Platform Upgrades & What’s New

Here you find information about changes compared to the previous platform version, what to consider and where to take action before upgrading.

Note

Before upgrading a machine, please read the General upgrade remarks and Significant breaking changes. Contact our support for upgrade assistance.

Overview

Why upgrade? Security

Upgrading to the latest platform version as soon as possible is important to get all security package updates and other security-related improvements provided by NixOS (our “upstream” distribution we build on).

We do back-ports for critical security issues but this may take longer in some cases and less important security fixes will not be back-ported most of the time.

NixOS provides regular security updates for about one month after the release. Upstream support for 24.11 ended on 2025-06-31.

New platform features are always developed for the current stable platform version and only critical bug fixes are back-ported to older versions.

How to upgrade?

To upgrade your machines, the Environment to one of the fc-25.05-… values.
This can be done either via our customer portal, or by setting the platform version using the API.

General upgrade remarks

Our goal is to make upgrades as smooth as possible without manual intervention but sometimes incompatible configuration has to be fixed before starting an upgrade.

Here are some remarks to make sure that an upgrade will run successfully:

Isolate application deployments

As a general advice: reduce platform dependencies of your application deployment by using Nix-managed service user environments as described in User Package Management or other forms of dependency isolation like containers.

Upgrade staging first

Upgrades should always be checked in a staging environment first. We usually upgrade customer staging machines from our side as soon as the new platform version is ready for general testing. This is announced via our Flying Circus Statuspage where you can also subscribe to updates.

Upgrade to the next platform version

We recommend upgrading platform versions one at a time without skipping versions. Here we assume that you are upgrading from the 24.11 platform.

Direct upgrades from older versions are possible in principle, but we cannot reliably test all combinations for all roles and custom configuration also plays a role here. Usually, problems that occur when skipping versions are only temporary, like service failures that go away with the next system rebuild or a system/service restart.

Check free disk space

About 8-10 GiB should be available on disk before starting an upgrade to avoid triggering a low-disk alarm.

Usually, upgrades have an on-disk size of about 3-6 GiB which may be higher in certain configurations. We keep old system versions and let the Nix garbage collection clean them up, so the additional space will be used for at least 3 days.

Consider performance impact while upgrading

Upgrading may take some time, depending on the number of activated roles and disk speed. For production machines, upgrades are usually done in a maintenance window to reduce impact on regular operations. A VM may have degraded performance for some minutes when packages are being downloaded and built.

With NixOS, the switch to the new system happens after a successful system build so most services are unavailable at the same time and only for a small time-window.

Significant breaking changes

Percona/ MySQL

Two versions of percona are actively supported: percona80 and percona84.
Both are LTS releases still receiving bug and security fixes.

percona83 is only included to allow upgrades towards percona84.

no password authentication for root user (all role versions)

Access to the database root user was changed to authentication via socket. Password authentication is disabled for that user, please switch to the unix user mysql for database root operations.

The platform used to provide the password for the database root user under /etc/local/mysql/mysql.passwd. That file does not exist anymore. Instead, invoke your mysql command via sudo -u mysql.
Example:

sudo -u mysql mysql myDb < someCommands.sql

Users of batou.lib.mysql can just pass USE_SUDO as the admin_password argument.

changed authentication mechanism in percona84

Version 8.4 of percona (role percona84) changes the default authentication mechanism from mysql_native_password to caching_sha2_password. After upgrading the role to 8.4. all passwords need to be migrated manually to the new hash format.

Please do the migration during this platform release cycle, our 25.11 platform with Percona 9.x will disable the deprecated hashing algorithm altogether.

See Migrate user password hash algorithm for detailed migration instructions.

K3S

k3s-1.32.x is the default k3s version in this release.

Please verify that existing clusters are upgraded to k3s-1.30.x before upgrading to NixOS 25.05.

k3s nodes are only allowed to be updated in steps of one minor version at a time. The Kubernetes control plane with the k3s-server role needs to be updated before the cluster’s worker nodes with the k3s-agent role are updated.

Contact support if you need help with updating your k3s cluster, or if you still need to use another specific k3s version for your cluster.

Slurm

This release contains a major version upgrade of Slurm from 24.05.x.x (NixOS 24.11) to 24.11.x.x. Nodes of a cluster need to be upgraded in a particular order, please consult the upgrade instructions of the role for details.

Gitlab

Gitlab version 18.0 will enable pseudonymised tracking and reporting of events data. To prevent this, an opt-out can already be configured in the current Gitlab version:

  • Visit <yourgitlabdomain>/admin/application_settings/metrics_and_profiling

  • uncheck Event tracking -> Enable event tracking

Postgresql>=16 is required, please upgrade your postgres role before updating.

Runner registration tokens have been deprecated for several releases already and are not supported anymore in Gitlab 18. Our support staff will take care of migrating your managed Gitlab instance to the new runner authentication token scheme ahead of the update. For advanced use cases like interactions between Gitlab and external runners not part of the Flying Circus platform, please reach out to our support.

Mailserver, mailstub

Both mailserver and mailstub roles are affected by changes in the underlying implementations:

  • DKIM signing and verification is now handled by rspamd instead of OpenDKIM. rspamd only supports relaxed canoncalisation.

  • policyd-spf was removed, SPF record verification of incoming mails is handled by rspamd.

    • The policydSPFExtraSkipAddresses option has been renamed to spfSkipAddresses, reflecting that change.

    • mailserver.policydSPFExtraConfig was removed.

  • flyingcircus.roles.mailserver.imprintUrl now requires a full URI starting with the http:// or https:// protocol. Protocol-less URIs had been deprecated in the 24.11 platform release.

Redis

  • redis: restructure internal password handling The password file /etc/local/redis/password now gets written as systemd ExecStartPre. (PL-133653)

    services.redis.servers."".requirePass must not be used anymore. There are three options to replace it with:

    • services.redis.servcers."".requirePassFile to retrieve the password from an external file

    • set flyingcircus.services.redis.password

    • just remove the option, causing the password to be autogenerated and stored at /etc/local/redis/password.
      Autogenerated passwords can not be read from the Nix config at evaluation time.

  • reading the Redis password at evaluation time from config.flyingcircus.services.redis.password is not supported anymore.

changes not affecting a specific role

  • mongodb: The option services.mongodb.initialRootPassword was removed in favour of services.mongodb.initialRootPasswordFile to securely provide the initial root password.

  • postgresql: pg_config has been moved to a separate package postgresql.pg_config or postgresql_<major version>.pg_config. Packages and environment relying on the presence of that command need to explicitly specify that package as a dependency.

    • Building other software against postgresql usually also requires libraries and headers as well, so in general the following dependencies need to be specified:

      • postgresql.pg_config.out

      • postgresql.out

      • postgresql.lib

      • postgresql.dev

    • For deplyoments using a batou_ext userenv, only postgresql.pg_config and postgresql are required.

Other notable changes

  • Nix was upgraded to version 2.28

  • agent: the command fc-manage switch now has a -R option which will activate the new configuration by performing an immediate reboot, similar to the process used for upgrading between major versions. (PL-133308)

  • improvements in configuring the nixpkgs package set:

    • Introduced option flyingcircus.permittedInsecurePackages to allow additional packages marked as insecure.

    • Improved error message when trying to use a package marked as insecure or unfree showing FCIO-specific instructions.

    • When importing the platform channel (import <fc> …), declarations of config.allowUnfreePredicate and config.permittedInsecurePackages don’t get discarded silently. In case of allowUnfreePredicate, at least one of the platform-provided or user-supplied predicate must evaluate to true to allow the instantiation of an unfree package.

  • docker: fix role not working on devhosts (PL-133607)

    This change also prepares the role to work on machines without FE interface or PUB interface.

  • Add a mechanism to upgrade XFS flags over time. Initially this will cause bigtime, inobtcount and nrext64 flags to be set. With bigtime set VMs from this release on will consistently support file times beyond 2038, even if they were bootstrapped on older releases. (PL-133321, PL-130365)

  • Prepare VMs to read ENC data (the config management metadata) seeded from the host from the separate cidata volume in the future. This allows disabling or reconfiguring /tmp to use tmpfs without breaking our configuration management. (PL-133311)

  • Invalid NixOS state_version files are automatically fixed to fit the expected YY.MM format. (PL-133559)

  • nginx: new JSON-based log format that is being used to ship access logs to a Loki instance automatically if one is present (PL-133702)

  • dstat: drop as it is unmaintained, replace with dool

    • dstat is now an alias for dool

  • less does not utilise external programs to improve rendering by default (lesspipe). To restore the previous behaviour, set programs.less.lessopen to ''|${lib.getExe' pkgs.lesspipe "lesspipe.sh"} %s''.

  • linux kernel: we now follow the 6.12.x LTS series of linux for production environments. This seems to help resolve some recent IO latency / stalling issues.

  • Kernel memory management: switch to smaller, fixed size dirty page buffers (PL-133760)

    This also seems to be a factor in the recent IO latency / stalling issues: The dirty page buffers were based on percentages of the installed RAM so far, but can cause long periods of stalling when the kernel passes the hard threshold to flush it.

    We now provide much smaller and fixed sizes for dirty pages (16 MiB to start flushing in the background and 64 MiB to enforce flushing).

  • For more details, see the release notes of NixOS 25.05.

Known issues

  • mailserver: Incoming e-mails via IPv4 are treated as local e-mails by rspamd, skipping SPF, DKIM, and DMARC checks

Significant package updates

as of 2025-06-24

  • awscli: 1.34 -> 1.37

  • awscli2: 2.19 -> 2.27

  • binutils: 2.43 -> 2.44

  • calibre: 7.21 -> 8.4

  • containerd: 1.7 -> 2.1

  • coreutils: 9.5 -> 9.7

  • curl: 8.12 -> 8.13

  • discourse: 3.3 -> 3.4

  • docker-compose: 2.30 -> 2.36

  • erlang: 25.3 -> 27.3

  • gcc: 13.3 -> 14.2 (other versions available under alias)

  • git: 2.47 -> 2.49

  • gitlab: 17.11 -> 18.0

  • go: 1.23 -> 1.24 (other versions available under alias)

  • grafana: 11.3 -> 12.0

  • haproxy: 3.0 -> 3.1

  • k3s: 1.30 -> 1.32 (other versions available under alias)

  • kubernetes-helm: 3.16 -> 3.17

  • libwebp: 1.4 -> 1.5

  • linux: 6.6 -> 6.12

  • matomo: 5.2 -> 5.3

  • nginx: 1.26 -> 1.28

  • nodejs: 20 -> 22 (other versions available under alias)

  • opensearch: 2.17 -> 2.19

  • openssh: 9.9 -> 10.0

  • openssl: 3.3 -> 3.4

  • podman: 5.2 -> 5.4

  • poetry: 1.8 -> 2.1

  • postfix: 3.9 -> 3.10

  • prometheus: 2.55 -> 3.1

  • python3Packages.boto3: 1.35 -> 1.36

  • python3Packages.rich: 13.8 -> 14.0

  • rclone: 1.68 -> 1.69

  • re2c: 3.1 -> 4.1

  • slurm: 24.05 -> 24.11

  • systemd: 256 -> 257

  • telegraf: 1.32 -> 1.34

  • util-linux: 2.39 -> 2.41

  • uv: 0.4 -> 0.7

  • varnish: 7.5 -> 7.7

  • xz: 5.6 -> 5.8