feat: service logs command to stream service logs (#196)

* chore: fix landing logo shadow

* feat: implement service logs command with colored output and strict ordering

* revert Makefile

* fix after rebase

* move logs command under services with root shortcut

* simplify server options for streaming logs and CLI flags

* refactor ContainerLogs grpc server

* update --tail flag

* minor docker.proto

* refactor client ServiceLogs and ContainerLogs

* move ProxyMachinesContext from api to client pkg

* minor refactor proto Stream

* add api/logs

* implement LogMerger

* fix LogMerger to correctly use semaphore

* increate inflish entries to 100 per stream

* send heartbeats

* refactor ContainerLogs to synchronise Send of entries and heartbeats to the steram

* minor logmerege

* remove ContainerName form ServiceLogEntryMetadata

* refactor ContainerLogs into docker.Service

* detect stalled container logs streams

* update logmerger tests

* fix comment in test

* refactor LogMerger with options

* uc logs: format one or multiple services

* make LogMerger emit heartbeats, emit entries <= watermark, rewrite tests

* update uc logs with new LogMerger

* go mod tidy

* fix after merge

---------

Co-authored-by: Evgenii Orlov <evgenii.orlov@semrush.com>

pkg/api/logs.go

@@ -0,0 +1,84 @@
+package api
+
+import (
+	"errors"
+	"time"
+
+	"github.com/psviderski/uncloud/internal/machine/api/pb"
+)
+
+const (
+	LogStreamUnknown LogStreamType = iota
+	LogStreamStdout
+	LogStreamStderr
+	// LogStreamHeartbeat represents a heartbeat log entry with a timestamp indicating that
+	// there are no older logs than this timestamp.
+	LogStreamHeartbeat
+)
+
+type LogStreamType int
+
+// LogStreamTypeFromProto converts a protobuf ContainerLogEntry.StreamType to the internal LogStreamType.
+func LogStreamTypeFromProto(s pb.ContainerLogEntry_StreamType) LogStreamType {
+	switch s {
+	case pb.ContainerLogEntry_STDOUT:
+		return LogStreamStdout
+	case pb.ContainerLogEntry_STDERR:
+		return LogStreamStderr
+	case pb.ContainerLogEntry_HEARTBEAT:
+		return LogStreamHeartbeat
+	default:
+		return LogStreamUnknown
+	}
+}
+
+// LogStreamTypeToProto converts LogStreamType to protobuf ContainerLogEntry.StreamType.
+func LogStreamTypeToProto(s LogStreamType) pb.ContainerLogEntry_StreamType {
+	switch s {
+	case LogStreamStdout:
+		return pb.ContainerLogEntry_STDOUT
+	case LogStreamStderr:
+		return pb.ContainerLogEntry_STDERR
+	case LogStreamHeartbeat:
+		return pb.ContainerLogEntry_HEARTBEAT
+	default:
+		return pb.ContainerLogEntry_UNKNOWN
+	}
+}
+
+// ServiceLogsOptions specifies parameters for ServiceLogs.
+type ServiceLogsOptions struct {
+	Follow bool
+	Tail   int
+	Since  string
+	Until  string
+}
+
+// ServiceLogEntry represents a single log entry from a service container.
+type ServiceLogEntry struct {
+	// Metadata may not be set if an error occurred (Err is not nil).
+	Metadata ServiceLogEntryMetadata
+	ContainerLogEntry
+}
+
+// ServiceLogEntryMetadata contains metadata about the source of a log entry.
+type ServiceLogEntryMetadata struct {
+	ServiceID   string
+	ServiceName string
+	ContainerID string
+	MachineID   string
+	MachineName string
+}
+
+// ContainerLogEntry represents a single log entry from a container.
+type ContainerLogEntry struct {
+	Stream    LogStreamType
+	Timestamp time.Time
+	Message   []byte
+	// Err indicates that an error occurred while streaming logs from a container.
+	// Other fields are not set if Err is not nil.
+	Err error
+}
+
+// ErrLogStreamStalled indicates that a log stream stopped sending data and may be unresponsive.
+var ErrLogStreamStalled = errors.New("log stream stopped responding")