kubernetes timescaledb statefulset：吊艙休閑丟失的更改

Question

我有一個Timescaledb服務器，在AKS中作為StatefulSet運行。 當我刪除並重新創建timescaledb pod時，它會出現，即使該pod與最初關聯的PV（永久卷）相關聯，更改也會丟失。 任何幫助表示贊賞。

下面是通過運行kubectl get statefulset timescaledb -o yaml提取的statefulset的PV，PVC配置kubectl get statefulset timescaledb -o yaml

  template:
    metadata:
      creationTimestamp: null
      labels:
        app: timescaledb
    spec:
      containers:
      - args:
        - -c
        - config_file=/etc/postgresql/postgresql.conf
        env:
        - name: POSTGRES_PASSWORD
          valueFrom:
            secretKeyRef:
              key: password
              name: timescaledb-secret
        image: docker.io/timescale/timescaledb:latest-pg9.6
        name: timescaledb-backend
        ports:
        - containerPort: 5432
          name: server
          protocol: TCP
        resources:
          requests:
            cpu: "3"
            memory: 6Gi
        volumeMounts:
        - mountPath: /var/lib/postgresql
          name: timescaledbdata
        - mountPath: /etc/postgresql
          name: timescaledb-config
      volumes:
      - configMap:
          defaultMode: 420
          name: timescaledb-config
        name: timescaledb-config
  volumeClaimTemplates:
  - metadata:
      annotations:
        volume.alpha.kubernetes.io/storage-class: standard
      creationTimestamp: null
      name: timescaledbdata
    spec:
      accessModes:
      - ReadWriteOnce
      dataSource: null
      resources:
        requests:
          storage: 200Gi
    status:
      phase: Pending

下面演示了在吊艙重新創建后丟失的創建的臨時數據庫test_db，並且在整個過程中，吊艙與Azure上的同一PV /磁盤相關聯。

root@e70a91715239:~/keys# k get pvc -l app=timescaledb
NAME                            STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
timescaledbdata-timescaledb-0   Bound    pvc-c7eb99cf-6a6b-11e9-b661-be660567cc75   200Gi      RWO            default        83d

root@e70a91715239:~/keys# k exec -ti timescaledb-0 bash
bash-4.4# psql -U postgres;
psql (9.6.13)
Type "help" for help.

postgres=# create database test_db;
CREATE DATABASE
postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges   
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 test_db   | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 
(4 rows)


root@e70a91715239:~/keys# k get pods | grep timescale
timescaledb-0                         1/1     Running   0          12m
root@e70a91715239:~/keys# k delete pod/timescaledb-0                            
pod "timescaledb-0" deleted                                                                                                                                         
root@e70a91715239:~/keys# k get pods | grep timescale       
timescaledb-0                         1/1     Running   0          14s   

root@e70a91715239:~/keys# k exec -ti timescaledb-0 bash                                                                                                             
bash-4.4# psql -U postgres
psql (9.6.13)
Type "help" for help.

postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges                                                                                    
-----------+----------+----------+------------+------------+-----------------------                                                                                 
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +                                                                                 
           |          |          |            |            | postgres=CTc/postgres                                                                                  
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +                                                                                 
           |          |          |            |            | postgres=CTc/postgres                                                                                  
(3 rows)

root@e70a91715239:~/keys# k get pvc -l app=timescaledb
NAME                            STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
timescaledbdata-timescaledb-0   Bound    pvc-c7eb99cf-6a6b-11e9-b661-be660567cc75   200Gi      RWO            default        83d

可能正在按提示進行重新初始化。 請參閱日志 。 關於為什么這樣做的任何指示。

更新1：我看了timescale盒中的掛載，它似乎對/var/lib/postgresql和/var/lib/postgresql/data具有不同的分區。 我不理解為什么。

Filesystem                Size      Used Available Use% Mounted on
overlay                  96.9G     22.1G     74.8G  23% /
tmpfs                    64.0M         0     64.0M   0% /dev
tmpfs                     7.8G         0      7.8G   0% /sys/fs/cgroup
/dev/sda1                96.9G     22.1G     74.8G  23% /docker-entrypoint-initdb.d
/dev/sda1                96.9G     22.1G     74.8G  23% /dev/termination-log
shm                      64.0M      4.0K     64.0M   0% /dev/shm
/dev/sda1                96.9G     22.1G     74.8G  23% /etc/resolv.conf
/dev/sda1                96.9G     22.1G     74.8G  23% /etc/hostname
/dev/sda1                96.9G     22.1G     74.8G  23% /etc/hosts
/dev/sdc                196.7G     59.3M    196.7G   0% /var/lib/postgresql
/dev/sda1                96.9G     22.1G     74.8G  23% /var/lib/postgresql/data 

不了解下面的配置如何發生上述安裝

        volumeMounts:
        - mountPath: /var/lib/postgresql
          name: timescaledbdata
        - mountPath: /etc/postgresql
          name: timescaledb-config

Answer 1

問題是在postgres:9.6 Dockerfile中有/var/lib/postgresql/data的VOLUME聲明，這引起了容器上的附加安裝。 當在/var/lib/postgresql進行卷掛載時，該掛載是臨時的。 但是我們無法將AKS卷掛載到/var/lib/postgresql/data因為該卷帶有lost+found子目錄，而Postgres希望使用空目錄來存儲DB文件。

解決方法是在/var/lib/postgresql/data上安裝卷，並告訴Postgres使用/var/lib/postgresql/data下的子目錄來存儲帶有PGDATA env var的文件。

以下是k8s statefulset配置中修復的相關部分

env:
- name: PGDATA
  value: "/var/lib/postgresql/data/dbfiles"        
...
volumeMounts:
- mountPath: /var/lib/postgresql/data
  name: timescaledata