nordic-dev.net/nixpkgs
nordic-dev.net/nixpkgs
2
0
Fork 0
mirror of https://github.com/NixOS/nixpkgs.git synced 2024-11-22 23:13:19 +00:00
Code Issues Packages Projects Releases Wiki Activity

nixos/manual: Add chapter about instance unit overrides

Browse Source
This commit is contained in:
Janne Heß 2023-08-13 14:35:44 +02:00
parent d995da11d8
commit da6c61cc19
No known key found for this signature in database
1 changed files with 30 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
nixos/doc/manual/administration/service-mgmt.chapter.md
View File

@ -118,3 +118,33 @@ the symlink, and this path is in `/nix/store/.../lib/systemd/user/`.
Hence [garbage collection](#sec-nix-gc) will remove that file and you
will wind up with a broken symlink in your systemd configuration, which
in turn will not make the service / timer start on login.
## Template units {#sect-nixos-systemd-template-units}
systemd supports templated units where a base unit can be started multiple
times with a different parameter. The syntax to accomplish this is
`service-name@instance-name.service`. Units get the instance name passed to
them (see `systemd.unit(5)`). NixOS has support for these kinds of units and
for template-specific overrides. A service needs to be defined twice, once
for the base unit and once for the instance. All instances must include
`overrideStrategy = "asDropin"` for the change detection to work. This
example illustrates this:
```nix
{
systemd.services = {
"base-unit@".serviceConfig = {
ExecStart = "...";
User = "...";
};
"base-unit@instance-a" = {
overrideStrategy = "asDropin"; # needed for templates to work
wantedBy = [ "multi-user.target" ]; # causes NixOS to manage the instance
};
"base-unit@instance-b" = {
overrideStrategy = "asDropin"; # needed for templates to work
wantedBy = [ "multi-user.target" ]; # causes NixOS to manage the instance
serviceConfig.User = "root"; # also override something for this specific instance
};
};
}
```