Improved log interface performance and streaming

This commit enhances the log interface by reducing lag and improving the
rendering speed. It introduces a feature to load the logs for the past day
first and logs are now streamed in real-time from backend, ensuring
immediate access to new logs. Additionally, a download button that
downloads all logs since container was started is now made available
at the top of the logs dialog.

api/Cargo.toml

@@ -13,6 +13,7 @@ path = "src/main.rs"
 
 [dependencies]
 async-trait = "0.1"
+async-stream = "0.3"
 base64 = "0.21"
 boa_engine = "0.17"
 bytesize = { version = "1.3", features = ["serde"] }

api/res/openapi.yml

@@ -246,12 +246,20 @@ paths:
           example: '2019-07-22T08:42:47-00:00'
         - in: query
           name: limit
-          description: The number of log lines to retrieve. If not present, 1000 lines will be retrieved.
+          description: The number of log lines to retrieve. If not present, all the lines from `since` are retrieved.
           schema:
             type: integer
+        - in: query
+          name: asAttachment
+          description: >-
+            Determines how the response is presented by the browser. When `true`, the response content is provided as a downloadable attachment.
+            If `false` or not provided, the response is displayed inline.
+          schema:
+            type: boolean
       responses:
         '200':
-          description: The available log statements
+          description: | 
+            The available log statements. MIME type `text/event-stream` supports streaming of logs.
           headers:
             Link:
               schema:

api/src/apps/mod.rs

@@ -36,6 +36,8 @@ use crate::models::{AppName, AppStatusChangeId, LogChunk, ServiceConfig};
 use crate::registry::Registry;
 use crate::registry::RegistryError;
 use chrono::{DateTime, FixedOffset};
+use futures::stream::BoxStream;
+use futures::StreamExt;
 use handlebars::RenderError;
 pub use host_meta_cache::new as host_meta_crawling;
 pub use host_meta_cache::HostMetaCache;
@@ -349,22 +351,38 @@ impl AppsService {
         }
     }
 
-    pub async fn get_logs(
-        &self,
-        app_name: &AppName,
-        service_name: &str,
-        since: &Option<DateTime<FixedOffset>>,
-        limit: usize,
+    pub async fn stream_logs<'a>(
+        &'a self,
+        app_name: &'a AppName,
+        service_name: &'a str,
+        since: &'a Option<DateTime<FixedOffset>>,
+        limit: &'a Option<usize>,
+    ) -> BoxStream<'a, Result<(DateTime<FixedOffset>, String), failure::Error>> {
+        self.infrastructure
+            .get_logs(app_name, service_name, since, limit, true)
+            .await
+    }
+
+    pub async fn get_logs<'a>(
+        &'a self,
+        app_name: &'a AppName,
+        service_name: &'a str,
+        since: &'a Option<DateTime<FixedOffset>>,
+        limit: &'a Option<usize>,
     ) -> Result<Option<LogChunk>, AppsServiceError> {
-        match self
+        let mut log_lines = Vec::new();
+        let mut log_stream = self
             .infrastructure
-            .get_logs(app_name, service_name, since, limit)
-            .await?
-        {
-            None => Ok(None),
-            Some(ref logs) if logs.is_empty() => Ok(None),
-            Some(logs) => Ok(Some(LogChunk::from(logs))),
+            .get_logs(app_name, service_name, since, limit, false)
+            .await;
+
+        while let Some(result) = log_stream.next().await {
+            if let Ok(log_line) = result {
+                log_lines.push(log_line);
+            }
         }
+
+        Ok(Some(LogChunk::from(log_lines)))
     }
 
     pub async fn change_status(
@@ -683,7 +701,7 @@ mod tests {
         .await?;
 
         let log_chunk = apps
-            .get_logs(&app_name, &String::from("service-a"), &None, 100)
+            .get_logs(&app_name, &String::from("service-a"), &None, &Some(100))
             .await
             .unwrap()
             .unwrap();
@@ -709,6 +727,58 @@ Log msg 3 of service-a of app master
         Ok(())
     }
 
+    #[tokio::test]
+    async fn should_stream_logs_from_infrastructure() -> Result<(), AppsServiceError> {
+        let config = Config::default();
+        let infrastructure = Box::new(Dummy::new());
+        let apps = AppsService::new(config, infrastructure)?;
+
+        let app_name = AppName::from_str("master").unwrap();
+        let services = vec![sc!("service-a"), sc!("service-b")];
+        apps.create_or_update(&app_name, &AppStatusChangeId::new(), None, &services)
+            .await?;
+        for service in services {
+            let mut log_stream = apps
+                .stream_logs(&app_name, service.service_name(), &None, &None)
+                .await;
+
+            assert_eq!(
+                log_stream.next().await.unwrap().unwrap(),
+                (
+                    DateTime::parse_from_rfc3339("2019-07-18T07:25:00.000000000Z").unwrap(),
+                    format!(
+                        "Log msg 1 of {} of app {app_name}\n",
+                        service.service_name()
+                    )
+                )
+            );
+
+            assert_eq!(
+                log_stream.next().await.unwrap().unwrap(),
+                (
+                    DateTime::parse_from_rfc3339("2019-07-18T07:30:00.000000000Z").unwrap(),
+                    format!(
+                        "Log msg 2 of {} of app {app_name}\n",
+                        service.service_name()
+                    )
+                )
+            );
+
+            assert_eq!(
+                log_stream.next().await.unwrap().unwrap(),
+                (
+                    DateTime::parse_from_rfc3339("2019-07-18T07:35:00.000000000Z").unwrap(),
+                    format!(
+                        "Log msg 3 of {} of app {app_name}\n",
+                        service.service_name()
+                    )
+                )
+            );
+        }
+
+        Ok(())
+    }
+
     #[tokio::test]
     async fn should_deploy_companions() -> Result<(), AppsServiceError> {
         let config = config_from_str!(