Merge pull request #22575 from MikaelCluseau/wip-issue-20466

Automatic merge from submit-queue

Add subPath to mount a child dir or file of a volumeMount

Allow users to specify a subPath in Container.volumeMounts so they can use a single volume for many mounts instead of creating many volumes. For instance, a user can now use a single PersistentVolume to store the Mysql database and the document root of an Apache server of a LAMP stack pod by mapping them to different subPaths in this single volume.

Also solves https://github.com/kubernetes/kubernetes/issues/20466.

api/swagger-spec/apps_v1alpha1.json

@@ -2031,6 +2031,10 @@
      "mountPath": {
       "type": "string",
       "description": "Path within the container at which the volume should be mounted.  Must not contain ':'."
+     },
+     "subPath": {
+      "type": "string",
+      "description": "Path within the volume from which the container's volume should be mounted. Defaults to \"\" (volume's root)."
      }
     }
    },

api/swagger-spec/batch_v1.json

@@ -2036,6 +2036,10 @@
      "mountPath": {
       "type": "string",
       "description": "Path within the container at which the volume should be mounted.  Must not contain ':'."
+     },
+     "subPath": {
+      "type": "string",
+      "description": "Path within the volume from which the container's volume should be mounted. Defaults to \"\" (volume's root)."
      }
     }
    },

api/swagger-spec/extensions_v1beta1.json

@@ -7343,6 +7343,10 @@
      "mountPath": {
       "type": "string",
       "description": "Path within the container at which the volume should be mounted.  Must not contain ':'."
+     },
+     "subPath": {
+      "type": "string",
+      "description": "Path within the volume from which the container's volume should be mounted. Defaults to \"\" (volume's root)."
      }
     }
    },

api/swagger-spec/v1.json

@@ -17330,6 +17330,10 @@
      "mountPath": {
       "type": "string",
       "description": "Path within the container at which the volume should be mounted.  Must not contain ':'."
+     },
+     "subPath": {
+      "type": "string",
+      "description": "Path within the volume from which the container's volume should be mounted. Defaults to \"\" (volume's root)."
      }
     }
    },

docs/api-reference/batch/v1/definitions.html

@@ -556,6 +556,13 @@ span.icon > [class^="icon-"], span.icon > [class*=" icon-"] { cursor: default; }
 <td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">subPath</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Path within the volume from which the container&#8217;s volume should be mounted. Defaults to "" (volume&#8217;s root).</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
+<td class="tableblock halign-left valign-top"></td>
+</tr>
 </tbody>
 </table>
 
@@ -3972,7 +3979,7 @@ Populated by the system when a graceful deletion is requested. Read-only. More i
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2016-05-02 18:47:09 UTC
+Last updated 2016-05-06 04:28:34 UTC
 </div>
 </div>
 </body>

docs/api-reference/extensions/v1beta1/definitions.html

@@ -770,6 +770,13 @@ span.icon > [class^="icon-"], span.icon > [class*=" icon-"] { cursor: default; }
 <td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">subPath</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Path within the volume from which the container&#8217;s volume should be mounted. Defaults to "" (volume&#8217;s root).</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
+<td class="tableblock halign-left valign-top"></td>
+</tr>
 </tbody>
 </table>
 
@@ -5962,7 +5969,7 @@ Both these may change in the future. Incoming requests are matched against the h
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2016-05-02 18:47:04 UTC
+Last updated 2016-05-06 04:28:25 UTC
 </div>
 </div>
 </body>

docs/api-reference/v1/definitions.html

@@ -803,6 +803,13 @@ span.icon > [class^="icon-"], span.icon > [class*=" icon-"] { cursor: default; }
 <td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
 <td class="tableblock halign-left valign-top"></td>
 </tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">subPath</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Path within the volume from which the container&#8217;s volume should be mounted. Defaults to "" (volume&#8217;s root).</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">string</p></td>
+<td class="tableblock halign-left valign-top"></td>
+</tr>
 </tbody>
 </table>
 
@@ -7839,7 +7846,7 @@ The resulting set of endpoints can be viewed as:<br>
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2016-05-02 18:46:58 UTC
+Last updated 2016-05-06 04:28:14 UTC
 </div>
 </div>
 </body>

hack/verify-flags/exceptions.txt

@@ -92,3 +92,4 @@ test/e2e/host_path.go:			fmt.Sprintf("--retry_time=%d", retryDuration),
 test/images/mount-tester/mt.go:	flag.BoolVar(&breakOnExpectedContent, "break_on_expected_content", true, "Break out of loop on expected content, (use with --file_content_in_loop flag only)")
 test/images/mount-tester/mt.go:	flag.IntVar(&retryDuration, "retry_time", 180, "Retry time during the loop")
 test/images/mount-tester/mt.go:	flag.StringVar(&readFileContentInLoopPath, "file_content_in_loop", "", "Path to read the file content in loop from")
+test/e2e/host_path.go:			fmt.Sprintf("--file_content_in_loop=%v", filePathInReader),

pkg/api/deep_copy_generated.go

@@ -2955,6 +2955,7 @@ func DeepCopy_api_VolumeMount(in VolumeMount, out *VolumeMount, c *conversion.Cl
 	out.Name = in.Name
 	out.ReadOnly = in.ReadOnly
 	out.MountPath = in.MountPath
+	out.SubPath = in.SubPath
 	return nil
 }
 

pkg/api/types.generated.go

@@ -14340,13 +14340,14 @@ func (x *VolumeMount) CodecEncodeSelf(e *codec1978.Encoder) {
 		} else {
 			yysep2 := !z.EncBinary()
 			yy2arr2 := z.EncBasicHandle().StructToArray
-			var yyq2 [3]bool
+			var yyq2 [4]bool
 			_, _, _ = yysep2, yyq2, yy2arr2
 			const yyr2 bool = false
 			yyq2[1] = x.ReadOnly != false
+			yyq2[3] = x.SubPath != ""
 			var yynn2 int
 			if yyr2 || yy2arr2 {
-				r.EncodeArrayStart(3)
+				r.EncodeArrayStart(4)
 			} else {
 				yynn2 = 2
 				for _, b := range yyq2 {
@@ -14420,6 +14421,31 @@ func (x *VolumeMount) CodecEncodeSelf(e *codec1978.Encoder) {
 					r.EncodeString(codecSelferC_UTF81234, string(x.MountPath))
 				}
 			}
+			if yyr2 || yy2arr2 {
+				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
+				if yyq2[3] {
+					yym13 := z.EncBinary()
+					_ = yym13
+					if false {
+					} else {
+						r.EncodeString(codecSelferC_UTF81234, string(x.SubPath))
+					}
+				} else {
+					r.EncodeString(codecSelferC_UTF81234, "")
+				}
+			} else {
+				if yyq2[3] {
+					z.EncSendContainerState(codecSelfer_containerMapKey1234)
+					r.EncodeString(codecSelferC_UTF81234, string("subPath"))
+					z.EncSendContainerState(codecSelfer_containerMapValue1234)
+					yym14 := z.EncBinary()
+					_ = yym14
+					if false {
+					} else {
+						r.EncodeString(codecSelferC_UTF81234, string(x.SubPath))
+					}
+				}
+			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayEnd1234)
 			} else {
@@ -14499,6 +14525,12 @@ func (x *VolumeMount) codecDecodeSelfFromMap(l int, d *codec1978.Decoder) {
 			} else {
 				x.MountPath = string(r.DecodeString())
 			}
+		case "subPath":
+			if r.TryDecodeAsNil() {
+				x.SubPath = ""
+			} else {
+				x.SubPath = string(r.DecodeString())
+			}
 		default:
 			z.DecStructFieldNotFound(-1, yys3)
 		} // end switch yys3
@@ -14510,16 +14542,16 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	var h codecSelfer1234
 	z, r := codec1978.GenHelperDecoder(d)
 	_, _, _ = h, z, r
-	var yyj7 int
+	var yyj8 int
-	var yyb7 bool
+	var yyb8 bool
-	var yyhl7 bool = l >= 0
+	var yyhl8 bool = l >= 0
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14529,13 +14561,13 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.Name = string(r.DecodeString())
 	}
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14545,13 +14577,13 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.ReadOnly = bool(r.DecodeBool())
 	}
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14561,18 +14593,34 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.MountPath = string(r.DecodeString())
 	}
-	for {
+	yyj8++
-		yyj7++
+	if yyhl8 {
-		if yyhl7 {
+		yyb8 = yyj8 > l
-			yyb7 = yyj7 > l
 	} else {
-			yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-		if yyb7 {
+	if yyb8 {
+		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
+		return
+	}
+	z.DecSendContainerState(codecSelfer_containerArrayElem1234)
+	if r.TryDecodeAsNil() {
+		x.SubPath = ""
+	} else {
+		x.SubPath = string(r.DecodeString())
+	}
+	for {
+		yyj8++
+		if yyhl8 {
+			yyb8 = yyj8 > l
+		} else {
+			yyb8 = r.CheckBreak()
+		}
+		if yyb8 {
 			break
 		}
 		z.DecSendContainerState(codecSelfer_containerArrayElem1234)
-		z.DecStructFieldNotFound(yyj7-1, "")
+		z.DecStructFieldNotFound(yyj8-1, "")
 	}
 	z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 }
@@ -52291,7 +52339,7 @@ func (x codecSelfer1234) decSliceVolumeMount(v *[]VolumeMount, d *codec1978.Deco
 
 			yyrg1 := len(yyv1) > 0
 			yyv21 := yyv1
-			yyrl1, yyrt1 = z.DecInferLen(yyl1, z.DecBasicHandle().MaxInitLen, 40)
+			yyrl1, yyrt1 = z.DecInferLen(yyl1, z.DecBasicHandle().MaxInitLen, 56)
 			if yyrt1 {
 				if yyrl1 <= cap(yyv1) {
 					yyv1 = yyv1[:yyrl1]

pkg/api/types.go

@@ -758,6 +758,9 @@ type VolumeMount struct {
 	ReadOnly bool `json:"readOnly,omitempty"`
 	// Required. Must not contain ':'.
 	MountPath string `json:"mountPath"`
+	// Path within the volume from which the container's volume should be mounted.
+	// Defaults to "" (volume's root).
+	SubPath string `json:"subPath,omitempty"`
 }
 
 // EnvVar represents an environment variable present in a Container.

pkg/api/v1/conversion_generated.go

@@ -6556,6 +6556,7 @@ func autoConvert_v1_VolumeMount_To_api_VolumeMount(in *VolumeMount, out *api.Vol
 	out.Name = in.Name
 	out.ReadOnly = in.ReadOnly
 	out.MountPath = in.MountPath
+	out.SubPath = in.SubPath
 	return nil
 }
 
@@ -6567,6 +6568,7 @@ func autoConvert_api_VolumeMount_To_v1_VolumeMount(in *api.VolumeMount, out *Vol
 	out.Name = in.Name
 	out.ReadOnly = in.ReadOnly
 	out.MountPath = in.MountPath
+	out.SubPath = in.SubPath
 	return nil
 }
 

pkg/api/v1/deep_copy_generated.go

@@ -2916,6 +2916,7 @@ func DeepCopy_v1_VolumeMount(in VolumeMount, out *VolumeMount, c *conversion.Clo
 	out.Name = in.Name
 	out.ReadOnly = in.ReadOnly
 	out.MountPath = in.MountPath
+	out.SubPath = in.SubPath
 	return nil
 }
 

pkg/api/v1/generated.pb.go

@@ -7164,6 +7164,10 @@ func (m *VolumeMount) MarshalTo(data []byte) (int, error) {
 	i++
 	i = encodeVarintGenerated(data, i, uint64(len(m.MountPath)))
 	i += copy(data[i:], m.MountPath)
+	data[i] = 0x22
+	i++
+	i = encodeVarintGenerated(data, i, uint64(len(m.SubPath)))
+	i += copy(data[i:], m.SubPath)
 	return i, nil
 }
 
@@ -9726,6 +9730,8 @@ func (m *VolumeMount) Size() (n int) {
 	n += 2
 	l = len(m.MountPath)
 	n += 1 + l + sovGenerated(uint64(l))
+	l = len(m.SubPath)
+	n += 1 + l + sovGenerated(uint64(l))
 	return n
 }
 
@@ -32282,6 +32288,35 @@ func (m *VolumeMount) Unmarshal(data []byte) error {
 			}
 			m.MountPath = string(data[iNdEx:postIndex])
 			iNdEx = postIndex
+		case 4:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field SubPath", wireType)
+			}
+			var stringLen uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowGenerated
+				}
+				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 ErrInvalidLengthGenerated
+			}
+			postIndex := iNdEx + intStringLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.SubPath = string(data[iNdEx:postIndex])
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := skipGenerated(data[iNdEx:])

pkg/api/v1/generated.proto

@@ -2705,6 +2705,10 @@ message VolumeMount {
   // Path within the container at which the volume should be mounted.  Must
   // not contain ':'.
   optional string mountPath = 3;
+
+  // Path within the volume from which the container's volume should be mounted.
+  // Defaults to "" (volume's root).
+  optional string subPath = 4;
 }
 
 // Represents the source of a volume to mount.

pkg/api/v1/types.generated.go

@@ -13943,13 +13943,14 @@ func (x *VolumeMount) CodecEncodeSelf(e *codec1978.Encoder) {
 		} else {
 			yysep2 := !z.EncBinary()
 			yy2arr2 := z.EncBasicHandle().StructToArray
-			var yyq2 [3]bool
+			var yyq2 [4]bool
 			_, _, _ = yysep2, yyq2, yy2arr2
 			const yyr2 bool = false
 			yyq2[1] = x.ReadOnly != false
+			yyq2[3] = x.SubPath != ""
 			var yynn2 int
 			if yyr2 || yy2arr2 {
-				r.EncodeArrayStart(3)
+				r.EncodeArrayStart(4)
 			} else {
 				yynn2 = 2
 				for _, b := range yyq2 {
@@ -14023,6 +14024,31 @@ func (x *VolumeMount) CodecEncodeSelf(e *codec1978.Encoder) {
 					r.EncodeString(codecSelferC_UTF81234, string(x.MountPath))
 				}
 			}
+			if yyr2 || yy2arr2 {
+				z.EncSendContainerState(codecSelfer_containerArrayElem1234)
+				if yyq2[3] {
+					yym13 := z.EncBinary()
+					_ = yym13
+					if false {
+					} else {
+						r.EncodeString(codecSelferC_UTF81234, string(x.SubPath))
+					}
+				} else {
+					r.EncodeString(codecSelferC_UTF81234, "")
+				}
+			} else {
+				if yyq2[3] {
+					z.EncSendContainerState(codecSelfer_containerMapKey1234)
+					r.EncodeString(codecSelferC_UTF81234, string("subPath"))
+					z.EncSendContainerState(codecSelfer_containerMapValue1234)
+					yym14 := z.EncBinary()
+					_ = yym14
+					if false {
+					} else {
+						r.EncodeString(codecSelferC_UTF81234, string(x.SubPath))
+					}
+				}
+			}
 			if yyr2 || yy2arr2 {
 				z.EncSendContainerState(codecSelfer_containerArrayEnd1234)
 			} else {
@@ -14102,6 +14128,12 @@ func (x *VolumeMount) codecDecodeSelfFromMap(l int, d *codec1978.Decoder) {
 			} else {
 				x.MountPath = string(r.DecodeString())
 			}
+		case "subPath":
+			if r.TryDecodeAsNil() {
+				x.SubPath = ""
+			} else {
+				x.SubPath = string(r.DecodeString())
+			}
 		default:
 			z.DecStructFieldNotFound(-1, yys3)
 		} // end switch yys3
@@ -14113,16 +14145,16 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	var h codecSelfer1234
 	z, r := codec1978.GenHelperDecoder(d)
 	_, _, _ = h, z, r
-	var yyj7 int
+	var yyj8 int
-	var yyb7 bool
+	var yyb8 bool
-	var yyhl7 bool = l >= 0
+	var yyhl8 bool = l >= 0
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14132,13 +14164,13 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.Name = string(r.DecodeString())
 	}
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14148,13 +14180,13 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.ReadOnly = bool(r.DecodeBool())
 	}
-	yyj7++
+	yyj8++
-	if yyhl7 {
+	if yyhl8 {
-		yyb7 = yyj7 > l
+		yyb8 = yyj8 > l
 	} else {
-		yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-	if yyb7 {
+	if yyb8 {
 		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 		return
 	}
@@ -14164,18 +14196,34 @@ func (x *VolumeMount) codecDecodeSelfFromArray(l int, d *codec1978.Decoder) {
 	} else {
 		x.MountPath = string(r.DecodeString())
 	}
-	for {
+	yyj8++
-		yyj7++
+	if yyhl8 {
-		if yyhl7 {
+		yyb8 = yyj8 > l
-			yyb7 = yyj7 > l
 	} else {
-			yyb7 = r.CheckBreak()
+		yyb8 = r.CheckBreak()
 	}
-		if yyb7 {
+	if yyb8 {
+		z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
+		return
+	}
+	z.DecSendContainerState(codecSelfer_containerArrayElem1234)
+	if r.TryDecodeAsNil() {
+		x.SubPath = ""
+	} else {
+		x.SubPath = string(r.DecodeString())
+	}
+	for {
+		yyj8++
+		if yyhl8 {
+			yyb8 = yyj8 > l
+		} else {
+			yyb8 = r.CheckBreak()
+		}
+		if yyb8 {
 			break
 		}
 		z.DecSendContainerState(codecSelfer_containerArrayElem1234)
-		z.DecStructFieldNotFound(yyj7-1, "")
+		z.DecStructFieldNotFound(yyj8-1, "")
 	}
 	z.DecSendContainerState(codecSelfer_containerArrayEnd1234)
 }
@@ -52344,7 +52392,7 @@ func (x codecSelfer1234) decSliceVolumeMount(v *[]VolumeMount, d *codec1978.Deco
 
 			yyrg1 := len(yyv1) > 0
 			yyv21 := yyv1
-			yyrl1, yyrt1 = z.DecInferLen(yyl1, z.DecBasicHandle().MaxInitLen, 40)
+			yyrl1, yyrt1 = z.DecInferLen(yyl1, z.DecBasicHandle().MaxInitLen, 56)
 			if yyrt1 {
 				if yyrl1 <= cap(yyv1) {
 					yyv1 = yyv1[:yyrl1]

pkg/api/v1/types.go

@@ -883,6 +883,9 @@ type VolumeMount struct {
 	// Path within the container at which the volume should be mounted.  Must
 	// not contain ':'.
 	MountPath string `json:"mountPath" protobuf:"bytes,3,opt,name=mountPath"`
+	// Path within the volume from which the container's volume should be mounted.
+	// Defaults to "" (volume's root).
+	SubPath string `json:"subPath,omitempty" protobuf:"bytes,4,opt,name=subPath"`
 }
 
 // EnvVar represents an environment variable present in a Container.

pkg/api/v1/types_swagger_doc_generated.go

@@ -1628,6 +1628,7 @@ var map_VolumeMount = map[string]string{
 	"name":      "This must match the Name of a Volume.",
 	"readOnly":  "Mounted read-only if true, read-write otherwise (false or unspecified). Defaults to false.",
 	"mountPath": "Path within the container at which the volume should be mounted.  Must not contain ':'.",
+	"subPath":   "Path within the volume from which the container's volume should be mounted. Defaults to \"\" (volume's root).",
 }
 
 func (VolumeMount) SwaggerDoc() map[string]string {

pkg/api/validation/validation.go

@@ -727,6 +727,28 @@ func validateDownwardAPIVolumeSource(downwardAPIVolume *api.DownwardAPIVolumeSou
 	return allErrs
 }
 
+// This validate will make sure targetPath:
+// 1. is not abs path
+// 2. does not start with '../'
+// 3. does not contain '/../'
+// 4. does not end with '/..'
+func validateSubPath(targetPath string, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if path.IsAbs(targetPath) {
+		allErrs = append(allErrs, field.Invalid(fldPath, targetPath, "must be a relative path"))
+	}
+	if strings.HasPrefix(targetPath, "../") {
+		allErrs = append(allErrs, field.Invalid(fldPath, targetPath, "must not start with '../'"))
+	}
+	if strings.Contains(targetPath, "/../") {
+		allErrs = append(allErrs, field.Invalid(fldPath, targetPath, "must not contain '/../'"))
+	}
+	if strings.HasSuffix(targetPath, "/..") {
+		allErrs = append(allErrs, field.Invalid(fldPath, targetPath, "must not end with '/..'"))
+	}
+	return allErrs
+}
+
 // This validate will make sure targetPath:
 // 1. is not abs path
 // 2. does not contain '..'
@@ -1149,6 +1171,9 @@ func validateVolumeMounts(mounts []api.VolumeMount, volumes sets.String, fldPath
 			allErrs = append(allErrs, field.Invalid(idxPath.Child("mountPath"), mnt.MountPath, "must be unique"))
 		}
 		mountpoints.Insert(mnt.MountPath)
+		if len(mnt.SubPath) > 0 {
+			allErrs = append(allErrs, validateSubPath(mnt.SubPath, fldPath.Child("subPath"))...)
+		}
 	}
 	return allErrs
 }

pkg/api/validation/validation_test.go

@@ -1213,6 +1213,10 @@ func TestValidateVolumeMounts(t *testing.T) {
 		{Name: "abc", MountPath: "/foo"},
 		{Name: "123", MountPath: "/bar"},
 		{Name: "abc-123", MountPath: "/baz"},
+		{Name: "abc-123", MountPath: "/baa", SubPath: ""},
+		{Name: "abc-123", MountPath: "/bab", SubPath: "baz"},
+		{Name: "abc-123", MountPath: "/bac", SubPath: ".baz"},
+		{Name: "abc-123", MountPath: "/bad", SubPath: "..baz"},
 	}
 	if errs := validateVolumeMounts(successCase, volumes, field.NewPath("field")); len(errs) != 0 {
 		t.Errorf("expected success: %v", errs)
@@ -1224,6 +1228,10 @@ func TestValidateVolumeMounts(t *testing.T) {
 		"empty mountpath":     {{Name: "abc", MountPath: ""}},
 		"colon mountpath":     {{Name: "abc", MountPath: "foo:bar"}},
 		"mountpath collision": {{Name: "foo", MountPath: "/path/a"}, {Name: "bar", MountPath: "/path/a"}},
+		"absolute subpath":    {{Name: "abc", MountPath: "/bar", SubPath: "/baz"}},
+		"subpath in ..":       {{Name: "abc", MountPath: "/bar", SubPath: "../baz"}},
+		"subpath contains ..": {{Name: "abc", MountPath: "/bar", SubPath: "baz/../bat"}},
+		"subpath ends in ..":  {{Name: "abc", MountPath: "/bar", SubPath: "./.."}},
 	}
 	for k, v := range errorCases {
 		if errs := validateVolumeMounts(v, volumes, field.NewPath("field")); len(errs) == 0 {

pkg/kubelet/kubelet.go

@@ -1187,10 +1187,14 @@ func makeMounts(pod *api.Pod, podDir string, container *api.Container, hostName,
 			vol.SELinuxLabeled = true
 			relabelVolume = true
 		}
+		hostPath := vol.Mounter.GetPath()
+		if mount.SubPath != "" {
+			hostPath = filepath.Join(hostPath, mount.SubPath)
+		}
 		mounts = append(mounts, kubecontainer.Mount{
 			Name:           mount.Name,
 			ContainerPath:  mount.MountPath,
-			HostPath:       vol.Mounter.GetPath(),
+			HostPath:       hostPath,
 			ReadOnly:       mount.ReadOnly,
 			SELinuxRelabel: relabelVolume,
 		})

test/e2e/host_path.go

@@ -88,6 +88,37 @@ var _ = framework.KubeDescribe("hostPath", func() {
 		}, namespace.Name,
 		)
 	})
+
+	It("should support subPath [Conformance]", func() {
+		volumePath := "/test-volume"
+		subPath := "sub-path"
+		fileName := "test-file"
+		retryDuration := 180
+
+		filePathInWriter := path.Join(volumePath, fileName)
+		filePathInReader := path.Join(volumePath, subPath, fileName)
+
+		source := &api.HostPathVolumeSource{
+			Path: "/tmp",
+		}
+		pod := testPodWithHostVol(volumePath, source)
+		// Write the file in the subPath from container 0
+		container := &pod.Spec.Containers[0]
+		container.VolumeMounts[0].SubPath = subPath
+		container.Args = []string{
+			fmt.Sprintf("--new_file_0644=%v", filePathInWriter),
+			fmt.Sprintf("--file_mode=%v", filePathInWriter),
+		}
+		// Read it from outside the subPath from container 1
+		pod.Spec.Containers[1].Args = []string{
+			fmt.Sprintf("--file_content_in_loop=%v", filePathInReader),
+			fmt.Sprintf("--retry_time=%d", retryDuration),
+		}
+
+		framework.TestContainerOutput("hostPath subPath", c, pod, 1, []string{
+			"content of file \"" + filePathInReader + "\": mount-tester new file",
+		}, namespace.Name)
+	})
 })
 
 //These constants are borrowed from the other test.