Sunday, February 2, 2020

Advanced Unattended Upgrade (Ubuntu): Chrome and Plex examples

Updated Aug 26, 2020

This is a question that pops up occasionally in various support forums:

Why doesn't (Ubuntu) Unattended Upgrades work for all applications? How can I get it to work for my application?

Good question.

Here is what happens under the hood: The default settings for Unattended Upgrades are for only packages in the "-security" pocket of the Ubuntu repositories.

Not "-updates", not "-backports", not "-universe", not any third-party repositories, not any PPAs. Just "-security".

This is a deliberately conservative choice -- while the Ubuntu Security Team keeps it's delta as small as possible, it's a historical fact that even small security patches have (unintentionally) introduced new bugs.


Here's how you can override that choice. 

Let's take a look at the top section of file /etc/apt/apt.conf.d/50unattended-upgrades, and focus on the "Allowed-Origins section." It's edited for clarity here:

Unattended-Upgrade::Allowed-Origins {
     "${distro_id}:${distro_codename}";
     "${distro_id}:${distro_codename}-security";
//   "${distro_id}:${distro_codename}-updates";
//   "${distro_id}:${distro_codename}-proposed";
//   "${distro_id}:${distro_codename}-backports";
};

There, you can see the various Ubuntu repo pockets.

You can also see that most of the options are commented out (the "//"). If you know how to use a basic text editor and sudo, you can safely change those settings. Warning: You can break your system quite horribly by enabling the wrong source. Enabling "-proposed" and other testing sources is a very bad idea.


How to add the -updates pocket of the Ubuntu Repos?

I've done this for years, BUT (this is important) I don't add lots of extra sources. Simply uncomment the line.

   "${distro_id}:${distro_codename}-updates";

That's all. When Unattended Upgrades runs next, it will load the new settings.

Bonus: Here's one way to do it using sed:

   sed -i 's~//\(."${distro_id}:${distro_codename}-updates";\)~\1~' /etc/apt/apt.conf.d/50unattended-upgrades

How to add the -universe pocket of the Ubuntu Repos?

You can create a '-universe' line like the others, but it won't do anything. It's already handled by the "-updates" line.


How to add a generic new repository that's not in the Ubuntu Repos?

Add a line in the format to the end of the section:

    //    "${distro_id}:${distro_codename}-backports";
    "origin:section"       <-------- Add this format
    };

The trick is finding out what the "origin" and "section" strings should be.

Step 1: Find the URL of the source that you want to add. It's located somewhere in /etc/apt/sources.list or /etc/apt/sources.list.* . It looks something like this...

    deb http://security.ubuntu.com/ubuntu eoan-security main restricted universe multiverse
      ...or...
    deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main
      ...or...
    deb https://downloads.plex.tv/repo/deb/ public main

Step 2: Find the corresponding Release file in your system for the URL.

    http://security.ubuntu.com/ubuntu eoan-security
      ...becomes...
    /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_eoan-security_InRelease


    http://dl.google.com/linux/chrome/deb/ stable
      ...becomes...
    /var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_InRelease


    https://downloads.plex.tv/repo/deb/ public
      ...becomes...
    /var/lib/apt/lists/downloads.plex.tv_repo_deb_dists_public_Release

Step 3: Use grep to find the "Origin" string.

    $ grep Origin /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_eoan-security_InRelease
    Origin: Ubuntu

    $ grep Origin /var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_InRelease
    Origin: Google LLC

    $ grep Origin /var/lib/apt/lists/downloads.plex.tv_repo_deb_dists_public_Release
    Origin: Artifactory

Step 4: With the Origin string and Section (after the space in the URL), we have all the information we need:

    "Ubuntu:eoan-security"
       ...or...
    "Google LLC:stable"
       ...or...
    "Artifactory:public"

You're ready to add the appropriate string to the config file.

Bonus: Here's one way to isolate most of these using shell script

    package="google-chrome-stable"
    url=$(apt-cache policy $package | grep "500 http://")
    var_path=$(echo $url | sed 's~/~_~g' | \
           sed 's~500 http:__\([a-z0-9._]*\) \([a-z0-9]*\)_.*~/var/lib/apt/lists/\1_dists_\2_InRelease~')
    origin=$(grep "Origin:" $var_path | cut -d" " -f2)
    section=$(echo $url | sed 's~500 http://\([a-z0-9._/]*\) \([a-z0-9]*\)/.*~\2~')
    echo "$origin":"$section"

Step 5: Run Unattended Upgrades once, then check the log to make sure Unattended Upgrades accepted the change.

    $ sudo unattended-upgrade
    $ less /var/log/unattended-upgrades/unattended-upgrades.log   (sometimes sudo may be needed)

You are looking for a recent line like:

    2020-02-02 13:36:23,165 INFO Allowed origins are: o=Ubuntu,a=eoan, o=Ubuntu,a=eoan-security, o=UbuntuESM,a=eoan, o=UbuntuESM,a=eoan-security, o=UbuntuESM,a=eoan-security

Your new source and section should be listed.


Summary for folks who just want to know how to update Chrome (stable)

  1. Edit (using sudo and a text editor) the file /etc/apt/apt.conf.d/50unattended-upgrades
  2. In the section "Unattended-Upgrade::Allowed-Origins {", add the following line BEFORE the final "};"
    "Google LLC:stable"

Summary for folks who just want to know how to update Plex

  1. Edit (using sudo and a text editor) the file /etc/apt/apt.conf.d/50unattended-upgrades 
  2. In the section "Unattended-Upgrade::Allowed-Origins {", add the following line BEFORE the final "};"
    "Artifactory:public"

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