nomad-driver-nix2/nix2/nix.go

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package nix2
import (
"bytes"
"encoding/json"
"fmt"
"os"
"os/exec"
"path/filepath"
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"github.com/hashicorp/nomad/helper/pluginutils/hclutils"
)
const (
closureNix = `
{ path }:
let
nixpkgs = builtins.getFlake "%s";
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inherit (nixpkgs.legacyPackages.x86_64-linux) buildPackages;
in buildPackages.closureInfo { rootPaths = builtins.storePath path; }
`
)
func prepareNixPackages(taskDir string, packages []string, nixpkgs string) (hclutils.MapStrStr, error) {
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mounts := make(hclutils.MapStrStr)
profileLink := filepath.Join(taskDir, "current-profile")
profile, err := nixBuildProfile(packages, profileLink)
if err != nil {
return nil, fmt.Errorf("Build of the flakes failed: %v", err)
}
closureLink := filepath.Join(taskDir, "current-closure")
closure, err := nixBuildClosure(profileLink, closureLink, nixpkgs)
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if err != nil {
return nil, fmt.Errorf("Build of the flakes failed: %v", err)
}
mounts[profile] = profile
if entries, err := os.ReadDir(profile); err != nil {
return nil, fmt.Errorf("Couldn't read profile directory: %w", err)
} else {
for _, entry := range entries {
if name := entry.Name(); name != "etc" {
mounts[filepath.Join(profile, name)] = "/" + name
continue
}
etcEntries, err := os.ReadDir(filepath.Join(profile, "etc"))
if err != nil {
return nil, fmt.Errorf("Couldn't read profile's /etc directory: %w", err)
}
for _, etcEntry := range etcEntries {
etcName := etcEntry.Name()
mounts[filepath.Join(profile, "etc", etcName)] = "/etc/" + etcName
}
}
}
requisites, err := nixRequisites(closure)
if err != nil {
return nil, fmt.Errorf("Couldn't determine flake requisites: %v", err)
}
for _, requisite := range requisites {
mounts[requisite] = requisite
}
return mounts, nil
}
func nixBuildProfile(flakes []string, link string) (string, error) {
cmd := exec.Command("nix", append(
[]string{
"--extra-experimental-features", "nix-command",
"--extra-experimental-features", "flakes",
"profile",
"install",
"--no-write-lock-file",
"--profile",
link},
flakes...)...)
stderr := &bytes.Buffer{}
cmd.Stderr = stderr
if err := cmd.Run(); err != nil {
return "", fmt.Errorf("%v failed: %s. Err: %v", cmd.Args, stderr.String(), err)
}
if target, err := os.Readlink(link); err == nil {
return os.Readlink(filepath.Join(filepath.Dir(link), target))
} else {
return "", err
}
}
func nixBuildClosure(profile string, link string, nixpkgs string) (string, error) {
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cmd := exec.Command(
"nix",
"--extra-experimental-features", "nix-command",
"--extra-experimental-features", "flakes",
"build",
"--out-link", link,
"--expr", fmt.Sprintf(closureNix, nixpkgs),
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"--impure",
"--no-write-lock-file",
"--argstr", "path", profile)
stderr := &bytes.Buffer{}
cmd.Stderr = stderr
if err := cmd.Run(); err != nil {
return "", fmt.Errorf("%v failed: %s. Err: %v", cmd.Args, stderr.String(), err)
}
return os.Readlink(link)
}
type nixPathInfo struct {
Path string `json:"path"`
NarHash string `json:"narHash"`
NarSize uint64 `json:"narSize"`
References []string `json:"references"`
Deriver string `json:"deriver"`
RegistrationTime uint64 `json:"registrationTime"`
Signatures []string `json:"signatures"`
}
func nixRequisites(path string) ([]string, error) {
cmd := exec.Command(
"nix",
"--extra-experimental-features", "nix-command",
"--extra-experimental-features", "flakes",
"path-info",
"--json",
"--recursive",
path)
stdout := &bytes.Buffer{}
cmd.Stdout = stdout
stderr := &bytes.Buffer{}
cmd.Stderr = stderr
if err := cmd.Run(); err != nil {
return nil, fmt.Errorf("%v failed: %s. Err: %v", cmd.Args, stderr.String(), err)
}
result := []*nixPathInfo{}
if err := json.Unmarshal(stdout.Bytes(), &result); err != nil {
return nil, err
}
requisites := []string{}
for _, result := range result {
requisites = append(requisites, result.Path)
}
return requisites, nil
}