# class Unicorn::Worker

This class and its members can be considered a stable interface and will not change in a backwards-incompatible fashion between releases of unicorn. Knowledge of this class is generally not not needed for most users of unicorn.

Some users may want to access it in the before_fork/after_fork hooks. See the `Unicorn::Configurator` RDoc for examples.

### Public Instance Methods

user(user, group = nil, chroot = false) click to toggle source

In most cases, you should be using the `Unicorn::Configurator#user` directive instead. This method should only be used if you need fine-grained control of exactly when you want to change permissions in your after_fork or after_worker_ready hooks, or if you want to use the chroot support.

Changes the worker process to the specified `user` and `group`, and chroots to the current working directory if `chroot` is set. This is only intended to be called from within the worker process from the `after_fork` hook. This should be called in the `after_fork` hook after any privileged functions need to be run (e.g. to set per-worker CPU affinity, niceness, etc)

`group` can be specified as a string, or as an array of two strings. If an array of two strings is given, the first string is used as the primary group of the process, and the second is used as the group of the log files.

Any and all errors raised within this method will be propagated directly back to the caller (usually the `after_fork` hook. These errors commonly include ArgumentError for specifying an invalid user/group and Errno::EPERM for insufficient privileges.

chroot support is only available in unicorn 5.3.0+ user and group switching appeared in unicorn 0.94.0 (2009-11-05)

    # File lib/unicorn/worker.rb, line 136
    def user(user, group = nil, chroot = false)
      # we do not protect the caller, checking Process.euid == 0 is
      # insufficient because modern systems have fine-grained
      # capabilities.  Let the caller handle any and all errors.
      uid = Etc.getpwnam(user).uid

      if group
        if group.is_a?(Array)
          group, log_group = group
          log_gid = Etc.getgrnam(log_group).gid
        end
        gid = Etc.getgrnam(group).gid
        log_gid ||= gid
      end

      Unicorn::Util.chown_logs(uid, log_gid)
      if gid && Process.egid != gid
        Process.initgroups(user, gid)
        Process::GID.change_privilege(gid)
      end
      if chroot
        chroot = Dir.pwd if chroot == true
        Dir.chroot(chroot)
        Dir.chdir('/')
      end
      Process.euid != uid and Process::UID.change_privilege(uid)
      @switched = true
    end