jenkinsPlugins2nix

jenkinsPlugins2nix: PLUGIN_NAME{:PLUGIN_VERSION} [PLUGIN_NAME{:PLUGIN_VERSION} ...]

Along with recent nixpkgs, you can then do the following.

jenkinsPlugins2nix github-api > plugins.nix

and in your configuration.nix:

services.jenkins.plugins = pkgs.callPackage plugins.nix {};