How to input heroku credentials in Travis Ruby on Rails - ruby

Question

Am working Ruby on Rails site, and I have implemented Travis CI with it and pushed to to GitHub, so as to Test my build before pushing to Heroku.
When Travis parsed my github source code, I get an error asking me to input my Heroku Credentials before Travis can push to Heroku.
What I want to do
How do I pass in my heroku credentials to Travis as requested without the >risk of putting it on version control?
Here is the Build on Travis: https://travis-ci.org/AfolabiOlaoluwa/LawVille/jobs/166099588
.travis.yml
language: ruby
rvm:
- 2.2.4
env:
global:
- secure: {{ I have my travis encrypted key here }}
- secure: {{ I another travis encrypted key here }}
- DB=sqlite
- DB=mysql
- DB=postgresql
- secure: {{ I have another travis encrypted key here }}
deploy:
provider: heroku
api_key:
secure: {{ I have HEROKU API KEY encrypted by travis here }}
script:
- RAILS_ENV=test bundle exec rake db:migrate --trace
- bundle exec rake db:test:prepare
before_script:
- mysql -e 'create database strano_test'
- psql -c 'create database strano_test' -U postgres
after_success:
- gem install heroku
- yes | ruby ./config/initializers/travis_deployer.rb
- git remote add heroku git#heroku.com:lawville.git
- heroku keys:clear
- yes | heroku keys:add
- git push heroku master

Answer 1

The answer from #andresk above is very useful, but encrypting the api-key only didnt work for me as you could see from our comments/correspondence.
What worked for me was, running setup heroku --org --force from the root of my app inside terminal and I followed the prompt to get my Travis file having the correct deploy script.
Note: the --force command is to force script written on the already existing .travis.yml file.
After responding to the prompts, my deploy script became:
deploy:
provider: heroku
api_key:
secure: encrypted_key_was_written_here
app: lawville # being app name on heroku which am deploying to.
on:
repo: AfolabiOlaoluwa/LawVille # GitHub Repo
That's what worked for me.

Answer 2

You don't need to manually push to heroku on after_success. Just having the deploy with your encrypted credentials is enough to automatically deploy after the build. So try removing the after_success commands and everything should work.
For more information, check here
If you need to store your credentials to be used on Travis, you can add secure environment to Travis. Go to More options > Settings there you can add the credentials as environment variables. Just make sure Display value in build log is set as off