Currently, we define the LuxiOp type as a simple enumeration, and leave
the arguments structure to the users of the Ganeti.Luxi module. This is
suboptimal for a couple of reasons: first, we decouple the operation
type from operation arguments, and that means we don't use the type
system for validation of the arguments; second, the clients themselves
have to know about the JSON encoding of the protocol.

For the above arguments, we change the operation type to contain the
arguments too, and then the entire conversion/serialization is
restricted to the Ganeti.Luxi module. Also, the removal of the JSON
encoding from the clients results in an overall simplification of the
code.

Incomplete pattern match…

These are not comprehensive, but at least we have a start.

QuickCheck's batch driver (at least v1) doesn't show the test aborts,
but simply discards the specific exception and increases the abort
count. This makes it hard to debug the tests, so we modify our own test
wrapper (which so far only tracked total failures) to show any
exceptions.

Since the unittests are not 'clean' from the p.o.v. of type
declarations, and cannot be made clean in all respects (e.g. orphan
instances), we silence some warnings for the test target, to have a
cleaner output.

The tests are moved to a separate data structure, and we can select a
subset of tests to run.

Some keys are optional in the Ganeti opcodes (e.g. ‘node’ in the
OpReplaceDisks), and as such we need to transform them in a Maybe value,
instead of failing.

The patch reworks a bit fromObj and adds maybeFromObj which parses such
optional values. It then uses it in the opcode reading.

This patch removes all old uses of fromJResult with the annotated
version, and removes the non-annotated version. All JSON parsing points
should now have annotated errors.

This allows, for example, the RAPI backend to detail which information
(instance or node data) fails to parse.

Currently fromObj doesn't detail what we're trying to read, which can
lead to cryptic messages: "Cannot read Int". The patch changes this
function to annotate the error messages with the key/value we're trying
to convert, by using a new version of fromJResult.

Since the display of the key in tryFromObj is now redundant (it was
already redundant in the 'not found' case), we remove it.

The new version of fromJResult (annotateJResult) simply prepends a
description string to the actual error message.

Instance, Node and Text modules have improved coverage.

The patch adds some simple unit-tests for both the allocation function
(we can allocate small instances on an empty cluster, we can allocate in
tiered more starting from any size) and the balancing functions (one
single instance is placed optimally, a full cluster plus an empty node
can be rebalanced). The coverage has increased greatly, since this is
the bulk of the algorithm/code.

Also, the cluster tests are now being run with different options, since
they are much slower.

This is done so we can test a longer pipeline.

This helps debugging via ghci.

After the name patches, we can pass in either the short or the full
name, so update the hbal man page accordingly.

This patch introduces some new functionality in the base Element type
and in Container which supports searching for all 'known' names of an
element, such that both short and full names are accept for various
options like '-O' and '--excluded-instances'.

Currently the name used internally is modified and holds the shortened
name of the nodes/instances. This has caused issues before, since we
always have to strip the suffix from input data and reapply it if we
need to send data back to Ganeti.

This patch changes the code such that the names are never modified, only
the alias, and all the internal computations can forget about the common
suffix addition/removal.

This new field ('alias') will hold the shortened/beautified display
name. When resetting the name, the alias is reset too, and there's a new
function to update only the alias.

First, we reduce the max size of the disks, since Int on 32bits will
overflow for big simulated clusters. This is a real issue, that will
need fixing in real life, but for now we just "silence" this test.

Second, we increase the amount of time a test is allowed to run,
otherwise on slower computers some tests might time-out.

This increases the overall coverage by 5%-10% (depending on coverage
type). Some modules are still not unittested at all, as HUnit is a
better choice for them.

… and export more functions. This will help with unit testing.

This patch moves from allowing no-limits for disk/cpu ratios, and always
use a real limit. For disk, it's simple since we use 0, which means no
reservations for disks. For CPU, we set an (arbitrary) limit of 64 v/p,
which should be reasonable as a default limit (it can be changed via the
command line).

Currently we just print a fake result and exit early. This is bad, since
it doesn't use the same codepaths for all the result printing, and has
already led to a bug where hspace looks like completely ignoring the
tiered specs request.

This patch changes the code to override the computation, instead of the
printout, thus allowing tiered specs results for such cases.

We returned the KM_POOL_* metrics as the final state, not as the delta
between the final and the initial state.

This patch adds the metrics of used/allocable/unallocable resources.

In case we're not enabling limits, let's restrict this to -1, instead of
-1 times the number of pcpus.

Given two cluster states, the new function can answer the following
questions:

- how much resources currently allocated
- how much resources finally allocated (delta from above is how much we
  can actually allocate on the cluster)
- unallocable resources (whatever is left free after the previous step)

We add a new field that tracks the available virtual cpus (expressed as
node cpus times the vcpu ratio).

* master:
  Fix iallocator crash when no solutions exist
  Fix IAllocator multi-evacuate message

Commit 54365762 added an un-guarded `head' call, which crashes with
“Prelude.head: empty list” when no results exists for the per-instance
allocation/relocation calls.

This patch fixes this, and also adds another check for an unguarded
`head' call during parsing of input data.
(cherry picked from commit e41f4ba0)

Since Ganeti passes full host names (not common-suffix-stripped), we
need to remove the suffix from the evac_nodes keys too. In case one node
is not part of the cluster, it will lead to a wrong error message, but
for now it fixes the problem.

Commit 54365762 added an un-guarded `head' call, which crashes with
“Prelude.head: empty list” when no results exists for the per-instance
allocation/relocation calls.

This patch fixes this, and also adds another check for an unguarded
`head' call during parsing of input data.

For some versions of haddock, this can create problems.

This removes some manual checks from a few places in the code with a
single list defined once.