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Merged
systemstart merged 1 commit into from
Jun 4, 2026
Merged

feat: mem and vcpu configurable #7

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19 changes: 16 additions & 3 deletions flake.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@
pi = { suffix = "-pi"; agentModule = ./modules/agents/pi.nix; dataDirName = "pi-microvm"; apiKeyVars = [ "ANTHROPIC_API_KEY" "OPENAI_API_KEY" "GEMINI_API_KEY" ]; };
};

mkRunnerScript = { pkgs, runner, dataDirName, apiKeyVars, agentName }:
mkRunnerScript = { pkgs, runner, dataDirName, apiKeyVars, agentName, defaultMem, defaultVcpu }:
let
virtiofsd = pkgs.virtiofsd;
hostname = "${agentName}-vm";
Expand All @@ -32,6 +32,8 @@
in pkgs.writeShellScriptBin "microvm-run" ''
set -euo pipefail
WORK="$(realpath "''${WORK_DIR:-$(pwd)}")"
VM_MEM="''${VM_MEM:-${toString defaultMem}}"
VM_VCPU="''${VM_VCPU:-${toString defaultVcpu}}"
Comment on lines +35 to +36

@coderabbitai coderabbitai Bot Jun 4, 2026

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⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Add runtime validation for VM_MEM and VM_VCPU.

The script reads VM_MEM and VM_VCPU from the environment without validation. Invalid values (non-numeric, negative, zero) will be passed to QEMU, potentially causing confusing errors.

🛡️ Proposed validation 
 VM_MEM="''${VM_MEM:-${toString defaultMem}}"
 VM_VCPU="''${VM_VCPU:-${toString defaultVcpu}}"
+
+# Validate VM_MEM is a positive integer
+if ! [[ "$VM_MEM" =~ ^[0-9]+$ ]] || [ "$VM_MEM" -le 0 ]; then
+  echo "error: VM_MEM must be a positive integer (got: $VM_MEM)" >&2
+  exit 1
+fi
+
+# Validate VM_VCPU is a positive integer
+if ! [[ "$VM_VCPU" =~ ^[0-9]+$ ]] || [ "$VM_VCPU" -le 0 ]; then
+  echo "error: VM_VCPU must be a positive integer (got: $VM_VCPU)" >&2
+  exit 1
+fi
+
 RUNTIME="''${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@flake.nix` around lines 35 - 36, Validate VM_MEM and VM_VCPU at runtime
before passing them to QEMU: check that VM_MEM and VM_VCPU (used in flake.nix
where VM_MEM="''${VM_MEM:-${toString defaultMem}}",
VM_VCPU="''${VM_VCPU:-${toString defaultVcpu}}") are positive integers (numeric,
>0) and fall back to the default values (defaultMem/defaultVcpu) or fail fast
with a clear error if they are invalid; implement the check using a Nix
expression (e.g., builtins.match or parseInt + comparisons) and replace the
direct interpolations with the validated/normalized variables so non-numeric,
zero or negative inputs are rejected or replaced before being handed to QEMU.

RUNTIME="''${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
ID="$(cat /proc/sys/kernel/random/uuid)"

Expand Down Expand Up @@ -256,6 +258,10 @@
-e "s|${hostname}-virtiofs-agent-home.sock|$AGENT_SOCK|g"
-e "s|/tmp/${hostname}-cri-storage|$CRI_DIR|g"
-e "s|${hostname}-virtiofs-cri-storage.sock|$CRI_SOCK|g"
# Runtime mem/vcpu override (VM_MEM / VM_VCPU env vars)
-e "s| -m ${toString defaultMem} | -m $VM_MEM |g"
-e "s| -smp ${toString defaultVcpu} | -smp $VM_VCPU |g"
-e "s|size=${toString defaultMem}M|size=''${VM_MEM}M|g"
)

# Run QEMU with corrected paths
Expand Down Expand Up @@ -321,8 +327,15 @@
packages = forSystems (system: let pkgs = nixpkgs.legacyPackages.${system}; in
{ default = self.packages.${system}.claude; } //
builtins.mapAttrs (name: flavor: let
runner = self.nixosConfigurations."${name}${flavor.suffix}-${system}".config.microvm.runner.qemu;
in mkRunnerScript { inherit pkgs runner; inherit (flavor) dataDirName apiKeyVars; agentName = name; }) vmFlavors
nixosCfg = self.nixosConfigurations."${name}${flavor.suffix}-${system}".config;
runner = nixosCfg.microvm.runner.qemu;
in mkRunnerScript {
inherit pkgs runner;
inherit (flavor) dataDirName apiKeyVars;
agentName = name;
defaultMem = nixosCfg.claude-vm.agent.mem;
defaultVcpu = nixosCfg.claude-vm.agent.vcpu;
}) vmFlavors
);
};
}
14 changes: 12 additions & 2 deletions modules/base.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,16 @@ in
default = "";
description = "Agent-specific shell init (runs before launch)";
};
mem = lib.mkOption {
type = lib.types.int;
default = 8192;
description = "VM memory in MB. Overridable at runtime via VM_MEM env var.";
};
vcpu = lib.mkOption {
type = lib.types.int;
default = 4;
description = "VM vCPU count. Overridable at runtime via VM_VCPU env var.";
};
Comment on lines +25 to +34

@coderabbitai coderabbitai Bot Jun 4, 2026

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⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Add validation to ensure positive values.

The mem and vcpu options accept any integer, including negative or zero values. While QEMU would reject these at runtime, adding Nix-level validation provides clearer error messages during configuration.

✅ Proposed validation 
     mem = lib.mkOption {
       type = lib.types.int;
       default = 8192;
       description = "VM memory in MB. Overridable at runtime via VM_MEM env var.";
     };
+    # Validate mem is positive
+    assertions = [{
+      assertion = cfg.mem > 0;
+      message = "claude-vm.agent.mem must be greater than 0";
+    }];
+
     vcpu = lib.mkOption {
       type = lib.types.int;
       default = 4;
       description = "VM vCPU count. Overridable at runtime via VM_VCPU env var.";
     };
+    # Validate vcpu is positive  
+    assertions = [{
+      assertion = cfg.vcpu > 0;
+      message = "claude-vm.agent.vcpu must be greater than 0";
+    }];

Alternatively, use a more restrictive type:

     mem = lib.mkOption {
-      type = lib.types.int;
+      type = lib.types.ints.positive;
       default = 8192;
       description = "VM memory in MB. Overridable at runtime via VM_MEM env var.";
     };
     vcpu = lib.mkOption {
-      type = lib.types.int;
+      type = lib.types.ints.positive;
       default = 4;
       description = "VM vCPU count. Overridable at runtime via VM_VCPU env var.";
     };
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
mem = lib.mkOption {
type = lib.types.int;
default = 8192;
description = "VM memory in MB. Overridable at runtime via VM_MEM env var.";
};
vcpu = lib.mkOption {
type = lib.types.int;
default = 4;
description = "VM vCPU count. Overridable at runtime via VM_VCPU env var.";
};
mem = lib.mkOption {
type = lib.types.ints.positive;
default = 8192;
description = "VM memory in MB. Overridable at runtime via VM_MEM env var.";
};
vcpu = lib.mkOption {
type = lib.types.ints.positive;
default = 4;
description = "VM vCPU count. Overridable at runtime via VM_VCPU env var.";
};
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@modules/base.nix` around lines 25 - 34, The mem and vcpu options currently
accept any integer (including <=0); add an option-level validation on both the
mem and vcpu lib.mkOption blocks to reject non-positive values (e.g. validation
= v: if v > 0 then true else "mem must be a positive integer (MB)" and similarly
for vcpu: "vcpu must be a positive integer"); update the error strings to
clearly name the option being validated so configuration-time errors are
helpful.

};

config = {
Expand All @@ -31,8 +41,8 @@ in

microvm = {
hypervisor = "qemu";
mem = 4096;
vcpu = 4;
mem = cfg.mem;
vcpu = cfg.vcpu;

writableStoreOverlay = "/nix/.rw-store";

Expand Down
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