internal/earlyconfig: Liberal config parsing for init

This is an alternative to the full config loader in the "configs" package
that is good for "early" use-cases like "terraform init", where we want
to find out what our dependencies are without getting tripped up on any
other errors that might be present.
This commit is contained in:
Martin Atkins 2019-01-08 15:23:09 -08:00
parent 21d65cfa9a
commit 8ca1fcec51
5 changed files with 373 additions and 0 deletions

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package earlyconfig
import (
"fmt"
"sort"
version "github.com/hashicorp/go-version"
"github.com/hashicorp/terraform-config-inspect/tfconfig"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/moduledeps"
"github.com/hashicorp/terraform/plugin/discovery"
"github.com/hashicorp/terraform/tfdiags"
)
// A Config is a node in the tree of modules within a configuration.
//
// The module tree is constructed by following ModuleCall instances recursively
// through the root module transitively into descendent modules.
type Config struct {
// RootModule points to the Config for the root module within the same
// module tree as this module. If this module _is_ the root module then
// this is self-referential.
Root *Config
// ParentModule points to the Config for the module that directly calls
// this module. If this is the root module then this field is nil.
Parent *Config
// Path is a sequence of module logical names that traverse from the root
// module to this config. Path is empty for the root module.
//
// This should only be used to display paths to the end-user in rare cases
// where we are talking about the static module tree, before module calls
// have been resolved. In most cases, a addrs.ModuleInstance describing
// a node in the dynamic module tree is better, since it will then include
// any keys resulting from evaluating "count" and "for_each" arguments.
Path addrs.Module
// ChildModules points to the Config for each of the direct child modules
// called from this module. The keys in this map match the keys in
// Module.ModuleCalls.
Children map[string]*Config
// Module points to the object describing the configuration for the
// various elements (variables, resources, etc) defined by this module.
Module *tfconfig.Module
// CallPos is the source position for the header of the module block that
// requested this module.
//
// This field is meaningless for the root module, where its contents are undefined.
CallPos tfconfig.SourcePos
// SourceAddr is the source address that the referenced module was requested
// from, as specified in configuration.
//
// This field is meaningless for the root module, where its contents are undefined.
SourceAddr string
// Version is the specific version that was selected for this module,
// based on version constraints given in configuration.
//
// This field is nil if the module was loaded from a non-registry source,
// since versions are not supported for other sources.
//
// This field is meaningless for the root module, where it will always
// be nil.
Version *version.Version
}
// ProviderDependencies returns the provider dependencies for the recieving
// config, including all of its descendent modules.
func (c *Config) ProviderDependencies() (*moduledeps.Module, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
var name string
if len(c.Path) > 0 {
name = c.Path[len(c.Path)-1]
}
ret := &moduledeps.Module{
Name: name,
}
providers := make(moduledeps.Providers)
for name, reqs := range c.Module.RequiredProviders {
inst := moduledeps.ProviderInstance(name)
var constraints version.Constraints
for _, reqStr := range reqs {
if reqStr == "" {
constraint, err := version.NewConstraint(reqStr)
if err != nil {
diags = diags.Append(wrapDiagnostic(tfconfig.Diagnostic{
Severity: tfconfig.DiagError,
Summary: "Invalid provider version constraint",
Detail: fmt.Sprintf("Invalid version constraint %q for provider %s.", reqStr, name),
}))
continue
}
constraints = append(constraints, constraint...)
}
}
providers[inst] = moduledeps.ProviderDependency{
Constraints: discovery.NewConstraints(constraints),
Reason: moduledeps.ProviderDependencyExplicit,
}
}
ret.Providers = providers
childNames := make([]string, 0, len(c.Children))
for name := range c.Children {
childNames = append(childNames, name)
}
sort.Strings(childNames)
for _, name := range childNames {
child, childDiags := c.Children[name].ProviderDependencies()
ret.Children = append(ret.Children, child)
diags = diags.Append(childDiags)
}
return ret, diags
}

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package earlyconfig
import (
"fmt"
"sort"
version "github.com/hashicorp/go-version"
"github.com/hashicorp/terraform-config-inspect/tfconfig"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/tfdiags"
)
// BuildConfig constructs a Config from a root module by loading all of its
// descendent modules via the given ModuleWalker.
func BuildConfig(root *tfconfig.Module, walker ModuleWalker) (*Config, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
cfg := &Config{
Module: root,
}
cfg.Root = cfg // Root module is self-referential.
cfg.Children, diags = buildChildModules(cfg, walker)
return cfg, diags
}
func buildChildModules(parent *Config, walker ModuleWalker) (map[string]*Config, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
ret := map[string]*Config{}
calls := parent.Module.ModuleCalls
// We'll sort the calls by their local names so that they'll appear in a
// predictable order in any logging that's produced during the walk.
callNames := make([]string, 0, len(calls))
for k := range calls {
callNames = append(callNames, k)
}
sort.Strings(callNames)
for _, callName := range callNames {
call := calls[callName]
path := make([]string, len(parent.Path)+1)
copy(path, parent.Path)
path[len(path)-1] = call.Name
vc, err := version.NewConstraint(call.Version)
if err != nil {
diags = diags.Append(wrapDiagnostic(tfconfig.Diagnostic{
Severity: tfconfig.DiagError,
Summary: "Invalid version constraint",
Detail: fmt.Sprintf("Module %q (declared at %s line %d) has invalid version constraint: %s.", callName, call.Pos.Filename, call.Pos.Line, err),
}))
continue
}
req := ModuleRequest{
Name: call.Name,
Path: path,
SourceAddr: call.Source,
VersionConstraints: vc,
Parent: parent,
CallPos: call.Pos,
}
mod, ver, modDiags := walker.LoadModule(&req)
diags = append(diags, modDiags...)
if mod == nil {
// nil can be returned if the source address was invalid and so
// nothing could be loaded whatsoever. LoadModule should've
// returned at least one error diagnostic in that case.
continue
}
child := &Config{
Parent: parent,
Root: parent.Root,
Path: path,
Module: mod,
CallPos: call.Pos,
SourceAddr: call.Source,
Version: ver,
}
child.Children, modDiags = buildChildModules(child, walker)
diags = diags.Append(modDiags)
ret[call.Name] = child
}
return ret, diags
}
// ModuleRequest is used as part of the ModuleWalker interface used with
// function BuildConfig.
type ModuleRequest struct {
// Name is the "logical name" of the module call within configuration.
// This is provided in case the name is used as part of a storage key
// for the module, but implementations must otherwise treat it as an
// opaque string. It is guaranteed to have already been validated as an
// HCL identifier and UTF-8 encoded.
Name string
// Path is a list of logical names that traverse from the root module to
// this module. This can be used, for example, to form a lookup key for
// each distinct module call in a configuration, allowing for multiple
// calls with the same name at different points in the tree.
Path addrs.Module
// SourceAddr is the source address string provided by the user in
// configuration.
SourceAddr string
// VersionConstraint is the version constraint applied to the module in
// configuration.
VersionConstraints version.Constraints
// Parent is the partially-constructed module tree node that the loaded
// module will be added to. Callers may refer to any field of this
// structure except Children, which is still under construction when
// ModuleRequest objects are created and thus has undefined content.
// The main reason this is provided is so that full module paths can
// be constructed for uniqueness.
Parent *Config
// CallRange is the source position for the header of the "module" block
// in configuration that prompted this request.
CallPos tfconfig.SourcePos
}
// ModuleWalker is an interface used with BuildConfig.
type ModuleWalker interface {
LoadModule(req *ModuleRequest) (*tfconfig.Module, *version.Version, tfdiags.Diagnostics)
}
// ModuleWalkerFunc is an implementation of ModuleWalker that directly wraps
// a callback function, for more convenient use of that interface.
type ModuleWalkerFunc func(req *ModuleRequest) (*tfconfig.Module, *version.Version, tfdiags.Diagnostics)
func (f ModuleWalkerFunc) LoadModule(req *ModuleRequest) (*tfconfig.Module, *version.Version, tfdiags.Diagnostics) {
return f(req)
}

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package earlyconfig
import (
"fmt"
"github.com/hashicorp/terraform-config-inspect/tfconfig"
"github.com/hashicorp/terraform/tfdiags"
)
func wrapDiagnostics(diags tfconfig.Diagnostics) tfdiags.Diagnostics {
ret := make(tfdiags.Diagnostics, len(diags))
for i, diag := range diags {
ret[i] = wrapDiagnostic(diag)
}
return ret
}
func wrapDiagnostic(diag tfconfig.Diagnostic) tfdiags.Diagnostic {
return wrappedDiagnostic{
d: diag,
}
}
type wrappedDiagnostic struct {
d tfconfig.Diagnostic
}
func (d wrappedDiagnostic) Severity() tfdiags.Severity {
switch d.d.Severity {
case tfconfig.DiagError:
return tfdiags.Error
case tfconfig.DiagWarning:
return tfdiags.Warning
default:
// Should never happen since there are no other severities
return 0
}
}
func (d wrappedDiagnostic) Description() tfdiags.Description {
// Since the inspect library doesn't produce precise source locations,
// we include the position information as part of the error message text.
// See the comment inside method "Source" for more information.
switch {
case d.d.Pos == nil:
return tfdiags.Description{
Summary: d.d.Summary,
Detail: d.d.Detail,
}
case d.d.Detail != "":
return tfdiags.Description{
Summary: d.d.Summary,
Detail: fmt.Sprintf("On %s line %d: %s", d.d.Pos.Filename, d.d.Pos.Line, d.d.Detail),
}
default:
return tfdiags.Description{
Summary: fmt.Sprintf("%s (on %s line %d)", d.d.Summary, d.d.Pos.Filename, d.d.Pos.Line),
}
}
}
func (d wrappedDiagnostic) Source() tfdiags.Source {
// Since the inspect library is constrained by the lowest common denominator
// between legacy HCL and modern HCL, it only returns ranges at whole-line
// granularity, and that isn't sufficient to populate a tfdiags.Source
// and so we'll just omit ranges altogether and include the line number in
// the Description text.
//
// Callers that want to return nicer errors should consider reacting to
// earlyconfig errors by attempting a follow-up parse with the normal
// config loader, which can produce more precise source location
// information.
return tfdiags.Source{}
}
func (d wrappedDiagnostic) FromExpr() *tfdiags.FromExpr {
return nil
}

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// Package earlyconfig is a specialized alternative to the top-level "configs"
// package that does only shallow processing of configuration and is therefore
// able to be much more liberal than the full config loader in what it accepts.
//
// In particular, it can accept both current and legacy HCL syntax, and it
// ignores top-level blocks that it doesn't recognize. These two characteristics
// make this package ideal for dependency-checking use-cases so that we are
// more likely to be able to return an error message about an explicit
// incompatibility than to return a less-actionable message about a construct
// not being supported.
//
// However, its liberal approach also means it should be used sparingly. It
// exists primarily for "terraform init", so that it is able to detect
// incompatibilities more robustly when installing dependencies. For most
// other use-cases, use the "configs" and "configs/configload" packages.
//
// Package earlyconfig is a wrapper around the terraform-config-inspect
// codebase, adding to it just some helper functionality for Terraform's own
// use-cases.
package earlyconfig

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package earlyconfig
import (
"github.com/hashicorp/terraform-config-inspect/tfconfig"
"github.com/hashicorp/terraform/tfdiags"
)
// LoadModule loads some top-level metadata for the module in the given
// directory.
func LoadModule(dir string) (*tfconfig.Module, tfdiags.Diagnostics) {
mod, diags := tfconfig.LoadModule(dir)
return mod, wrapDiagnostics(diags)
}