水平擴展

在使用黏性工作階段的負載平衡器後方執行多個 Ayakaleaf Pro 副本。

一個副本的每次編譯都只會使用一個節點的 CPU：在我們配備 2 個 vCPU 的測試節點上，六個同時進行的編譯所花的時間是單一編譯的三倍，而其他節點則處於閒置狀態。多個副本可以將使用者及其編譯分散到各個節點上。

這遵循 Overleaf 的水平擴展設計，並轉換為 Kubernetes 的做法：

需求	本文的做法
共用的 MongoDB 與 Redis	安裝時的 10-mongo.yaml 與 20-redis.yaml
共用的密鑰	步驟 2 中的 Secret overleaf-secrets 已包含這些密鑰
專案檔案與歷史記錄存放於 S3（而非 NFS）	任何 S3 服務，請參閱 S3；該頁以叢集內的 Garage 為例
每個副本各有一個本機磁碟，用於編譯與上傳	每個節點上的 hostPath /srv/overleaf-ha
持久路由、WebSocket、10 分鐘逾時、50 MB 上傳	使用 Overleaf 範例設定的 HAProxy
git-bridge 以單一執行個體的形式與某個副本相鄰	以 overleaf-0 作為其相鄰副本的 git-bridge

請從一開始就規劃好 S3。已將檔案保存在其磁碟區上的執行個體，必須先進行 S3 遷移。此設定會取代步驟 5 中的 Deployment：請在套用 StatefulSet 之前將其刪除（kubectl delete -f 40-overleaf.yaml）。

1. S3 儲存空間

   依照 S3 中的說明，使用您的 S3 服務或叢集內的 Garage 設定三個儲存貯體與兩個使用者，並將四個金鑰放入 Secret overleaf-s3。以下設定使用該頁中的 Garage 範例。

2. 設定

   此 ConfigMap 會取代 30-config.yaml。它新增了 S3 與 git-bridge，並將 OVERLEAF_SITE_URL 指向負載平衡器：

   60-config.yaml

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: overleaf-env
     namespace: overleaf
   data:
     OVERLEAF_APP_NAME: Ayakaleaf Pro
     OVERLEAF_SITE_URL: http://192.0.2.10:30081      # the load balancer (HAProxy) URL
     OVERLEAF_ADMIN_EMAIL: [e-mail]
     # Emails: add the sender and the SMTP server together, see Email delivery
     OVERLEAF_MONGO_URL: mongodb://mongo-0.mongo:27017,mongo-1.mongo:27017,mongo-2.mongo:27017/sharelatex?replicaSet=overleaf
     OVERLEAF_REDIS_HOST: redis
     REDIS_HOST: redis
     ENABLED_LINKED_FILE_TYPES: project_file,project_output_file,url
     ENABLE_CONVERSIONS: "true"
     EMAIL_CONFIRMATION_DISABLED: "true"
     OVERLEAF_TRUSTED_PROXY_IPS: loopback,10.244.0.0/16   # HAProxy runs in the pod CIDR
     # Sandboxed compiles, node paths: each replica owns /srv/overleaf-ha on its node
     SANDBOXED_COMPILES: "true"
     SANDBOXED_COMPILES_SIBLING_CONTAINERS: "true"
     DOCKER_RUNNER: "true"
     SANDBOXED_COMPILES_HOST_DIR_COMPILES: /srv/overleaf-ha/data/compiles
     SANDBOXED_COMPILES_HOST_DIR_OUTPUT: /srv/overleaf-ha/data/output
     SANDBOXED_COMPILES_HOST_DIR_CACHE: /srv/overleaf-ha/data/cache
     ALL_TEX_LIVE_DOCKER_IMAGES: ghcr.io/ayaka-notes/texlive-full:2026.1
     ALL_TEX_LIVE_DOCKER_IMAGE_NAMES: TeX Live 2026
     TEX_LIVE_DOCKER_IMAGE: ghcr.io/ayaka-notes/texlive-full:2026.1
     # S3 (required for more than one replica); keys are in the Secret overleaf-s3
     OVERLEAF_FILESTORE_BACKEND: s3
     OVERLEAF_FILESTORE_TEMPLATE_FILES_BUCKET_NAME: overleaf-template-files
     OVERLEAF_FILESTORE_S3_ENDPOINT: http://garage:3900
     OVERLEAF_FILESTORE_S3_PATH_STYLE: "true"
     OVERLEAF_FILESTORE_S3_REGION: garage
     OVERLEAF_HISTORY_BACKEND: s3
     OVERLEAF_HISTORY_PROJECT_BLOBS_BUCKET: overleaf-project-blobs
     OVERLEAF_HISTORY_CHUNKS_BUCKET: overleaf-chunks
     OVERLEAF_HISTORY_S3_ENDPOINT: http://garage:3900
     OVERLEAF_HISTORY_S3_PATH_STYLE: "true"
     OVERLEAF_HISTORY_S3_REGION: garage
     # Git integration: one git-bridge, its sibling is overleaf-0
     GIT_BRIDGE_ENABLED: "true"
     GIT_BRIDGE_HOST: 10.96.100.80      # the git-bridge Service's fixed ClusterIP, see 75-git-bridge.yaml
     GIT_BRIDGE_PORT: "8000"
   
3. 副本

   70-overleaf.yaml

   apiVersion: v1
   kind: Service
   metadata:
     name: overleaf-hl
     namespace: overleaf
   spec:
     clusterIP: None            # stable DNS per replica: overleaf-0.overleaf-hl, ...
     selector:
       app: overleaf-ha
     ports:
       - {name: http, port: 80}
       - {name: web, port: 3000}       # git-bridge API (sibling only)
       - {name: history, port: 3100}   # history-v1, used by git-bridge via V1_HISTORY_URL
   ---
   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: overleaf
     namespace: overleaf
   spec:
     serviceName: overleaf-hl
     replicas: 3
     # OrderedReady: overleaf-0 runs the migrations alone before the next replica starts
     podManagementPolicy: OrderedReady
     selector:
       matchLabels:
         app: overleaf-ha
     template:
       metadata:
         labels:
           app: overleaf-ha
       spec:
         terminationGracePeriodSeconds: 60
         # Keep the environment to the ConfigMap and Secrets: no REDIS_PORT=tcp://..., GIT_BRIDGE_PORT=tcp://...
         enableServiceLinks: false
         affinity:
           podAntiAffinity:            # one replica per node: each uses that node's Docker and disk
             requiredDuringSchedulingIgnoredDuringExecution:
               - labelSelector:
                   matchLabels:
                     app: overleaf-ha
                 topologyKey: kubernetes.io/hostname
         containers:
           - name: sharelatex
             image: ghcr.io/ayaka-notes/overleaf-pro:6.3.2
             env:
               - name: POD_NAME
                 valueFrom:
                   fieldRef:
                     fieldPath: metadata.name
               # Each replica hands out history URLs with its own stable name, so git-bridge can reach them
               - name: V1_HISTORY_URL
                 value: http://$(POD_NAME).overleaf-hl.overleaf.svc.cluster.local:3100/api
             envFrom:
               - configMapRef: {name: overleaf-env}
               - secretRef: {name: overleaf-secrets}
               - secretRef: {name: overleaf-s3}
             ports:
               - containerPort: 80
             readinessProbe:
               httpGet: {path: /status, port: 80}
               periodSeconds: 10
             resources:
               requests: {cpu: 500m, memory: 1536Mi}
               limits: {memory: 3Gi}
             volumeMounts:
               - {name: local, mountPath: /var/lib/overleaf}
               - {name: docker-sock, mountPath: /var/run/docker.sock}
         volumes:
           # Local disk for ephemeral files (compiles, output, uploads); the HOST_DIR_* paths are under it
           - name: local
             hostPath: {path: /srv/overleaf-ha, type: DirectoryOrCreate}
           - name: docker-sock
             hostPath: {path: /var/run/docker.sock, type: Socket}
   

   • 使用 StatefulSet，而非 Deployment。每個副本都會取得一個穩定的名稱（overleaf-0、overleaf-1、…），供負載平衡器 Cookie 與 git-bridge 參照，而 OrderedReady 會先單獨啟動 overleaf-0，因此只有一個副本會執行資料庫遷移。
   • 每個節點一個副本。每個副本都透過其節點的 Docker 啟動編譯，並將編譯保存在其節點的 /srv/overleaf-ha 中。
   • 每個副本各自的 V1_HISTORY_URL。每個副本都以自己的名稱提供歷史記錄連結，讓 git-bridge 能夠連線。
4. git-bridge

   75-git-bridge.yaml

   apiVersion: v1
   kind: Service
   metadata:
     name: git-bridge
     namespace: overleaf
   spec:
     # Fixed ClusterIP (inside the service CIDR): the sharelatex image's nginx proxies /git/ with
     # `resolver 127.0.0.11` (Docker's DNS), which does not exist in Kubernetes, so GIT_BRIDGE_HOST is this IP
     clusterIP: 10.96.100.80
     selector:
       app: git-bridge
     ports:
       - {name: http, port: 8000}
   ---
   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: git-bridge
     namespace: overleaf
   spec:
     serviceName: git-bridge
     replicas: 1
     selector:
       matchLabels:
         app: git-bridge
     template:
       metadata:
         labels:
           app: git-bridge
       spec:
         # Service "git-bridge" would inject GIT_BRIDGE_PORT=tcp://..., which git-bridge reads as its port
         enableServiceLinks: false
         containers:
           - name: git-bridge
             image: ghcr.io/ayaka-notes/overleaf-pro/git-bridge:6.3.2   # same version as the sharelatex image
             command: ["/server-pro-start.sh"]
             securityContext:
               runAsUser: 0
             env:
               - {name: GIT_BRIDGE_API_BASE_URL, value: "http://overleaf-0.overleaf-hl.overleaf.svc.cluster.local:3000/api/v0/"}
               - {name: GIT_BRIDGE_OAUTH2_SERVER, value: "http://overleaf-0.overleaf-hl.overleaf.svc.cluster.local"}
               - {name: GIT_BRIDGE_POSTBACK_BASE_URL, value: "http://git-bridge.overleaf.svc.cluster.local:8000"}
               - {name: GIT_BRIDGE_ROOT_DIR, value: /data/git-bridge}
             ports:
               - containerPort: 8000
             resources:
               requests: {cpu: 100m, memory: 256Mi}
               limits: {memory: 768Mi}
             volumeMounts:
               - {name: data, mountPath: /data/git-bridge}
     volumeClaimTemplates:
       - metadata:
           name: data
         spec:
           accessModes: [ReadWriteOnce]
           resources:
             requests:
               storage: 5Gi
   

   關於 GIT_BRIDGE_HOST 為何是固定 IP 位址，請參閱 Git 整合。

5. 負載平衡器

   此 HAProxy 設定是 Overleaf 的範例加上五項變更：/project/<id>/mcp 與 /git/ 一樣路由至 overleaf-0（請參閱 MCP Server）；在連接埠 8080 上使用一般 HTTP（映像檔以非 root 使用者執行，在 containerd 下無法繫結連接埠 80）；透過叢集 DNS 找到伺服器（pod IP 在每次重新啟動時都會改變）；使用 DaemonSet 讓每個節點都能回應；以及使用 balance leastconn 取代預設的 roundrobin（請參閱下方的問與答）。

   80-haproxy.yaml

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: haproxy-config
     namespace: overleaf
   data:
     haproxy.cfg: |
       global
         log stdout format raw local0 info
   
       resolvers kubedns
         parse-resolv-conf
         hold valid 10s
   
       defaults
         mode                    http
         # New sessions go to the replica with the fewest open connections (editors keep a WebSocket open)
         balance                 leastconn
         option                  httpchk HEAD /status
         http-check              expect status 200
         default-server          check resolvers kubedns init-addr none
         log                     global
         option                  httplog
         # Reroute to a different backend if the sticky one is down
         option                  redispatch 1
         retries                 3
         # Sticky session for 24h of inactivity -- compile output is deleted after 24h
         cookie                  server-pro-ha insert maxidle 24h
         timeout queue           1m
         timeout connect         15s
         timeout client          1m
         # Allow slow compiles -- hard-coded limit in clsi is 10min
         timeout server          10m
         # Disconnect the editor after 23h
         timeout tunnel          23h
         # Lower than NGINX_KEEPALIVE_TIMEOUT (65s) in the sharelatex container
         timeout http-keep-alive 60s
   
       listen overleaf
         bind :8080
         option forwardfor
         # When TLS ends in front of HAProxy, also pass:  http-request set-header X-Forwarded-Proto https
         # git requests go to the git-bridge sibling
         use-server overleaf-0 if { path_beg /git/ }
         # MCP clients send no cookie: keep compile, log and PDF download on one replica
         use-server overleaf-0 if { path_reg ^/project/[0-9a-f]{24}/mcp(/|$) }
         http-response add-header X-Served-By %s
         stats enable
         stats uri /haproxy
         server overleaf-0 overleaf-0.overleaf-hl.overleaf.svc.cluster.local:80 cookie overleaf-0
         server overleaf-1 overleaf-1.overleaf-hl.overleaf.svc.cluster.local:80 cookie overleaf-1
         server overleaf-2 overleaf-2.overleaf-hl.overleaf.svc.cluster.local:80 cookie overleaf-2
   ---
   apiVersion: apps/v1
   # DaemonSet: one HAProxy per node, so the NodePort answers on every node with externalTrafficPolicy
   # Local. The cookie holds the replica name, so stickiness works whichever HAProxy a request hits.
   kind: DaemonSet
   metadata:
     name: haproxy
     namespace: overleaf
   spec:
     selector:
       matchLabels:
         app: haproxy
     template:
       metadata:
         labels:
           app: haproxy
         annotations:
           config-hash: "1"   # bump to restart after editing the ConfigMap
       spec:
         containers:
           - name: haproxy
             image: haproxy:lts-alpine
             ports:
               - containerPort: 8080
             resources:
               requests: {cpu: 50m, memory: 32Mi}
               limits: {memory: 256Mi}
             volumeMounts:
               - {name: config, mountPath: /usr/local/etc/haproxy}
         volumes:
           - name: config
             configMap:
               name: haproxy-config
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: haproxy
     namespace: overleaf
   spec:
     type: NodePort
     externalTrafficPolicy: Local    # keep the client IP (no SNAT); only nodes running HAProxy answer
     selector:
       app: haproxy
     ports:
       - {name: http, port: 80, targetPort: 8080, nodePort: 30081}
   

   kubectl delete -f 40-overleaf.yaml --ignore-not-found
   kubectl apply -f 60-config.yaml -f 70-overleaf.yaml -f 75-git-bridge.yaml -f 80-haproxy.yaml
   kubectl -n overleaf rollout status statefulset/overleaf --timeout=20m
   curl -sI http://192.0.2.10:30081/login | grep -i x-served-by
   

   externalTrafficPolicy: Local 會在 X-Forwarded-For 中保留使用者的 IP 位址。

6. TLS

   依照 TLS 代理中的說明在 HAProxy 終止 HTTPS，然後在 60-config.yaml 中將 OVERLEAF_SITE_URL 設為 https:// 位址，並設定 OVERLEAF_SECURE_COOKIE: "true"。

​

預期效果

我們在三個各配備 2 個 vCPU 與 4 GB 記憶體的節點上測試了三個副本，MongoDB、Redis、Garage、git-bridge 與 HAProxy 也位於相同的節點上：

• 12 位使用者同時編譯一份 600 頁的文件：12 位使用者全部完成編譯並取得 PDF，每個副本 4 位使用者；每一輪耗時 8 到 18 秒。每個節點都保有至少 1.3 GB 的可用記憶體。
• 每位使用者都固定在一個副本上（Cookie server-pro-ha），包括必須來自執行編譯之副本的 PDF 下載。透過 HTTPS 時也是如此，包括編輯器的 WebSocket。
• 當某個副本停止時，其使用者會在約 15 到 20 秒內遇到錯誤，直到 HAProxy 將其標記為停止；之後他們會移至另一個副本並維持登入狀態，因為工作階段保存在 Redis 中。

​

問與答

為什麼使用 balance leastconn？

回答：在我們的測試中，使用 Overleaf 的範例（roundrobin，每個節點一個 HAProxy）時，12 位新使用者在三個副本上的分布為 8、3 與 1，而最忙碌的副本讓最慢的使用者等待了 29 秒。使用 leastconn（優先選擇開啟連線最少的副本，每個編輯器都會保持一個開啟的 WebSocket）時，同樣的測試得到 4、4 與 4 的分布，耗時 18 秒。黏性不受影響：它來自 Cookie。

可以使用我的 ingress 控制器來取代 HAProxy 嗎？

回答：可以，只要它能依 Cookie 路由至穩定的副本、支援 WebSocket、允許 10 分鐘的請求時間與 50 MB 的上傳、將其 keep-alive 逾時設定在 65 秒以下、傳送 X-Forwarded-For 與 X-Forwarded-Proto，並將 /git/ 與 /project/<id>/mcp 傳送至 overleaf-0。請路由至各副本自己的名稱（overleaf-N.overleaf-hl），而不是會平衡每個請求的 Service。

如何新增第四個副本？

回答：新增一個安裝了 Docker 與 TeX Live 映像檔的節點，在 70-overleaf.yaml 中設定 replicas: 4，並在 HAProxy 設定中新增一行 server overleaf-3 ...（同時遞增 config-hash，讓 HAProxy 重新啟動）。