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lxd reset/reinit with snap

first delete all container instances and all images
then execute:

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sudo snap remove --purge lxd

then

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sudo snap install lxd --channel=4.0/stable

last

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lxd init

Posted on Edited on In

安装acme.sh

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$ curl https://get.acme.sh sh
$ source ~/.bashrc

会自动添加cron任务

创建api token

acme.sh支持name.com，访问https://www.name.com/account/settings/api，随意设置token昵称acme_sh_dns，生成token
编辑~/.acme.sh/account.conf添加如下两行：

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export Namecom_Username="your_name_com_username"
export Namecom_Token="*********"

Namecom_Username指定你在name.com的用户名而不是token name

申请证书

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$ acme.sh --issue --dns dns_namecom -d g.openwares.net

可以会有提示

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g.openwares.net:Verify error:DNS problem: SERVFAIL looking up CAA for openwares.net - the domain's nameservers may be malfunctioning

忽略即可

安装证书

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$ acme.sh --install-cert -d g.openwares.net \\
--cert-file /path/to/certfile/cert.pem \\
--key-file /path/to/keyfile/key.pem \\
--fullchain-file /path/to/fullchain/certfile/fullchain.pem

自动更新
acme.sh自动安装了crontab入口，acme.sh会自动记录下申请证书和安装证书的命令，所以会在设定的周期内自动更新证书。

Posted on Edited on In

使用alacarte删除了几个菜单项后，再也打不开gnome main menu了，终端下运行alacarte出现错误:

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$ alacarte
usr/share/alacarte/Alacarte/MainWindow.py:22: PyGIWarning: GMenu was imported without specifying a version first. Use gi.require_version('GMenu', '3.0') before import to ensure that the right version gets loaded.
 from gi.repository import Gtk, GdkPixbuf, Gdk, GMenu

(alacarte:1718): Gtk-CRITICAL **: 16:54:24.699: gtk_accel_label_set_accel_closure: assertion 'gtk_accel_group_from_accel_closure (accel_closure) != NULL' failed

(alacarte:1718): Gtk-CRITICAL **: 16:54:24.699: gtk_accel_label_set_accel_closure: assertion 'gtk_accel_group_from_accel_closure (accel_closure) != NULL' failed
Traceback (most recent call last):
 File "/usr/bin/alacarte", line 26, in <module>
 main()
 File "/usr/share/alacarte/Alacarte/MainWindow.py", line 464, in main
 app.setMenuBasename(basename)
 File "/usr/share/alacarte/Alacarte/MainWindow.py", line 62, in setMenuBasename
 self.editor = MenuEditor(menu_basename)
 File "/usr/share/alacarte/Alacarte/MenuEditor.py", line 36, in __init__
 self.load()
 File "/usr/share/alacarte/Alacarte/MenuEditor.py", line 49, in load
 if not self.tree.load_sync():
gi.repository.GLib.Error: g-markup-error-quark: Error on line 1 char 1: Document was empty or contained only whitespace (1)

发现~/.config/menus目录下多了一个空白文件gnome-applications.menu，将其删除问题解决。

Posted on Edited on In

一、判断主备角色
有几个方法可以判断：
1、查看wal进程

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$ ps aux grep wal

如果进程名有”postgres: 11/main: walwriter”字样，则为主库，walwriter为wal发送方。
如果进程名有”postgres: 11/main: walreceiver streaming 2A/ACAA1088”字样，则为备库，walreceiver为wal接收方。
2、pg_is_in_recovery函数

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$ sudo -u postgres psql
postgres=# select pg_is_in_recovery();
pg_is_in_recovery
-------------------
 f
(1 row)

显示f说明是主库，显示t说明为备库。
3、查看数据库控制信息

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$ sudo -u postgres /usr/lib/postgresql/11/bin/pg_controldata -D /var/lib/postgresql/11/main/
g_control version number: 1100
Catalog version number: 201809051
Database system identifier: 6745356148899875633
Database cluster state: in production
pg_control last modified: Thu 09 Jul 2020 02:40:49 PM CST
Latest checkpoint location: 825/245660D8
Latest checkpoint's REDO location: 825/245660A0
...

Database cluster state这行为in production说明位主库，为in archive recovery说明为备库。
4、通过recovery.conf 文件判断
一般的，备库才有recovery.conf，主库一般没有或是改名为recovery.done

二、主备切换
1、使用trigger文件切换

a. 在备库启动时在 recovery.conf 文件中加入一个触发文件的路径（新加则需要重启备库）

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trigger_file='/var/lib/postgresql/11/main/.postgresql.trigger'

b. 关闭主库：

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$ sudo systemctl stop postgresql@11-main.service

或者
先查看postgresql集群信息

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$ pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
11 main 5432 online postgres /var/lib/postgresql/11/main /var/log/postgresql/postgresql-11-main.log

然后执行：

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$ sudo pg_ctlcluster 11 main stop

c.在备库上创建trigger文件

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$ sudo touch /var/lib/postgresql/11/main/.postgresql.trigger

可以看到备库上的recovery文件已经成为done了,此时备库已经被激活为主库，可以直接做读写操作了
在新主库上创建复制槽

d. 原主库搭建为新备库
准备recovery.conf文件，primary_conninfo指向新主库，使用合适的复制槽，然后重新启动数据库即可。

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recovery_target_timeline='latest'
standby_mode = 'on'
primary_conninfo = 'host=59.206.31.149 port=5432 user=xxxx password=xxxx'
primary_slot_name = 'repl_slot_2'

这里必须添加recovery_target_timeline=’latest’，因为主备切换时timeline更新了。
注意pg_hba_conf中对replication的权限设定

2、使用pg_ctlcluster命令切换
a. 停止应用程序，关闭主库
b. 备库提升为主库
备库端执行：

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$ sudo pg_ctlcluster 11 main promote

c. 老主库上配置recovery.conf文件，启动原主库为新的备库

References:
[1]26.3. Failover
[2]PostgreSQL 流复制的主备切换
[3]PostgreSQL Switchover vs. Failover
[4]PostgreSQL主备切换