In Nomad prior to Consul Connect, all Consul checks work the same
except for Script checks. Because the Task being checked is running in
its own container namespaces, the check is executed by Nomad in the
Task's context. If the Script check passes, Nomad uses the TTL check
feature of Consul to update the check status. This means in order to
run a Script check, we need to know what Task to execute it in.
To support Consul Connect, we need Group Services, and these need to
be registered in Consul along with their checks. We could push the
Service down into the Task, but this doesn't work if someone wants to
associate a service with a task's ports, but do script checks in
another task in the allocation.
Because Nomad is handling the Script check and not Consul anyways,
this moves the script check handling into the task runner so that the
task runner can own the script check's configuration and
lifecycle. This will allow us to pass the group service check
configuration down into a task without associating the service itself
with the task.
When tasks are checked for script checks, we walk back through their
task group to see if there are script checks associated with the
task. If so, we'll spin off script check tasklets for them. The
group-level service and any restart behaviors it needs are entirely
encapsulated within the group service hook.
Consul registers Connect services automatically, however Nomad thinks it
owns them due to the _nomad prefix. Since the services are managed by
Consul, Nomad needs to explicitly ignore them or otherwies they will be
removed.
* adds meta object to service in job spec, sends it to consul
* adds tests for service meta
* fix tests
* adds docs
* better hashing for service meta, use helper for copying meta when registering service
* tried to be DRY, but looks like it would be more work to use the
helper function
Fixes#6041
Unlike all other Consul operations, boostrapping requires Consul be
available. This PR tries Consul 3 times with a backoff to account for
the group services being asynchronously registered with Consul.
When a nomad client restarts/upgraded, nomad restores state from running
task and starts the sync loop. If sync loop runs early, it may
deregister services from Consul prematurely even when Consul has the
running service as healthy.
This is not ideal, as re-registering the service means potentially
waiting a whole service health check interval before declaring the
service healthy.
We attempt to mitigate this by introducing an initialization probation
period. During this time, we only deregister services and checks that
were explicitly deregistered, and leave unrecognized ones alone. This
serves as a grace period for restoring to complete, or for operators to
restore should they recognize they restored with the wrong nomad data
directory.
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.
This commit causes sync to skip deregistering checks that are not
managed by nomad, such as service maintenance mode checks. This is
handled in the same way as service registrations - by doing a Nomad
specific prefix match.
The current implementation of Service Registration uses a hash of the
nomad-internal state of a service to register it with Consul, this means that
any update to the service invalidates this name and we then deregister, and
recreate the service in Consul.
While this behaviour slightly simplifies reasoning about service registration,
this becomes problematic when we add consul health checks to a service. When
the service is re-registered, so are the checks, which default to failing for
at least one check period.
This commit migrates us to using a stable identifier based on the
allocation, task, and service identifiers, and uses the difference
between the remote and local state to decide when to push updates.
It uses the existing hashing mechanic to decide when UpdateTask should
regenerate service registrations for providing to Sync, but this should
be removable as part of a future refactor.
It additionally introduces the _nomad-check- prefix for check
definitions, to allow for future allowing of consul features like
maintenance mode.
This commit fixes an issue where if a nomad client and server shared the same consul instance, the server would deregister any services and checks registered by clients for running tasks.
Also refactor Consul ServiceClient to take a struct instead of a massive
set of arguments. Meant updating a lot of code but it should be far
easier to extend in the future as you will only need to update a single
struct instead of every single call site.
Adds an e2e test for canary tags.
Periodically sync services and checks from Nomad to Consul. This is
mostly useful when testing with the Consul dev agent which does not
persist state across restarts. However, this is a reasonable safety
measure to prevent skew between Consul's state and Nomad's
services+checks.
Also modernized the test suite a bit.
Instead of checking Consul's version on startup to see if it supports
TLSSkipVerify, assume that it does and only log in the job service
handler if we discover Consul does not support TLSSkipVerify.
The old code would break TLSSkipVerify support if Nomad started before
Consul (such as on system boot) as TLSSkipVerify would default to false
if Consul wasn't running. Since TLSSkipVerify has been supported since
Consul 0.7.2, it's safe to relax our handling.
Related to #3681
If a user specifies an invalid port *label* when using
address_mode=driver they'll get an error message about the label being
an invalid number which is very confusing.
I also added a bunch of testing around Service.AddressMode validation
since I was concerned by the linked issue that there were cases I was
missing. Unfortunately when address_mode=driver is used there's only so
much validation that can be done as structs/structs.go validation never
peeks into the driver config which would be needed to verify the port
labels/map.
Fixes#3681
When in drive address mode Nomad should always advertise the driver's IP
in Consul even when no network exists. This matches the 0.6 behavior.
When in host address mode Nomad advertises the alloc's network's IP if
one exists. Otherwise it lets Consul determine the IP.
I also added some much needed logging around Docker's network discovery.
The allocID and taskName parameters are useless for agents, but it's
still nice to reuse the same hash method for agent and task services.
This brings in the lowercase mode for the agent hash as well.
Fixes#3620
Previously we concatenated tags into task service IDs. This could break
deregistration of tag names that contained double //s like some Fabio
tags.
This change breaks service ID backward compatibility so on upgrade all
users services and checks will be removed and re-added with new IDs.
This change has the side effect of including all service fields in the
ID's hash, so we no longer have to track PortLabel and AddressMode
changes independently.
Also skip getting an address for script checks which don't use them.
Fixed a weird invalid reserved port in a TaskRunner test helper as well
as a problem with our mock Alloc/Job. Hopefully the latter doesn't cause
other tests to fail, but we were referencing an invalid PortLabel and
just not catching it before.
Fixes#3380
Adds address_mode to checks (but no auto) and allows services and checks
to set literal port numbers when using address_mode=driver.
This allows SDNs, overlays, etc to advertise internal and host addresses
as well as do checks against either.
Fixes an issue in which the allocation health watcher was checking for
allocations health based on un-interpolated services and checks. Change
the interface for retrieving check information from Consul to retrieving
all registered services and checks by allocation. In the future this
will allow us to output nicer messages.
Fixes https://github.com/hashicorp/nomad/issues/2969
From https://golang.org/pkg/sync/atomic/#pkg-note-BUG :
On both ARM and x86-32, it is the caller's responsibility to arrange for
64-bit alignment of 64-bit words accessed atomically. The first word in
a global variable or in an allocated struct or slice can be relied upon
to be 64-bit aligned.
