Currently, nomad "plugin" processes (e.g. executor, logmon, docker_logger) are started as CLI
commands to be handled by command CLI framework. Plugin launchers use
`discover.NomadBinary()` to identify the binary and start it.
This has few downsides: The trivial one is that when running tests, one
must re-compile the nomad binary as the tests need to invoke the nomad
executable to start plugin. This is frequently overlooked, resulting in
puzzlement.
The more significant issue with `executor` in particular is in relation
to external driver:
* Plugin must identify the path of invoking nomad binary, which is not
trivial; `discvoer.NomadBinary()` now returns the path to the plugin
rather than to nomad, preventing external drivers from launching
executors.
* The external driver may get a different version of executor than it
expects (specially if we make a binary incompatible change in future).
This commit addresses both downside by having the plugin invocation
handling through an `init()` call, similar to how libcontainer init
handler is done in [1] and recommened by libcontainer [2]. `init()`
will be invoked and handled properly in tests and external drivers.
For external drivers, this change will cause external drivers to launch
the executor that's compiled against.
There a are a couple of downsides to this approach:
* These specific packages (i.e executor, logmon, and dockerlog) need to
be careful in use of `init()`, package initializers. Must avoid having
command execution rely on any other init in the package. I prefixed
files with `z_` (golang processes files in lexical order), but ensured
we don't depend on order.
* The command handling is spread in multiple packages making it a bit
less obvious how plugin starts are handled.
[1] drivers/shared/executor/libcontainer_nsenter_linux.go
[2] eb4aeed24f/libcontainer (using-libcontainer)
It is possible to provide multiple identically named services with
different port assignments in a Nomad configuration.
We introduced a regression when migrating to stable service identifiers where
multiple services with the same name would conflict, and the last definition
would take precedence.
This commit includes the port label in the stable service identifier to
allow the previous behaviour where this was supported, for example
providing:
```hcl
service {
name = "redis-cache"
tags = ["global", "cache"]
port = "db"
check {
name = "alive"
type = "tcp"
interval = "10s"
timeout = "2s"
}
}
service {
name = "redis-cache"
tags = ["global", "foo"]
port = "foo"
check {
name = "alive"
type = "tcp"
port = "db"
interval = "10s"
timeout = "2s"
}
}
service {
name = "redis-cache"
tags = ["global", "bar"]
port = "bar"
check {
name = "alive"
type = "tcp"
port = "db"
interval = "10s"
timeout = "2s"
}
}
```
in a nomad task definition is now completely valid. Each service
definition with the same name must still have a unique port label however.
We currently only run cleanup Service Hooks when a task is either
Killed, or Exited. However, due to the implementation of a task runner,
tasks are only Exited if they every correctly started running, which is
not true when you recieve an error early in the task start flow, such as
not being able to pull secrets from Vault.
This updates the service hook to also call consul deregistration
routines during a task Stop lifecycle event, to ensure that any
registered checks and services are cleared in such cases.
fixes#5770
Currently when you submit a manual request to the alloc lifecycle API
with a version of Curl that will submit empty bodies, the alloc restart
api will fail with an EOF error.
This behaviour is undesired, as it is reasonable to not submit a body at
all when restarting an entire allocation rather than an individual task.
This fixes it by ignoring EOF (not unexpected EOF) errors and treating
them as entire task restarts.
When a client is running against an old server (e.g. running 0.8),
`alloc.AllocatedResources` may be nil, and we need to check the
deprecated `alloc.TaskResources` instead.
Fixes https://github.com/hashicorp/nomad/issues/5810
