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chore: add custom slog handler for cloud logging
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| package log | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "io" | ||
| "log/slog" | ||
| "runtime" | ||
|
|
||
| "cloud.google.com/go/logging" | ||
| "go.opentelemetry.io/otel/trace" | ||
| ) | ||
|
|
||
| const ( | ||
| cloudLoggingSourceKey = "logging.googleapis.com/sourceLocation" | ||
| cloudLoggingLabelsKey = "logging.googleapis.com/labels" | ||
| cloudLoggingTraceKey = "logging.googleapis.com/trace" | ||
| cloudLoggingTraceSpanKey = "logging.googleapis.com/spanId" | ||
| cloudLoggingTraceSampledKey = "logging.googleapis.com/trace_sampled" | ||
|
|
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| cloudLoggingMessageKey = "message" | ||
| cloudLoggingSeverityKey = "severity" | ||
| cloudLoggingEnvironmentLabel = "env" | ||
| cloudLoggingServiceLabel = "app" | ||
| cloudLoggingTraceFormat = "projects/%s/traces/%s" | ||
| ) | ||
|
|
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| type CloudLoggingHandler struct { | ||
| handler slog.Handler | ||
| environment string | ||
| service string | ||
| projectID string | ||
| } | ||
|
|
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| type CloudLoggingHandlerOptions struct { | ||
| AddSource bool | ||
| Level slog.Level | ||
| Environment string | ||
| Service string | ||
| ProjectID string | ||
| ReplaceAttr func(groups []string, a slog.Attr) slog.Attr | ||
| } | ||
|
|
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| // Ensure CloudLoggingHandler implements slog.Handler. | ||
| var _ slog.Handler = (*CloudLoggingHandler)(nil) | ||
|
|
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| // NewCloudLoggingHandler creates a new CloudLoggingHandler. | ||
| func NewCloudLoggingHandler(out io.Writer, options *CloudLoggingHandlerOptions) *CloudLoggingHandler { | ||
| replaceAttr := func(groups []string, attr slog.Attr) slog.Attr { | ||
| cattr := attrReplacerForCloudLogging(groups, attr) | ||
| if options.ReplaceAttr != nil { | ||
| cattr = options.ReplaceAttr(groups, cattr) | ||
| } | ||
| return cattr | ||
| } | ||
|
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| handler := slog.NewJSONHandler(out, &slog.HandlerOptions{ | ||
| AddSource: options.AddSource, | ||
| Level: options.Level, | ||
| ReplaceAttr: replaceAttr, | ||
| }) | ||
|
|
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| return &CloudLoggingHandler{ | ||
| handler: handler, | ||
| environment: options.Environment, | ||
| service: options.Service, | ||
| projectID: options.ProjectID, | ||
| } | ||
| } | ||
|
|
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| // Enabled implements the slog.Handler interface. | ||
| func (h *CloudLoggingHandler) Enabled(ctx context.Context, level slog.Level) bool { | ||
| return h.handler.Enabled(ctx, level) | ||
| } | ||
|
|
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| // Handle implements the slog.Handler interface. | ||
| func (h *CloudLoggingHandler) Handle(ctx context.Context, record slog.Record) error { | ||
| record.AddAttrs( | ||
| slog.Group(cloudLoggingLabelsKey, | ||
| slog.String(cloudLoggingServiceLabel, h.service), | ||
| slog.String(cloudLoggingEnvironmentLabel, h.environment), | ||
| ), | ||
| ) | ||
| record.Level = h.toCloudLoggingLevel(record.Level) | ||
|
|
||
| // set trace | ||
| sc := trace.SpanContextFromContext(ctx) | ||
| if sc.IsValid() { | ||
| trace := fmt.Sprintf(cloudLoggingTraceFormat, h.projectID, sc.TraceID().String()) | ||
| record.AddAttrs( | ||
| slog.String(cloudLoggingTraceKey, trace), | ||
| slog.String(cloudLoggingTraceSpanKey, sc.SpanID().String()), | ||
| slog.Bool(cloudLoggingTraceSampledKey, sc.TraceFlags().IsSampled()), | ||
| ) | ||
| } | ||
|
|
||
| return h.handler.Handle(ctx, record) | ||
| } | ||
|
|
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| // WithAttrs implements the slog.Handler interface. | ||
| func (h *CloudLoggingHandler) WithAttrs(attrs []slog.Attr) slog.Handler { | ||
| return h.handler.WithAttrs(attrs) | ||
| } | ||
|
|
||
| // WithGroup implements the slog.Handler interface. | ||
| func (h *CloudLoggingHandler) WithGroup(name string) slog.Handler { | ||
| return h.handler.WithGroup(name) | ||
| } | ||
|
|
||
| func (h *CloudLoggingHandler) toCloudLoggingLevel(level slog.Level) slog.Level { | ||
| switch level { | ||
| case SeverityDebug: | ||
| return slog.Level(logging.Debug) | ||
| case SeverityInfo: | ||
| return slog.Level(logging.Info) | ||
| case SeverityNotice: | ||
| return slog.Level(logging.Notice) | ||
| case SeverityWarning: | ||
| return slog.Level(logging.Warning) | ||
| case SeverityError: | ||
| return slog.Level(logging.Error) | ||
| case SeverityCritical: | ||
| return slog.Level(logging.Critical) | ||
| } | ||
| return slog.Level(logging.Info) | ||
| } | ||
|
|
||
| // attrReplacerForCloudLogging is default attribute replacer. | ||
| func attrReplacerForCloudLogging(_ []string, attr slog.Attr) slog.Attr { | ||
| switch attr.Key { | ||
| case slog.MessageKey: | ||
| attr.Key = cloudLoggingMessageKey | ||
| case slog.LevelKey: | ||
| attr.Key = cloudLoggingSeverityKey | ||
| attr.Value = slog.StringValue(logging.Severity(attr.Value.Any().(slog.Level)).String()) | ||
| case slog.SourceKey: | ||
| attr.Key = cloudLoggingSourceKey | ||
| // Replace the value of the "source" attribute with the value of the "sourceLocation" attribute. | ||
| const skip = 9 | ||
| _, file, line, ok := runtime.Caller(skip) | ||
| if !ok { | ||
| return attr | ||
| } | ||
| v := fmt.Sprintf("%s:%d", file, line) | ||
| attr.Value = slog.StringValue(v) | ||
| } | ||
|
|
||
| return attr | ||
| } |
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