d166c854b6
This option requests compatibility with older NixOS releases with respect to stateful data, in cases where new releases have defaults that might be incompatible with system state of existing NixOS deployments. For instance, if we change the default version of PostgreSQL, existing deployments will break if the new version can't read databases created by the old version. So for example, setting system.stateVersion = "15.07"; requests that options like services.postgresql.package use defaults corresponding to the 15.07 release branch. Note that nixos-generate-config emits this option. (In the future, NixOps may set system.stateVersion to the NixOS release in use when the machine was created.) See also #7939 for another motivating example.
95 lines
2.7 KiB
Nix
95 lines
2.7 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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{
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options = {
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system.stateVersion = mkOption {
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type = types.str;
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default = config.system.nixosRelease;
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description = ''
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Every once in a while, a new NixOS release may change
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configuration defaults in a way incompatible with stateful
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data. For instance, if the default version of PostgreSQL
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changes, the new version will probably be unable to read your
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existing databases. To prevent such breakage, you can set the
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value of this option to the NixOS release with which you want
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to be compatible. The effect is that NixOS will option
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defaults corresponding to the specified release (such as using
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an older version of PostgreSQL).
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'';
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};
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system.nixosVersion = mkOption {
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internal = true;
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type = types.str;
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description = "NixOS version.";
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};
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system.nixosRelease = mkOption {
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internal = true;
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type = types.str;
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default = readFile "${toString pkgs.path}/.version";
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description = "NixOS release.";
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};
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system.nixosVersionSuffix = mkOption {
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internal = true;
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type = types.str;
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description = "NixOS version suffix.";
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};
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system.nixosRevision = mkOption {
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internal = true;
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type = types.str;
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description = "NixOS Git revision hash.";
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};
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system.nixosCodeName = mkOption {
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internal = true;
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type = types.str;
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description = "NixOS release code name.";
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};
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system.defaultChannel = mkOption {
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internal = true;
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type = types.str;
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default = https://nixos.org/channels/nixos-unstable;
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description = "Default NixOS channel to which the root user is subscribed.";
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};
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};
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config = {
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system.nixosVersion = mkDefault (config.system.nixosRelease + config.system.nixosVersionSuffix);
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system.nixosVersionSuffix =
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let suffixFile = "${toString pkgs.path}/.version-suffix"; in
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mkDefault (if pathExists suffixFile then readFile suffixFile else "pre-git");
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system.nixosRevision =
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let fn = "${toString pkgs.path}/.git-revision"; in
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mkDefault (if pathExists fn then readFile fn else "master");
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# Note: code names must only increase in alphabetical order.
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system.nixosCodeName = "Dingo";
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# Generate /etc/os-release. See
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# http://0pointer.de/public/systemd-man/os-release.html for the
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# format.
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environment.etc."os-release".text =
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''
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NAME=NixOS
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ID=nixos
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VERSION="${config.system.nixosVersion} (${config.system.nixosCodeName})"
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VERSION_ID="${config.system.nixosVersion}"
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PRETTY_NAME="NixOS ${config.system.nixosVersion} (${config.system.nixosCodeName})"
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HOME_URL="http://nixos.org/"
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'';
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};
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}
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