I had this with a sinatra application. (Heroku does support Sinatra).
The instructions on the heroku blog post were incomplete
https://blog.heroku.com/32_deploy_merb_sinatra_or_any_rack_app_to_heroku
My program ran fine locally but I got that error when trying to push to heroku.
The heroku blogpost didn't include the need to make a gemfile and do bundle install. The program was running locally fine, but to make it work on heroku it needed a Gemfile and bundle install on it.
this link here https://teamtreehouse.com/community/how-can-i-make-my-sinatra-app-public mentioned that I needed a Gemfile, and mentioned the contents of the Gemfile. And then to do bundle install. Then once that is done, then follow the instructions on that heroku blog post, of making the program file, and the config.ru and the git repo and doing heroku create (which also creates the remote), then git push heroku master.
i.e.
Gemfile as mentioned at treehouse link
# define our source to look for gems
source "http://rubygems.org/"
# declare the sinatra dependency
gem "sinatra"
And bundle install to install that Gemfile.
bundle install
hello.rb (as mentioned on heroku blogpost)
require 'rubygems'
require 'sinatra'
get '/' do
"Hello from Sinatra on Heroku!"
end
config.ru
require './hello'
run Sinatra::Application
git
$ git init
Initialized empty Git repository in /Users/adam/hello/.git/
$ git add .
$ git commit -m "sinatra and heroku, two great tastes"
[master (root-commit)]: created 93a9e6d: "sinatra and heroku, two great tastes"
2 files changed, 9 insertions(+), 0 deletions(-)
create mode 100644 config.ru
create mode 100644 hello.rb
heroku create
$ heroku create
Created http://severe-spring-77.heroku.com/ | git@heroku.com:severe-spring-77.git
Git remote heroku added
the push to heroku
$ git push heroku master
Counting objects: 4, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (4/4), 385 bytes, done.
Total 4 (delta 0), reused 0 (delta 0)
-----> Heroku receiving push
-----> Verifying repository integrity... done, looks like a Rack app.
Compiled slug size is 0.1MB
-----> Launching....... done
App deployed to Heroku
To git@heroku.com:severe-spring-77.git
* [new branch] master -> master