I could not find a correct answer for this at the time, and I don't want to ask for the scope "repo" since it's too overkill for my application, it asks for code read/write permssions. Here's what worked for me (I'm using Ruby along with the octokit gem (https://github.com/octokit/octokit.rb)), special thanks to Ivan from the github dev support:
1.- During Oauth, ask for the "read:org" scope and get the Oauth 2 token from Github
2.- initialize octokit's client:
client = Octokit::Client.new(access_token: my_oauth2_token)
3.- Retrieve the user's organizations, we can do it because of the "read:org" scope
organizations = client.organizations
4.- For each organization, retrieve a Github admin Team to which this user belongs. And then, use this Team to retrieve the repos available
organizations.each do |organization|
admin_team = client.organization_teams(organization[:id]).select { |repo| repo[:permission] == 'admin' }.first
org_repos << client.team_repositories(admin_team[:id])
end
Yes, you will definitely need more requests to gather all the available repos, but as I said before, In my case, I did not want to ask for the "user" scope.
Note: Yes, the user have to be a member of an "admin" Team within a given Organization to be able to see the private repos.
