Improve shim debug logging

- Add log statements in service entry points.
- Propagate `-debug` flag from shim invokation to the service
- Load options when shim process is invoked to ensure runsc commands
  use the correct set of options, e.g. --debug --debug-logs=...
- Add debug options to the shim configuration directly, so it doesn't
  rely on containerd configuration (and restart) to enable shim debug.
- Save shim logs to dedicated file, so it's easier to read logs. They
  would be mixed with containerd logs and hard to distinguish
  otherwise.

PiperOrigin-RevId: 342179868

1 files changed, 48 insertions, 0 deletions

diff --git a/pkg/shim/v2/state.go b/pkg/shim/v2/state.go
new file mode 100644
index 000000000..1f4be33d3
--- /dev/null
+++ b/pkg/shim/v2/state.go
@@ -0,0 +1,48 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v2
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"path/filepath"
+)
+
+const filename = "state.json"
+
+// state holds information needed between shim invocations.
+type state struct {
+	// Rootfs is the full path to the location rootfs was mounted.
+	Rootfs string `json:"rootfs"`
+
+	// Options is the configuration loaded from config.toml.
+	Options options `json:"options"`
+}
+
+func (s state) load(path string) error {
+	data, err := ioutil.ReadFile(filepath.Join(path, filename))
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(data, &s)
+}
+
+func (s state) save(path string) error {
+	data, err := json.Marshal(&s)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(filepath.Join(path, filename), data, 0644)
+}