每当我在我的VPS（CentOS Linux版本7.0.1406（核心））上运行bundle install时，我在安装pg gem时都会收到一个错误。

No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header

***extconf.rb failed***

Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

我可以安装pg单机版：gem install pg -- --with-pg-config=/usr/pgsql-9.4/bin/pg_config，问题已解决。
所以我添加了一个capistrano任务来为部署创建一个./bundle/config，并在我的VPS上设置了build.pg键和pg_config的路径。

desc "Create bundle config"
task :prepare_bundle_config do
  on roles(:app) do
    within release_path do
      execute :bundle, 'config build.pg --with-pg-config=/usr/pgsql-9.4/bin/pg_config --local'
    end
  end
end

我已经安装了必要的软件包：

postgresql94-server.x86_64
postgresql94-devel.x86_64
postgresql94-libs.x86_64
libpqxx.x86_64
libpqxx-devel.x86_64

以下是我安装的capistrano* gems

bundle list | grep capistrano

* capistrano (3.3.5)
* capistrano-bundler (1.1.4)
* capistrano-rails (1.1.2)
* capistrano-rbenv (2.0.3)
* capistrano-stats (1.1.1)

我在这里错过了什么，以成功地安装pg与bundler？请留下评论，如果你需要任何额外的信息，我会更新这篇文章。