metropolis/proto: move log-related types to common

Having them in API is kinda weird, especially as we're
generating/parsing them from a few libraries already.

Change-Id: I87b4b51f151443c60b87e3e50753c395fcf6e845
Reviewed-on: https://review.monogon.dev/c/monogon/+/1437
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/cli/dbg/BUILD.bazel b/metropolis/cli/dbg/BUILD.bazel
index 4eed080..5991f63 100644
--- a/metropolis/cli/dbg/BUILD.bazel
+++ b/metropolis/cli/dbg/BUILD.bazel
@@ -8,6 +8,7 @@
     deps = [
         "//metropolis/pkg/logtree",
         "//metropolis/proto/api",
+        "//metropolis/proto/common",
         "@io_k8s_cli_runtime//pkg/genericclioptions",
         "@io_k8s_component_base//cli",
         "@io_k8s_kubectl//pkg/cmd",
diff --git a/metropolis/cli/dbg/main.go b/metropolis/cli/dbg/main.go
index 0af835a..f7eb1a4 100644
--- a/metropolis/cli/dbg/main.go
+++ b/metropolis/cli/dbg/main.go
@@ -34,7 +34,9 @@
 	"k8s.io/kubectl/pkg/cmd/util"
 
 	"source.monogon.dev/metropolis/pkg/logtree"
+
 	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 func main() {
@@ -110,8 +112,8 @@
 		}
 
 		if *logsRecursive {
-			req.Filters = append(req.Filters, &apb.LogFilter{
-				Filter: &apb.LogFilter_WithChildren_{WithChildren: &apb.LogFilter_WithChildren{}},
+			req.Filters = append(req.Filters, &cpb.LogFilter{
+				Filter: &cpb.LogFilter_WithChildren_{WithChildren: &cpb.LogFilter_WithChildren{}},
 			})
 		}
 
@@ -137,6 +139,14 @@
 				}
 				fmt.Println(entry.String())
 			}
+			for _, entry := range res.StreamEntries {
+				entry, err := logtree.LogEntryFromProto(entry)
+				if err != nil {
+					fmt.Printf("error decoding entry: %v", err)
+					continue
+				}
+				fmt.Println(entry.String())
+			}
 		}
 	case "kubectl":
 		// Pop "kubectl" arg (the k8s cli library internally parses os.Args).
diff --git a/metropolis/cli/metroctl/BUILD.bazel b/metropolis/cli/metroctl/BUILD.bazel
index 73a0a6e..71258e9 100644
--- a/metropolis/cli/metroctl/BUILD.bazel
+++ b/metropolis/cli/metroctl/BUILD.bazel
@@ -32,6 +32,7 @@
         "//metropolis/node/core/rpc",
         "//metropolis/pkg/logtree",
         "//metropolis/proto/api",
+        "//metropolis/proto/common",
         "@com_github_adrg_xdg//:xdg",
         "@com_github_spf13_cobra//:cobra",
         "@io_k8s_apimachinery//pkg/apis/meta/v1:meta",
diff --git a/metropolis/cli/metroctl/cmd_node_logs.go b/metropolis/cli/metroctl/cmd_node_logs.go
index 21d5637..beae6ab 100644
--- a/metropolis/cli/metroctl/cmd_node_logs.go
+++ b/metropolis/cli/metroctl/cmd_node_logs.go
@@ -11,6 +11,7 @@
 	"source.monogon.dev/metropolis/cli/metroctl/core"
 	"source.monogon.dev/metropolis/pkg/logtree"
 	"source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 var nodeLogsCmd = &cobra.Command{
@@ -59,10 +60,10 @@
 			Dn:          "",
 			BacklogMode: api.GetLogsRequest_BACKLOG_ALL,
 			StreamMode:  api.GetLogsRequest_STREAM_DISABLE,
-			Filters: []*api.LogFilter{
+			Filters: []*cpb.LogFilter{
 				{
-					Filter: &api.LogFilter_WithChildren_{
-						WithChildren: &api.LogFilter_WithChildren{},
+					Filter: &cpb.LogFilter_WithChildren_{
+						WithChildren: &cpb.LogFilter_WithChildren{},
 					},
 				},
 			},
diff --git a/metropolis/node/core/BUILD.bazel b/metropolis/node/core/BUILD.bazel
index 37897e5..281266b 100644
--- a/metropolis/node/core/BUILD.bazel
+++ b/metropolis/node/core/BUILD.bazel
@@ -35,6 +35,7 @@
         "//metropolis/pkg/supervisor",
         "//metropolis/pkg/tpm",
         "//metropolis/proto/api",
+        "//metropolis/proto/common",
         "@com_github_containerd_containerd//:containerd",
         "@com_github_containerd_containerd//namespaces",
         "@org_golang_google_grpc//:go_default_library",
diff --git a/metropolis/node/core/debug_service_enabled.go b/metropolis/node/core/debug_service_enabled.go
index fc77edb..3494270 100644
--- a/metropolis/node/core/debug_service_enabled.go
+++ b/metropolis/node/core/debug_service_enabled.go
@@ -37,6 +37,7 @@
 	"source.monogon.dev/metropolis/pkg/logtree"
 	"source.monogon.dev/metropolis/pkg/supervisor"
 	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 const (
@@ -139,13 +140,13 @@
 	// Parse proto filters into logtree options.
 	for i, filter := range req.Filters {
 		switch inner := filter.Filter.(type) {
-		case *apb.LogFilter_WithChildren_:
+		case *cpb.LogFilter_WithChildren_:
 			options = append(options, logtree.WithChildren())
-		case *apb.LogFilter_OnlyRaw_:
+		case *cpb.LogFilter_OnlyRaw_:
 			options = append(options, logtree.OnlyRaw())
-		case *apb.LogFilter_OnlyLeveled_:
+		case *cpb.LogFilter_OnlyLeveled_:
 			options = append(options, logtree.OnlyLeveled())
-		case *apb.LogFilter_LeveledWithMinimumSeverity_:
+		case *cpb.LogFilter_LeveledWithMinimumSeverity_:
 			severity, err := logtree.SeverityFromProto(inner.LeveledWithMinimumSeverity.Minimum)
 			if err != nil {
 				return status.Errorf(codes.InvalidArgument, "filter %d has invalid severity: %v", i, err)
@@ -179,7 +180,7 @@
 	maxChunkSize := 2000
 
 	// Serve all backlog entries in chunks.
-	chunk := make([]*apb.LogEntry, 0, maxChunkSize)
+	chunk := make([]*cpb.LogEntry, 0, maxChunkSize)
 	for _, entry := range reader.Backlog {
 		p := entry.Proto()
 		if p == nil {
@@ -195,7 +196,7 @@
 			if err != nil {
 				return err
 			}
-			chunk = make([]*apb.LogEntry, 0, maxChunkSize)
+			chunk = make([]*cpb.LogEntry, 0, maxChunkSize)
 		}
 	}
 
@@ -207,7 +208,7 @@
 		if err != nil {
 			return err
 		}
-		chunk = make([]*apb.LogEntry, 0, maxChunkSize)
+		chunk = make([]*cpb.LogEntry, 0, maxChunkSize)
 	}
 
 	// Start serving streaming data, if streaming has been requested.
@@ -227,7 +228,7 @@
 			continue
 		}
 		err := srv.Send(&apb.GetLogsResponse{
-			StreamEntries: []*apb.LogEntry{p},
+			StreamEntries: []*cpb.LogEntry{p},
 		})
 		if err != nil {
 			return err
diff --git a/metropolis/pkg/logbuffer/BUILD.bazel b/metropolis/pkg/logbuffer/BUILD.bazel
index cd0e3af..e890df8 100644
--- a/metropolis/pkg/logbuffer/BUILD.bazel
+++ b/metropolis/pkg/logbuffer/BUILD.bazel
@@ -8,7 +8,7 @@
     ],
     importpath = "source.monogon.dev/metropolis/pkg/logbuffer",
     visibility = ["//metropolis:__subpackages__"],
-    deps = ["//metropolis/proto/api"],
+    deps = ["//metropolis/proto/common"],
 )
 
 go_test(
diff --git a/metropolis/pkg/logbuffer/linebuffer.go b/metropolis/pkg/logbuffer/linebuffer.go
index 6fd9a62..16f7b1a 100644
--- a/metropolis/pkg/logbuffer/linebuffer.go
+++ b/metropolis/pkg/logbuffer/linebuffer.go
@@ -22,7 +22,7 @@
 	"strings"
 	"sync"
 
-	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 // Line is a line stored in the log buffer - a string, that has been perhaps
@@ -47,15 +47,15 @@
 }
 
 // ProtoLog returns a Logging-specific protobuf structure.
-func (l *Line) ProtoLog() *apb.LogEntry_Raw {
-	return &apb.LogEntry_Raw{
+func (l *Line) ProtoLog() *cpb.LogEntry_Raw {
+	return &cpb.LogEntry_Raw{
 		Data:           l.Data,
 		OriginalLength: int64(l.OriginalLength),
 	}
 }
 
 // LineFromLogProto converts a Logging-specific protobuf message back into a Line.
-func LineFromLogProto(raw *apb.LogEntry_Raw) (*Line, error) {
+func LineFromLogProto(raw *cpb.LogEntry_Raw) (*Line, error) {
 	if raw.OriginalLength < int64(len(raw.Data)) {
 		return nil, fmt.Errorf("original_length smaller than length of data")
 	}
diff --git a/metropolis/pkg/logtree/BUILD.bazel b/metropolis/pkg/logtree/BUILD.bazel
index 5c4237c..2e2f07e 100644
--- a/metropolis/pkg/logtree/BUILD.bazel
+++ b/metropolis/pkg/logtree/BUILD.bazel
@@ -20,7 +20,7 @@
     visibility = ["//metropolis:__subpackages__"],
     deps = [
         "//metropolis/pkg/logbuffer",
-        "//metropolis/proto/api",
+        "//metropolis/proto/common",
         "@com_github_mitchellh_go_wordwrap//:go-wordwrap",
         "@org_golang_google_protobuf//types/known/timestamppb",
     ],
diff --git a/metropolis/pkg/logtree/leveled.go b/metropolis/pkg/logtree/leveled.go
index 6e44ef4..5c57222 100644
--- a/metropolis/pkg/logtree/leveled.go
+++ b/metropolis/pkg/logtree/leveled.go
@@ -19,7 +19,7 @@
 import (
 	"fmt"
 
-	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 // LeveledLogger is a generic interface for glog-style logging. There are four
@@ -144,32 +144,32 @@
 	}
 }
 
-func SeverityFromProto(s apb.LeveledLogSeverity) (Severity, error) {
+func SeverityFromProto(s cpb.LeveledLogSeverity) (Severity, error) {
 	switch s {
-	case apb.LeveledLogSeverity_INFO:
+	case cpb.LeveledLogSeverity_INFO:
 		return INFO, nil
-	case apb.LeveledLogSeverity_WARNING:
+	case cpb.LeveledLogSeverity_WARNING:
 		return WARNING, nil
-	case apb.LeveledLogSeverity_ERROR:
+	case cpb.LeveledLogSeverity_ERROR:
 		return ERROR, nil
-	case apb.LeveledLogSeverity_FATAL:
+	case cpb.LeveledLogSeverity_FATAL:
 		return FATAL, nil
 	default:
 		return "", fmt.Errorf("unknown severity value %d", s)
 	}
 }
 
-func (s Severity) ToProto() apb.LeveledLogSeverity {
+func (s Severity) ToProto() cpb.LeveledLogSeverity {
 	switch s {
 	case INFO:
-		return apb.LeveledLogSeverity_INFO
+		return cpb.LeveledLogSeverity_INFO
 	case WARNING:
-		return apb.LeveledLogSeverity_WARNING
+		return cpb.LeveledLogSeverity_WARNING
 	case ERROR:
-		return apb.LeveledLogSeverity_ERROR
+		return cpb.LeveledLogSeverity_ERROR
 	case FATAL:
-		return apb.LeveledLogSeverity_FATAL
+		return cpb.LeveledLogSeverity_FATAL
 	default:
-		return apb.LeveledLogSeverity_INVALID
+		return cpb.LeveledLogSeverity_INVALID
 	}
 }
diff --git a/metropolis/pkg/logtree/leveled_payload.go b/metropolis/pkg/logtree/leveled_payload.go
index 909d88a..c0852ae 100644
--- a/metropolis/pkg/logtree/leveled_payload.go
+++ b/metropolis/pkg/logtree/leveled_payload.go
@@ -24,7 +24,7 @@
 
 	tpb "google.golang.org/protobuf/types/known/timestamppb"
 
-	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 // LeveledPayload is a log entry for leveled logs (as per leveled.go). It contains
@@ -66,8 +66,9 @@
 // unified with a rowspan- like mechanism.
 //
 // For example, this function can return:
-//   prefix = "I1102 17:20:06.921395 foo.go:42] "
-//   lines = []string{"current tags:", " - one", " - two"}
+//
+//	prefix = "I1102 17:20:06.921395 foo.go:42] "
+//	lines = []string{"current tags:", " - one", " - two"}
 //
 // With this data, the result should be presented to users this way in text form:
 // I1102 17:20:06.921395 foo.go:42] current tags:
@@ -113,8 +114,8 @@
 func (p *LeveledPayload) Severity() Severity { return p.severity }
 
 // Proto converts a LeveledPayload to protobuf format.
-func (p *LeveledPayload) Proto() *apb.LogEntry_Leveled {
-	return &apb.LogEntry_Leveled{
+func (p *LeveledPayload) Proto() *cpb.LogEntry_Leveled {
+	return &cpb.LogEntry_Leveled{
 		Lines:     p.Messages(),
 		Timestamp: tpb.New(p.Timestamp()),
 		Severity:  p.Severity().ToProto(),
@@ -123,7 +124,7 @@
 }
 
 // LeveledPayloadFromProto parses a protobuf message into the internal format.
-func LeveledPayloadFromProto(p *apb.LogEntry_Leveled) (*LeveledPayload, error) {
+func LeveledPayloadFromProto(p *cpb.LogEntry_Leveled) (*LeveledPayload, error) {
 	severity, err := SeverityFromProto(p.Severity)
 	if err != nil {
 		return nil, fmt.Errorf("could not convert severity: %w", err)
diff --git a/metropolis/pkg/logtree/logtree_entry.go b/metropolis/pkg/logtree/logtree_entry.go
index a020910..72cc409 100644
--- a/metropolis/pkg/logtree/logtree_entry.go
+++ b/metropolis/pkg/logtree/logtree_entry.go
@@ -23,7 +23,7 @@
 	"github.com/mitchellh/go-wordwrap"
 
 	"source.monogon.dev/metropolis/pkg/logbuffer"
-	apb "source.monogon.dev/metropolis/proto/api"
+	cpb "source.monogon.dev/metropolis/proto/common"
 )
 
 // LogEntry contains a log entry, combining both leveled and raw logging into a
@@ -207,19 +207,19 @@
 
 // Convert this LogEntry to proto. Returned value may be nil if given LogEntry is
 // invalid, eg. contains neither a Raw nor Leveled entry.
-func (l *LogEntry) Proto() *apb.LogEntry {
-	p := &apb.LogEntry{
+func (l *LogEntry) Proto() *cpb.LogEntry {
+	p := &cpb.LogEntry{
 		Dn: string(l.DN),
 	}
 	switch {
 	case l.Leveled != nil:
 		leveled := l.Leveled
-		p.Kind = &apb.LogEntry_Leveled_{
+		p.Kind = &cpb.LogEntry_Leveled_{
 			Leveled: leveled.Proto(),
 		}
 	case l.Raw != nil:
 		raw := l.Raw
-		p.Kind = &apb.LogEntry_Raw_{
+		p.Kind = &cpb.LogEntry_Raw_{
 			Raw: raw.ProtoLog(),
 		}
 	default:
@@ -230,7 +230,7 @@
 
 // Parse a proto LogEntry back into internal structure. This can be used in log
 // proto API consumers to easily print received log entries.
-func LogEntryFromProto(l *apb.LogEntry) (*LogEntry, error) {
+func LogEntryFromProto(l *cpb.LogEntry) (*LogEntry, error) {
 	dn := DN(l.Dn)
 	if _, err := dn.Path(); err != nil {
 		return nil, fmt.Errorf("could not convert DN: %w", err)
@@ -239,13 +239,13 @@
 		DN: dn,
 	}
 	switch inner := l.Kind.(type) {
-	case *apb.LogEntry_Leveled_:
+	case *cpb.LogEntry_Leveled_:
 		leveled, err := LeveledPayloadFromProto(inner.Leveled)
 		if err != nil {
 			return nil, fmt.Errorf("could not convert leveled entry: %w", err)
 		}
 		res.Leveled = leveled
-	case *apb.LogEntry_Raw_:
+	case *cpb.LogEntry_Raw_:
 		line, err := logbuffer.LineFromLogProto(inner.Raw)
 		if err != nil {
 			return nil, fmt.Errorf("could not convert raw entry: %w", err)
diff --git a/metropolis/proto/api/debug.proto b/metropolis/proto/api/debug.proto
index 156f036..b70d1a0 100644
--- a/metropolis/proto/api/debug.proto
+++ b/metropolis/proto/api/debug.proto
@@ -28,19 +28,8 @@
     // GetDebugKubeconfig issues kubeconfigs with arbitrary identities and groups for debugging
     rpc GetDebugKubeconfig(GetDebugKubeconfigRequest) returns (GetDebugKubeconfigResponse);
 
-    // GetLogs Returns historical and/or streaming logs for a given DN with given filters from the system global
-    // LogTree.
-    //
-    // For more information about this API, see //metropolis/pkg/logtree. But, in summary:
-    //   - All logging is performed to a DN (distinguished name), which is a dot-delimited string like foo.bar.baz.
-    //   - Log entries can be either raw (coming from unstructured logging from an external service, like a running
-    //     process) or leveled (emitted by Metropolis code with a source line, timestamp, and severity).
-    //   - The DNs form a tree of logging nodes - and when requesting logs, a given subtree of DNs can be requested,
-    //     instead of just a given DN.
-    //   - All supervised processes live at `root.<supervisor DN>`. For more example paths, see the console logs of
-    //     a running Metropolis node, or request all logs (at DN "").
-    //
-    // TODO(q3k): move method and its related messages to the non-debug node endpoint once we have one.
+    // A reimplementation of metropolis.api.NodeManagement.Logs that's available
+    // before the node starts up the management service.
     rpc GetLogs(GetLogsRequest) returns (stream GetLogsResponse);
 
     // Trace enables tracing of Metropolis using the Linux ftrace infrastructure.
diff --git a/metropolis/proto/api/management.proto b/metropolis/proto/api/management.proto
index 3c869a9..5b66311 100644
--- a/metropolis/proto/api/management.proto
+++ b/metropolis/proto/api/management.proto
@@ -185,6 +185,22 @@
 // NodeManagement runs on every node of the cluster and providers management
 // and troubleshooting RPCs to operators. All requests must be authenticated.
 service NodeManagement {
+  // GetLogs Returns historical and/or streaming logs for a given DN with given
+  // filters from the system global LogTree.
+  //
+  // For more information about this API, see //metropolis/pkg/logtree. But, in
+  // summary:
+  //   - All logging is performed to a DN (distinguished name), which is a
+  //     dot-delimited string like foo.bar.baz.
+  //   - Log entries can be either raw (coming from unstructured logging from
+  //     an external service, like a running process) or leveled (emitted by
+  //     Metropolis code with a source line, timestamp, and severity).
+  //   - The DNs form a tree of logging nodes - and when requesting logs, a
+  //     given subtree of DNs can be requested, instead of just a given DN.
+  //   - All supervised processes live at `root.<supervisor DN>`. For more
+  //     example paths, see the console logs of a running Metropolis node, or
+  //     request all logs (at DN "").
+  //
   rpc Logs(GetLogsRequest) returns (stream GetLogsResponse) {
     option (metropolis.proto.ext.authorization) = {
       need: PERMISSION_READ_NODE_LOGS
@@ -192,58 +208,12 @@
   }
 }
 
-
-// Severity level corresponding to //metropolis/pkg/logtree.Severity.
-enum LeveledLogSeverity {
-  INVALID = 0;
-  INFO = 1;
-  WARNING = 2;
-  ERROR = 3;
-  FATAL = 4;
-}
-
-// Filter set when requesting logs for a given DN. This message is equivalent to
-// the following GADT enum:
-// data LogFilter = WithChildren
-//                | OnlyRaw
-//                | OnlyLeveled
-//                | LeveledWithMinimumSeverity(Severity)
-//
-// Multiple LogFilters can be chained/combined when requesting logs, as long as
-// they do not conflict.
-message LogFilter {
-  // Entries will be returned not only for the given DN, but all child DNs as
-  // well. For instance, if the requested DN is foo, entries logged to foo,
-  // foo.bar and foo.bar.baz will all be returned.
-  message WithChildren {
-  }
-  // Only raw logging entries will be returned. Conflicts with OnlyLeveled
-  // filters.
-  message OnlyRaw {
-  }
-  // Only leveled logging entries will be returned. Conflicts with OnlyRaw
-  // filters.
-  message OnlyLeveled {
-  }
-  // If leveled logs are returned, all entries at severity lower than `minimum`
-  // will be discarded.
-  message LeveledWithMinimumSeverity {
-    LeveledLogSeverity minimum = 1;
-  }
-  oneof filter {
-    WithChildren with_children = 1;
-    OnlyRaw only_raw = 3;
-    OnlyLeveled only_leveled = 4;
-    LeveledWithMinimumSeverity leveled_with_minimum_severity = 5;
-  }
-}
-
 message GetLogsRequest {
   // DN from which to request logs. All supervised runnables live at `root.`,
   // the init code lives at `init.`.
   string dn = 1;
   // Filters to apply to returned data.
-  repeated LogFilter filters = 2;
+  repeated metropolis.proto.common.LogFilter filters = 2;
 
   enum BacklogMode {
     BACKLOG_INVALID = 0;
@@ -259,39 +229,22 @@
 
   enum StreamMode {
     STREAM_INVALID = 0;
-    // No streaming entries, gRPC stream will be closed as soon as all backlog data is served.
+    // No streaming entries, gRPC stream will be closed as soon as all backlog
+    // data is served.
     STREAM_DISABLE = 1;
-    // Entries will be streamed as early as available right after all backlog data is served.
+    // Entries will be streamed as early as available right after all backlog
+    // data is served.
     STREAM_UNBUFFERED = 2;
   }
   StreamMode stream_mode = 5;
 }
 
-message LogEntry {
-  message Leveled {
-    repeated string lines = 1;
-    google.protobuf.Timestamp timestamp = 2;
-    LeveledLogSeverity severity = 3;
-    string location = 4;
-  }
-  message Raw {
-    string data = 1;
-    int64 original_length = 2;
-  }
-
-  string dn = 1;
-  oneof kind {
-    Leveled leveled = 2;
-    Raw raw = 3;
-  }
-}
-
 message GetLogsResponse {
-  // Entries from the requested historical entries (via WithBackLog). They will all be served before the first
-  // stream_entries are served (if any).
-  repeated LogEntry backlog_entries = 1;
-  // Entries streamed as they arrive. Currently no server-side buffering is enabled, instead every line is served
-  // as early as it arrives. However, this might change in the future, so this behaviour cannot be depended
-  // upon.
-  repeated LogEntry stream_entries = 2;
+  // Entries from the requested historical entries (via WithBackLog). They will
+  // all be served before the first stream_entries are served (if any).
+  repeated metropolis.proto.common.LogEntry backlog_entries = 1;
+  // Entries streamed as they arrive. Currently no server-side buffering is
+  // enabled, instead every line is served as early as it arrives. However, this
+  // might change in the future, so this behaviour cannot be depended upon.
+  repeated metropolis.proto.common.LogEntry stream_entries = 2;
 }
\ No newline at end of file
diff --git a/metropolis/proto/common/common.proto b/metropolis/proto/common/common.proto
index 183f790..a884dff 100644
--- a/metropolis/proto/common/common.proto
+++ b/metropolis/proto/common/common.proto
@@ -189,3 +189,77 @@
     // mesh, and are programmed by other nodes into their wireguard peer config.
     repeated Prefix prefixes = 2;
 }
+
+// Severity level corresponding to //metropolis/pkg/logtree.Severity.
+enum LeveledLogSeverity {
+    INVALID = 0;
+    INFO = 1;
+    WARNING = 2;
+    ERROR = 3;
+    FATAL = 4;
+}
+
+// Filter set when requesting logs for a given DN. This message is equivalent to
+// the following GADT enum:
+// data LogFilter = WithChildren
+//                | OnlyRaw
+//                | OnlyLeveled
+//                | LeveledWithMinimumSeverity(Severity)
+//
+// Multiple LogFilters can be chained/combined when requesting logs, as long as
+// they do not conflict.
+message LogFilter {
+    // Entries will be returned not only for the given DN, but all child DNs as
+    // well. For instance, if the requested DN is foo, entries logged to foo,
+    // foo.bar and foo.bar.baz will all be returned.
+    message WithChildren {
+    }
+    // Only raw logging entries will be returned. Conflicts with OnlyLeveled
+    // filters.
+    message OnlyRaw {
+    }
+    // Only leveled logging entries will be returned. Conflicts with OnlyRaw
+    // filters.
+    message OnlyLeveled {
+    }
+    // If leveled logs are returned, all entries at severity lower than `minimum`
+    // will be discarded.
+    message LeveledWithMinimumSeverity {
+        LeveledLogSeverity minimum = 1;
+    }
+    oneof filter {
+        WithChildren with_children = 1;
+        OnlyRaw only_raw = 3;
+        OnlyLeveled only_leveled = 4;
+        LeveledWithMinimumSeverity leveled_with_minimum_severity = 5;
+    }
+}
+
+// LogEntry corresponding to logtree.LogEntry in //metropolis/pkg/logtree.
+message LogEntry {
+    // A leveled log entry emitted from a compatible system, eg. Metorpolis code
+    // or a klog-parsed line.
+    message Leveled {
+        repeated string lines = 1;
+        google.protobuf.Timestamp timestamp = 2;
+        LeveledLogSeverity severity = 3;
+        // Source of the error, expressed as file:line.
+        string location = 4;
+    }
+    // Raw log entry, captured from an external system without parting. Might
+    // contain some timestamp/level/origin information embedded in data. Data
+    // contained within should be treated as unsanitized external data.
+    message Raw {
+        string data = 1;
+        // Original length of line, set if data was truncated.
+        int64 original_length = 2;
+    }
+
+    // Origin DN.
+    string dn = 1;
+    oneof kind {
+        Leveled leveled = 2;
+        Raw raw = 3;
+    }
+}
+