Torjus Håkestad
14f5b31faf
Add a new "builder" capability to trigger Nix builds on a dedicated build host via NATS messaging. This allows pre-building NixOS configurations before deployment. New components: - Builder mode: subscribes to build.<repo>.* subjects, executes nix build - Build CLI command: triggers builds with progress tracking - MCP build tool: available with --enable-builds flag - Builder metrics: tracks build success/failure per repo and host - NixOS module: services.homelab-deploy.builder The builder uses a YAML config file to define allowed repositories with their URLs and default branches. Builds can target all hosts or specific hosts, with real-time progress updates. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
117 lines
3.0 KiB
Go
117 lines
3.0 KiB
Go
package builder
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"os/exec"
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"time"
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)
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// Executor handles the execution of nix build commands.
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type Executor struct {
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timeout time.Duration
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}
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// NewExecutor creates a new build executor.
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func NewExecutor(timeout time.Duration) *Executor {
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return &Executor{
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timeout: timeout,
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}
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}
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// BuildResult contains the result of a build execution.
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type BuildResult struct {
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Success bool
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ExitCode int
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Stdout string
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Stderr string
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Error error
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}
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// FlakeShowResult contains the parsed output of nix flake show.
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type FlakeShowResult struct {
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NixosConfigurations map[string]any `json:"nixosConfigurations"`
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}
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// ListHosts returns the list of hosts (nixosConfigurations) available in a flake.
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func (e *Executor) ListHosts(ctx context.Context, flakeURL, branch string) ([]string, error) {
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ctx, cancel := context.WithTimeout(ctx, 60*time.Second)
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defer cancel()
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flakeRef := fmt.Sprintf("%s?ref=%s", flakeURL, branch)
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cmd := exec.CommandContext(ctx, "nix", "flake", "show", "--json", flakeRef)
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var stdout, stderr bytes.Buffer
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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if err := cmd.Run(); err != nil {
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if ctx.Err() == context.DeadlineExceeded {
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return nil, fmt.Errorf("timeout listing hosts")
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}
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return nil, fmt.Errorf("failed to list hosts: %w\n%s", err, stderr.String())
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}
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var result FlakeShowResult
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if err := json.Unmarshal(stdout.Bytes(), &result); err != nil {
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return nil, fmt.Errorf("failed to parse flake show output: %w", err)
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}
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hosts := make([]string, 0, len(result.NixosConfigurations))
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for host := range result.NixosConfigurations {
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hosts = append(hosts, host)
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}
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return hosts, nil
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}
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// Build builds a single host's system configuration.
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func (e *Executor) Build(ctx context.Context, flakeURL, branch, host string) *BuildResult {
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ctx, cancel := context.WithTimeout(ctx, e.timeout)
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defer cancel()
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// Build the flake reference for the system toplevel
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flakeRef := fmt.Sprintf("%s?ref=%s#nixosConfigurations.%s.config.system.build.toplevel", flakeURL, branch, host)
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cmd := exec.CommandContext(ctx, "nix", "build", "--no-link", flakeRef)
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var stdout, stderr bytes.Buffer
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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err := cmd.Run()
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result := &BuildResult{
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Stdout: stdout.String(),
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Stderr: stderr.String(),
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}
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if err != nil {
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result.Success = false
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result.Error = err
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if ctx.Err() == context.DeadlineExceeded {
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result.Error = fmt.Errorf("build timed out after %v", e.timeout)
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}
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if exitErr, ok := err.(*exec.ExitError); ok {
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result.ExitCode = exitErr.ExitCode()
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} else {
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result.ExitCode = -1
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}
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} else {
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result.Success = true
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result.ExitCode = 0
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}
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return result
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}
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// BuildCommand returns the command that would be executed (for logging/debugging).
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func (e *Executor) BuildCommand(flakeURL, branch, host string) string {
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flakeRef := fmt.Sprintf("%s?ref=%s#nixosConfigurations.%s.config.system.build.toplevel", flakeURL, branch, host)
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return fmt.Sprintf("nix build --no-link %s", flakeRef)
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}
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