4 files changed, 191 insertions, 14 deletions

diff --git a/server/initializers/constants.ts b/server/initializers/constants.ts
index 908231a88..7c0c5a87c 100644
--- a/server/initializers/constants.ts
+++ b/server/initializers/constants.ts
@@ -168,10 +168,15 @@ const SCHEDULER_INTERVALS_MS = {
   updateVideos: 60000, // 1 minute
   youtubeDLUpdate: 60000 * 60 * 24, // 1 day
   checkPlugins: CONFIG.PLUGINS.INDEX.CHECK_LATEST_VERSIONS_INTERVAL,
+  autoFollowIndexInstances: 60000 * 60 * 24, // 1 day
   removeOldViews: 60000 * 60 * 24, // 1 day
   removeOldHistory: 60000 * 60 * 24 // 1 day
 }
 
+const INSTANCES_INDEX = {
+  HOSTS_PATH: '/api/v1/instances/hosts'
+}
+
 // ---------------------------------------------------------------------------
 
 const CONSTRAINTS_FIELDS = {
@@ -633,6 +638,7 @@ if (isTestInstance() === true) {
   SCHEDULER_INTERVALS_MS.removeOldHistory = 5000
   SCHEDULER_INTERVALS_MS.removeOldViews = 5000
   SCHEDULER_INTERVALS_MS.updateVideos = 5000
+  SCHEDULER_INTERVALS_MS.autoFollowIndexInstances = 5000
   REPEAT_JOBS[ 'videos-views' ] = { every: 5000 }
 
   REDUNDANCY.VIDEOS.RANDOMIZED_FACTOR = 1
@@ -683,6 +689,7 @@ export {
   PREVIEWS_SIZE,
   REMOTE_SCHEME,
   FOLLOW_STATES,
+  INSTANCES_INDEX,
   DEFAULT_USER_THEME_NAME,
   SERVER_ACTOR_NAME,
   PLUGIN_GLOBAL_CSS_FILE_NAME,
diff --git a/server/lib/schedulers/auto-follow-index-instances.ts b/server/lib/schedulers/auto-follow-index-instances.ts
new file mode 100644
index 000000000..ef11fc87f
--- /dev/null
+++ b/server/lib/schedulers/auto-follow-index-instances.ts
@@ -0,0 +1,72 @@
+import { logger } from '../../helpers/logger'
+import { AbstractScheduler } from './abstract-scheduler'
+import { INSTANCES_INDEX, SCHEDULER_INTERVALS_MS, SERVER_ACTOR_NAME } from '../../initializers/constants'
+import { CONFIG } from '../../initializers/config'
+import { chunk } from 'lodash'
+import { doRequest } from '@server/helpers/requests'
+import { ActorFollowModel } from '@server/models/activitypub/actor-follow'
+import { JobQueue } from '@server/lib/job-queue'
+import { getServerActor } from '@server/helpers/utils'
+
+export class AutoFollowIndexInstances extends AbstractScheduler {
+
+  private static instance: AbstractScheduler
+
+  protected schedulerIntervalMs = SCHEDULER_INTERVALS_MS.autoFollowIndexInstances
+
+  private lastCheck: Date
+
+  private constructor () {
+    super()
+  }
+
+  protected async internalExecute () {
+    return this.autoFollow()
+  }
+
+  private async autoFollow () {
+    if (CONFIG.FOLLOWINGS.INSTANCE.AUTO_FOLLOW_INDEX.ENABLED === false) return
+
+    const indexUrl = CONFIG.FOLLOWINGS.INSTANCE.AUTO_FOLLOW_INDEX.INDEX_URL
+
+    logger.info('Auto follow instances of index %s.', indexUrl)
+
+    try {
+      const serverActor = await getServerActor()
+
+      const uri = indexUrl + INSTANCES_INDEX.HOSTS_PATH
+
+      const qs = this.lastCheck ? { since: this.lastCheck.toISOString() } : {}
+      this.lastCheck = new Date()
+
+      const { body } = await doRequest({ uri, qs, json: true })
+
+      const hosts: string[] = body.data.map(o => o.host)
+      const chunks = chunk(hosts, 20)
+
+      for (const chunk of chunks) {
+        const unfollowedHosts = await ActorFollowModel.keepUnfollowedInstance(chunk)
+
+        for (const unfollowedHost of unfollowedHosts) {
+          const payload = {
+            host: unfollowedHost,
+            name: SERVER_ACTOR_NAME,
+            followerActorId: serverActor.id,
+            isAutoFollow: true
+          }
+
+          await JobQueue.Instance.createJob({ type: 'activitypub-follow', payload })
+                  .catch(err => logger.error('Cannot create follow job for %s.', unfollowedHost, err))
+        }
+      }
+
+    } catch (err) {
+      logger.error('Cannot auto follow hosts of index %s.', indexUrl, { err })
+    }
+
+  }
+
+  static get Instance () {
+    return this.instance || (this.instance = new this())
+  }
+}
diff --git a/server/models/activitypub/actor-follow.ts b/server/models/activitypub/actor-follow.ts
index c8b3aae9f..0833b9a93 100644
--- a/server/models/activitypub/actor-follow.ts
+++ b/server/models/activitypub/actor-follow.ts
@@ -1,5 +1,5 @@
 import * as Bluebird from 'bluebird'
-import { values } from 'lodash'
+import { values, difference } from 'lodash'
 import {
   AfterCreate,
   AfterDestroy,
@@ -21,7 +21,7 @@ import { FollowState } from '../../../shared/models/actors'
 import { ActorFollow } from '../../../shared/models/actors/follow.model'
 import { logger } from '../../helpers/logger'
 import { getServerActor } from '../../helpers/utils'
-import { ACTOR_FOLLOW_SCORE, FOLLOW_STATES } from '../../initializers/constants'
+import { ACTOR_FOLLOW_SCORE, FOLLOW_STATES, SERVER_ACTOR_NAME } from '../../initializers/constants'
 import { ServerModel } from '../server/server'
 import { createSafeIn, getSort } from '../utils'
 import { ActorModel, unusedActorAttributesForAPI } from './actor'
@@ -435,6 +435,45 @@ export class ActorFollowModel extends Model<ActorFollowModel> {
                            })
   }
 
+  static async keepUnfollowedInstance (hosts: string[]) {
+    const followerId = (await getServerActor()).id
+
+    const query = {
+      attributes: [],
+      where: {
+        actorId: followerId
+      },
+      include: [
+        {
+          attributes: [ ],
+          model: ActorModel.unscoped(),
+          required: true,
+          as: 'ActorFollowing',
+          where: {
+            preferredUsername: SERVER_ACTOR_NAME
+          },
+          include: [
+            {
+              attributes: [ 'host' ],
+              model: ServerModel.unscoped(),
+              required: true,
+              where: {
+                host: {
+                  [Op.in]: hosts
+                }
+              }
+            }
+          ]
+        }
+      ]
+    }
+
+    const res = await ActorFollowModel.findAll(query)
+    const followedHosts = res.map(res => res.ActorFollowing.Server.host)
+
+    return difference(hosts, followedHosts)
+  }
+
   static listAcceptedFollowerUrlsForAP (actorIds: number[], t: Transaction, start?: number, count?: number) {
     return ActorFollowModel.createListAcceptedFollowForApiQuery('followers', actorIds, t, start, count)
   }
diff --git a/server/tests/api/server/auto-follows.ts b/server/tests/api/server/auto-follows.ts
index 32ad259c9..dea9191f2 100644
--- a/server/tests/api/server/auto-follows.ts
+++ b/server/tests/api/server/auto-follows.ts
@@ -6,10 +6,12 @@ import {
   acceptFollower,
   cleanupTests,
   flushAndRunMultipleServers,
+  MockInstancesIndex,
   ServerInfo,
   setAccessTokensToServers,
   unfollow,
-  updateCustomSubConfig
+  updateCustomSubConfig,
+  wait
 } from '../../../../shared/extra-utils/index'
 import { follow, getFollowersListPaginationAndSort, getFollowingListPaginationAndSort } from '../../../../shared/extra-utils/server/follows'
 import { waitJobs } from '../../../../shared/extra-utils/server/jobs'
@@ -22,13 +24,14 @@ async function checkFollow (follower: ServerInfo, following: ServerInfo, exists:
     const res = await getFollowersListPaginationAndSort(following.url, 0, 5, '-createdAt')
     const follows = res.body.data as ActorFollow[]
 
-    if (exists === true) {
-      expect(res.body.total).to.equal(1)
+    const follow = follows.find(f => {
+      return f.follower.host === follower.host && f.state === 'accepted'
+    })
 
-      expect(follows[ 0 ].follower.host).to.equal(follower.host)
-      expect(follows[ 0 ].state).to.equal('accepted')
+    if (exists === true) {
+      expect(follow).to.exist
     } else {
-      expect(follows.filter(f => f.state === 'accepted')).to.have.lengthOf(0)
+      expect(follow).to.be.undefined
     }
   }
 
@@ -36,13 +39,14 @@ async function checkFollow (follower: ServerInfo, following: ServerInfo, exists:
     const res = await getFollowingListPaginationAndSort(follower.url, 0, 5, '-createdAt')
     const follows = res.body.data as ActorFollow[]
 
-    if (exists === true) {
-      expect(res.body.total).to.equal(1)
+    const follow = follows.find(f => {
+      return f.following.host === following.host && f.state === 'accepted'
+    })
 
-      expect(follows[ 0 ].following.host).to.equal(following.host)
-      expect(follows[ 0 ].state).to.equal('accepted')
+    if (exists === true) {
+      expect(follow).to.exist
     } else {
-      expect(follows.filter(f => f.state === 'accepted')).to.have.lengthOf(0)
+      expect(follow).to.be.undefined
     }
   }
 }
@@ -71,7 +75,7 @@ describe('Test auto follows', function () {
   before(async function () {
     this.timeout(30000)
 
-    servers = await flushAndRunMultipleServers(2)
+    servers = await flushAndRunMultipleServers(3)
 
     // Get the access tokens
     await setAccessTokensToServers(servers)
@@ -142,6 +146,61 @@ describe('Test auto follows', function () {
     })
   })
 
+  describe('Auto follow index', function () {
+    const instanceIndexServer = new MockInstancesIndex()
+
+    before(async () => {
+      await instanceIndexServer.initialize()
+    })
+
+    it('Should not auto follow index if the option is not enabled', async function () {
+      this.timeout(30000)
+
+      await wait(5000)
+      await waitJobs(servers)
+
+      await checkFollow(servers[ 0 ], servers[ 1 ], false)
+      await checkFollow(servers[ 1 ], servers[ 0 ], false)
+    })
+
+    it('Should auto follow the index', async function () {
+      this.timeout(30000)
+
+      instanceIndexServer.addInstance(servers[1].host)
+
+      const config = {
+        followings: {
+          instance: {
+            autoFollowIndex: {
+              indexUrl: 'http://localhost:42100',
+              enabled: true
+            }
+          }
+        }
+      }
+      await updateCustomSubConfig(servers[0].url, servers[0].accessToken, config)
+
+      await wait(5000)
+      await waitJobs(servers)
+
+      await checkFollow(servers[ 0 ], servers[ 1 ], true)
+
+      await resetFollows(servers)
+    })
+
+    it('Should follow new added instances in the index but not old ones', async function () {
+      this.timeout(30000)
+
+      instanceIndexServer.addInstance(servers[2].host)
+
+      await wait(5000)
+      await waitJobs(servers)
+
+      await checkFollow(servers[ 0 ], servers[ 1 ], false)
+      await checkFollow(servers[ 0 ], servers[ 2 ], true)
+    })
+  })
+
   after(async function () {
     await cleanupTests(servers)
   })