DEVX-163: fix: use stderr=STDOUT to capture all docker push output in one stream

src/devx/tools/build_image.py

@@ -269,17 +269,19 @@ def _run_push(cmd: list[str]) -> subprocess.CompletedProcess[str]:
 
     Docker sends push progress/errors to both stdout and stderr depending
     on the error type, so both streams are checked for the 500 status.
+    Uses stderr=STDOUT to merge both streams into stdout, ensuring all
+    output is captured in one place (docker push output behavior varies
+    depending on TTY detection).
     """
     result = subprocess.run(  # nosec B603
         cmd,
-        capture_output=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
         text=True,
         check=False,
     )
-    if result.returncode != 0:
-        combined = f"{result.stderr}\n{result.stdout}"
-        if "500" in combined:
-            raise PushHTTP500Error(combined.strip())
+    if result.returncode != 0 and "500" in (result.stdout or ""):
+        raise PushHTTP500Error(result.stdout.strip())
     return result
 
 
@@ -334,7 +336,7 @@ def push_image(
         if result.returncode == 0:
             click.echo(f"Pushed {ft}")
             continue
-        combined_output = f"{result.stderr}\n{result.stdout}".strip()
+        combined_output = (result.stdout or "").strip()
         # Gitea #31964: push fails because tag already exists.
         # Delete the old manifest and retry once.
         if username and token and "already exists" in combined_output.lower():
@@ -350,14 +352,15 @@ def push_image(
             click.echo(f"  Retrying push {ft}...")
             result = subprocess.run(  # nosec B603
                 cmd,
-                capture_output=True,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT,
                 text=True,
                 check=False,
             )
             if result.returncode == 0:
                 click.echo(f"Pushed {ft} (after retry)")
                 continue
-            combined_output = f"{result.stderr}\n{result.stdout}".strip()
+            combined_output = (result.stdout or "").strip()
         click.echo(
             _("Push failed for {tag}: {error}", tag=ft, error=combined_output),
             err=True,

tests/unit/test_build_image.py

@@ -198,7 +198,7 @@ class TestBuildImage:
 class TestPushImage:
     def test_success(self) -> None:
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest", "1.0"])
-        mock_result = MagicMock(returncode=0, stderr="", stdout="")
+        mock_result = MagicMock(returncode=0, stdout="")
         with patch("devx.tools.build_image.subprocess.run", return_value=mock_result) as mock_run:
             assert push_image(spec, "git.example.com") is True
             assert mock_run.call_count == 2
@@ -206,8 +206,8 @@ class TestPushImage:
     def test_partial_failure(self) -> None:
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest", "1.0"])
         results = [
-            MagicMock(returncode=0, stderr="", stdout=""),
-            MagicMock(returncode=1, stderr="push failed", stdout=""),
+            MagicMock(returncode=0, stdout=""),
+            MagicMock(returncode=1, stdout="push failed"),
         ]
         with patch("devx.tools.build_image.subprocess.run", side_effect=results):
             assert push_image(spec, "git.example.com") is False
@@ -221,7 +221,7 @@ class TestPushImage:
     def test_no_delete_on_success_with_creds(self) -> None:
         """Push-first: no delete needed when push succeeds."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
-        mock_result = MagicMock(returncode=0, stderr="", stdout="")
+        mock_result = MagicMock(returncode=0, stdout="")
         with (
             patch("devx.tools.build_image.subprocess.run", return_value=mock_result),
             patch("devx.tools.build_image.delete_remote_manifest") as mock_del,
@@ -231,7 +231,7 @@ class TestPushImage:
 
     def test_no_delete_without_creds(self) -> None:
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
-        mock_result = MagicMock(returncode=0, stderr="", stdout="")
+        mock_result = MagicMock(returncode=0, stdout="")
         with (
             patch("devx.tools.build_image.subprocess.run", return_value=mock_result),
             patch("devx.tools.build_image.delete_remote_manifest") as mock_del,
@@ -243,8 +243,8 @@ class TestPushImage:
         """Gitea #31964: push fails with 'already exists', delete + retry."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
         results = [
-            MagicMock(returncode=1, stderr="package version already exists", stdout=""),
-            MagicMock(returncode=0, stderr="", stdout=""),
+            MagicMock(returncode=1, stdout="package version already exists"),
+            MagicMock(returncode=0, stdout=""),
         ]
         with (
             patch("devx.tools.build_image.subprocess.run", side_effect=results),
@@ -263,7 +263,7 @@ class TestPushImage:
     def test_no_delete_on_non_already_exists_failure(self) -> None:
         """Push fails for other reasons (non-500) — old manifest preserved."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
-        mock_result = MagicMock(returncode=1, stderr="denied: requested access to the resource is denied", stdout="")
+        mock_result = MagicMock(returncode=1, stdout="denied: requested access to the resource is denied")
         with (
             patch("devx.tools.build_image.subprocess.run", return_value=mock_result),
             patch("devx.tools.build_image.delete_remote_manifest") as mock_del,
@@ -275,8 +275,8 @@ class TestPushImage:
         """Gitea #31964 retry also fails — both pushes fail."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
         results = [
-            MagicMock(returncode=1, stderr="package version already exists", stdout=""),
-            MagicMock(returncode=1, stderr="push failed again", stdout=""),
+            MagicMock(returncode=1, stdout="package version already exists"),
+            MagicMock(returncode=1, stdout="push failed again"),
         ]
         with (
             patch("devx.tools.build_image.subprocess.run", side_effect=results),
@@ -288,8 +288,8 @@ class TestPushImage:
         """HTTP 500 from registry race condition — retry succeeds."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
         results = [
-            MagicMock(returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"),
-            MagicMock(returncode=0, stderr="", stdout=""),
+            MagicMock(returncode=1, stdout="received unexpected HTTP status: 500 Internal Server Error"),
+            MagicMock(returncode=0, stdout=""),
         ]
         with (
             patch("devx.tools.build_image.subprocess.run", side_effect=results),
@@ -302,9 +302,7 @@ class TestPushImage:
     def test_http_500_retries_all_fail(self) -> None:
         """HTTP 500 retries exhausted — push fails, no delete attempted."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
-        mock_result = MagicMock(
-            returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"
-        )
+        mock_result = MagicMock(returncode=1, stdout="received unexpected HTTP status: 500 Internal Server Error")
         with (
             patch("devx.tools.build_image.subprocess.run", return_value=mock_result),
             patch("devx.tools.build_image.delete_remote_manifest") as mock_del,
@@ -313,31 +311,20 @@ class TestPushImage:
             assert push_image(spec, "git.example.com", username="user", token="tok") is False
             mock_del.assert_not_called()
 
-    def test_run_push_raises_on_500_stderr(self) -> None:
-        """_run_push raises PushHTTP500Error when stderr contains 500."""
+    def test_run_push_raises_on_500(self) -> None:
+        """_run_push raises PushHTTP500Error when stdout contains 500."""
         from devx.tools.build_image import _run_push
 
-        mock_result = MagicMock(returncode=1, stderr="HTTP 500 Internal Server Error", stdout="")
-        with patch("devx.tools.build_image.subprocess.run", return_value=mock_result):
-            with pytest.raises(PushHTTP500Error, match="HTTP 500"):
-                _run_push(["docker", "push", "img:latest"])
-
-    def test_run_push_raises_on_500_stdout(self) -> None:
-        """_run_push raises PushHTTP500Error when stdout contains 500 (docker sends to stdout)."""
-        from devx.tools.build_image import _run_push
-
-        mock_result = MagicMock(
-            returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"
-        )
+        mock_result = MagicMock(returncode=1, stdout="received unexpected HTTP status: 500 Internal Server Error")
         with patch("devx.tools.build_image.subprocess.run", return_value=mock_result):
             with pytest.raises(PushHTTP500Error, match="500"):
                 _run_push(["docker", "push", "img:latest"])
 
     def test_run_push_no_raise_on_non_500(self) -> None:
-        """_run_push returns result when stderr has no 500."""
+        """_run_push returns result when stdout has no 500."""
         from devx.tools.build_image import _run_push
 
-        mock_result = MagicMock(returncode=1, stderr="denied: access denied", stdout="")
+        mock_result = MagicMock(returncode=1, stdout="denied: access denied")
         with patch("devx.tools.build_image.subprocess.run", return_value=mock_result):
             result = _run_push(["docker", "push", "img:latest"])
             assert result.returncode == 1
@@ -346,7 +333,7 @@ class TestPushImage:
         """_run_push returns result on success."""
         from devx.tools.build_image import _run_push
 
-        mock_result = MagicMock(returncode=0, stderr="", stdout="")
+        mock_result = MagicMock(returncode=0, stdout="")
         with patch("devx.tools.build_image.subprocess.run", return_value=mock_result):
             result = _run_push(["docker", "push", "img:latest"])
             assert result.returncode == 0