标题: Ubuntu 22禁用apt和snap自动升级

创建: 2022-04-21 15:33
更新: 2023-07-21 11:26
链接: https://scz.617.cn/unix/202204211533.txt

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目录:

    ☆ 背景介绍
    ☆ 禁用apt相关的自动升级
    ☆ 处理snap相关的自动升级
        1) 禁用snapd
        2) /etc/hosts (未测试)
        3) metered connection
        4) 与refresh相关的snap配置
        5) 人工修改last-refresh
        6) defer_snap_update_1.sh
        7) 自编译snapd (未测试)
    ☆ 参考资源

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☆ 背景介绍

突然SystemTap、crash、eBPF都不太正常，无意中发现"uname -r"从5.15.0-48-generic
升到5.15.0-50-generic，坑我。很多研究性质的VM并不想自动升级，包括安全补丁，
应该禁用自动升级。

☆ 禁用apt相关的自动升级

参[1]

$ cat /etc/apt/apt.conf.d/20auto-upgrades
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Unattended-Upgrade "1";

这是缺省内容，改成

APT::Periodic::Update-Package-Lists "0";
APT::Periodic::Download-Upgradeable-Packages "0";
APT::Periodic::AutocleanInterval "0";
APT::Periodic::Unattended-Upgrade "0";

上面是CLI方式，也可以GUI禁用。

Software & Updates
  Updates
    Automatically check for updates
      Daily (Default)
      Never
    When there are security updates
      Download and install automatically (Default)
      Display immediately
    When there are other updates
      Display weekly (Default)
      Display every two weeks
    Notify me of a new Ubuntu version
      For long-term support versions (Default)
      Never

☆ 处理snap相关的自动升级

上面只是禁用了Ubuntu 22与apt相关的自动升级，还有与snap相关的自动升级需要处
理，比如snap版Firefox、Opera会每天升级，病得不轻。无法正常禁止snap自动升级，
但有一些非常规手段，参[2]、[3]。

此处不讨论为何不卸载snap，只对付一种情形，既想用snap又不想让它自动升级。无
此需求者，请绕行。

1) 禁用snapd

--------------------------------------------------------------------------
systemctl stop snapd.service
systemctl disable snapd.service
systemctl status snapd.service

systemctl enable snapd.service
systemctl start snapd.service
systemctl status snapd.service
snap refresh
--------------------------------------------------------------------------

"stop+disable"不够狠，启动Firefox时会自动启动snapd，必须"stop+mask"禁用之。

--------------------------------------------------------------------------
systemctl stop snapd.service
systemctl mask snapd.service
systemctl status snapd.service

systemctl unmask snapd.service
systemctl start snapd.service
systemctl status snapd.service
snap refresh
--------------------------------------------------------------------------

"stop+mask"之后，snapd禁得死死的，但同时无法启动Firefox，不符预期。

2) /etc/hosts (未测试)

127.0.0.1   api.snapcraft.io
127.0.0.1   search.apps.ubuntu.com

iptables -A OUTPUT -d api.snapcraft.io -j DROP
iptables -A OUTPUT -d search.apps.ubuntu.com -j DROP

3) metered connection

Settings
  Network
    Wired
      Details
        Metered connection: has data limits or can incur charges
          On

此时软件升级或其他较大流量的下载操作不会自动启动，但snap需要额外设置

snap set system refresh.metered=hold

正常情况下snap自动升级最多暂停90天。

4) 与refresh相关的snap配置

参[4]，snapd缺省每天4次检查更新，神经病啊，可以更改这种BT行为。

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snap refresh

    手动强制更新

snap refresh --time

    查看更新计划

snap refresh --unhold firefox

    Removed general refresh hold of "firefox"

snap refresh --unhold

    Removed auto-refresh hold on all snaps
--------------------------------------------------------------------------
snap set system refresh.timer=fri5,14:00-14:05
snap set system refresh.hold="$(date --iso-8601=seconds -d 'today+100 days')"
snap set system refresh.metered=hold
snap set system refresh.retain=2
snap set core experimental.refresh-app-awareness=true

    可以unset

snap get system refresh.timer
snap get system refresh.hold
snap get system refresh.metered
snap get system refresh.retain
snap get core experimental.refresh-app-awareness

snap get -d system

    查看全部配置
--------------------------------------------------------------------------
refresh.timer

    每月最后一个周五的14:00-14:05开始更新，旧版可能是

    snap set core refresh.schedule=fri5,14:00-14:05

    fri5表示第5个周五，也即每月最后一个周五

refresh.hold

    将更新推迟指定天数，官方文档[4]说最长90天，为什么我测下来有95天？

refresh.metered

    NetworkManager检测到"metered connection"时暂停snap更新

refresh.retain

    保持最新的2个版本

experimental.refresh-app-awareness

    避免升级正在运行中的软件
--------------------------------------------------------------------------
import time

def delta ( day1, day2 ) :
    sec1    = int( time.mktime( time.strptime( day1, "%Y-%m-%d" ) ) )
    sec2    = int( time.mktime( time.strptime( day2, "%Y-%m-%d" ) ) )
    return ( sec2 - sec1 ) // 60 // 60 // 24
#
# end of delta
#

print( delta( "2022-11-4", "2023-2-7" ) )
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5) 人工修改last-refresh

$ snap refresh --time
timer: fri5,14:00-14:05
last: today at 12:22 CST
hold: 2023-02-07
next: in 21 days, at 14:00 CST (but held)

$ snap refresh --time
timer: fri5,14:00-14:05
last: yesterday at 12:22 CST
hold: 2023-02-07
next: in 20 days, at 14:00 CST (but held)

next值反映了timer值，2022.11.25是本月最后一个周五。

hold值有上限，从last开始计数，不超过90天(官方说辞)。我在2022.11.4有过
last-refresh，当天设置refresh.hold推迟更新100天，snap根据各种阈值计算后允
许推迟至2023.2.7。在2022.11.5再次设置refresh.hold推迟更新100天，无效，hold
值停留在2023.2.7。

参[2]，Alan Pope曾经用crontab每天定时设置refresh.hold，以此推迟更新。若只
是这样操作，至少现在已无法永久推迟更新，因为last值不会更新。参[3]，据说
snap配置文件中的"last-refresh"值只在snapd进行"automatic refresh"时得到更新，
"manually refresh"不会更新该值，未验证该说法。

snap配置文件是"/var/lib/snapd/state.json"，里面有个

"last-refresh":"2022-11-04T12:22:49.342452532+08:00",

这就是last值所在，可以人工修改该值。

$ date +%Y-%m-%dT%H:%M:%S.%N%:z
2022-11-05T14:10:37.971117940+08:00

$ date --iso-8601=ns
2022-11-05T14:10:41,633708955+08:00

$ date --rfc-3339=ns
2022-11-05 14:11:39.756739004+08:00

仔细看上述三种输出，第一种与"last-refresh"的格式完全一样，第二种秒与纳秒之
间是逗号，第三种年月日与时分秒之间没有T。

6) defer_snap_update_1.sh

该脚本人工修改snap配置文件中的"last-refresh"，再设置refresh.hold。只要定期
执行该脚本，即可不断推迟更新，不受90天的硬限制。

--------------------------------------------------------------------------
#!/bin/bash
systemctl stop snapd
jq -c ".data[\"last-refresh\"] = \"$(date +%Y-%m-%dT%H:%M:%S.%N%:z)\"" /var/lib/snapd/state.json > /tmp/state.json
mv /tmp/state.json /var/lib/snapd/state.json
chmod 600 /var/lib/snapd/state.json
systemctl start snapd
snap set system refresh.timer=fri5,14:00-14:05
snap set system refresh.hold="$(date --iso-8601=seconds -d 'today+100 days')"
snap set system refresh.metered=hold
snap set system refresh.retain=2
snap set core experimental.refresh-app-awareness=true
snap refresh --time
--------------------------------------------------------------------------

$ ./defer_snap_update_1.sh
timer: fri5,14:00-14:05
last: today at 14:17 CST
hold: 2023-02-08
next: in 20 days, at 14:00 CST (but held)

尝试在/etc/rc.local中执行defer_snap_update_1.sh，通过state.json的时间戳确
认脚本执行过，但"snap refresh --time"查看last值，未刷新，原因不明。

7) 自编译snapd (未测试)

参[2]，Alan Pope有演示，但这个太重型了，我不喜欢。

☆ 参考资源

[1] Disable Automatic Updates on Ubuntu 22.04 Jammy Jellyfish Linux - Korbin Brown [2022-04-21]
    https://linuxconfig.org/disable-automatic-updates-on-ubuntu-22-04-jammy-jellyfish-linux

[2] Disabling snap Autorefresh - Alan Pope [2021-05-29]
    https://popey.com/blog/2021/05/disabling-snap-autorefresh/

[3] How to disable autorefresh in snap - [2017-06-30]
    https://askubuntu.com/questions/930593/how-to-disable-autorefresh-in-snap

    https://github.com/snapcore/snapd/blob/master/tests/lib/tools/snapd-state
    (有个prevent_autorefresh函数)

[4] Managing updates
    https://snapcraft.io/docs/keeping-snaps-up-to-date
    https://forum.snapcraft.io/t/managing-updates/7022
    (后者更详细)

    Getting started
    https://snapcraft.io/docs/getting-started

    Experimental feature: snap refresh awareness and update inhibition - Igor Ljubuncic [2020-02-27]
    https://snapcraft.io/blog/experimental-feature-snap-refresh-awareness-and-update-inhibition

    System options
    https://forum.snapcraft.io/t/system-options/29860

    Setting system options
    https://forum.snapcraft.io/t/setting-system-options/87