(url.to_string())
             .body(serde_json::to_string(&self)?)
             .header("User-Agent", "GU-PR-Bot")
             .send()
-            .await?
-            .text()
-            .await
-            .context(format!("Failed to get response from: {}", &webhook_url))?;
+            .await?;
 
-        serde_json::from_str(&response).context(format!(
-            "Failed to parse JSON when querying {}: {}",
-            &webhook_url, response
-        ))
+        if response
+            .status()
+            .eq(&reqwest::StatusCode::TOO_MANY_REQUESTS)
+            && attempt < max_attempts
+        {
+            /*
+            Sleep for 1.5 seconds to avoid rate limiting, at 60 requests per minute.
+            See https://developers.google.com/workspace/chat/limits
+            */
+            info!(
+                "Received {} response. Sleeping for 1.5 seconds before retrying (attempt {})",
+                response.status(),
+                attempt
+            );
+            tokio::time::sleep(time::Duration::from_millis(1500)).await;
+            Box::pin(self.send(webhook_url, thread_key, attempt + 1)).await
+        } else {
+            let response_text = response.text().await.context(format!(
+                "Failed to get response from: {} after {} attempts",
+                &webhook_url, attempt
+            ))?;
+
+            serde_json::from_str(&response_text).context(format!(
+                "Failed to parse JSON when querying {}: {}",
+                &webhook_url, response_text
+            ))
+        }
     }
 }
 

src/main.rs

@@ -189,12 +189,16 @@ async fn main() -> Result<(), Error> {
         info!("Using thread key {}", thread_key);
 
         GoogleChatMessage::from(message)
-            .send(&webhook_url, &thread_key)
+            .send(&webhook_url, &thread_key, 0)
             .await?;
 
         for pull_request in pull_requests_to_review {
+            info!(
+                "Sending message for PR {} #{}",
+                pull_request.head.repo.name, pull_request.number
+            );
             GoogleChatMessage::from(make_message(pull_request, show_pr_age))
-                .send(&webhook_url, &thread_key)
+                .send(&webhook_url, &thread_key, 0)
                 .await?;
         }
     } else {