Implement plugins for logging drivers

Logging plugins use the same HTTP interface as other plugins for basic
command operations meanwhile actual logging operations are handled (on
Unix) via a fifo.

The plugin interface looks like so:

```go
type loggingPlugin interface {
  StartLogging(fifoPath string, loggingContext Context) error
  StopLogging(fifoPath)
```

This means a plugin must implement `LoggingDriver.StartLogging` and
`LoggingDriver.StopLogging` endpoints and be able to consume the passed
in fifo.

Logs are sent via stream encoder to the fifo encoded with protobuf.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Upstream-commit: 27bd6842f8518780b99fdb42f8e7f84c17856d87
Component: engine

components/engine/api/types/plugins/logdriver/entry.pb.go

@@ -0,0 +1,449 @@
+// Code generated by protoc-gen-gogo.
+// source: entry.proto
+// DO NOT EDIT!
+
+/*
+	Package logdriver is a generated protocol buffer package.
+
+	It is generated from these files:
+		entry.proto
+
+	It has these top-level messages:
+		LogEntry
+*/
+package logdriver
+
+import proto "github.com/gogo/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+import io "io"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.GoGoProtoPackageIsVersion2 // please upgrade the proto package
+
+type LogEntry struct {
+	Source   string `protobuf:"bytes,1,opt,name=source,proto3" json:"source,omitempty"`
+	TimeNano int64  `protobuf:"varint,2,opt,name=time_nano,json=timeNano,proto3" json:"time_nano,omitempty"`
+	Line     []byte `protobuf:"bytes,3,opt,name=line,proto3" json:"line,omitempty"`
+	Partial  bool   `protobuf:"varint,4,opt,name=partial,proto3" json:"partial,omitempty"`
+}
+
+func (m *LogEntry) Reset()                    { *m = LogEntry{} }
+func (m *LogEntry) String() string            { return proto.CompactTextString(m) }
+func (*LogEntry) ProtoMessage()               {}
+func (*LogEntry) Descriptor() ([]byte, []int) { return fileDescriptorEntry, []int{0} }
+
+func (m *LogEntry) GetSource() string {
+	if m != nil {
+		return m.Source
+	}
+	return ""
+}
+
+func (m *LogEntry) GetTimeNano() int64 {
+	if m != nil {
+		return m.TimeNano
+	}
+	return 0
+}
+
+func (m *LogEntry) GetLine() []byte {
+	if m != nil {
+		return m.Line
+	}
+	return nil
+}
+
+func (m *LogEntry) GetPartial() bool {
+	if m != nil {
+		return m.Partial
+	}
+	return false
+}
+
+func init() {
+	proto.RegisterType((*LogEntry)(nil), "LogEntry")
+}
+func (m *LogEntry) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *LogEntry) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if len(m.Source) > 0 {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintEntry(dAtA, i, uint64(len(m.Source)))
+		i += copy(dAtA[i:], m.Source)
+	}
+	if m.TimeNano != 0 {
+		dAtA[i] = 0x10
+		i++
+		i = encodeVarintEntry(dAtA, i, uint64(m.TimeNano))
+	}
+	if len(m.Line) > 0 {
+		dAtA[i] = 0x1a
+		i++
+		i = encodeVarintEntry(dAtA, i, uint64(len(m.Line)))
+		i += copy(dAtA[i:], m.Line)
+	}
+	if m.Partial {
+		dAtA[i] = 0x20
+		i++
+		if m.Partial {
+			dAtA[i] = 1
+		} else {
+			dAtA[i] = 0
+		}
+		i++
+	}
+	return i, nil
+}
+
+func encodeFixed64Entry(dAtA []byte, offset int, v uint64) int {
+	dAtA[offset] = uint8(v)
+	dAtA[offset+1] = uint8(v >> 8)
+	dAtA[offset+2] = uint8(v >> 16)
+	dAtA[offset+3] = uint8(v >> 24)
+	dAtA[offset+4] = uint8(v >> 32)
+	dAtA[offset+5] = uint8(v >> 40)
+	dAtA[offset+6] = uint8(v >> 48)
+	dAtA[offset+7] = uint8(v >> 56)
+	return offset + 8
+}
+func encodeFixed32Entry(dAtA []byte, offset int, v uint32) int {
+	dAtA[offset] = uint8(v)
+	dAtA[offset+1] = uint8(v >> 8)
+	dAtA[offset+2] = uint8(v >> 16)
+	dAtA[offset+3] = uint8(v >> 24)
+	return offset + 4
+}
+func encodeVarintEntry(dAtA []byte, offset int, v uint64) int {
+	for v >= 1<<7 {
+		dAtA[offset] = uint8(v&0x7f | 0x80)
+		v >>= 7
+		offset++
+	}
+	dAtA[offset] = uint8(v)
+	return offset + 1
+}
+func (m *LogEntry) Size() (n int) {
+	var l int
+	_ = l
+	l = len(m.Source)
+	if l > 0 {
+		n += 1 + l + sovEntry(uint64(l))
+	}
+	if m.TimeNano != 0 {
+		n += 1 + sovEntry(uint64(m.TimeNano))
+	}
+	l = len(m.Line)
+	if l > 0 {
+		n += 1 + l + sovEntry(uint64(l))
+	}
+	if m.Partial {
+		n += 2
+	}
+	return n
+}
+
+func sovEntry(x uint64) (n int) {
+	for {
+		n++
+		x >>= 7
+		if x == 0 {
+			break
+		}
+	}
+	return n
+}
+func sozEntry(x uint64) (n int) {
+	return sovEntry(uint64((x << 1) ^ uint64((int64(x) >> 63))))
+}
+func (m *LogEntry) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowEntry
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: LogEntry: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: LogEntry: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Source", wireType)
+			}
+			var stringLen uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				stringLen |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			intStringLen := int(stringLen)
+			if intStringLen < 0 {
+				return ErrInvalidLengthEntry
+			}
+			postIndex := iNdEx + intStringLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Source = string(dAtA[iNdEx:postIndex])
+			iNdEx = postIndex
+		case 2:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field TimeNano", wireType)
+			}
+			m.TimeNano = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.TimeNano |= (int64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 3:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Line", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthEntry
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Line = append(m.Line[:0], dAtA[iNdEx:postIndex]...)
+			if m.Line == nil {
+				m.Line = []byte{}
+			}
+			iNdEx = postIndex
+		case 4:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Partial", wireType)
+			}
+			var v int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				v |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			m.Partial = bool(v != 0)
+		default:
+			iNdEx = preIndex
+			skippy, err := skipEntry(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthEntry
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func skipEntry(dAtA []byte) (n int, err error) {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return 0, ErrIntOverflowEntry
+			}
+			if iNdEx >= l {
+				return 0, io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		wireType := int(wire & 0x7)
+		switch wireType {
+		case 0:
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				iNdEx++
+				if dAtA[iNdEx-1] < 0x80 {
+					break
+				}
+			}
+			return iNdEx, nil
+		case 1:
+			iNdEx += 8
+			return iNdEx, nil
+		case 2:
+			var length int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowEntry
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				length |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			iNdEx += length
+			if length < 0 {
+				return 0, ErrInvalidLengthEntry
+			}
+			return iNdEx, nil
+		case 3:
+			for {
+				var innerWire uint64
+				var start int = iNdEx
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return 0, ErrIntOverflowEntry
+					}
+					if iNdEx >= l {
+						return 0, io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					innerWire |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				innerWireType := int(innerWire & 0x7)
+				if innerWireType == 4 {
+					break
+				}
+				next, err := skipEntry(dAtA[start:])
+				if err != nil {
+					return 0, err
+				}
+				iNdEx = start + next
+			}
+			return iNdEx, nil
+		case 4:
+			return iNdEx, nil
+		case 5:
+			iNdEx += 4
+			return iNdEx, nil
+		default:
+			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
+		}
+	}
+	panic("unreachable")
+}
+
+var (
+	ErrInvalidLengthEntry = fmt.Errorf("proto: negative length found during unmarshaling")
+	ErrIntOverflowEntry   = fmt.Errorf("proto: integer overflow")
+)
+
+func init() { proto.RegisterFile("entry.proto", fileDescriptorEntry) }
+
+var fileDescriptorEntry = []byte{
+	// 149 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xe2, 0xe2, 0x4e, 0xcd, 0x2b, 0x29,
+	0xaa, 0xd4, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x57, 0xca, 0xe5, 0xe2, 0xf0, 0xc9, 0x4f, 0x77, 0x05,
+	0x89, 0x08, 0x89, 0x71, 0xb1, 0x15, 0xe7, 0x97, 0x16, 0x25, 0xa7, 0x4a, 0x30, 0x2a, 0x30, 0x6a,
+	0x70, 0x06, 0x41, 0x79, 0x42, 0xd2, 0x5c, 0x9c, 0x25, 0x99, 0xb9, 0xa9, 0xf1, 0x79, 0x89, 0x79,
+	0xf9, 0x12, 0x4c, 0x0a, 0x8c, 0x1a, 0xcc, 0x41, 0x1c, 0x20, 0x01, 0xbf, 0xc4, 0xbc, 0x7c, 0x21,
+	0x21, 0x2e, 0x96, 0x9c, 0xcc, 0xbc, 0x54, 0x09, 0x66, 0x05, 0x46, 0x0d, 0x9e, 0x20, 0x30, 0x5b,
+	0x48, 0x82, 0x8b, 0xbd, 0x20, 0xb1, 0xa8, 0x24, 0x33, 0x31, 0x47, 0x82, 0x45, 0x81, 0x51, 0x83,
+	0x23, 0x08, 0xc6, 0x75, 0xe2, 0x39, 0xf1, 0x48, 0x8e, 0xf1, 0xc2, 0x23, 0x39, 0xc6, 0x07, 0x8f,
+	0xe4, 0x18, 0x93, 0xd8, 0xc0, 0x6e, 0x30, 0x06, 0x04, 0x00, 0x00, 0xff, 0xff, 0x2d, 0x24, 0x5a,
+	0xd4, 0x92, 0x00, 0x00, 0x00,
+}

components/engine/api/types/plugins/logdriver/entry.proto

@@ -0,0 +1,8 @@
+syntax = "proto3";
+
+message LogEntry {
+	string source = 1;
+	int64 time_nano = 2;
+	bytes line = 3;
+	bool partial = 4;
+}

components/engine/api/types/plugins/logdriver/gen.go

@@ -0,0 +1,3 @@
+//go:generate protoc --gogofast_out=import_path=github.com/docker/docker/api/types/plugins/logdriver:. entry.proto
+
+package logdriver

components/engine/api/types/plugins/logdriver/io.go

@@ -0,0 +1,87 @@
+package logdriver
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+const binaryEncodeLen = 4
+
+// LogEntryEncoder encodes a LogEntry to a protobuf stream
+// The stream should look like:
+//
+// [uint32 binary encoded message size][protobuf message]
+//
+// To decode an entry, read the first 4 bytes to get the size of the entry,
+// then read `size` bytes from the stream.
+type LogEntryEncoder interface {
+	Encode(*LogEntry) error
+}
+
+// NewLogEntryEncoder creates a protobuf stream encoder for log entries.
+// This is used to write out  log entries to a stream.
+func NewLogEntryEncoder(w io.Writer) LogEntryEncoder {
+	return &logEntryEncoder{
+		w:   w,
+		buf: make([]byte, 1024),
+	}
+}
+
+type logEntryEncoder struct {
+	buf []byte
+	w   io.Writer
+}
+
+func (e *logEntryEncoder) Encode(l *LogEntry) error {
+	n := l.Size()
+
+	total := n + binaryEncodeLen
+	if total > len(e.buf) {
+		e.buf = make([]byte, total)
+	}
+	binary.BigEndian.PutUint32(e.buf, uint32(n))
+
+	if _, err := l.MarshalTo(e.buf[binaryEncodeLen:]); err != nil {
+		return err
+	}
+	_, err := e.w.Write(e.buf[:total])
+	return err
+}
+
+// LogEntryDecoder decodes log entries from a stream
+// It is expected that the wire format is as defined by LogEntryEncoder.
+type LogEntryDecoder interface {
+	Decode(*LogEntry) error
+}
+
+// NewLogEntryDecoder creates a new stream decoder for log entries
+func NewLogEntryDecoder(r io.Reader) LogEntryDecoder {
+	return &logEntryDecoder{
+		lenBuf: make([]byte, binaryEncodeLen),
+		buf:    make([]byte, 1024),
+		r:      r,
+	}
+}
+
+type logEntryDecoder struct {
+	r      io.Reader
+	lenBuf []byte
+	buf    []byte
+}
+
+func (d *logEntryDecoder) Decode(l *LogEntry) error {
+	_, err := io.ReadFull(d.r, d.lenBuf)
+	if err != nil {
+		return err
+	}
+
+	size := int(binary.BigEndian.Uint32(d.lenBuf))
+	if len(d.buf) < size {
+		d.buf = make([]byte, size)
+	}
+
+	if _, err := io.ReadFull(d.r, d.buf[:size]); err != nil {
+		return err
+	}
+	return l.Unmarshal(d.buf[:size])
+}