func main() {

    client := github.NewClient(nil)

    opt := &github.RepositoryListByOrgOptions{Type: "public"}
    // get our public repositories list to the repos variable
    repos, _, _ := client.Repositories.ListByOrg(context.Background(), os.Getenv("GITHUB_ORG_NAME"), opt)

    // the list of repositories that are expected to be public
    allowedRepos := strings.Fields(os.Getenv("ALLOWED_REPOS"))

    for _, repo := range repos {
        fmt.Printf("nChecking %sn", *repo.Name)
        if isAllowedRepo(*repo.Name, allowedRepos) {
            fmt.Printf("OK: repo %s found in Allowedn", *repo.Name)
        } else {
            fmt.Printf("ALARM: repo %s was NOT found in Allowed!n", *repo.Name)
            sendSlackAlarm(*repo.Name, *repo.HTMLURL)
        }
    }
}

func isAllowedRepo(repoName string, allowedRepos []string) bool {

    // and just iterate the repoName over the allowedRepos list
    for _, i := range allowedRepos {
        if i == repoName {
            return true
        }
    }

    return false
}