1 // Copyright 2016 The Linux Foundation 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package schema 16 17 import ( 18 "embed" 19 "net/http" 20 21 v1 "github.com/opencontainers/image-spec/specs-go/v1" 22 ) 23 24 // Media types for the OCI image formats 25 const ( 26 ValidatorMediaTypeDescriptor Validator = v1.MediaTypeDescriptor 27 ValidatorMediaTypeLayoutHeader Validator = v1.MediaTypeLayoutHeader 28 ValidatorMediaTypeManifest Validator = v1.MediaTypeImageManifest 29 ValidatorMediaTypeImageIndex Validator = v1.MediaTypeImageIndex 30 ValidatorMediaTypeImageConfig Validator = v1.MediaTypeImageConfig 31 ValidatorMediaTypeImageLayer unimplemented = v1.MediaTypeImageLayer 32 ) 33 34 var ( 35 // fs stores the embedded http.FileSystem 36 // having the OCI JSON schema files in root "/". 37 //go:embed *.json 38 fs embed.FS 39 40 // schemaNamespaces is a set of URI prefixes which are treated as containing the schema files of fs. 41 // This is necessary because *.json schema files in this directory use "id" and "$ref" attributes which evaluate to such URIs, e.g. 42 // ./image-manifest-schema.json URI contains 43 // "id": "https://opencontainers.org/schema/image/manifest", 44 // and 45 // "$ref": "content-descriptor.json" 46 // which evaluates as a link to https://opencontainers.org/schema/image/content-descriptor.json . 47 // 48 // To support such links without accessing the network (and trying to load content which is not hosted at these URIs), 49 // fsLoaderFactory accepts any URI starting with one of the schemaNamespaces below, 50 // and uses _escFS to load them from the root of its in-memory filesystem tree. 51 // 52 // (Note that this must contain subdirectories before its parent directories for fsLoaderFactory.refContents to work.) 53 schemaNamespaces = []string{ 54 "https://opencontainers.org/schema/image/descriptor/", 55 "https://opencontainers.org/schema/image/index/", 56 "https://opencontainers.org/schema/image/manifest/", 57 "https://opencontainers.org/schema/image/", 58 "https://opencontainers.org/schema/descriptor/", 59 "https://opencontainers.org/schema/", 60 } 61 62 // specs maps OCI schema media types to schema URIs. 63 // These URIs are expected to be used only by fsLoaderFactory (which trims schemaNamespaces defined above) 64 // and should never cause a network access. 65 specs = map[Validator]string{ 66 ValidatorMediaTypeDescriptor: "https://opencontainers.org/schema/content-descriptor.json", 67 ValidatorMediaTypeLayoutHeader: "https://opencontainers.org/schema/image/image-layout-schema.json", 68 ValidatorMediaTypeManifest: "https://opencontainers.org/schema/image/image-manifest-schema.json", 69 ValidatorMediaTypeImageIndex: "https://opencontainers.org/schema/image/image-index-schema.json", 70 ValidatorMediaTypeImageConfig: "https://opencontainers.org/schema/image/config-schema.json", 71 } 72 ) 73 74 // FileSystem returns an in-memory filesystem including the schema files. 75 // The schema files are located at the root directory. 76 func FileSystem() http.FileSystem { 77 return http.FS(fs) 78 } 79