fcos translate.go: add warn on small or constrained root partition

config/common/errors.go

@@ -68,6 +68,8 @@ var (
 	// partition
 	ErrReuseByLabel         = errors.New("partitions cannot be reused by label; number must be specified except on boot disk (/dev/disk/by-id/coreos-boot-disk) or when wipe_table is true")
 	ErrWrongPartitionNumber = errors.New("incorrect partition number; a new partition will be created using reserved label")
+	ErrRootTooSmall         = errors.New("root should have 8GiB of space assigned")
+	ErrRootConstrained      = errors.New("root is configured too small, and has no room to expand")
 
 	// MachineConfigs
 	ErrFieldElided              = errors.New("field ignored in raw mode")

config/fcos/v1_3/translate.go

@@ -70,16 +70,70 @@ func (c Config) ToIgn3_2Unvalidated(options common.TranslateOptions) (types.Conf
 	}
 	r.Merge(c.processBootDevice(&ret, &ts, options))
 	for i, disk := range ret.Storage.Disks {
-		// In the boot_device.mirror case, nothing specifies partition numbers
-		// so match existing partitions only when `wipeTable` is false
-		if !util.IsTrue(disk.WipeTable) {
-			for j, partition := range disk.Partitions {
-				// check for reserved partlabels
-				if partition.Label != nil {
+		for p, partition := range disk.Partitions {
+			// if the partition is not nil and is root
+			if partition.Label != nil {
+				if *partition.Label == "root" {
+					if partition.SizeMiB == nil || *partition.SizeMiB == 0 {
+						// Root is set to "fill available" (0 or unspecified)
+						// Check if it's constrained by the next partition on disk
+						// Sort partitions by disk position (StartMiB) to find the next partition
+						var rootStart int
+						if partition.StartMiB != nil {
+							rootStart = *partition.StartMiB
+						}
+
+						// Find the partition that comes immediately after root on disk
+						var nextPartition *types.Partition
+						for idx, ap := range disk.Partitions {
+							// Skip the root partition itself
+							if idx == p {
+								continue
+							}
+
+							var apStart int
+							if ap.StartMiB != nil {
+								apStart = *ap.StartMiB
+							}
+
+							// Only consider partitions that start after root
+							// (or auto-positioned partitions which will be placed after root)
+							if apStart > rootStart || (apStart == 0 && rootStart >= 0) {
+								if nextPartition == nil {
+									nextPartition = &ap
+								} else {
+									var nextStart int
+									if nextPartition.StartMiB != nil {
+										nextStart = *nextPartition.StartMiB
+									}
+									// If this partition starts before the current "next", it's closer to root
+									if (apStart > 0 && apStart < nextStart) || (nextStart == 0 && apStart > 0) {
+										nextPartition = &ap
+									}
+								}
+							}
+						}
+
+						// Check if the next partition constrains root
+						if nextPartition != nil {
+							if nextPartition.StartMiB == nil || *nextPartition.StartMiB == 0 {
+								r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "label"), common.ErrRootConstrained)
+							}
+						}
+					} else if *partition.SizeMiB < 8192 {
+						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "size_mib"), common.ErrRootTooSmall)
+					}
+				}
+
+				// In the boot_device.mirror case, nothing specifies partition numbers
+				// so match existing partitions only when `wipeTable` is false
+				if !util.IsTrue(disk.WipeTable) {
+					// check for reserved partlabels
 					if (*partition.Label == "BIOS-BOOT" && partition.Number != 1) || (*partition.Label == "PowerPC-PReP-boot" && partition.Number != 1) || (*partition.Label == "EFI-SYSTEM" && partition.Number != 2) || (*partition.Label == "boot" && partition.Number != 3) || (*partition.Label == "root" && partition.Number != 4) {
-						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", j, "label"), common.ErrWrongPartitionNumber)
+						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "label"), common.ErrWrongPartitionNumber)
 					}
 				}
+
 			}
 		}
 	}

config/fcos/v1_3/translate_test.go

@@ -1423,3 +1423,178 @@ func TestTranslateBootDevice(t *testing.T) {
 		})
 	}
 }
+
+// TestPartitionSorting tests that partitions are properly sorted by disk position,
+// not by partition number, when detecting constraints.
+func TestPartitionSorting(t *testing.T) {
+	tests := []struct {
+		name   string
+		in     Config
+		report report.Report
+	}{
+		// Root partition with default size (0, fill available) followed by a partition
+		// with explicit StartMiB = 0 (auto-positioned). The next partition should be
+		// the one that comes AFTER root on disk.
+		{
+			name: "root partition constrained by disk position not partition number",
+			in: Config{
+				Config: base.Config{
+					Storage: base.Storage{
+						Disks: []base.Disk{
+							{
+								Device: "/dev/vda",
+								Partitions: []base.Partition{
+									{
+										Label:   util.StrToPtr("root"),
+										Number:  4,
+										SizeMiB: util.IntToPtr(0), // fill available
+									},
+									{
+										Label:    util.StrToPtr("data"),
+										StartMiB: util.IntToPtr(0), // auto-positioned - will be placed after root
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			report: report.Report{
+				Entries: []report.Entry{
+					{
+						Kind:    report.Warn,
+						Message: common.ErrRootConstrained.Error(),
+						Context: path.New("yaml", "storage", "disks", 0, "partitions", 0, "label"),
+					},
+				},
+			},
+		},
+		// Root partition followed by a partition with explicit StartMiB that would
+		// constrain root.
+		{
+			name: "root constrained by explicit StartMiB partition",
+			in: Config{
+				Config: base.Config{
+					Storage: base.Storage{
+						Disks: []base.Disk{
+							{
+								Device: "/dev/vda",
+								Partitions: []base.Partition{
+									{
+										Label:    util.StrToPtr("root"),
+										Number:   4,
+										SizeMiB:  util.IntToPtr(0), // fill available
+										StartMiB: util.IntToPtr(2048),
+									},
+									{
+										Label:    util.StrToPtr("var"),
+										StartMiB: util.IntToPtr(0), // auto-positioned - constrains root
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			report: report.Report{
+				Entries: []report.Entry{
+					{
+						Kind:    report.Warn,
+						Message: common.ErrRootConstrained.Error(),
+						Context: path.New("yaml", "storage", "disks", 0, "partitions", 0, "label"),
+					},
+				},
+			},
+		},
+		// Root partition NOT constrained because next partition has explicit StartMiB
+		{
+			name: "root not constrained with explicit StartMiB after",
+			in: Config{
+				Config: base.Config{
+					Storage: base.Storage{
+						Disks: []base.Disk{
+							{
+								Device: "/dev/vda",
+								Partitions: []base.Partition{
+									{
+										Label:    util.StrToPtr("root"),
+										Number:   4,
+										SizeMiB:  util.IntToPtr(0), // fill available
+										StartMiB: util.IntToPtr(2048),
+									},
+									{
+										Label:    util.StrToPtr("data"),
+										StartMiB: util.IntToPtr(10240), // explicit position - does NOT constrain root
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			report: report.Report{},
+		},
+		// Root partition too small (explicit size < 8192 MiB)
+		{
+			name: "root partition too small",
+			in: Config{
+				Config: base.Config{
+					Storage: base.Storage{
+						Disks: []base.Disk{
+							{
+								Device: "/dev/vda",
+								Partitions: []base.Partition{
+									{
+										Label:   util.StrToPtr("root"),
+										Number:  4,
+										SizeMiB: util.IntToPtr(4096),
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			report: report.Report{
+				Entries: []report.Entry{
+					{
+						Kind:    report.Warn,
+						Message: common.ErrRootTooSmall.Error(),
+						Context: path.New("json", "storage", "disks", 0, "partitions", 0, "size_mib"),
+					},
+				},
+			},
+		},
+		// Root partition exactly 8192 MiB
+		{
+			name: "root partition exactly 8GiB",
+			in: Config{
+				Config: base.Config{
+					Storage: base.Storage{
+						Disks: []base.Disk{
+							{
+								Device: "/dev/vda",
+								Partitions: []base.Partition{
+									{
+										Label:   util.StrToPtr("root"),
+										Number:  4,
+										SizeMiB: util.IntToPtr(8192),
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			report: report.Report{},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			_, translations, r := test.in.ToIgn3_2Unvalidated(common.TranslateOptions{})
+			r = confutil.TranslateReportPaths(r, translations)
+			assert.Equal(t, test.report, r, "report mismatch")
+		})
+	}
+}

config/fcos/v1_4/translate.go

@@ -70,16 +70,70 @@ func (c Config) ToIgn3_3Unvalidated(options common.TranslateOptions) (types.Conf
 	}
 	r.Merge(c.processBootDevice(&ret, &ts, options))
 	for i, disk := range ret.Storage.Disks {
-		// In the boot_device.mirror case, nothing specifies partition numbers
-		// so match existing partitions only when `wipeTable` is false
-		if !util.IsTrue(disk.WipeTable) {
-			for j, partition := range disk.Partitions {
-				// check for reserved partlabels
-				if partition.Label != nil {
+		for p, partition := range disk.Partitions {
+			// if the partition is not nil and is root
+			if partition.Label != nil {
+				if *partition.Label == "root" {
+					if partition.SizeMiB == nil || *partition.SizeMiB == 0 {
+						// Root is set to "fill available" (0 or unspecified)
+						// Check if it's constrained by the next partition on disk
+						// Sort partitions by disk position (StartMiB) to find the next partition
+						var rootStart int
+						if partition.StartMiB != nil {
+							rootStart = *partition.StartMiB
+						}
+
+						// Find the partition that comes immediately after root on disk
+						var nextPartition *types.Partition
+						for idx, ap := range disk.Partitions {
+							// Skip the root partition itself
+							if idx == p {
+								continue
+							}
+
+							var apStart int
+							if ap.StartMiB != nil {
+								apStart = *ap.StartMiB
+							}
+
+							// Only consider partitions that start after root
+							// (or auto-positioned partitions which will be placed after root)
+							if apStart > rootStart || (apStart == 0 && rootStart >= 0) {
+								if nextPartition == nil {
+									nextPartition = &ap
+								} else {
+									var nextStart int
+									if nextPartition.StartMiB != nil {
+										nextStart = *nextPartition.StartMiB
+									}
+									// If this partition starts before the current "next", it's closer to root
+									if (apStart > 0 && apStart < nextStart) || (nextStart == 0 && apStart > 0) {
+										nextPartition = &ap
+									}
+								}
+							}
+						}
+
+						// Check if the next partition constrains root
+						if nextPartition != nil {
+							if nextPartition.StartMiB == nil || *nextPartition.StartMiB == 0 {
+								r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "label"), common.ErrRootConstrained)
+							}
+						}
+					} else if *partition.SizeMiB < 8192 {
+						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "size_mib"), common.ErrRootTooSmall)
+					}
+				}
+
+				// In the boot_device.mirror case, nothing specifies partition numbers
+				// so match existing partitions only when `wipeTable` is false
+				if !util.IsTrue(disk.WipeTable) {
+					// check for reserved partlabels
 					if (*partition.Label == "BIOS-BOOT" && partition.Number != 1) || (*partition.Label == "PowerPC-PReP-boot" && partition.Number != 1) || (*partition.Label == "EFI-SYSTEM" && partition.Number != 2) || (*partition.Label == "boot" && partition.Number != 3) || (*partition.Label == "root" && partition.Number != 4) {
-						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", j, "label"), common.ErrWrongPartitionNumber)
+						r.AddOnWarn(path.New("json", "storage", "disks", i, "partitions", p, "label"), common.ErrWrongPartitionNumber)
 					}
 				}
+
 			}
 		}
 	}