system service --log-level=trace: support hijack

When the service is running with trace log level it wraps the
`http.ResponseWriter` to log extra information. The problem is that the
new type does not keep all the functions from the embedded type.
Instead we have to implement them ourselves, however only Write() was
implemented. Thus `Hijack()`could not be called on the writer. To
prevent these issues we would implement all the interfaces that the
inner type supports (Header, WriteHeader, Flush, Hijack).

Fixes #17749

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

pkg/api/server/handler_logging.go

@@ -1,7 +1,10 @@
 package server
 
 import (
+	"bufio"
+	"errors"
 	"io"
+	"net"
 	"net/http"
 	"time"
 
@@ -33,6 +36,28 @@ func (l responseWriter) Write(b []byte) (int, error) {
 	return l.ResponseWriter.Write(b)
 }
 
+func (l responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	if wrapped, ok := l.ResponseWriter.(http.Hijacker); ok {
+		return wrapped.Hijack()
+	}
+
+	return nil, nil, errors.New("ResponseWriter does not support hijacking")
+}
+
+func (l responseWriter) Header() http.Header {
+	return l.ResponseWriter.Header()
+}
+
+func (l responseWriter) WriteHeader(statusCode int) {
+	l.ResponseWriter.WriteHeader(statusCode)
+}
+
+func (l responseWriter) Flush() {
+	if wrapped, ok := l.ResponseWriter.(http.Flusher); ok {
+		wrapped.Flush()
+	}
+}
+
 func loggingHandler() mux.MiddlewareFunc {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

test/system/251-system-service.bats

@@ -69,3 +69,22 @@ function teardown() {
 
     systemctl stop $SERVICE_NAME
 }
+
+# Regression test for https://github.com/containers/podman/issues/17749
+@test "podman-system-service --log-level=trace should be able to hijack" {
+    skip_if_remote "podman system service unavailable over remote"
+
+    port=$(random_free_port)
+    URL=tcp://127.0.0.1:$port
+
+    systemd-run --unit=$SERVICE_NAME $PODMAN --log-level=trace system service $URL --time=0
+    wait_for_port 127.0.0.1 $port
+
+    out=o-$(random_string)
+    cname=c-$(random_string)
+    run_podman --url $URL run --name $cname $IMAGE echo $out
+    assert "$output" == "$out" "service is able to hijack and stream output back"
+
+    run_podman --url $URL rm $cname
+    systemctl stop $SERVICE_NAME
+}