In order to handle optional attributes, the Variable type needs to keep
track of the type constraint for decoding and conversion, as well as the
concrete type for creating values and type comparison.
Since the Type field is referenced throughout the codebase, and for
future refactoring if the handling of optional attributes changes
significantly, the constraint is now loaded into an entirely new field
called ConstraintType. This prevents types containing
ObjectWithOptionalAttrs from escaping the decode/conversion codepaths
into the rest of the codebase.
Objects with optional attributes are only used for the decoding of
HCL, and those types should never be exposed elsewhere within
terraform.
Separate the external ImpliedType method from the cty.Type generated
internally for the decoder spec. This unfortunately causes our
ImpliedType method to return a different type than the
hcldec.ImpliedType function, but the former is only used within
terraform for concrete values, while the latter is used to decode
HCL. Renaming the ImpliedType methods could be done to further
differentiate them, but that does cause fairly large diff in the
codebase that does not seem worth the effort at this time.
Thus far our various interactions with the bits of state we keep
associated with a working directory have all been implemented directly
inside the "command" package -- often in the huge command.Meta type -- and
not managed collectively via a single component.
There's too many little codepaths reading and writing from the working
directory and data directory to refactor it all in one step, but this is
an attempt at a first step towards a future where everything that reads
and writes from the current working directory would do so via an object
that encapsulates the implementation details and offers a high-level API
to read and write all of these session-persistent settings.
The design here continues our gradual path towards using a dependency
injection style where "package main" is solely responsible for directly
interacting with the OS command line, the OS environment, the OS working
directory, the stdio streams, and the CLI configuration, and then
communicating the resulting information to the rest of Terraform by wiring
together objects. It seems likely that eventually we'll have enough wiring
code in package main to justify a more explicit organization of that code,
but for this commit the new "workdir.Dir" object is just wired directly in
place of its predecessors, without any significant change of code
organization at that top layer.
This first commit focuses on the main files and directories we use to
find provider plugins, because a subsequent commit will lightly reorganize
the separation of concerns for plugin launching with a similar goal of
collecting all of the relevant logic together into one spot.
Previously our graph walker expected to recieve a data structure
containing schemas for all of the provider and provisioner plugins used in
the configuration and state. That made sense back when
terraform.NewContext was responsible for loading all of the schemas before
taking any other action, but it no longer has that responsiblity.
Instead, we'll now make sure that the "contextPlugins" object reaches all
of the locations where we need schema -- many of which already had access
to that object anyway -- and then load the needed schemas just in time.
The contextPlugins object memoizes schema lookups, so we can safely call
it many times with the same provider address or provisioner type name and
know that it'll still only load each distinct plugin once per Context
object.
As of this commit, the Context.Schemas method is now a public interface
only and not used by logic in the "terraform" package at all. However,
that does leave us in a rather tenuous situation of relying on the fact
that all practical users of terraform.Context end up calling "Schemas" at
some point in order to verify that we have all of the expected versions
of plugins. That's a non-obvious implicit dependency, and so in subsequent
commits we'll gradually move all responsibility for verifying plugin
versions into the caller of terraform.NewContext, which'll heal a
long-standing architectural wart whereby the caller is responsible for
installing and locating the plugin executables but not for verifying that
what's installed is conforming to the current configuration and dependency
lock file.
Previously the graph builders all expected to be given a full manifest
of all of the plugin component schemas that they could need during their
analysis work. That made sense when terraform.NewContext would always
proactively load all of the schemas before doing any other work, but we
now have a load-as-needed strategy for schemas.
We'll now have the graph builders use the contextPlugins object they each
already hold to retrieve individual schemas when needed. This avoids the
need to prepare a redundant data structure to pass alongside the
contextPlugins object, and leans on the memoization behavior inside
contextPlugins to preserve the old behavior of loading each provider's
schema only once.
By tolerating ProviderSchema and ProvisionerSchema potentially returning
errors, we can slightly simplify EvalContextBuiltin by having it retrieve
individual schemas when needed directly from the "Plugins" object.
EvalContextBuiltin already needs to be holding a contextPlugins instance
for other reasons anyway, so this allows us to get the same result with
fewer moving parts.
The responsibility for actually instantiating a single plugin and reading
out its schema now belongs to the contextPlugins type, which memoizes the
results by each plugin's unique identifier so that we can avoid retrieving
the same schemas multiple times when working with the same context.
This doesn't change the API of Context.Schemas but it does restore the
spirit of an earlier version of terraform.Context which did all of the
schema loading proactively inside terraform.NewContext. In an earlier
commit we reduced the scope of terraform.NewContext, making schema loading
a separate step, but in the process of doing that removed the effective
memoization of the schema results that terraform.NewContext was providing.
The memoization here will play out in a different way than before, because
we'll be treating each plugin call as separate rather than proactively
loading them all up front, but this is effectively the same because all
of our operation methods on Context call Context.Schemas early in their
work and thus end up forcing all of the necessary schemas to load up
front nonetheless.
In the v0.12 timeframe we made contextComponentFactory an interface with
the expectation that we'd write mocks of it for tests, but in practice we
ended up just always using the same "basicComponentFactory" implementation
throughout.
In the interests of simplification then, here we replace that interface
and its sole implementation with a new concrete struct type
contextPlugins.
Along with the general benefit that this removes an unneeded indirection,
this also means that we can add additional methods to the struct type
without the usual restriction that interface types prefer to be small.
In particular, in a future commit I'm planning to add methods for loading
provider and provisioner schemas, working with the currently-unused new
fields this commit has included in contextPlugins, as compared to its
predecessor basicComponentFactory.
In earlier Terraform versions we used the set of all available plugins of
each type to make graph-building decisions, but in modern Terraform we
make those decisions based entirely on the configuration.
Consequently, we no longer need the methods which can enumerate all of the
known plugin components of a given type. Instead, we just try to
instantiate each of the plugins that the configuration refers to and then
handle the error when that fails, which typically means that the user
needs to run "terraform init" to install some new plugins.
In earlier incarnations of these transformers we used the set of all
available providers for tasks such as generating implied provider
configuration nodes.
However, in modern Terraform we can extract all of the information we need
from the configuration itself, and so these transformers weren't actually
using this set of provider addresses.
These also ended up getting left behind as sets of string rather than sets
of addrs.Provider in our earlier refactoring work, which didn't really
matter because the result wasn't used anywhere anyway.
Rather than updating these to use addrs.Provider instead, I've just
removed the unused arguments entirely in the hope of making it easier to
see what inputs these transformers use to make their decisions.
The public interface for loading schemas is Context.Schemas, which can
take into account the context's records of which plugin versions and
checksums we're expecting. loadSchemas is an implementation detail of
that, representing the part we run only after we've verified all of the
plugins.
For resources which are planned to move, render the previous run address
as additional information in the plan UI. For the case of a move-only
resource (which otherwise is unchanged), we also render that as a
planned change, but without any corresponding action symbol.
If all changes in the plan are moves without changes, the plan is no
longer considered "empty". In this case, we skip rendering the action
symbols in the UI.
This package level variable can be overridden at link time to allow
temporarily disabling the UI warning when experimental features are
enabled. This makes it easier to understand how UI will render when the
feature is no longer experimental.
This change is only for those developing Terraform.
This is the first test exercising the basic functionality of config-driven
move. We previously had it skipped because Terraform's previous design
of treating all three of the state artifacts as mutable attributes of
terraform.Context meant that it was too late during planning to deal with
the move operations, and thus this test was failing.
Thanks to the previous commit, which changes the terraform.Context API
such that we can defer creating the three state artifacts until we're
already doing planning, this test now works and shows Terraform correctly
handling a resource that was formerly called "a" and is now called "b",
with a "moved" block recording that renaming.
Previously terraform.Context was built in an unfortunate way where all of
the data was provided up front in terraform.NewContext and then mutated
directly by subsequent operations. That made the data flow hard to follow,
commonly leading to bugs, and also meant that we were forced to take
various actions too early in terraform.NewContext, rather than waiting
until a more appropriate time during an operation.
This (enormous) commit changes terraform.Context so that its fields are
broadly just unchanging data about the execution context (current
workspace name, available plugins, etc) whereas the main data Terraform
works with arrives via individual method arguments and is returned in
return values.
Specifically, this means that terraform.Context no longer "has-a" config,
state, and "planned changes", instead holding on to those only temporarily
during an operation. The caller is responsible for propagating the outcome
of one step into the next step so that the data flow between operations is
actually visible.
However, since that's a change to the main entry points in the "terraform"
package, this commit also touches every file in the codebase which
interacted with those APIs. Most of the noise here is in updating tests
to take the same actions using the new API style, but this also affects
the main-code callers in the backends and in the command package.
My goal here was to refactor without changing observable behavior, but in
practice there are a couple externally-visible behavior variations here
that seemed okay in service of the broader goal:
- The "terraform graph" command is no longer hooked directly into the
core graph builders, because that's no longer part of the public API.
However, I did include a couple new Context functions whose contract
is to produce a UI-oriented graph, and _for now_ those continue to
return the physical graph we use for those operations. There's no
exported API for generating the "validate" and "eval" graphs, because
neither is particularly interesting in its own right, and so
"terraform graph" no longer supports those graph types.
- terraform.NewContext no longer has the responsibility for collecting
all of the provider schemas up front. Instead, we wait until we need
them. However, that means that some of our error messages now have a
slightly different shape due to unwinding through a differently-shaped
call stack. As of this commit we also end up reloading the schemas
multiple times in some cases, which is functionally acceptable but
likely represents a performance regression. I intend to rework this to
use caching, but I'm saving that for a later commit because this one is
big enough already.
The proximal reason for this change is to resolve the chicken/egg problem
whereby there was previously no single point where we could apply "moved"
statements to the previous run state before creating a plan. With this
change in place, we can now do that as part of Context.Plan, prior to
forking the input state into the three separate state artifacts we use
during planning.
However, this is at least the third project in a row where the previous
API design led to piling more functionality into terraform.NewContext and
then working around the incorrect order of operations that produces, so
I intend that by paying the cost/risk of this large diff now we can in
turn reduce the cost/risk of future projects that relate to our main
workflow actions.
Here we wire through the "move results" into the graph walk data
structures so that all of the the nodes which produce
plans.ResourceInstanceChange values can capture the "PrevRunAddr" for
each resource instance.
This doesn't actually quite work yet, because the logic in Context.Plan
isn't actually correct and so the updated state from
refactoring.ApplyMoves isn't actually visible as the "previous run state".
For that reason, the context test in this commit is currently skipped,
with the intent of re-enabling it once the updated state is properly
propagating into the plan graph walk and thus we can actually react to
the result of the move while choosing actions for those addresses.
In order to expose the effect of any relevant "moved" statements we dealt
with prior to creating the plan, we'll record with each
ResourceInstanceChange both is current address and the address it was
tracked at for the previous run.
To save consumers of these objects from having to special-case the
situation where there _was_ no previous run (e.g. because this is a Create
change), we'll just pretend the previous run address was the same as the
current address in that case, the same as for an update without any
renaming in effect.
This includes a breaking change to the plan file format, but one that
doesn't require a version number increment because there is no ambiguity
between the two formats and so mismatched parsers will already fail with
an error message.
As of this commit we've just added the new field but not yet populated it
with any useful information: it always just matches Addr. A future commit
will wire this up to the result of applying the moves so that we can
populate it correctly. We also don't yet expose this new information
anywhere in the UI layer.
While blocks were not allowed to be computed by the provider, nested
objects can be. Remove the errors regarding blocks and verify unknown
values are valid.
We have a few different .proto files in this repository that all need to
get recompiled into .pb.go files each time we change them, but we were
previously handling that with some scripts that just assumed that protoc
and the relevant plugins were already installed on the system somewhere,
at the right versions.
In practice we've been constantly flopping between different versions of
these tools due to folks having different versions installed in their
development environments. In particular, the state of the .pb.go files
in the prior commit wasn't reproducible by any single version of the tools
because they've all slightly diverged from one another.
In the interests of being more consistent here and avoiding accidental
inconsistencies, we'll now centralize the protocol buffer compile steps
all into a single tool that knows how to fetch and install the expected
versions of the various tools we need and then run those tools with the
right options to get a stable result.
If we want to upgrade to either a newer protoc or a newer protoc-gen-go
in future then we'll do that in a central location and update all of the
.pb.go files at the same time, so that we're always consistently tracking
the same version of protocol buffers everywhere.
While doing this I attempted to keep as close as possible to the toolchain
we'd most recently used, but since they were not consistent with each
other they've now all changed which version numbers they record at minimum,
and the planproto stub in particular now also has a slightly different
descriptor serialization but is otherwise offering the same API.
CanChainFrom needs to be able to handle move statements from different
relative modules, re-implementing with addrs.anyKey
Add the anyKey InstanceKey value to the addrs package to simplify module
path comparison. This allows all combinations of module path
representation to be normalized into a ModuleInstance which can be
compared directly, rather than dealing with multiple levels of different
prefix types.
The -force-copy flag to init should automatically migrate state.
Previously this was not applied to one case: when migrating from
a backend with multiple workspaces to another backend supporting
multiple workspaces. I believe this was an oversight so this commit
fixes that.
We're aware of several quirks of this command's current design, which
result from some existing architectural limitations that we can't address
immediately.
However, we do still want to make this command available in its current
capacity as an incremental improvement, so as a compromise we'll document
it as experimental. Our intent here is to exclude it from the
Terraform 1.0 Compatibility Promises so that we can have the space to
continue to improve the design as other parts of the overall Terraform
system gain new capabilities.
We don't currently have any concrete plan for this command to be
stabilized and subject to compatibility promises. That decision will
follow from ongoing discussions with other teams whose systems may need to
change in order to support the final design of "terraform add".
The code adopted from block diffs was not set to handle null and unknown
values, as those are not allowed for blocks.
We also revert the change to formatting nested object types as single
attributes, because the attribute formatter cannot handle sensitive
values from the schema. This presents some awkward syntax for diffs for
now, but should suffice until the entire formatter can be refactored to
better handle these new nested types.
Go 1.17 includes a breaking change to both net.ParseIP and net.ParseCIDR
functions to reject IPv4 address octets written with leading zeros.
Our use of these functions as part of the various CIDR functions in the
Terraform language doesn't have the same security concerns that the Go
team had in evaluating this change to the standard library, and so we
can't justify an exception to our v1.0 compatibility promises on the same
sort of security grounds that the Go team used to justify their
compatibility exception.
For that reason, we'll now use our own fork of the Go library functions
which has the new check disabled in order to preserve the prior behavior.
We're taking this path, rather than pre-normalizing the IP address before
calling into the standard library, because an additional normalization
layer would be entirely new code and additional complexity, whereas this
fork is relatively minor in terms of code size and avoids any significant
changes to our own calls to these functions.
Thanks to the Kubernetes team for their prior work on carving out a subset
of the "net" package for their similar backward-compatibility concern.
Our "ipaddr" package here is a lightly-modified fork of their fork, with
only the comments changed to talk about Terraform instead of Kubernetes.
This fork is not intended for use in any other future feature
implementations, because they wouldn't be subject to the same
compatibility constraints as our existing functions. We will use these
forked implementations for new callers only if consistency with the
behavior of the existing functions is a key requirement.
Chris Arcand