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Unify logging with slog #161
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,236 @@ | ||
| /* | ||
| Copyright The containerd Authors. | ||
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| 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 | ||
|
|
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| http://www.apache.org/licenses/LICENSE-2.0 | ||
|
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| 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. | ||
| */ | ||
|
|
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| // Package logging provides unified structured logging utilities for the | ||
| // shim and vminitd components. | ||
| package logging | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "context" | ||
| "encoding/json" | ||
| "io" | ||
| "log/slog" | ||
| "os" | ||
| "strings" | ||
| "time" | ||
|
|
||
| "github.com/containerd/log" | ||
| ) | ||
|
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| // SetupShimLog configures slog-based logging for the shim process. | ||
| // It opens the platform-specific log output (FIFO on Unix, named pipe | ||
| // on Windows), then creates a slog TextHandler and sets it as the | ||
| // default logger with a "component=shim" attribute. | ||
| // | ||
| // The base handler (without component) is stored for use by | ||
| // [ForwardConsoleLogs] so that forwarded records carry their own | ||
| // component rather than inheriting "shim". | ||
| // | ||
| // For the short-lived start and delete actions, only [log.UseSlog] is | ||
| // called to route logrus through slog; the log output is not opened. | ||
| func SetupShimLog() { | ||
| log.UseSlog() | ||
|
|
||
| var ( | ||
| debug bool | ||
| ns string | ||
| id string | ||
| attrs []slog.Attr | ||
| ) | ||
| args := os.Args[1:] | ||
| for i := 0; i < len(args); i++ { | ||
| switch args[i] { | ||
| case "start", "delete": | ||
| return | ||
| case "-debug": | ||
| debug = true | ||
| case "-namespace": | ||
| if i+1 < len(args) { | ||
| i++ | ||
| ns = args[i] | ||
| attrs = append(attrs, slog.String("ns", ns)) | ||
| } | ||
| case "-id": | ||
| if i+1 < len(args) { | ||
| i++ | ||
| id = args[i] | ||
| attrs = append(attrs, slog.String("id", id)) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| w := openShimLog(ns, id) | ||
|
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| var level slog.LevelVar | ||
| if debug { | ||
| level.Set(slog.LevelDebug) | ||
| log.SetLevel("debug") //nolint:errcheck | ||
| } | ||
|
|
||
| handler := slog.NewTextHandler(w, &slog.HandlerOptions{Level: &level}).WithAttrs(attrs) | ||
| SetBaseHandler(handler) | ||
| slog.SetDefault(slog.New(handler).With("component", "shim")) | ||
| } | ||
|
|
||
| // baseHandler is the slog handler used by ForwardConsoleLogs to emit | ||
| // records without the caller's pre-applied attributes (e.g. component=shim). | ||
| var baseHandler slog.Handler | ||
|
|
||
| // SetBaseHandler stores the base handler for use by ForwardConsoleLogs. | ||
| // This should be called before any console forwarding starts, typically | ||
| // during init with the handler before any .With() attributes are applied. | ||
| func SetBaseHandler(h slog.Handler) { | ||
| baseHandler = h | ||
| } | ||
|
|
||
| // consoleHandler returns the handler that ForwardConsoleLogs should use. | ||
| // It prefers the base handler set via SetBaseHandler, falling back to | ||
| // the default slog handler. | ||
| func consoleHandler() slog.Handler { | ||
| if baseHandler != nil { | ||
| return baseHandler | ||
| } | ||
| return slog.Default().Handler() | ||
| } | ||
|
|
||
| // ForwardConsoleLogs reads lines from r and re-emits them as structured | ||
| // log entries through the base [slog.Handler] set via [SetBaseHandler]. | ||
| // | ||
| // Lines that are valid JSON objects (emitted by vminitd's JSON slog handler) | ||
| // are parsed and re-emitted preserving the original level, message, | ||
| // and attributes. All other lines are treated as kernel messages and emitted | ||
| // at INFO level with component=kmsg. | ||
| // | ||
| // The base handler is used directly (rather than the default logger) so that | ||
| // pre-applied attributes such as component=shim are not added to forwarded | ||
| // records, which carry their own component. | ||
| // | ||
| // If raw is non-nil, every line is also written there verbatim (useful for | ||
| // tests that need the unprocessed console output). | ||
| func ForwardConsoleLogs(r io.Reader, raw io.Writer) { | ||
| scanner := bufio.NewScanner(r) | ||
| for scanner.Scan() { | ||
| line := scanner.Text() | ||
|
|
||
| if raw != nil { | ||
| raw.Write([]byte(line)) | ||
| raw.Write([]byte("\n")) | ||
| } | ||
|
|
||
| if line == "" { | ||
| continue | ||
| } | ||
|
|
||
| if strings.HasPrefix(line, "{") { | ||
| if forwardJSONLog(line) { | ||
| continue | ||
| } | ||
| } | ||
|
|
||
| // Kernel message — parse optional "[ 1.234567] " timestamp prefix. | ||
| msg := line | ||
| attrs := []slog.Attr{slog.String("component", "kmsg")} | ||
| if after, ktime, ok := parseKernelTimestamp(line); ok { | ||
| msg = after | ||
| attrs = append(attrs, slog.String("ktime", ktime)) | ||
| } | ||
| record := slog.NewRecord(time.Now(), slog.LevelInfo, msg, 0) | ||
| record.AddAttrs(attrs...) | ||
| handler := consoleHandler() | ||
| if handler.Enabled(context.Background(), slog.LevelInfo) { | ||
| handler.Handle(context.Background(), record) //nolint:errcheck | ||
| } | ||
| } | ||
| if err := scanner.Err(); err != nil { | ||
| record := slog.NewRecord(time.Now(), slog.LevelWarn, "console log reader stopped", 0) | ||
| record.AddAttrs(slog.String("component", "kmsg"), slog.Any("error", err)) | ||
| handler := consoleHandler() | ||
| if handler.Enabled(context.Background(), slog.LevelWarn) { | ||
| handler.Handle(context.Background(), record) //nolint:errcheck | ||
| } | ||
| } | ||
| } | ||
|
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| // forwardJSONLog attempts to parse line as a JSON slog record and emit it | ||
| // through the console handler. Returns true if the line was handled. | ||
| func forwardJSONLog(line string) bool { | ||
| var fields map[string]json.RawMessage | ||
| if err := json.Unmarshal([]byte(line), &fields); err != nil { | ||
| return false | ||
| } | ||
|
|
||
| // A valid vminitd log must at least have "msg". | ||
| rawMsg, ok := fields["msg"] | ||
| if !ok { | ||
| return false | ||
| } | ||
|
|
||
| var msg string | ||
| if err := json.Unmarshal(rawMsg, &msg); err != nil { | ||
| return false | ||
| } | ||
| delete(fields, "msg") | ||
|
|
||
| var level slog.Level | ||
| if raw, ok := fields["level"]; ok { | ||
| var s string | ||
| if err := json.Unmarshal(raw, &s); err == nil { | ||
| level.UnmarshalText([]byte(s)) //nolint:errcheck | ||
| } | ||
| delete(fields, "level") | ||
| } | ||
|
|
||
| // Discard the VM-side timestamp — the guest clock is not | ||
| // synchronised and typically reads as epoch. | ||
| delete(fields, "time") | ||
| t := time.Now() | ||
|
|
||
| handler := consoleHandler() | ||
| if !handler.Enabled(context.Background(), level) { | ||
| return true | ||
| } | ||
|
|
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| record := slog.NewRecord(t, level, msg, 0) | ||
| for k, v := range fields { | ||
| var val any | ||
| if err := json.Unmarshal(v, &val); err == nil { | ||
| record.AddAttrs(slog.Any(k, val)) | ||
| } | ||
| } | ||
|
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| handler.Handle(context.Background(), record) //nolint:errcheck | ||
| return true | ||
| } | ||
|
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| // parseKernelTimestamp extracts the "[ seconds.usecs] " prefix from a | ||
| // kernel log line. Returns the message after the prefix, the timestamp | ||
| // string, and whether a timestamp was found. | ||
| func parseKernelTimestamp(line string) (msg, ktime string, ok bool) { | ||
| if len(line) < 3 || line[0] != '[' { | ||
| return "", "", false | ||
| } | ||
| end := strings.IndexByte(line, ']') | ||
| if end < 0 { | ||
| return "", "", false | ||
| } | ||
| ktime = strings.TrimSpace(line[1:end]) | ||
| msg = line[end+1:] | ||
| if len(msg) > 0 && msg[0] == ' ' { | ||
| msg = msg[1:] | ||
| } | ||
| return msg, ktime, true | ||
| } | ||
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ForwardConsoleLogs uses bufio.Scanner with the default 64K token limit. A single long console line (e.g., large JSON payloads or kernel messages) will trigger ErrTooLong, stop scanning, and drop all subsequent console output (only emitting a single WARN). Consider switching to a bufio.Reader ReadString/ReadBytes loop, or call scanner.Buffer with a larger max token size appropriate for expected console output.