Commit graph

133 commits

Author SHA1 Message Date
Pat Gavlin 1ecdc83a33 Implement more precise delete-before-replace semantics. (#2369)
This implements the new algorithm for deciding which resources must be
deleted due to a delete-before-replace operation.

We need to compute the set of resources that may be replaced by a
change to the resource under consideration. We do this by taking the
complete set of transitive dependents on the resource under
consideration and removing any resources that would not be replaced by
changes to their dependencies. We determine whether or not a resource
may be replaced by substituting unknowns for input properties that may
change due to deletion of the resources their value depends on and
calling the resource provider's Diff method.

This is perhaps clearer when described by example. Consider the
following dependency graph:

  A
__|__
B   C
|  _|_
D  E F

In this graph, all of B, C, D, E, and F transitively depend on A. It may
be the case, however, that changes to the specific properties of any of
those resources R that would occur if a resource on the path to A were
deleted and recreated may not cause R to be replaced. For example, the
edge from B to A may be a simple dependsOn edge such that a change to
B does not actually influence any of B's input properties. In that case,
neither B nor D would need to be deleted before A could be deleted.

In order to make the above algorithm a reality, the resource monitor
interface has been updated to include a map that associates an input
property key with the list of resources that input property depends on.
Older clients of the resource monitor will leave this map empty, in
which case all input properties will be treated as depending on all
dependencies of the resource. This is probably overly conservative, but
it is less conservative than what we currently implement, and is
certainly correct.
2019-01-28 09:46:30 -08:00
Louis DeJardin f35d4cd017 Small typo in comment
`read` spelled `reead`
2019-01-15 15:11:49 -08:00
Pat Gavlin ab36b1116f
Handle unconfigured plugins in Diff. (#2238)
After #2088, we began calling `Diff` on providers that are not configured
due to unknown configuration values. This hit an assertion intended to
detect exactly this scenario, which was previously unexpected.

These changes adjust `Diff` to indicate that a Diff is unavailable and
return an error message that describes why. The step generator then
interprets the diff as indicating a normal update and issues the error
message to the diagnostic stream.

Fixes #2223.
2018-11-21 16:53:29 -08:00
Pat Gavlin 676adf62b8
Use an explicit address when dialing plugins (#2224)
This is necessary in order for gRPC's proxy support to properly respect
NO_PROXY.

Fixes #2134.
2018-11-19 13:47:39 -08:00
Matt Ellis 992b048dbf Adopt golangci-lint and address issues
We run the same suite of changes that we did on gometalinter. This
ended up catching a few new issues, some of which were addressed and
some of which were baselined.
2018-11-08 14:11:47 -08:00
Joe Duffy 9aedb234af
Tidy up some data structures (#2135)
In preparation for some workspace restructuring, I decided to scratch a
few itches of my own in the code:

* Change project's RuntimeInfo field to just Runtime, to match the
  serialized name in JSON/YAML.

* Eliminate the no-longer-used Context and NoDefaultIgnores fields on
  project, and all of the associated legacy PPC-related code.

* Eliminate the no-longer-used IgnoreFile constant.

* Remove a bunch of "// nolint: lll" annotations, and simply format
  the structures with comments on dedicated lines, to avoid overly
  lengthy lines and lint suppressions.

* Mark Dependencies and InitErrors as `omitempty` in the JSON
  serialization directives for CheckpointV2 files. This was done for
  the YAML directives, but (presumably accidentally) omitted for JSON.
2018-11-01 08:28:11 -07:00
James Nugent 59a8a7fbfe Add Go 1.10+ versions of archive hashes in tests
Go 1.10 made some breaking changes to the headers in archive/tar [1] and
archive/zip [2], breaking the expected values in tests. In order to keep
tests passing with both, wherever a hardcoded hash is expect we switch
on `runtime.Version()` to select whether we want the Go 1.9 (currently
supported Go version) or later version of the hash.

Eventually these switches should be removed in favour of using the later
version only, so they are liberally commented to explain the reasoning.

[1]: https://golang.org/doc/go1.10#archive/tar
[2]: https://golang.org/doc/go1.10#archive/zip
2018-10-30 21:59:36 -05:00
Pat Gavlin 72a6ed320c
Do not propose replacement of providers in preview. (#2088)
Providers with unknown properties are currently considered to require
replacement. This was intended to indicate that we could not be sure
whether or not replacement was reqiuired. Unfortunately, this was not a
good user experience, as replacement would never be required at runtime.
This caused quite a bit of confusion--never proposing replacement seems
to be the better option.
2018-10-23 10:23:28 -07:00
Sean Gillespie ae87c469c5
Improve error message for missing provider plugins (#2040)
If a version is available, the returned error now includes the version
that was searched for and a command to install the missing plugin.
2018-10-10 15:18:41 -07:00
Sean Gillespie 2d4a3f7a6a
Move management of root resource state to engine (#1944)
* Protobuf changes

* Move management of root resource state to engine

This commit fixes a persistent side-by-side issue in the NodeJS SDK by
moving the management of root resource state to the engine. Doing so
adds two new endpoints to the Engine gRPC service: 1) GetRootResource
and 2) SetRootResource, which get and set the root resource
respectively.

* Rebase against master, regenerate proto
2018-09-18 11:47:34 -07:00
Pat Gavlin 4a550e308f
Fix provider cancellation. (#1914)
We signal provider cancellation by hangning a goroutine off of the plan
executor's parent context. To ensure clean shutdown, this goroutine also
listens on a channel that closes once the plan has finished executing.
Unfortunately, we were closing this channel too early, and the close was
racing with the cancellation signal. These changes ensure that the
channel closes after the plan has fully completed.

Fixes #1906.
Fixes pulumi/pulumi-kubernetes#185.
2018-09-10 15:18:25 -07:00
Alex Clemmer dea68b8b37 Implement status sinks
This commit reverts most of #1853 and replaces it with functionally
identical logic, using the notion of status message-specific sinks.

In other words, where the original commit implemented ephemeral status
messages by adding an `isStatus` parameter to most of the logging
methdos in pulumi/pulumi, this implements ephemeral status messages as a
parallel logging sink, which emits _only_ ephemeral status messages.

The original commit message in that PR was:

> Allow log events to be marked "status" events
>
> This commit will introduce a field, IsStatus to LogRequest. A "status"
> logging event will be displayed in the Info column of the main
> display, but will not be printed out at the end, when resource
> operations complete.
>
> For example, for complex resource initialization, we'd like to display
> a series of intermediate results: [1/4] Service object created, for
> example. We'd like these to appear in the Info column, but not at the
> end, where they are not helpful to the user.
2018-08-31 15:56:53 -07:00
Alex Clemmer 9e58fd1aaa Revert "Plumb LogRequest.IsStatus through the logging subsystem"
This reverts commit 3066cbcbd7.
2018-08-31 15:56:53 -07:00
Alex Clemmer 3066cbcbd7 Plumb LogRequest.IsStatus through the logging subsystem 2018-08-30 17:17:20 -07:00
Matt Ellis acf0fb278a Fix wierd interactions due to Cobra and glog
The glog package force the use of golang's underyling flag package,
which Cobra does not use. To work around this, we had a complicated
dance around defining flags in multiple places, calling flag.Parse
explicitly and then stomping values in the flag package with values we
got from Cobra.

Because we ended up parsing parts of the command line twice, each with
a different set of semantics, we ended up with bad UX in some
cases. For example:

`$ pulumi -v=10 --logflow update`

Would fail with an error message that looked nothing like normal CLI
errors, where as:

`$ pulumi -v=10 update --logflow`

Would behave as you expect. To address this, we now do two things:

- We never call flag.Parse() anymore. Wacking the flags with values we
  got from Cobra is sufficent for what we care about.

- We use a forked copy of glog which does not complain when
  flag.Parse() is not called before logging.

Fixes #301
Fixes #710
Fixes #968
2018-08-20 14:08:40 -07:00
Sean Gillespie d83774ca96
Fix two issues that can cause hangs during refresh (#1770)
1. 'readID' was never assigned to and was always the default value,
leading the refresh source to believe a resource was deleted
2. The refresh source could hang when a resource is deleted.
2018-08-13 21:43:10 -07:00
Alex Clemmer a172f1a048 Implement partial Read
Some time ago, we introduced the concept of the initialization error to
Pulumi (i.e., an error where the resource was successfully created but
failed to fully initialize). This was originally implemented in `Create`
and `Update`  methods of the resource provider interface; when we
detected an initialization failure, we'd pack the live version of the
object into the error, and return that to the engine.

Omitted from this initial implementation was a similar semantics for
`Read`. There are many implications of this, but one of them is that a
`pulumi refresh` will erase any initialization errors that had
previously been observed, even if the initialization errors still exist
in the resource.

This commit will introduce the initialization error semantics to `Read`,
fixing this issue.
2018-08-10 15:10:14 -07:00
Pat Gavlin a222705143
Implement first-class providers. (#1695)
### First-Class Providers
These changes implement support for first-class providers. First-class
providers are provider plugins that are exposed as resources via the
Pulumi programming model so that they may be explicitly and multiply
instantiated. Each instance of a provider resource may be configured
differently, and configuration parameters may be source from the
outputs of other resources.

### Provider Plugin Changes
In order to accommodate the need to verify and diff provider
configuration and configure providers without complete configuration
information, these changes adjust the high-level provider plugin
interface. Two new methods for validating a provider's configuration
and diffing changes to the same have been added (`CheckConfig` and
`DiffConfig`, respectively), and the type of the configuration bag
accepted by `Configure` has been changed to a `PropertyMap`.

These changes have not yet been reflected in the provider plugin gRPC
interface. We will do this in a set of follow-up changes. Until then,
these methods are implemented by adapters:
- `CheckConfig` validates that all configuration parameters are string
  or unknown properties. This is necessary because existing plugins
  only accept string-typed configuration values.
- `DiffConfig` either returns "never replace" if all configuration
  values are known or "must replace" if any configuration value is
  unknown. The justification for this behavior is given
  [here](https://github.com/pulumi/pulumi/pull/1695/files#diff-a6cd5c7f337665f5bb22e92ca5f07537R106)
- `Configure` converts the config bag to a legacy config map and
  configures the provider plugin if all config values are known. If any
  config value is unknown, the underlying plugin is not configured and
  the provider may only perform `Check`, `Read`, and `Invoke`, all of
  which return empty results. We justify this behavior becuase it is
  only possible during a preview and provides the best experience we
  can manage with the existing gRPC interface.

### Resource Model Changes
Providers are now exposed as resources that participate in a stack's
dependency graph. Like other resources, they are explicitly created,
may have multiple instances, and may have dependencies on other
resources. Providers are referred to using provider references, which
are a combination of the provider's URN and its ID. This design
addresses the need during a preview to refer to providers that have not
yet been physically created and therefore have no ID.

All custom resources that are not themselves providers must specify a
single provider via a provider reference. The named provider will be
used to manage that resource's CRUD operations. If a resource's
provider reference changes, the resource must be replaced. Though its
URN is not present in the resource's dependency list, the provider
should be treated as a dependency of the resource when topologically
sorting the dependency graph.

Finally, `Invoke` operations must now specify a provider to use for the
invocation via a provider reference.

### Engine Changes
First-class providers support requires a few changes to the engine:
- The engine must have some way to map from provider references to
  provider plugins. It must be possible to add providers from a stack's
  checkpoint to this map and to register new/updated providers during
  the execution of a plan in response to CRUD operations on provider
  resources.
- In order to support updating existing stacks using existing Pulumi
  programs that may not explicitly instantiate providers, the engine
  must be able to manage the "default" providers for each package
  referenced by a checkpoint or Pulumi program. The configuration for
  a "default" provider is taken from the stack's configuration data.

The former need is addressed by adding a provider registry type that is
responsible for managing all of the plugins required by a plan. In
addition to loading plugins froma checkpoint and providing the ability
to map from a provider reference to a provider plugin, this type serves
as the provider plugin for providers themselves (i.e. it is the
"provider provider").

The latter need is solved via two relatively self-contained changes to
plan setup and the eval source.

During plan setup, the old checkpoint is scanned for custom resources
that do not have a provider reference in order to compute the set of
packages that require a default provider. Once this set has been
computed, the required default provider definitions are conjured and
prepended to the checkpoint's resource list. Each resource that
requires a default provider is then updated to refer to the default
provider for its package.

While an eval source is running, each custom resource registration,
resource read, and invoke that does not name a provider is trapped
before being returned by the source iterator. If no default provider
for the appropriate package has been registered, the eval source
synthesizes an appropriate registration, waits for it to complete, and
records the registered provider's reference. This reference is injected
into the original request, which is then processed as usual. If a
default provider was already registered, the recorded reference is
used and no new registration occurs.

### SDK Changes
These changes only expose first-class providers from the Node.JS SDK.
- A new abstract class, `ProviderResource`, can be subclassed and used
  to instantiate first-class providers.
- A new field in `ResourceOptions`, `provider`, can be used to supply
  a particular provider instance to manage a `CustomResource`'s CRUD
  operations.
- A new type, `InvokeOptions`, can be used to specify options that
  control the behavior of a call to `pulumi.runtime.invoke`. This type
  includes a `provider` field that is analogous to
  `ResourceOptions.provider`.
2018-08-06 17:50:29 -07:00
Matt Ellis 645ca2eb56 Allow more types for runtimeOptions
Instead of just allowing booleans, type the map as string->interface{}
so in the future we could pass string or number options to the
language host.
2018-08-06 14:00:58 -07:00
Matt Ellis ce5eaa8343 Support TypeScript in a more first-class way
This change lets us set runtime specific options in Pulumi.yaml, which
will flow as arguments to the language hosts. We then teach the nodejs
host that when the `typescript` is set to `true` that it should load
ts-node before calling into user code. This allows using typescript
natively without an explicit compile step outside of Pulumi.

This works even when a tsconfig.json file is not present in the
application and should provide a nicer inner loop for folks writing
typescript (I'm pretty sure everyone has run into the "but I fixed
that bug!  Why isn't it getting picked up?  Oh, I forgot to run tsc"
problem.

Fixes #958
2018-08-06 14:00:58 -07:00
CyrusNajmabadi 58ae413bca
Do not add a newline between a stream of info messages. The contract is that these will just be appended continguously. (#1688) 2018-08-02 10:55:15 -04:00
Alex Clemmer f037c7d143 Checkpoint resource initialization errors
When a resource fails to initialize (i.e., it is successfully created,
but fails to transition to a fully-initialized state), and a user
subsequently runs `pulumi update` without changing that resource, our
CLI will fail to warn the user that this resource is not initialized.

This commit begins the process of allowing our CLI to report this by
storing a list of initialization errors in the checkpoint.
2018-07-20 17:59:06 -07:00
Alex Clemmer d182525fec Add signal cancellation to resource provider 2018-07-15 11:05:44 -10:00
CyrusNajmabadi 4761a32cc1
Add support for providing a log stream-id to our RPC interface. (#1627) 2018-07-11 15:04:00 -07:00
Alex Clemmer 582a002ccb FIX: Build break in partial update integration test 2018-07-06 18:03:42 -07:00
Alex Clemmer 456deaf442 Small cleanups and comments 2018-07-06 15:57:08 -07:00
Sean Gillespie 1cbf8bdc40 Partial status for resource providers
This commit adds CLI support for resource providers to provide partial
state upon failure. For resource providers that model resource
operations across multiple API calls, the Provider RPC interface can now
accomodate saving bags of state for resource operations that failed.
This is a common pattern for Terraform-backed providers that try to do
post-creation steps on resource as part of Create or Update resource
operations.
2018-07-02 13:32:23 -07:00
Sean Gillespie b5e4d87687
Improve the error message when data source invocations fail (#1472) 2018-06-07 11:21:38 -07:00
joeduffy 5967259795 Add license headers 2018-05-22 15:02:47 -07:00
CyrusNajmabadi 72e00810c4
Filter the logs we emit to glog so that we don't leak out secrets. (#1371) 2018-05-15 15:28:00 -07:00
Joe Duffy 369c619ab9
Skip loading language plugins when not needed (#1367)
In pulumi/pulumi#1356, we observed that we can fail during a destroy
because we attempt to load the language plugin, which now eagerly looks
for the @pulumi/pulumi package.

This is also blocking ingestion of the latest engine bits into the PPC.

It turns out that for destroy (and refresh), we have no need for the
language plugin.  So, let's skip loading it when appropriate.
2018-05-14 20:32:53 -07:00
Joe Duffy 457c34ff50
Add a PULUMI_DEV flag, and suppress warnings (#1361)
This change suppresses the warning

    warning: resource plugin aws is expected to have version >=0.11.3,
        but has 0.11.1-dev-1523506162-g06ec765; the wrong version may
        be on your path, or this may be a bug in the plugin

when the PULUMI_DEV envvar is set to a truthy value.

This warning keeps popping up in demos since I'm always using dev builds
and I'd like a way to shut it off, even though this can legitimately
point out a problem.  Eventually I'll switch to official buildsa but,
until then, it seems worth having a simple way to suppress.
2018-05-11 20:59:01 -07:00
CyrusNajmabadi 092696948d
Restore streaming of plugin outputs to the progress display. (#1333) 2018-05-07 15:11:52 -07:00
Joe Duffy f92eb0a4e8 Run Configure calls in parallel (#1321)
As of this change, the engine will run all Configure calls in parallel.
This improves startup performance, since otherwise, we would block
waiting for all plugins to be configured before proceeding to run a
program.  Emperically, this is about 1.5-2s for AWS programs, and
manifests as a delay between the purple "Previewing update of stack"
being printed, and the corresponding grey "Previewing update" message.

This is done simply by using a Goroutine for Configure, and making sure
to synchronize on all actual CRUD operations.  I toyed with using double
checked locking to eliminate lock acquisitions -- something we may want
to consider as we add more fine-grained parallelism -- however, I've
kept it simple to avoid all the otherwise implied memory model woes.

I made the judgment call that GetPluginInfo may proceed before
Configure has settled.  (Otherwise, we'd immediately call it and block
after loading the plugin, obviating the parallelism benefits.)  I also
made the judgment call to do this in the engine, after flip flopping
several times about possibly making it a provider's own decision.
2018-05-04 14:29:47 -07:00
Sean Gillespie 14baf866f6
Snapshot management overhaul and refactor (#1273)
* Refactor the SnapshotManager interface

Lift snapshot management out of the engine by delegating it to the
SnapshotManager implementation in pkg/backend.

* Add a event interface for plugin loads and use that interface to record plugins in the snapshot

* Remove dead code

* Add comments to Events

* Add a number of tests for SnapshotManager

* CR feedback: use a successful bit on 'End' instead of having a separate 'Abort' API

* CR feedback

* CR feedback: register plugins one-at-a-time instead of the entire state at once
2018-04-25 17:20:08 -07:00
CyrusNajmabadi 7b96b8cdcf
Produce a single message for the text we receive when running, not a message per line of output. (#1191) 2018-04-13 15:44:35 -07:00
Joe Duffy 479a2e6ad5
Add an ID property to ReadResponse (#1145)
The RPC provider interface needs a way to convey back to the engine
that a resource being read no longer exists.  To do this, we'll return
the ID property that was read back.  If it is empty, it means the
resource is gone.  If it is non-empty, we expect it to match the input.
2018-04-10 12:58:50 -07:00
CyrusNajmabadi a759f2e085
Switch to a resource-progress oriented view for pulumi preview/update/destroy (#1116) 2018-04-10 12:03:11 -07:00
Joe Duffy f2ae3a7afc
Permit plugin versions to float (#1122)
This change lets plugin versions to float in two ways:

1) If a `pulumi plugin install` detects a newer version is available
   already, there's no need to download and install the older version.

2) If the engine attempts to load a plugin at a particular version,
   if a newer version is available, it will be accepted without error.

As part of this, we permit $PATH to have the final say when determining
which version to accept.  That is, it can always override the choice.

Note that I highly suspect, in the limit, that we'll want to stop doing
this for major version incompatibilities. For now, since we don't
envision any such version changes imminently, this will suffice.
2018-04-05 16:37:50 -07:00
joeduffy 22584e7e37 Make some resource model changes
This commit changes two things about our resource model:

* Stop performing Pulumi Engine-side diffing of resource state.
  Instead, we defer to the resource plugins themselves to determine
  whether a change was made and, if so, the extent of it.  This
  manifests as a simple change to the Diff function; it is done in
  a backwards compatible way so that we continue with legacy diffing
  for existing resource provider plugins.

* Add a Read RPC method for resource providers.  It simply takes a
  resource's ID and URN, plus an optional bag of further qualifying
  state, and it returns the current property state as read back from
  the actual live environment.  Note that the optional bag of state
  must at least include enough additional properties for resources
  wherein the ID is insufficient for the provider to perform a lookup.
  It may, however, include the full bag of prior state, for instance
  in the case of a refresh operation.

This is part of pulumi/pulumi#1108.
2018-04-05 08:14:25 -07:00
Sean Gillespie a3a6101e79
Improve the error message arising from missing required configs for resource providers (#1097)
* Improve the error message arising from missing required configs for
resource providers

If the resource provider that we are speaking to is new enough, it will send
across a list of keys and their descriptions alongside an error
indicating that the provider we are configuring is missing required
config. This commit packages up the list of missing keys into an error
that can be presented nicely to the user.

* Code review feedback: renaming simplification and correcting errors in comments
2018-04-04 10:08:17 -07:00
Sean Gillespie 91c550f1e0
Send structured errors across RPC boundaries (#1072)
* Send structured errors across RPC boundaries

This brings us closer to gRPC best practices where we send structured
errors with error codes across RPC endpoints. The new "rpcerrors"
package can wrap errors from RPC endpoints, so RPC servers can attach
some additional context as to why a request failed.

* Code review feedback:

1. Rename rpcerrors -> rpcerror, better package name
2. Rename RPCError -> Error, RPCErrorCause -> ErrorCause, names
suggested by gometalinter to improve their package-qualified names
3. Fix import organization in rpcerror.go
2018-03-28 17:07:35 -07:00
Pat Gavlin a23b10a9bf
Update the copyright end date to 2018. (#1068)
Just what it says on the tin.
2018-03-21 12:43:21 -07:00
Joe Duffy 5924f6b8c3
Ensure destroy plugins are present (#1043)
This change uses the prior checkpoint's deployment manifest to pre-
populate all plugins required to complete the destroy operation.  This
allows for subsequent attempts to load a resource's plugin to match the
already-loaded version.  This approach obviously doesn't work in a
hypothetical future world where plugins for the same resource provider
are loaded side-by-side, but we already know that.
2018-03-12 16:27:39 -07:00
Sean Gillespie 703a954839
Improve error messages output by the CLI (#1011)
* Improve error messages output by the CLI

This fixes a couple known issues with the way that we present errors
from the Pulumi CLI:
    1. Any errors from RPC endpoints were bubbling up as they were to
    the top-level, which was unfortunate because they contained
    RPC-specific noise that we don't want to present to the user. This
    commit unwraps errors from resource providers.
    2. The "catastrophic error" message often got printed twice
    3. Fatal errors are often printed twice, because our CLI top-level
    prints out the fatal error that it receives before exiting. A lot of
    the time this error has already been printed.
    4. Errors were prefixed by PU####.

* Feedback: Omit the 'catastrophic' error message and use a less verbose error message as the final error

* Code review feedback: interpretRPCError -> resourceStateAndError

* Code review feedback: deleting some commented-out code, error capitalization

* Cleanup after rebase
2018-03-09 15:43:16 -08:00
pat@pulumi.com dc36b9569a Serialize plugin loads.
As it stands, we allow plugin load requests to race. Not only does this
create a situation in which we may load and then immediately throw away
a plugin (potentially leaking its process), it also creates the
possibility of races when reading from/writing to the various plugin
caches. These changes serialize all plugin loads and cache accesses by
running all accesses for a particular host in a single goroutine.

Fixes #1020.
2018-03-09 11:31:02 -08:00
Matt Ellis 5dfd720bc3 Remove config.AsModuleMember()
This API was introduced to aid the refactoring, but it isn't something
we want to support long term. Remove it and for a few places, push
passing config.Key around more, instead of converting to the old type
eagerly.
2018-03-08 10:52:25 -08:00
Matt Ellis 81a273c7bb Change represention of config.Key
config.Key has become a pair of namespace and name. Because the whole
world has not changed yet, there continues to be a way to convert
between a tokens.ModuleMember and config.Key, however now sometime the
conversion from tokens.ModuleMember can fail (when the module member
is not of the form `<package>:config:<name>`).
2018-03-08 10:52:25 -08:00
pat@pulumi.com 45a4a41e0d Configure resource providers upon load.
As it stands, we only configure those providers for which configuration
is present. This can lead to surprising failure modes if those providers
are then used to create resources. These changes ensure that all
resource providers that are not configured during plan initialization
are configured upon first load.

Fixes #758.
2018-03-06 16:38:53 -08:00
Matt Ellis ed7a4d9157 Check plugin cache first; make version mismatch a warning
Previously, we would prefer a plugin on the $PATH which is more or
less always the case for people hacking on `pulumi`. Later, when we
went to check the loaded plugin version matched the one we requested,
we fail.

Now, if we have a version, we'll first consult the local plugin
cache. If that fails, we'll fall back to the $PATH as we used to.

When we are loading a plugin without a version, we continue to use the
one on the $PATH (without testing the cache) on the assumption it is
newer.

In addition, we've turned the "plugin versions are mis-matched" from
an error into a warning. We expect that we'll only ever see this
warning when something strange is going on (since in the normal case,
we'll have found the exact version in the cache) but having it not
hard fail does help in development cases.

Fixes #977
2018-02-26 11:39:50 -08:00