Nomad runs one logmon process and also one docker_logger process for each
running allocation. A naive look at memory usage shows 10-30 MB of RSS, but a
closer look shows that most of this memory (ex. all but ~2MB for logmon) is
shared (`Shared_Clean` in Linux pmap).
But a heap dump of docker_logger shows that it currently has an extra ~2500 KiB
of heap (anonymously-mapped unshared memory) used for init blocks coming from
the agent code (ex. mostly regexes from go-version, structs, and the Consul
SDK). The packages for running logmon, docker_logger, and executor have an init
block that parses `os.Args` to drop into their own logic, which prevents them
from loading all the rest of the agent code and saves on memory, so this was
unexpected.
It looks like we accidentally reordered the imports in main to undo some of the
work originally done in 404d2d4c98f1df930be1ae9852fe6e6ae8c1517e. This changeset
restores the ordering. A follow-up heap dump shows this saves ~2MB of unshared
RSS per docker_logger process.
This PR adds support for the raw_exec driver on systems with only cgroups v2.
The raw exec driver is able to use cgroups to manage processes. This happens
only on Linux, when exec_driver is enabled, and the no_cgroups option is not
set. The driver uses the freezer controller to freeze processes of a task,
issue a sigkill, then unfreeze. Previously the implementation assumed cgroups
v1, and now it also supports cgroups v2.
There is a bit of refactoring in this PR, but the fundamental design remains
the same.
Closes#12351#12348
This commit uses the go-colorable library to enable support for coloured
UI output on Windows. This acts as a compatibility layer that takes
standard unix-y terminal codes and translates them into the requisite
windows calls as required.
* 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
