Noticed that ACL endpoints return 500 status code for user errors. This
is confusing and can lead to false monitoring alerts.
Here, I introduce a concept of RPCCoded errors to be returned by RPC
that signal a code in addition to error message. Codes for now match
HTTP codes to ease reasoning.
```
$ nomad acl bootstrap
Error bootstrapping: Unexpected response code: 500 (ACL bootstrap already done (reset index: 9))
$ nomad acl bootstrap
Error bootstrapping: Unexpected response code: 400 (ACL bootstrap already done (reset index: 9))
```
* client: improve group service stanza interpolation and check_restart support
Interpolation can now be done on group service stanzas. Note that some task runtime specific information
that was previously available when the service was registered poststart of a task is no longer available.
The check_restart stanza for checks defined on group services will now properly restart the allocation upon
check failures if configured.
handle the case where we request a server-id which is this current server
update docs, error on node and server id params
more accurate names for tests
use shared no leader err, formatting
rm bad comment
remove redundant variable
When inferring whether to use TTY, check both stdin and stdout are
terminals.
Otherwise, we get failures like the following:
```
$ nomad alloc exec --job example echo hi
hi
$ echo | nomad alloc exec --job example echo hi
hi
$ nomad alloc exec --job example echo hi | head -n1
failed to exec into task: not a terminal
```
This is the basic code to add the Windows Service Manager hooks to Nomad.
Includes vendoring golang.org/x/sys/windows/svc and added Docs:
* guide for installing as a windows service.
* configuration for logging to file from PR #6429
Nomad web UI currently fails when querying client nodes for allocation
state end endpoints, due to CORS policy.
The issue is that CORS requests that are marked `withCredentials` need
the http server to include a `Access-Control-Allow-Credentials` [1].
But Nomad Task Logs and filesystem requests include authenticating
information and thus marked with `credentials=true`[2][3].
It's worth noting that the browser currently sends credentials and
authentication token to servers anyway; it's just that the response is
not made available to caller nomad ui javascript. For task logs
specifically, nomad ui retries again by querying the web ui address
(typically pointing to a nomad server) which will forward the request
to the nomad client agent appropriately.
[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials
[2] 101d0373ee/ui/app/components/task-log.js (L50)
[3] 101d0373ee/ui/app/services/token.js (L25-L39)
Addresses feedback around monitor implementation
subselect on stopCh to prevent blocking forever.
Set up a separate goroutine to check every 3 seconds for dropped
messages.
rename returned ch to avoid confusion
