Previously, Nomad used hand rolled HTTP requests to interact with the
EC2 metadata API. Recently however, we switched to using the AWS SDK for
this fingerprinting.
The default behaviour of the AWS SDK is to perform retries with
exponential backoff when a request fails. This is problematic for Nomad,
because interacting with the EC2 API is in our client start path.
Here we revert to our pre-existing behaviour of not performing retries
in the fast path, as if the metadata service is unavailable, it's likely
that nomad is not running in AWS.
Copy the updated version of freeport (sdk/freeport), and tweak it for use
in Nomad tests. This means staying below port 10000 to avoid conflicts with
the lib/freeport that is still transitively used by the old version of
consul that we vendor. Also provide implementations to find ephemeral ports
of macOS and Windows environments.
Ports acquired through freeport are supposed to be returned to freeport,
which this change now also introduces. Many tests are modified to include
calls to a cleanup function for Server objects.
This should help quite a bit with some flakey tests, but not all of them.
Our port problems will not go away completely until we upgrade our vendor
version of consul. With Go modules, we'll probably do a 'replace' to swap
out other copies of freeport with the one now in 'nomad/helper/freeport'.
Operators commonly have docker logs aggregated using various tools and
don't need nomad to manage their docker logs. Worse, Nomad uses a
somewhat heavy docker api call to collect them and it seems to cause
problems when a client runs hundreds of log collections.
Here we add a knob to disable log aggregation completely for nomad.
When log collection is disabled, we avoid running logmon and
docker_logger for the docker tasks in this implementation.
The downside here is once disabled, `nomad logs ...` commands and API
no longer return logs and operators must corrolate alloc-ids with their
aggregated log info.
This is meant as a stop gap measure. Ideally, we'd follow up with at
least two changes:
First, we should optimize behavior when we can such that operators don't
need to disable docker log collection. Potentially by reverting to
using pre-0.9 syslog aggregation in linux environments, though with
different trade-offs.
Second, when/if logs are disabled, nomad logs endpoints should lookup
docker logs api on demand. This ensures that the cost of log collection
is paid sparingly.
Add an RPC timeout for logmon. In
https://github.com/hashicorp/nomad/issues/6461#issuecomment-559747758 ,
`logmonClient.Stop` locked up and indefinitely blocked the task runner
destroy operation.
This is an incremental improvement. We still need to follow up to
understand how we got to that state, and the full impact of locked-up
Stop and its link to pending allocations on restart.
Some code cleanup:
* Use a field for setting EC2 metadata instead of env-vars in testing;
but keep environment variables for backward compatibility reasons
* Update tests to use testify
TestClient_UpdateNodeFromFingerprintKeepsConfig checks a test node
network interface, which is hardcoded to `eth0` and is updated
asynchronously. This causes flakiness when eth0 isn't available.
Here, we hardcode the value to an arbitrary network interface.
When spinning a second client, ensure that it uses new driver
instances, rather than reuse the already shutdown unhealthy drivers from
first instance.
This speeds up tests significantly, but cutting ~50 seconds or so, the
timeout in NewClient until drivers fingerprints. They never do because
drivers were shutdown already.
TestClient_RestoreError is very slow, taking ~81 seconds.
It has few problematic patterns. It's unclear what it tests, it
simulates a failure condition where all state db lookup fails and
asserts that alloc fails. Though starting from
https://github.com/hashicorp/nomad/pull/6216 , we don't fail allocs in
that condition but rather restart them.
Also, the drivers used in second client `c2` are the same singleton
instances used in `c1` and already shutdown. We ought to start healthy
new driver instances.
* 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.
Adds new package that can be used by client and server RPC endpoints to
facilitate monitoring based off of a logger
clean up old code
small comment about write
rm old comment about minsize
rename to Monitor
Removes connection logic from monitor command
Keep connection logic in endpoints, use a channel to send results from
monitoring
use new multisink logger and interfaces
small test for dropped messages
update go-hclogger and update sink/intercept logger interfaces
makeAllocTaskServices did not do a nil check on AllocatedResources
which causes a panic when upgrading directly from 0.8 to 0.10. While
skipping 0.9 is not supported we intend to fix serious crashers caused
by such upgrades to prevent cluster outages.
I did a quick audit of the client package and everywhere else that
accesses AllocatedResources appears to be properly guarded by a nil
check.
Danielle