How to use the Ubuntu snapshot service

The Ubuntu snapshot service allows you to access old packages in the Ubuntu archive based on past dates. Some of the use cases for this service include:

• Installing a superseded version of a package as it existed at a particular date and time, which is useful to troubleshoot bugs or regressions, or to allow reproducibility.

• Setting upgrades to known states, which can be useful to ensure homogeneity for a fleet of Ubuntu installations and to ensure predictability upon package upgrades (including unattended upgrades).

• Support a structured update workflow by validating snapshots in different environments or by rolling out package upgrades in stages for a large set of machines.

Here we show how to set up and use the snapshot service.

Prerequisites

Snapshots are supported in Ubuntu 23.10 onwards and on updated installations of Ubuntu 20.04 LTS (starting from apt 2.0.10) and Ubuntu 22.04 LTS (starting from apt 2.4.11).

In Ubuntu 24.04 LTS and later, apt will automatically detect whether a repository supports snapshots. Therefore, there is no need for additional configuration before you can start using the Ubuntu snapshot service. For Ubuntu versions lower than 24.04, you need to set a snapshot option in the relevant entries of the /etc/apt/sources.list file. For instance:

If you have the following contents in the /etc/apt/sources.list file

deb http://archive.ubuntu.com/ubuntu jammy main universe restricted multiverse
deb http://archive.ubuntu.com/ubuntu jammy-updates main universe restricted multiverse
deb http://archive.ubuntu.com/ubuntu jammy-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu jammy-security main restricted universe multiverse

you can enable the snapshot service for all components in all pockets by changing it to

deb [snapshot=yes] http://archive.ubuntu.com/ubuntu jammy main universe restricted multiverse
deb [snapshot=yes] http://archive.ubuntu.com/ubuntu jammy-updates main universe restricted multiverse
deb [snapshot=yes] http://archive.ubuntu.com/ubuntu jammy-backports main restricted universe multiverse
deb [snapshot=yes] http://security.ubuntu.com/ubuntu jammy-security main restricted universe multiverse

Without the setup shown above, apt will simply ignore snapshot related command line options in Ubuntu releases lower than 24.04.

The following table describes whether the snapshot service can be used with each supported Ubuntu release, and whether or not it is necessary to configure the snapshot option in the sources.list file.

Ubuntu Release	Supports Snapshot Service?	Need to configure sources.list?
Next Ubuntu releases	Yes	No
Ubuntu 25.10	Yes	No
Ubuntu 25.04	Yes	No
Ubuntu 24.04 LTS	Yes	No
Ubuntu 22.04 LTS	Yes (with apt >= 2.4.11)	Yes
Ubuntu 20.04 LTS	Yes (with apt >= 2.0.10)	Yes

Quick start

You can start using the snapshot service right away by passing the --snapshot option to apt followed by a timestamp in the format shown below.

$ sudo apt install hello --update --snapshot 20240301T030400Z

The --snapshot option and the the timestamp format are discussed with more details in the next sections.

Using the snapshot service

There are several options when it comes to setting up Ubuntu snapshot services. Here we present the most relevant, supported ones.

Below, we refer to the snapshot ID as $SNAPSHOT_ID. This is a UTC date and time formatted as YYYYMMDDTHHMMSSZ, e.g., 20240430T214500Z, which refers to the snapshot that represents the state of the Ubuntu archive on April 30th, 2024, at 21:45:00 UTC.

Currently, the Ubuntu snapshot service provides snapshots for any date and time after 1 March 2023.

The --snapshot CLI option

The snapshot service can be used through the --snapshot (or -S) CLI option for apt, which receives a snapshot ID argument.

$ sudo apt update --snapshot $SNAPSHOT_ID
$ sudo apt install $PACKAGE_NAME --snapshot $SNAPSHOT_ID

You can also use the short, atomic version to merge the two actions above in a single command, which will download the package information from the repository, then download and install the package:

$ sudo apt install $PACKAGE_NAME --update --snapshot $SNAPSHOT_ID

or using the short version of the snapshot option:

$ sudo apt install $PACKAGE_NAME --update -S $SNAPSHOT_ID

For instance, if you want to install Docker as it was released when Ubuntu 24.04 LTS first came out, you could try a snapshot from May 2025:

$ sudo apt update --snapshot 20240501T120000Z

Note that you will need to keep using the snapshot option to let apt operate over the snapshot repositories. For example, if you want to check what versions of Docker are available with the snapshot:

$ apt policy docker.io --snapshot 20240501T120000Z
docker.io:
  Installed: (none)
  Candidate: 24.0.7-0ubuntu4
  Version table:
     24.0.7-0ubuntu4 500
        500 https://snapshot.ubuntu.com/ubuntu/20240501T120000Z noble/universe amd64 Packages

If you forget to use the snapshot option, apt will operate over the regular archive:

$ apt policy docker.io
docker.io:
  Installed: (none)
  Candidate: 28.2.2-0ubuntu1~24.04.1
  Version table:
     28.2.2-0ubuntu1~24.04.1 500
        500 http://archive.ubuntu.com/ubuntu noble-updates/universe amd64 Packages
     27.5.1-0ubuntu3~24.04.2 500
        500 http://security.ubuntu.com/ubuntu noble-security/universe amd64 Packages
     24.0.7-0ubuntu4 500
        500 http://archive.ubuntu.com/ubuntu noble/universe amd64 Packages

Then, you can install Docker from that snapshot:

$ sudo apt install docker.io --snapshot 20240501T120000Z
...
$ docker --version
Docker version 24.0.7, build 24.0.7-0ubuntu4

Now, let’s say you checked the Docker package publishing history in Launchpad and (for some reason) decided you want to install version 26.1.3-0ubuntu1~24.04.1, which, as inferred from the publishing history, superseded docker.io 24.0.7-0ubuntu4.1 in noble-updates on 2024-11-25. Then, 24.0.7-0ubuntu4.1 was removed from the -updates pocket on 2024-11-26.

You could then use 20241126T230000Z as the snapshot ID to get the target package (26.1.3-0ubuntu1~24.04.1):

$ sudo apt install docker.io --update --snapshot 20241126T230000Z
...
$ docker --version
Docker version 26.1.3, build 26.1.3-0ubuntu1~24.04.1

Note

Note that, at the time of writing, the version of docker.io in the noble-security pocket is 27.5.1-0ubuntu3~24.04.2, i.e., the version used in the example above may be affected by known vulnerabilities. When using the snapshot service, do make sure to check the latest version available in your Ubuntu release’s -security pocket to make sure you are not installing a vulnerable package.

Configuring the snapshot service for specific repositories

In your apt repositories configuration files, it is possible to specify snapshots to be used for each specific repository.

For Ubuntu 24.04 LTS and later, which uses the deb822 style by default, we add a Snapshot option to the relevant sources file in the following format:

Snapshot: $SNAPSHOT_ID

For Ubuntu series lower than 24.04, you change the value of the snapshot option in your sources file, i.e., if you had the following entry in your /etc/apt/sources.list file

deb [snapshot=yes] http://archive.ubuntu.com/ubuntu ...

you replace the yes value with the snapshot ID:

deb [snapshot=$SNAPSHOT_ID] http://archive.ubuntu.com/ubuntu ...

Let’s say you want to pin a specific snapshot for all the pockets in your Ubuntu 24.04 LTS server. Then, you add the Snapshot options to /etc/apt/sources.list.d/ubuntu.sources:

Types: deb
URIs: http://archive.ubuntu.com/ubuntu
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
Snapshot: 20250530T223000Z

Types: deb
URIs: http://security.ubuntu.com/ubuntu
Suites: noble-security
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
Snapshot: 20250530T223000Z

Afterwards, you can run the following commands to install the Docker version present in that snapshot:

$ sudo apt install --update docker.io

to install the Docker version present in that snapshot.

$ docker --version
Docker version 27.5.1, build 27.5.1-0ubuntu3~24.04.1

Note that, when you configure a repository to use a snapshot using the method described above, apt will always ignore the --snapshot option:

$ sudo apt install --update docker.io --snapshot 20251013T2300Z
...
Hit:5 https://snapshot.ubuntu.com/ubuntu/20250530T223000Z noble InRelease
Hit:6 https://snapshot.ubuntu.com/ubuntu/20250530T223000Z noble-updates InRelease
Hit:7 https://snapshot.ubuntu.com/ubuntu/20250530T223000Z noble-backports InRelease
Hit:8 https://snapshot.ubuntu.com/ubuntu/20250530T223000Z noble-security InRelease
...
docker.io is already the newest version (27.5.1-0ubuntu3~24.04.1).
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

As you can see from the logs above, apt is still using the snapshot configured in /etc/apt/sources.list.d/ubuntu.sources, ignoring the --snapshot CLI option.

Configuring the snapshot service globally

As an alternative to configuring a specific snapshot for each individual repository, as described in the previous section, you can configure a snapshot globally for all repositories that have snapshots enabled.

Warning

If you are following these examples until here, make sure to revert the changes to the sources configuration file made in the previous section.

Let’s configure apt to default to a specific snapshot by setting the APT::Snapshot option:

$ echo 'APT::Snapshot "20250801T111111Z";' | sudo tee /etc/apt/apt.conf.d/50snapshot

The system will now default to fetching packages from the configured snapshot:

$ sudo apt install docker.io --update
...
$ docker --version
Docker version 27.5.1, build 27.5.1-0ubuntu3~24.04.2

Note that, in contrast to repositories with snapshots configured in the sources file as shown in the previous section, configuring a snapshot globally will not make apt ignore the --snapshot CLI option:

$ sudo apt install docker.io --update --snapshot 20251013T120000Z
$ docker --version
Docker version 28.2.2, build 28.2.2-0ubuntu1~24.04.1

You can revert the global configuration by removing the file which added it:

$ sudo rm /etc/apt/apt.conf.d/50snapshot

Further reading

• The Ubuntu snapshot service official page and documentation

• Securing multiple Ubuntu instances while maximising uptime

• Integrating the Ubuntu Snapshot Service into systems management and update tools