vm defaults: host-aware sizing + spec line on spawn + doctor check

Replaces the static model.Default* constants that drove --vcpu / --memory
/ --disk-size with a three-layer resolver:

  1. [vm_defaults] in ~/.config/banger/config.toml (if set)
  2. host-derived heuristics (cpus/4 capped at 4; ram/8 capped at 8 GiB)
  3. baked-in constants (floor)

Visibility:

- Every `vm run` / `vm create` prints a `spec:` line before progress
  begins: `spec: 4 vcpu · 8192 MiB · 8G disk`. Matches the VM that
  actually gets created because the CLI is now the single source of
  truth — it resolves, populates the flag defaults, and forwards the
  explicit values to the daemon.
- `banger doctor` adds a "vm defaults" check showing per-field
  provenance (config|auto|builtin) and the config file path for
  overrides.
- `--help` shows the resolved defaults (e.g. `--vcpu int (default 4)`
  on an 8-core host).

No `banger config init` command, no first-run side effects, no writes
to the user's filesystem behind their back. Users who want explicit
control set the keys; everyone else gets sensible numbers that track
their hardware.
This commit is contained in:
Thales Maciel 2026-04-19 13:06:51 -03:00
parent 78ff482bfa
commit 21b74639d8
No known key found for this signature in database
GPG key ID: 33112E6833C34679
10 changed files with 594 additions and 56 deletions

View file

@ -750,13 +750,14 @@ func newVMCommand() *cobra.Command {
}
func newVMRunCommand() *cobra.Command {
defaults := effectiveVMDefaults()
var (
name string
imageName string
vcpu = model.DefaultVCPUCount
memory = model.DefaultMemoryMiB
systemOverlaySize = model.FormatSizeBytes(model.DefaultSystemOverlaySize)
workDiskSize = model.FormatSizeBytes(model.DefaultWorkDiskSize)
vcpu = defaults.VCPUCount
memory = defaults.MemoryMiB
systemOverlaySize = model.FormatSizeBytes(defaults.SystemOverlaySizeByte)
workDiskSize = model.FormatSizeBytes(defaults.WorkDiskSizeBytes)
natEnabled bool
branchName string
fromRef = "HEAD"
@ -842,10 +843,10 @@ Three modes:
}
cmd.Flags().StringVar(&name, "name", "", "vm name")
cmd.Flags().StringVar(&imageName, "image", "", "image name or id (defaults to config's default_image_name; auto-pulled from imagecat if missing)")
cmd.Flags().IntVar(&vcpu, "vcpu", model.DefaultVCPUCount, "vcpu count")
cmd.Flags().IntVar(&memory, "memory", model.DefaultMemoryMiB, "memory in MiB")
cmd.Flags().StringVar(&systemOverlaySize, "system-overlay-size", model.FormatSizeBytes(model.DefaultSystemOverlaySize), "system overlay size")
cmd.Flags().StringVar(&workDiskSize, "disk-size", model.FormatSizeBytes(model.DefaultWorkDiskSize), "work disk size")
cmd.Flags().IntVar(&vcpu, "vcpu", defaults.VCPUCount, "vcpu count")
cmd.Flags().IntVar(&memory, "memory", defaults.MemoryMiB, "memory in MiB")
cmd.Flags().StringVar(&systemOverlaySize, "system-overlay-size", model.FormatSizeBytes(defaults.SystemOverlaySizeByte), "system overlay size")
cmd.Flags().StringVar(&workDiskSize, "disk-size", model.FormatSizeBytes(defaults.WorkDiskSizeBytes), "work disk size")
cmd.Flags().BoolVar(&natEnabled, "nat", false, "enable NAT")
cmd.Flags().StringVar(&branchName, "branch", "", "create and switch to a new guest branch")
cmd.Flags().StringVar(&fromRef, "from", "HEAD", "base ref for --branch")
@ -998,13 +999,14 @@ func promptYesNo(in io.Reader, out io.Writer, prompt string) (bool, error) {
}
func newVMCreateCommand() *cobra.Command {
defaults := effectiveVMDefaults()
var (
name string
imageName string
vcpu = model.DefaultVCPUCount
memory = model.DefaultMemoryMiB
systemOverlaySize = model.FormatSizeBytes(model.DefaultSystemOverlaySize)
workDiskSize = model.FormatSizeBytes(model.DefaultWorkDiskSize)
vcpu = defaults.VCPUCount
memory = defaults.MemoryMiB
systemOverlaySize = model.FormatSizeBytes(defaults.SystemOverlaySizeByte)
workDiskSize = model.FormatSizeBytes(defaults.WorkDiskSizeBytes)
natEnabled bool
noStart bool
)
@ -1033,10 +1035,10 @@ func newVMCreateCommand() *cobra.Command {
}
cmd.Flags().StringVar(&name, "name", "", "vm name")
cmd.Flags().StringVar(&imageName, "image", "", "image name or id (defaults to config's default_image_name; auto-pulled from imagecat if missing)")
cmd.Flags().IntVar(&vcpu, "vcpu", model.DefaultVCPUCount, "vcpu count")
cmd.Flags().IntVar(&memory, "memory", model.DefaultMemoryMiB, "memory in MiB")
cmd.Flags().StringVar(&systemOverlaySize, "system-overlay-size", model.FormatSizeBytes(model.DefaultSystemOverlaySize), "system overlay size")
cmd.Flags().StringVar(&workDiskSize, "disk-size", model.FormatSizeBytes(model.DefaultWorkDiskSize), "work disk size")
cmd.Flags().IntVar(&vcpu, "vcpu", defaults.VCPUCount, "vcpu count")
cmd.Flags().IntVar(&memory, "memory", defaults.MemoryMiB, "memory in MiB")
cmd.Flags().StringVar(&systemOverlaySize, "system-overlay-size", model.FormatSizeBytes(defaults.SystemOverlaySizeByte), "system overlay size")
cmd.Flags().StringVar(&workDiskSize, "disk-size", model.FormatSizeBytes(defaults.WorkDiskSizeBytes), "work disk size")
cmd.Flags().BoolVar(&natEnabled, "nat", false, "enable NAT")
cmd.Flags().BoolVar(&noStart, "no-start", false, "create without starting")
_ = cmd.RegisterFlagCompletionFunc("image", completeImageNames)
@ -2563,33 +2565,73 @@ func vmSetParamsFromFlags(idOrName string, vcpu, memory int, diskSize string, na
}
func vmCreateParamsFromFlags(cmd *cobra.Command, name, imageName string, vcpu, memory int, systemOverlaySize, workDiskSize string, natEnabled, noStart bool) (api.VMCreateParams, error) {
// The flag defaults are already resolved from config + host
// heuristics at command-build time, so we always forward the flag
// values to the daemon. This makes the CLI the single source of
// truth for effective defaults and lets the progress renderer show
// exactly what the VM will be sized at.
if err := validatePositiveSetting("vcpu", vcpu); err != nil {
return api.VMCreateParams{}, err
}
if err := validatePositiveSetting("memory", memory); err != nil {
return api.VMCreateParams{}, err
}
params := api.VMCreateParams{
Name: name,
ImageName: imageName,
NATEnabled: natEnabled,
NoStart: noStart,
}
if cmd.Flags().Changed("vcpu") {
if err := validatePositiveSetting("vcpu", vcpu); err != nil {
return api.VMCreateParams{}, err
}
params.VCPUCount = &vcpu
}
if cmd.Flags().Changed("memory") {
if err := validatePositiveSetting("memory", memory); err != nil {
return api.VMCreateParams{}, err
}
params.MemoryMiB = &memory
}
if cmd.Flags().Changed("system-overlay-size") {
params.SystemOverlaySize = systemOverlaySize
}
if cmd.Flags().Changed("disk-size") {
params.WorkDiskSize = workDiskSize
Name: name,
ImageName: imageName,
NATEnabled: natEnabled,
NoStart: noStart,
VCPUCount: &vcpu,
MemoryMiB: &memory,
SystemOverlaySize: systemOverlaySize,
WorkDiskSize: workDiskSize,
}
return params, nil
}
// effectiveVMDefaults resolves the default sizing applied to commands
// that accept --vcpu / --memory / --disk-size flags when the user
// doesn't set them. It combines config overrides (if any) with
// host-derived heuristics, falling back to baked-in constants.
//
// Called at command-build time, which runs before any RunE. It
// reads config.toml and /proc — any read error collapses to builtin
// constants so the CLI stays usable even on a misconfigured host.
func effectiveVMDefaults() model.VMDefaults {
var override model.VMDefaultsOverride
if layout, err := paths.Resolve(); err == nil {
if cfg, err := config.Load(layout); err == nil {
override = cfg.VMDefaults
}
}
host, err := system.ReadHostResources()
if err != nil {
return model.ResolveVMDefaults(override, 0, 0)
}
return model.ResolveVMDefaults(override, host.CPUCount, host.TotalMemoryBytes)
}
// printVMSpecLine writes a one-line sizing summary to out. Always
// emitted (even non-TTY) so logs and CI output carry the numbers.
func printVMSpecLine(out io.Writer, params api.VMCreateParams) {
vcpu := model.DefaultVCPUCount
if params.VCPUCount != nil {
vcpu = *params.VCPUCount
}
memory := model.DefaultMemoryMiB
if params.MemoryMiB != nil {
memory = *params.MemoryMiB
}
diskBytes := int64(model.DefaultWorkDiskSize)
if strings.TrimSpace(params.WorkDiskSize) != "" {
if parsed, err := model.ParseSize(params.WorkDiskSize); err == nil {
diskBytes = parsed
}
}
_, _ = fmt.Fprintf(out, "spec: %d vcpu · %d MiB · %s disk\n",
vcpu, memory, model.FormatSizeBytes(diskBytes))
}
func validatePositiveSetting(label string, value int) error {
if value <= 0 {
return fmt.Errorf("%s must be a positive integer", label)
@ -3479,6 +3521,7 @@ type anyWriter interface {
}
func runVMCreate(ctx context.Context, socketPath string, stderr io.Writer, params api.VMCreateParams) (model.VMRecord, error) {
printVMSpecLine(stderr, params)
begin, err := vmCreateBeginFunc(ctx, socketPath, params)
if err != nil {
return model.VMRecord{}, err

View file

@ -268,7 +268,11 @@ func TestVMRunFlagsExist(t *testing.T) {
}
}
func TestVMCreateFlagsShowStaticDefaults(t *testing.T) {
func TestVMCreateFlagsShowResolvedDefaults(t *testing.T) {
// Defaults are resolved at command-build time from config + host
// heuristics. Guarantee only that the values are sensible-positive
// and match the resolver's output — the exact numbers depend on
// the host the tests run on.
root := NewBangerCommand()
vm, _, err := root.Find([]string{"vm"})
if err != nil {
@ -279,17 +283,23 @@ func TestVMCreateFlagsShowStaticDefaults(t *testing.T) {
t.Fatalf("find create: %v", err)
}
if got := create.Flags().Lookup("vcpu").DefValue; got != fmt.Sprintf("%d", model.DefaultVCPUCount) {
t.Fatalf("vcpu default = %q, want %d", got, model.DefaultVCPUCount)
for _, flagName := range []string{"vcpu", "memory"} {
flag := create.Flags().Lookup(flagName)
if flag == nil {
t.Fatalf("flag %q missing", flagName)
}
if flag.DefValue == "" || flag.DefValue == "0" {
t.Errorf("flag %q default = %q, want a positive integer", flagName, flag.DefValue)
}
}
if got := create.Flags().Lookup("memory").DefValue; got != fmt.Sprintf("%d", model.DefaultMemoryMiB) {
t.Fatalf("memory default = %q, want %d", got, model.DefaultMemoryMiB)
}
if got := create.Flags().Lookup("system-overlay-size").DefValue; got != model.FormatSizeBytes(model.DefaultSystemOverlaySize) {
t.Fatalf("system-overlay-size default = %q, want %q", got, model.FormatSizeBytes(model.DefaultSystemOverlaySize))
}
if got := create.Flags().Lookup("disk-size").DefValue; got != model.FormatSizeBytes(model.DefaultWorkDiskSize) {
t.Fatalf("disk-size default = %q, want %q", got, model.FormatSizeBytes(model.DefaultWorkDiskSize))
for _, flagName := range []string{"system-overlay-size", "disk-size"} {
flag := create.Flags().Lookup(flagName)
if flag == nil {
t.Fatalf("flag %q missing", flagName)
}
if !strings.ContainsAny(flag.DefValue, "GMK") {
t.Errorf("flag %q default = %q, want a formatted size like '8G'", flagName, flag.DefValue)
}
}
}
@ -385,7 +395,11 @@ func TestVMSetParamsFromFlags(t *testing.T) {
}
}
func TestVMCreateParamsFromFlagsOmitsStaticDefaultsWhenFlagsAreUnchanged(t *testing.T) {
func TestVMCreateParamsFromFlagsAlwaysPopulatesResolvedValues(t *testing.T) {
// Post-resolver behavior: the CLI is the single source of truth for
// effective defaults. Whether or not the user changed a flag, the
// daemon receives the explicit value so the spec printed to the
// user matches the VM that gets created.
cmd := NewBangerCommand()
vm, _, err := cmd.Find([]string{"vm"})
if err != nil {
@ -400,18 +414,46 @@ func TestVMCreateParamsFromFlagsOmitsStaticDefaultsWhenFlagsAreUnchanged(t *test
create,
"devbox",
"default",
model.DefaultVCPUCount,
model.DefaultMemoryMiB,
model.FormatSizeBytes(model.DefaultSystemOverlaySize),
model.FormatSizeBytes(model.DefaultWorkDiskSize),
3,
4096,
"10G",
"20G",
false,
false,
)
if err != nil {
t.Fatalf("vmCreateParamsFromFlags: %v", err)
}
if params.VCPUCount != nil || params.MemoryMiB != nil || params.SystemOverlaySize != "" || params.WorkDiskSize != "" {
t.Fatalf("expected unchanged defaults to stay omitted: %+v", params)
if params.VCPUCount == nil || *params.VCPUCount != 3 {
t.Errorf("VCPUCount = %v, want 3", params.VCPUCount)
}
if params.MemoryMiB == nil || *params.MemoryMiB != 4096 {
t.Errorf("MemoryMiB = %v, want 4096", params.MemoryMiB)
}
if params.SystemOverlaySize != "10G" {
t.Errorf("SystemOverlaySize = %q, want 10G", params.SystemOverlaySize)
}
if params.WorkDiskSize != "20G" {
t.Errorf("WorkDiskSize = %q, want 20G", params.WorkDiskSize)
}
}
func TestVMCreateParamsFromFlagsRejectsNonPositive(t *testing.T) {
cmd := NewBangerCommand()
vm, _, err := cmd.Find([]string{"vm"})
if err != nil {
t.Fatalf("find vm: %v", err)
}
create, _, err := vm.Find([]string{"create"})
if err != nil {
t.Fatalf("find create: %v", err)
}
if _, err := vmCreateParamsFromFlags(create, "x", "", 0, 1024, "8G", "8G", false, false); err == nil {
t.Error("expected error for vcpu=0")
}
if _, err := vmCreateParamsFromFlags(create, "x", "", 2, 0, "8G", "8G", false, false); err == nil {
t.Error("expected error for memory=0")
}
}

View file

@ -0,0 +1,53 @@
package cli
import (
"bytes"
"strings"
"testing"
"banger/internal/api"
)
func TestPrintVMSpecLineWithAllFields(t *testing.T) {
vcpu, mem := 2, 2048
params := api.VMCreateParams{
VCPUCount: &vcpu,
MemoryMiB: &mem,
WorkDiskSize: "8G",
}
var buf bytes.Buffer
printVMSpecLine(&buf, params)
got := buf.String()
for _, want := range []string{"spec:", "2 vcpu", "2048 MiB", "8G"} {
if !strings.Contains(got, want) {
t.Errorf("output missing %q:\n%s", want, got)
}
}
if !strings.HasSuffix(got, "\n") {
t.Error("spec line should terminate with newline")
}
}
func TestPrintVMSpecLineFallsBackToBuiltinsOnNilFields(t *testing.T) {
// Empty params — the printer reaches for DefaultVCPUCount /
// DefaultMemoryMiB / DefaultWorkDiskSize so output is still sane.
var buf bytes.Buffer
printVMSpecLine(&buf, api.VMCreateParams{})
got := buf.String()
// Not asserting exact values — just that it produced a plausible
// line with the three labels.
for _, want := range []string{"spec:", "vcpu", "MiB", "disk"} {
if !strings.Contains(got, want) {
t.Errorf("output missing %q:\n%s", want, got)
}
}
}
func TestPrintVMSpecLineIgnoresUnparseableDiskSize(t *testing.T) {
// Falls back to builtin default; must not panic or print garbage.
var buf bytes.Buffer
printVMSpecLine(&buf, api.VMCreateParams{WorkDiskSize: "not-a-size"})
if !strings.Contains(buf.String(), "spec:") {
t.Errorf("expected spec line even with bad input, got %q", buf.String())
}
}