terraform/internal/addrs/parse_ref.go

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package addrs
import (
"fmt"
"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/hclsyntax"
"github.com/hashicorp/terraform/internal/tfdiags"
)
// Reference describes a reference to an address with source location
// information.
type Reference struct {
Subject Referenceable
SourceRange tfdiags.SourceRange
Remaining hcl.Traversal
}
// ParseRef attempts to extract a referencable address from the prefix of the
// given traversal, which must be an absolute traversal or this function
// will panic.
//
// If no error diagnostics are returned, the returned reference includes the
// address that was extracted, the source range it was extracted from, and any
// remaining relative traversal that was not consumed as part of the
// reference.
//
// If error diagnostics are returned then the Reference value is invalid and
// must not be used.
func ParseRef(traversal hcl.Traversal) (*Reference, tfdiags.Diagnostics) {
ref, diags := parseRef(traversal)
// Normalize a little to make life easier for callers.
if ref != nil {
if len(ref.Remaining) == 0 {
ref.Remaining = nil
}
}
return ref, diags
}
// ParseRefStr is a helper wrapper around ParseRef that takes a string
// and parses it with the HCL native syntax traversal parser before
// interpreting it.
//
// This should be used only in specialized situations since it will cause the
// created references to not have any meaningful source location information.
// If a reference string is coming from a source that should be identified in
// error messages then the caller should instead parse it directly using a
// suitable function from the HCL API and pass the traversal itself to
// ParseRef.
//
// Error diagnostics are returned if either the parsing fails or the analysis
// of the traversal fails. There is no way for the caller to distinguish the
// two kinds of diagnostics programmatically. If error diagnostics are returned
// the returned reference may be nil or incomplete.
func ParseRefStr(str string) (*Reference, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
traversal, parseDiags := hclsyntax.ParseTraversalAbs([]byte(str), "", hcl.Pos{Line: 1, Column: 1})
diags = diags.Append(parseDiags)
if parseDiags.HasErrors() {
return nil, diags
}
ref, targetDiags := ParseRef(traversal)
diags = diags.Append(targetDiags)
return ref, diags
}
func parseRef(traversal hcl.Traversal) (*Reference, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
root := traversal.RootName()
rootRange := traversal[0].SourceRange()
switch root {
case "count":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: CountAttr{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
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case "each":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: ForEachAttr{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
case "data":
if len(traversal) < 3 {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: `The "data" object must be followed by two attribute names: the data source type and the resource name.`,
Subject: traversal.SourceRange().Ptr(),
})
return nil, diags
}
remain := traversal[1:] // trim off "data" so we can use our shared resource reference parser
return parseResourceRef(DataResourceMode, rootRange, remain)
lang: Allow "resource." prefix as another way to refer to resources The current way to refer to a managed resource is to use its resource type name as a top-level symbol in the reference. This is convenient and makes sense given that managed resources are the primary kind of object in Terraform. However, it does mean that an externally-extensible namespace (the set of all possible resource type names) overlaps with a reserved word namespace (the special prefixes like "path", "var", etc), and thus introducing any new reserved prefix in future risks masking an existing resource type so it can't be used anymore. We only intend to introduce new reserved symbols as part of future language editions that each module can opt into separately, and when doing so we will always research to try to choose a name that doesn't overlap with commonly-used providers, but not all providers are visible to us and so there is always a small chance that the name we choose will already be in use by a third-party provider. In preparation for that event, this introduces an alternative way to refer to managed resources that mimics the reference style used for data resources: resource.type.name . When using this form, the second portion is _always_ a resource type name and never a reserved word. There is currently no need to use this because all of the already-reserved symbol names are effectively blocked from use by existing Terraform versions that lack this escape hatch. Therefore there's no explicit documentation about it yet. The intended use for this is that a module upgrade tool for a future language edition would detect references to resource types that have now become reserved words and add the "resource." prefix to keep that functionality working. Existing modules that aren't opted in to the new language edition would keep working without that prefix, thus keeping to compatibility promises.
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case "resource":
// This is an alias for the normal case of just using a managed resource
// type as a top-level symbol, which will serve as an escape mechanism
// if a later edition of the Terraform language introduces a new
// reference prefix that conflicts with a resource type name in an
// existing provider. In that case, the edition upgrade tool can
// rewrite foo.bar into resource.foo.bar to ensure that "foo" remains
// interpreted as a resource type name rather than as the new reserved
// word.
if len(traversal) < 3 {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: `The "resource" object must be followed by two attribute names: the resource type and the resource name.`,
Subject: traversal.SourceRange().Ptr(),
})
return nil, diags
}
remain := traversal[1:] // trim off "resource" so we can use our shared resource reference parser
return parseResourceRef(ManagedResourceMode, rootRange, remain)
case "local":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: LocalValue{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
case "module":
callName, callRange, remain, diags := parseSingleAttrRef(traversal)
if diags.HasErrors() {
return nil, diags
}
// A traversal starting with "module" can either be a reference to an
// entire module, or to a single output from a module instance,
// depending on what we find after this introducer.
callInstance := ModuleCallInstance{
Call: ModuleCall{
Name: callName,
},
Key: NoKey,
}
if len(remain) == 0 {
// Reference to an entire module. Might alternatively be a
// reference to a single instance of a particular module, but the
// caller will need to deal with that ambiguity since we don't have
// enough context here.
return &Reference{
Subject: callInstance.Call,
SourceRange: tfdiags.SourceRangeFromHCL(callRange),
Remaining: remain,
}, diags
}
if idxTrav, ok := remain[0].(hcl.TraverseIndex); ok {
var err error
callInstance.Key, err = ParseInstanceKey(idxTrav.Key)
if err != nil {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid index key",
Detail: fmt.Sprintf("Invalid index for module instance: %s.", err),
Subject: &idxTrav.SrcRange,
})
return nil, diags
}
remain = remain[1:]
if len(remain) == 0 {
// Also a reference to an entire module instance, but we have a key
// now.
return &Reference{
Subject: callInstance,
SourceRange: tfdiags.SourceRangeFromHCL(hcl.RangeBetween(callRange, idxTrav.SrcRange)),
Remaining: remain,
}, diags
}
}
if attrTrav, ok := remain[0].(hcl.TraverseAttr); ok {
remain = remain[1:]
return &Reference{
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Subject: AbsModuleCallOutput{
Name: attrTrav.Name,
Call: callInstance,
},
SourceRange: tfdiags.SourceRangeFromHCL(hcl.RangeBetween(callRange, attrTrav.SrcRange)),
Remaining: remain,
}, diags
}
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: "Module instance objects do not support this operation.",
Subject: remain[0].SourceRange().Ptr(),
})
return nil, diags
case "path":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: PathAttr{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
case "self":
return &Reference{
Subject: Self,
SourceRange: tfdiags.SourceRangeFromHCL(rootRange),
Remaining: traversal[1:],
}, diags
case "terraform":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: TerraformAttr{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
case "var":
name, rng, remain, diags := parseSingleAttrRef(traversal)
return &Reference{
Subject: InputVariable{Name: name},
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
case "template", "lazy", "arg":
// These names are all pre-emptively reserved in the hope of landing
// some version of "template values" or "lazy expressions" feature
// before the next opt-in language edition, but don't yet do anything.
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Reserved symbol name",
Detail: fmt.Sprintf("The symbol name %q is reserved for use in a future Terraform version. If you are using a provider that already uses this as a resource type name, add the prefix \"resource.\" to force interpretation as a resource type name.", root),
Subject: rootRange.Ptr(),
})
return nil, diags
default:
return parseResourceRef(ManagedResourceMode, rootRange, traversal)
}
}
func parseResourceRef(mode ResourceMode, startRange hcl.Range, traversal hcl.Traversal) (*Reference, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
if len(traversal) < 2 {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: `A reference to a resource type must be followed by at least one attribute access, specifying the resource name.`,
Subject: hcl.RangeBetween(traversal[0].SourceRange(), traversal[len(traversal)-1].SourceRange()).Ptr(),
})
return nil, diags
}
var typeName, name string
switch tt := traversal[0].(type) { // Could be either root or attr, depending on our resource mode
case hcl.TraverseRoot:
typeName = tt.Name
case hcl.TraverseAttr:
typeName = tt.Name
default:
// If it isn't a TraverseRoot then it must be a "data" reference.
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: `The "data" object does not support this operation.`,
Subject: traversal[0].SourceRange().Ptr(),
})
return nil, diags
}
attrTrav, ok := traversal[1].(hcl.TraverseAttr)
if !ok {
var what string
switch mode {
case DataResourceMode:
what = "data source"
default:
what = "resource type"
}
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: fmt.Sprintf(`A reference to a %s must be followed by at least one attribute access, specifying the resource name.`, what),
Subject: traversal[1].SourceRange().Ptr(),
})
return nil, diags
}
name = attrTrav.Name
rng := hcl.RangeBetween(startRange, attrTrav.SrcRange)
remain := traversal[2:]
resourceAddr := Resource{
Mode: mode,
Type: typeName,
Name: name,
}
resourceInstAddr := ResourceInstance{
Resource: resourceAddr,
Key: NoKey,
}
if len(remain) == 0 {
// This might actually be a reference to the collection of all instances
// of the resource, but we don't have enough context here to decide
// so we'll let the caller resolve that ambiguity.
return &Reference{
Subject: resourceAddr,
SourceRange: tfdiags.SourceRangeFromHCL(rng),
}, diags
}
if idxTrav, ok := remain[0].(hcl.TraverseIndex); ok {
var err error
resourceInstAddr.Key, err = ParseInstanceKey(idxTrav.Key)
if err != nil {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid index key",
Detail: fmt.Sprintf("Invalid index for resource instance: %s.", err),
Subject: &idxTrav.SrcRange,
})
return nil, diags
}
remain = remain[1:]
rng = hcl.RangeBetween(rng, idxTrav.SrcRange)
}
return &Reference{
Subject: resourceInstAddr,
SourceRange: tfdiags.SourceRangeFromHCL(rng),
Remaining: remain,
}, diags
}
func parseSingleAttrRef(traversal hcl.Traversal) (string, hcl.Range, hcl.Traversal, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
root := traversal.RootName()
rootRange := traversal[0].SourceRange()
if len(traversal) < 2 {
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: fmt.Sprintf("The %q object cannot be accessed directly. Instead, access one of its attributes.", root),
Subject: &rootRange,
})
return "", hcl.Range{}, nil, diags
}
if attrTrav, ok := traversal[1].(hcl.TraverseAttr); ok {
return attrTrav.Name, hcl.RangeBetween(rootRange, attrTrav.SrcRange), traversal[2:], diags
}
diags = diags.Append(&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid reference",
Detail: fmt.Sprintf("The %q object does not support this operation.", root),
Subject: traversal[1].SourceRange().Ptr(),
})
return "", hcl.Range{}, nil, diags
}