* client/executor: refactor client to remove interpolation
* executor: POC libcontainer based executor
* vendor: use hashicorp libcontainer fork
* vendor: add libcontainer/nsenter dep
* executor: updated executor interface to simplify operations
* executor: implement logging pipe
* logmon: new logmon plugin to manage task logs
* driver/executor: use logmon for log management
* executor: fix tests and windows build
* executor: fix logging key names
* executor: fix test failures
* executor: add config field to toggle between using libcontainer and standard executors
* logmon: use discover utility to discover nomad executable
* executor: only call libcontainer-shim on main in linux
* logmon: use seperate path configs for stdout/stderr fifos
* executor: windows fixes
* executor: created reusable pid stats collection utility that can be used in an executor
* executor: update fifo.Open calls
* executor: fix build
* remove executor from docker driver
* executor: Shutdown func to kill and cleanup executor and its children
* executor: move linux specific universal executor funcs to seperate file
* move logmon initialization to a task runner hook
* client: doc fixes and renaming from code review
* taskrunner: use shared config struct for logmon fifo fields
* taskrunner: logmon only needs to be started once per task
`/usr/bin/yes` could produce output very quickly (100s of MBps on my
laptop) and therefore could cause log files to roll over.
A bash loop with a sleep avoids that issue. The test is slower but
should be much more resilient to the massive timing differences between
workstations and Travis.
- Properly expects the hard-coded mounts (alloc, dev, and proc) and hardcoded local directories (local and tmp)
- Also verifies that etc contains only the requested paths
- Simplify map length check in Linux Executor
- Added a `chroot_env` test for config parser
- Moved `ChrootEnv` field from ExecutorCommand to ExecutorContext
- Added a test for `chroot_env` functionality
