Failed requests due to API client errors are to be marked as DEBUG.
The Error log level should be reserved to signal problems with the
cluster and are actionable for nomad system operators. Logs due to
misbehaving API clients don't represent a system level problem and seem
spurius to nomad maintainers at best. These log messages can also be
attack vectors for deniel of service attacks by filling servers disk
space with spurious log messages.
We use the education team's "countdash" demo in many places
to showcase Nomad's Consul Connect integration. This change
adds a Dockerfile for each of `counter-dashboard` and
`counter-api` that can be used to build artifacts to publish
to Nomad's Docker Hub organization.
The recent "0.0.3" release of the `countdash` demo includes
changes we want in order to demo task group service checks.
Pipe http server log to hclog, so that it uses the same logging format
as rest of nomad logs. Also, supports emitting them as json logs, when
json formatting is set.
The http server logs are emitted as Trace level, as they are typically
repsent HTTP client errors (e.g. failed tls handshakes, invalid headers,
etc).
Though, Panic logs represent server errors and are relayed as Error
level.
Protect against a panic when we attempt to start a container with a name
that conflicts with an existing one. If the existing one is being
deleted while nomad first attempts to create the container, the
createContainer will fail with `container already exists`, but we get
nil container reference from the `containerByName` lookup, and cause a
crash.
I'm not certain how we get into the state, except for being very
unlucky. I suspect that this case may be the result of a concurrent
restart or the docker engine API not being fully consistent (e.g. an
earlier call purged the container, but docker didn't free up resources
yet to create a new container with the same name immediately yet).
If that's the case, then re-attempting creation will hopefully succeed,
or we'd at least fail enough times for the alloc to be rescheduled to
another node.
This page has not been updated (yet) to reflect that support for all 3 job types (service, batch, system) which shipped in 0.9.2.
The current page implies that preemption is only available for system jobs.
This is early preparation for Nomad 0.12, where we plan to move Preemption from Enterprise feature suite to OSS for all.
The BinPackIter accounted for node reservations twice when scoring nodes
which could bias scores toward nodes with reservations.
Pseudo-code for previous algorithm:
```
proposed = reservedResources + sum(allocsResources)
available = nodeResources - reservedResources
score = 1 - (proposed / available)
```
The node's reserved resources are added to the total resources used by
allocations, and then the node's reserved resources are later
substracted from the node's overall resources.
The new algorithm is:
```
proposed = sum(allocResources)
available = nodeResources - reservedResources
score = 1 - (proposed / available)
```
The node's reserved resources are no longer added to the total resources
used by allocations.
My guess as to how this bug happened is that the resource utilization
variable (`util`) is calculated and returned by the `AllocsFit` function
which needs to take reserved resources into account as a basic
feasibility check.
To avoid re-calculating alloc resource usage (because there may be a
large number of allocs), we reused `util` in the `ScoreFit` function.
`ScoreFit` properly accounts for reserved resources by subtracting them
from the node's overall resources. However since `util` _also_ took
reserved resources into account the score would be incorrect.
Prior to the fix the added test output:
```
Node: reserved Score: 1.0000
Node: reserved2 Score: 1.0000
Node: no-reserved Score: 0.9741
```
The scores being 1.0 for *both* nodes with reserved resources is a good
hint something is wrong as they should receive different scores. Upon
further inspection the double accounting of reserved resources caused
their scores to be >1.0 and clamped.
After the fix the added test outputs:
```
Node: no-reserved Score: 0.9741
Node: reserved Score: 0.9480
Node: reserved2 Score: 0.8717
```
