feat: Add configuration option for popularity data URL

tools/nixery/server/builder/builder.go

@@ -134,6 +134,10 @@ func BuildImage(ctx *context.Context, cfg *config.Config, cache *LocalCache, ima
 			"--argstr", "srcArgs", srcArgs,
 		}
 
+		if cfg.PopUrl != "" {
+			args = append(args, "--argstr", "popularityUrl", cfg.PopUrl)
+		}
+
 		cmd := exec.Command("nixery-build-image", args...)
 
 		outpipe, err := cmd.StdoutPipe()

tools/nixery/server/config/config.go

@@ -68,6 +68,7 @@ type Config struct {
 	Pkgs    PkgSource                 // Source for Nix package set
 	Timeout string                    // Timeout for a single Nix builder (seconds)
 	WebDir  string                    // Directory with static web assets
+	PopUrl  string                    // URL to the Nix package popularity count
 }
 
 func FromEnv() (*Config, error) {
@@ -83,5 +84,6 @@ func FromEnv() (*Config, error) {
 		Signing: signingOptsFromEnv(),
 		Timeout: getConfig("NIX_TIMEOUT", "Nix builder timeout", "60"),
 		WebDir:  getConfig("WEB_DIR", "Static web file dir", ""),
+		PopUrl:  os.Getenv("NIX_POPULARITY_URL"),
 	}, nil
 }