升级到Capistrano 3部署Github错误

Question

我正在从第2章更新到第3章，尝试部署时遇到了问题。去年我一直在使用Cap 2，而在尝试运行“ cap production deploy”时，出现以下错误：

DEBUG [59193620] Command: ( export GIT_ASKPASS="/bin/echo" GIT_SSH="/tmp/git-ssh-project-production-username.sh" ; /usr/bin/env git ls-remote git@github.com:githubaccount/project.git HEAD )


DEBUG [59193620] ssh: Could not resolve hostname github.com: Name or service not known


DEBUG [59193620] fatal: Could not read from remote repository.


Please make sure you have the correct access rights


and the repository exists.

我进入了所有可以想象的位置，并添加了ssh-key，但这并不能使我克服此错误。谁能告诉我什么时候出问题了？