using omnibus build tool to package a full app - ruby

Question

So I am tasked with packaging a Ruby application. The idea is to eliminate the need to apt-get any packages or gem install anything. the package is all-inclusive.
I've gotten as far as finding Omnibus (there is also fmp-cookery but it doesnt seem to be as well known)
I've figured out the general structure of omnibus projects but now getting problems with specifics:
1) I have a bunch of recipies that run with Chef AT INSTALL TIME. These setup the DB and nginx configs. Whats the best way to run through these on target machine?
2) I added a bundle install line in my build scripts, but this now dubplicates my requirements. For example nokogiri gets installed twice. Once as my actual project Gem and another time as another requirement of omnibus. So then I end up with 2 binaries one in /#{instal_dir}/embedded/bin and one in ${install_dir}/embedded/lib/ruby/.../gems any way to prevent this?

Answer 1

Building an installer is bit more involved than creating a chef cookbook.
User needs to write a DSL for each module (this has instructions on gathering the artifacts and installing it on specific OS).
After creating the omnibus project, refer to the README file to get started with basics.
Refer to this github project for details on how to build your own DSLs. Gitlab omnibus project has DSLs for some modules like postgresql etc.
https://gitlab.com/gitlab-org/omnibus-gitlab/tree/master
Example DSL for embedding nginx module in your installer looks like this:
name "nginx"
default_version "1.9.10"
dependency "pcre"
dependency "openssl"
source url: "http://nginx.org/download/nginx-#{version}.tar.gz",
md5: "64cc970988356a5e0fc4fcd1ab84fe57"
relative_path "nginx-#{version}"
build do
command ["./configure",
"--prefix=#{install_dir}/embedded",
"--with-http_ssl_module",
"--with-http_stub_status_module",
"--with-http_gzip_static_module",
"--with-http_v2_module",
"--with-ipv6",
"--with-debug",
"--with-ld-opt=-L#{install_dir}/embedded/lib",
"--with-cc-opt=\"-L#{install_dir}/embedded/lib -I#{install_dir}/embedded/include\""].join(" ")
command "make -j #{workers}", :env => {"LD_RUN_PATH" => "#{install_dir}/embedded/lib"}
command "make install"
end