Add nodeinfo endpoint for federation purposes (#16953)

Nodeinfo is a way to expose certain metadata about a server for use of discovery regarding functionality of its federation capabilities.

Two endpoints are required:
1. `/.well-known/nodeinfo` which informs client where it can find the location of the location of its metadata (including which version of the schema is used)
2. the endpoint which exposes the metadata in json format according to schema.

Notes:
* `openRegistrations` is a required field, but I propose to set to false as default in case someone writes a crawler to discover "open" gitea instances
* to limit data leakage I also propose to not include the `usage` field (note it is required so it should be included, but left as empty).

More info:
https://github.com/jhass/nodeinfo
https://github.com/jhass/nodeinfo/tree/main/schemas/2.1
http://nodeinfo.diaspora.software/protocol.html

custom/conf/app.example.ini

@@ -2081,6 +2081,15 @@ PATH =
 ;; Allow private addresses defined by RFC 1918, RFC 1122, RFC 4632 and RFC 4291 (false by default)
 ;ALLOW_LOCALNETWORKS = false
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;[federation]
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Enable/Disable federation capabilities
+; ENABLED = true
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; default storage for attachments, lfs and avatars

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -953,6 +953,10 @@ Task queue configuration has been moved to `queue.task`. However, the below conf
 - `ALLOW_LOCALNETWORKS`: **false**: Allow private addresses defined by RFC 1918, RFC 1122, RFC 4632 and RFC 4291
 - `SKIP_TLS_VERIFY`: **false**: Allow skip tls verify
 
+## Federation (`federation`)
+
+- `ENABLED`: **true**: Enable/Disable federation capabilities
+
 ## Mirror (`mirror`)
 
 - `ENABLED`: **true**: Enables the mirror functionality. Set to **false** to disable all mirrors.

modules/setting/federation.go

@@ -0,0 +1,22 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package setting
+
+import "code.gitea.io/gitea/modules/log"
+
+// Federation settings
+var (
+	Federation = struct {
+		Enabled bool
+	}{
+		Enabled: true,
+	}
+)
+
+func newFederationService() {
+	if err := Cfg.Section("federation").MapTo(&Federation); err != nil {
+		log.Fatal("Failed to map Federation settings: %v", err)
+	}
+}

modules/setting/setting.go

@@ -1188,6 +1188,7 @@ func NewServices() {
 	NewQueueService()
 	newProject()
 	newMimeTypeMap()
+	newFederationService()
 }
 
 // NewServicesForInstall initializes the services for install

modules/structs/nodeinfo.go

@@ -0,0 +1,44 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package structs
+
+// NodeInfo contains standardized way of exposing metadata about a server running one of the distributed social networks
+type NodeInfo struct {
+	Version           string           `json:"version"`
+	Software          NodeInfoSoftware `json:"software"`
+	Protocols         []string         `json:"protocols"`
+	Services          NodeInfoServices `json:"services"`
+	OpenRegistrations bool             `json:"openRegistrations"`
+	Usage             NodeInfoUsage    `json:"usage"`
+	Metadata          struct{}         `json:"metadata"`
+}
+
+// NodeInfoSoftware contains Metadata about server software in use
+type NodeInfoSoftware struct {
+	Name       string `json:"name"`
+	Version    string `json:"version"`
+	Repository string `json:"repository"`
+	Homepage   string `json:"homepage"`
+}
+
+// NodeInfoServices contains the third party sites this server can connect to via their application API
+type NodeInfoServices struct {
+	Inbound  []string `json:"inbound"`
+	Outbound []string `json:"outbound"`
+}
+
+// NodeInfoUsage contains usage statistics for this server
+type NodeInfoUsage struct {
+	Users         NodeInfoUsageUsers `json:"users"`
+	LocalPosts    int                `json:"localPosts,omitempty"`
+	LocalComments int                `json:"localComments,omitempty"`
+}
+
+// NodeInfoUsageUsers contains statistics about the users of this server
+type NodeInfoUsageUsers struct {
+	Total          int `json:"total,omitempty"`
+	ActiveHalfyear int `json:"activeHalfyear,omitempty"`
+	ActiveMonth    int `json:"activeMonth,omitempty"`
+}

routers/api/v1/api.go

@@ -580,6 +580,9 @@ func Routes(sessioner func(http.Handler) http.Handler) *web.Route {
 			})
 		}
 		m.Get("/version", misc.Version)
+		if setting.Federation.Enabled {
+			m.Get("/nodeinfo", misc.NodeInfo)
+		}
 		m.Get("/signing-key.gpg", misc.SigningKey)
 		m.Post("/markdown", bind(api.MarkdownOption{}), misc.Markdown)
 		m.Post("/markdown/raw", misc.MarkdownRaw)

routers/api/v1/misc/nodeinfo.go

@@ -0,0 +1,45 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package misc
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/structs"
+)
+
+// NodeInfo returns the NodeInfo for the Gitea instance to allow for federation
+func NodeInfo(ctx *context.APIContext) {
+	// swagger:operation GET /nodeinfo miscellaneous getNodeInfo
+	// ---
+	// summary: Returns the nodeinfo of the Gitea application
+	// produces:
+	// - application/json
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/NodeInfo"
+
+	nodeInfo := &structs.NodeInfo{
+		Version: "2.1",
+		Software: structs.NodeInfoSoftware{
+			Name:       "gitea",
+			Version:    setting.AppVer,
+			Repository: "https://github.com/go-gitea/gitea.git",
+			Homepage:   "https://gitea.io/",
+		},
+		Protocols: []string{"activitypub"},
+		Services: structs.NodeInfoServices{
+			Inbound:  []string{},
+			Outbound: []string{},
+		},
+		OpenRegistrations: setting.Service.ShowRegistrationButton,
+		Usage: structs.NodeInfoUsage{
+			Users: structs.NodeInfoUsageUsers{},
+		},
+	}
+	ctx.JSON(http.StatusOK, nodeInfo)
+}

routers/api/v1/swagger/nodeinfo.go

@@ -0,0 +1,16 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package swagger
+
+import (
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// NodeInfo
+// swagger:response NodeInfo
+type swaggerResponseNodeInfo struct {
+	// in:body
+	Body api.NodeInfo `json:"body"`
+}

routers/web/nodeinfo.go

@@ -0,0 +1,33 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package web
+
+import (
+	"fmt"
+	"net/http"
+
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+type nodeInfoLinks struct {
+	Links []nodeInfoLink `json:"links"`
+}
+
+type nodeInfoLink struct {
+	Href string `json:"href"`
+	Rel  string `json:"rel"`
+}
+
+// NodeInfoLinks returns links to the node info endpoint
+func NodeInfoLinks(ctx *context.Context) {
+	nodeinfolinks := &nodeInfoLinks{
+		Links: []nodeInfoLink{{
+			fmt.Sprintf("%sapi/v1/nodeinfo", setting.AppURL),
+			"http://nodeinfo.diaspora.software/ns/schema/2.1",
+		}},
+	}
+	ctx.JSON(http.StatusOK, nodeinfolinks)
+}

routers/web/web.go

@@ -234,6 +234,9 @@ func RegisterRoutes(m *web.Route) {
 	// for health check
 	m.Get("/", Home)
 	m.Get("/.well-known/openid-configuration", user.OIDCWellKnown)
+	if setting.Federation.Enabled {
+		m.Get("/.well-known/nodeinfo", NodeInfoLinks)
+	}
 	m.Group("/explore", func() {
 		m.Get("", func(ctx *context.Context) {
 			ctx.Redirect(setting.AppSubURL + "/explore/repos")

templates/swagger/v1_json.tmpl

@@ -615,6 +615,23 @@
         }
       }
     },
+    "/nodeinfo": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "miscellaneous"
+        ],
+        "summary": "Returns the nodeinfo of the Gitea application",
+        "operationId": "getNodeInfo",
+        "responses": {
+          "200": {
+            "$ref": "#/responses/NodeInfo"
+          }
+        }
+      }
+    },
     "/notifications": {
       "get": {
         "consumes": [
@@ -15560,6 +15577,127 @@
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
     },
+    "NodeInfo": {
+      "description": "NodeInfo contains standardized way of exposing metadata about a server running one of the distributed social networks",
+      "type": "object",
+      "properties": {
+        "metadata": {
+          "type": "object",
+          "x-go-name": "Metadata"
+        },
+        "openRegistrations": {
+          "type": "boolean",
+          "x-go-name": "OpenRegistrations"
+        },
+        "protocols": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "x-go-name": "Protocols"
+        },
+        "services": {
+          "$ref": "#/definitions/NodeInfoServices"
+        },
+        "software": {
+          "$ref": "#/definitions/NodeInfoSoftware"
+        },
+        "usage": {
+          "$ref": "#/definitions/NodeInfoUsage"
+        },
+        "version": {
+          "type": "string",
+          "x-go-name": "Version"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
+    "NodeInfoServices": {
+      "description": "NodeInfoServices contains the third party sites this server can connect to via their application API",
+      "type": "object",
+      "properties": {
+        "inbound": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "x-go-name": "Inbound"
+        },
+        "outbound": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "x-go-name": "Outbound"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
+    "NodeInfoSoftware": {
+      "description": "NodeInfoSoftware contains Metadata about server software in use",
+      "type": "object",
+      "properties": {
+        "homepage": {
+          "type": "string",
+          "x-go-name": "Homepage"
+        },
+        "name": {
+          "type": "string",
+          "x-go-name": "Name"
+        },
+        "repository": {
+          "type": "string",
+          "x-go-name": "Repository"
+        },
+        "version": {
+          "type": "string",
+          "x-go-name": "Version"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
+    "NodeInfoUsage": {
+      "description": "NodeInfoUsage contains usage statistics for this server",
+      "type": "object",
+      "properties": {
+        "localComments": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "LocalComments"
+        },
+        "localPosts": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "LocalPosts"
+        },
+        "users": {
+          "$ref": "#/definitions/NodeInfoUsageUsers"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
+    "NodeInfoUsageUsers": {
+      "description": "NodeInfoUsageUsers contains statistics about the users of this server",
+      "type": "object",
+      "properties": {
+        "activeHalfyear": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "ActiveHalfyear"
+        },
+        "activeMonth": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "ActiveMonth"
+        },
+        "total": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "Total"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
     "Note": {
       "description": "Note contains information related to a git note",
       "type": "object",
@@ -17533,6 +17671,12 @@
         }
       }
     },
+    "NodeInfo": {
+      "description": "NodeInfo",
+      "schema": {
+        "$ref": "#/definitions/NodeInfo"
+      }
+    },
     "Note": {
       "description": "Note",
       "schema": {