diff --git a/internal/cloudapi/v2/v2_disk_test.go b/internal/cloudapi/v2/v2_disk_test.go
new file mode 100644
index 000000000..95b34cd05
--- /dev/null
+++ b/internal/cloudapi/v2/v2_disk_test.go
@@ -0,0 +1,530 @@
+package v2_test
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/osbuild/images/pkg/distro/test_distro"
+	"github.com/osbuild/osbuild-composer/internal/test"
+)
+
+func TestComposeDiskCustomizationsValidation(t *testing.T) {
+	srv, _, _, cancel := newV2Server(t, t.TempDir(), false, false)
+	defer cancel()
+
+	testCases := map[string]string{
+		"simple": `
+{
+	"disk": {
+		"minsize": "100 GiB",
+		"partitions": [
+			{
+				"mountpoint": "/home",
+				"fs_type": "ext4",
+				"minsize": "2 GiB"
+			}
+		]
+	}
+}
+`,
+
+		"simple-with-type": `
+{
+	"disk": {
+		"minsize": "100 GiB",
+		"partitions": [
+			{
+				"type": "plain",
+				"mountpoint": "/home",
+				"fs_type": "xfs",
+				"minsize": "2 GiB"
+			}
+		]
+	}
+}
+`,
+
+		"large-plain": `
+{
+	"disk": {
+		"type": "gpt",
+		"partitions": [
+			{
+				"mountpoint": "/data",
+				"fs_type": "ext4",
+				"minsize": "1 GiB"
+			},
+			{
+				"mountpoint": "/home",
+				"label": "home",
+				"fs_type": "ext4",
+				"minsize": "2 GiB"
+			},
+			{
+				"mountpoint": "/home/shadowman",
+				"fs_type": "ext4",
+				"minsize": "5 GiB"
+			},
+			{
+				"mountpoint": "/var",
+				"fs_type": "xfs",
+				"minsize": "4 GiB"
+			},
+			{
+				"mountpoint": "/opt",
+				"fs_type": "ext4",
+				"minsize": "10 GiB"
+			},
+			{
+				"mountpoint": "/media",
+				"fs_type": "ext4",
+				"minsize": "9 GiB"
+			},
+			{
+				"mountpoint": "/root",
+				"fs_type": "ext4",
+				"minsize": "1 GiB"
+			},
+			{
+				"mountpoint": "/srv",
+				"fs_type": "xfs",
+				"minsize": "3 GiB"
+			},
+			{
+				"fs_type": "swap",
+				"minsize": "1 GiB"
+			}
+		]
+	}
+}
+`,
+
+		"lvm": `
+{
+	"disk": {
+		"type": "gpt",
+		"partitions": [
+			{
+				"mountpoint": "/data",
+				"minsize": "1 GiB",
+				"label": "data",
+				"fs_type": "ext4"
+			},
+			{
+				"type": "lvm",
+				"name": "testvg",
+				"minsize": "200 GiB",
+				"logical_volumes": [
+					{
+						"name": "homelv",
+						"mountpoint": "/home",
+						"label": "home",
+						"fs_type": "ext4",
+						"minsize": "2 GiB"
+					},
+					{
+						"name": "shadowmanlv",
+						"mountpoint": "/home/shadowman",
+						"fs_type": "ext4",
+						"minsize": "5 GiB"
+					},
+					{
+						"name": "foolv",
+						"mountpoint": "/foo",
+						"fs_type": "ext4",
+						"minsize": "1 GiB"
+					},
+					{
+						"name": "usrlv",
+						"mountpoint": "/usr",
+						"fs_type": "ext4",
+						"minsize": "4 GiB"
+					},
+					{
+						"name": "optlv",
+						"mountpoint": "/opt",
+						"fs_type": "ext4",
+						"minsize": "1 GiB"
+					},
+					{
+						"name": "medialv",
+						"mountpoint": "/media",
+						"fs_type": "ext4",
+						"minsize": "10 GiB"
+					},
+					{
+						"name": "roothomelv",
+						"mountpoint": "/root",
+						"fs_type": "ext4",
+						"minsize": "1 GiB"
+					},
+					{
+						"name": "srvlv",
+						"mountpoint": "/srv",
+						"fs_type": "ext4",
+						"minsize": "10 GiB"
+					},
+					{
+						"name": "swap-lv",
+						"fs_type": "swap",
+						"minsize": "1 GiB"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+		"btrfs": `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "plain",
+				"mountpoint": "/data",
+				"minsize": "12 GiB",
+				"fs_type": "xfs"
+			},
+			{
+				"type": "btrfs",
+				"minsize": "10 GiB",
+				"subvolumes": [
+					{
+						"name": "subvol-home",
+						"mountpoint": "/home"
+					},
+					{
+						"name": "subvol-shadowman",
+						"mountpoint": "/home/shadowman"
+					},
+					{
+						"name": "subvol-foo",
+						"mountpoint": "/foo"
+					},
+					{
+						"name": "subvol-usr",
+						"mountpoint": "/usr"
+					},
+					{
+						"name": "subvol-opt",
+						"mountpoint": "/opt"
+					},
+					{
+						"name": "subvol-media",
+						"mountpoint": "/media"
+					},
+					{
+						"name": "subvol-root",
+						"mountpoint": "/root"
+					},
+					{
+						"name": "subvol-srv",
+						"mountpoint": "/srv"
+					}
+				]
+			},
+			{
+				"type": "plain",
+				"fs_type": "swap",
+				"label": "swap-part",
+				"minsize": "1 GiB"
+			}
+		]
+	}
+}
+`,
+	}
+
+	resp := `{"href": "/api/image-builder-composer/v2/compose", "kind": "ComposeId"}`
+	for name, customizations := range testCases {
+		t.Run(name, func(t *testing.T) {
+			body := fmt.Sprintf(`
+	{
+		"distribution": "%s",
+		"customizations": %s,
+		"image_request":{
+			"architecture": "%s",
+			"image_type": "aws",
+			"repositories": [{
+				"baseurl": "somerepo.org",
+				"rhsm": false
+			}],
+			"upload_options": {
+				"region": "eu-central-1"
+			}
+		}
+	}`, test_distro.TestDistro1Name, customizations, test_distro.TestArch3Name)
+
+			test.TestRouteWithReply(t, srv.Handler("/api/image-builder-composer/v2"), false, "POST", "/api/image-builder-composer/v2/compose", body, http.StatusCreated, resp, "id")
+		})
+	}
+}
+
+func TestComposeDiskCustomizationsErrors(t *testing.T) {
+	srv, _, _, cancel := newV2Server(t, t.TempDir(), false, false)
+	defer cancel()
+
+	type testCase struct {
+		customizations string
+		expResponse    string
+	}
+
+	// one of two responses is returned depending on the exact origin of the error:
+	//  1. IMAGE-BUILDER-COMPOSER-30 is returned when the customization failed at the schema level, when it fails to validate against the openapi schema
+	//  2. IMAGE-BUILDER-COMPOSER-35 is returned when the customization failed the Disk.Validate() call at the blueprint level
+	validationErrorResp := `{"href": "/api/image-builder-composer/v2/errors/30", "kind": "Error", "reason": "Request could not be validated", "code": "IMAGE-BUILDER-COMPOSER-30"}`
+	invalidCustomizationResp := `{"href": "/api/image-builder-composer/v2/errors/35", "kind": "Error", "reason": "Invalid image customization", "code": "IMAGE-BUILDER-COMPOSER-35"}`
+
+	testCases := map[string]testCase{
+		"empty": {
+			customizations: `{"disk": {}}`,
+			expResponse:    validationErrorResp,
+		},
+		"number-minsize": {
+			customizations: `
+{
+	"disk": {
+		"minsize": 1024,
+		"partitions": [
+			{
+				"mountpoint": "/",
+				"minsize": "2 GiB",
+				"fs_type": "ext4"
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"no-fs-type": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"mountpoint": "/",
+				"minsize": "2 GiB"
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"swap-with-mountpoint": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"mountpoint": "/",
+				"fs_type": "swap"
+			}
+		]
+	}
+}
+`,
+			expResponse: invalidCustomizationResp,
+		},
+		"nonswap-without-mountpoint": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"fs_type": "xfs"
+			}
+		]
+	}
+}
+`,
+			expResponse: invalidCustomizationResp,
+		},
+		"swap-with-mountpoint-lvm": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "lvm",
+				"logical_volumes": [{
+					"mountpoint": "/",
+					"fs_type": "swap"
+				}]
+			}
+		]
+	}
+}
+`,
+			expResponse: invalidCustomizationResp,
+		},
+		"nonswap-without-mountpoint-lvm": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "lvm",
+				"logical_volumes": [{
+					"fs_type": "xfs"
+				}]
+			}
+		]
+	}
+}
+`,
+			expResponse: invalidCustomizationResp,
+		},
+		"notype-with-lv": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"logical_volumes": [
+					{
+						"name": "homelv",
+						"mountpoint": "/home",
+						"label": "home",
+						"fs_type": "ext4",
+						"minsize": "2 GiB"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"plain-with-lv": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "plain",
+				"logical_volumes": [
+					{
+						"name": "homelv",
+						"mountpoint": "/home",
+						"label": "home",
+						"fs_type": "ext4",
+						"minsize": "2 GiB"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"notype-with-subvol": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"subvolumes": [
+					{
+						"name": "home",
+						"mountpoint": "/home"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"plain-with-subvol": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "plain",
+				"subvolumes": [
+					{
+						"name": "home",
+						"mountpoint": "/home"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"lvm-with-subvol": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "lvm",
+				"subvolumes": [
+					{
+						"name": "home",
+						"mountpoint": "/home"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+		"btrfs-with-lv": {
+			customizations: `
+{
+	"disk": {
+		"partitions": [
+			{
+				"type": "btrfs",
+				"logical_volumes": [
+					{
+						"name": "homelv",
+						"mountpoint": "/home",
+						"label": "home",
+						"fs_type": "ext4",
+						"minsize": "2 GiB"
+					}
+				]
+			}
+		]
+	}
+}
+`,
+			expResponse: validationErrorResp,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			body := fmt.Sprintf(`
+	{
+		"distribution": "%s",
+		"customizations": %s,
+		"image_request":{
+			"architecture": "%s",
+			"image_type": "aws",
+			"repositories": [{
+				"baseurl": "somerepo.org",
+				"rhsm": false
+			}],
+			"upload_options": {
+				"region": "eu-central-1"
+			}
+		}
+	}`, test_distro.TestDistro1Name, tc.customizations, test_distro.TestArch3Name)
+			test.TestRoute(t, srv.Handler("/api/image-builder-composer/v2"), false, "POST", "/api/image-builder-composer/v2/compose", body, http.StatusBadRequest, tc.expResponse, "id", "operation_id", "details")
+		})
+	}
+}