Skip to content

extraConfig and extraArgs for firecracker #434

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

extraConfig and extraArgs for firecracker #434

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
b6c5f9c
firecracker: Add extraConfig option
bjackman Nov 7, 2025
2c0e70e
fireracker: Add extraArgs option
bjackman Nov 10, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 4 additions & 3 deletions lib/runners/firecracker.nix
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ let
}.${system};

# Firecracker config, as JSON in `configFile`
config = {
baseConfig = {
boot-source = {
kernel_image_path = kernelPath;
initrd_path = initrdPath;
Expand Down Expand Up @@ -65,6 +65,7 @@ let
} // lib.optionalAttrs (cpu != null) {
cpu-config = pkgs.writeText "cpu-config.json" (builtins.toJSON cpu);
};
config = lib.recursiveUpdate baseConfig microvmConfig.firecracker.extraConfig;

configFile = pkgs.writers.writeJSON "firecracker-${hostName}.json" config;

Expand All @@ -86,15 +87,15 @@ in {
then throw "hotpluggedMem not implemented for Firecracker"
else if credentialFiles != {}
then throw "credentialFiles are not implemented for Firecracker"
else lib.escapeShellArgs [
else lib.escapeShellArgs ([
"${pkgs.firecracker}/bin/firecracker"
"--config-file" configFile
"--api-sock" (
if socket != null
then socket
else throw "Firecracker must be configured with an API socket (option microvm.socket)!"
)
];
] ++ microvmConfig.firecracker.extraArgs);

preStart = ''
${preStart}
Expand Down
12 changes: 12 additions & 0 deletions nixos-modules/microvm/options.nix
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -590,6 +590,18 @@ in
description = "Custom CPU template passed to firecracker.";
};

firecracker.extraArgs = mkOption {
type = with types; listOf str;
default = [];
description = "Extra arguments to pass to firecracker.";
};

firecracker.extraConfig = mkOption {
type = types.attrs;
Copy link
Member

@SuperSandro2000 SuperSandro2000 Nov 23, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

That type does not merge. We need to use a submodule of attrs.

default = {};
description = "Extra config to merge into Firecracker JSON configuration";
};

prettyProcnames = mkOption {
type = types.bool;
default = true;
Expand Down