API: container logs flush status code

API clients expect the status code quickly otherwise they can time out. If we do not flush we may not write the header immediately and only when futher logs are send. Fixes #23712 Signed-off-by: Paul Holzinger <[email protected]>
containers · Nov 1, 2024 · e6d9878 · e6d9878
1 parent 768ad86
commit e6d9878
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Showing 2 changed files with 15 additions and 3 deletions.
diff --git a/pkg/api/handlers/compat/containers_logs.go b/pkg/api/handlers/compat/containers_logs.go
@@ -106,6 +106,13 @@ func LogsFromContainer(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusOK)
 
+	flush := func() {
+		if flusher, ok := w.(http.Flusher); ok {
+			flusher.Flush()
+		}
+	}
+	flush()
+
 	var frame strings.Builder
 	header := make([]byte, 8)
 
@@ -167,8 +174,6 @@ func LogsFromContainer(w http.ResponseWriter, r *http.Request) {
 		if _, err := io.WriteString(w, frame.String()); err != nil {
 			log.Errorf("unable to write frame string: %q", err)
 		}
-		if flusher, ok := w.(http.Flusher); ok {
-			flusher.Flush()
-		}
+		flush()
 	}
 }
diff --git a/test/apiv2/20-containers.at b/test/apiv2/20-containers.at
@@ -150,6 +150,13 @@ podman run --name $CTRNAME -d $IMAGE sleep 25
 t GET containers/$CTRNAME/top?stream=false 200 \
   .Processes.[0].[6]="00:00:00" \
   .Processes.[0].[7]="sleep 25"
+
+# check logs output, IMPORTANT the container should write no logs to reproduce #23712
+APIV2_TEST_EXPECT_TIMEOUT=1 t GET "containers/${CTRNAME}/logs?follow=true&stdout=true&stderr=true" 999
+is "" "$(<$WORKDIR/curl.result.out)" "Container MUST NOT log output"
+like "$(<$WORKDIR/curl.headers.out)" ".*HTTP.* 200 OK.*" \
+     "Received headers from /container/<id>/logs"
+
 podman rm -f -t0 $CTRNAME
 
 CTRNAME=test123