112 lines
4.3 KiB
Go
112 lines
4.3 KiB
Go
package terraform
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import (
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"fmt"
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"github.com/hashicorp/hcl/v2"
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"github.com/hashicorp/terraform/tfdiags"
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"github.com/zclconf/go-cty/cty"
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)
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// evaluateResourceForEachExpression interprets a "for_each" argument on a resource.
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//
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// Returns a cty.Value map, and diagnostics if necessary. It will return nil if
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// the expression is nil, and is used to distinguish between an unset for_each and an
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// empty map
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func evaluateResourceForEachExpression(expr hcl.Expression, ctx EvalContext) (forEach map[string]cty.Value, diags tfdiags.Diagnostics) {
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forEachMap, known, diags := evaluateResourceForEachExpressionKnown(expr, ctx)
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if !known {
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// Attach a diag as we do with count, with the same downsides
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diags = diags.Append(&hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Invalid for_each argument",
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Detail: `The "for_each" value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how many instances will be created. To work around this, use the -target argument to first apply only the resources that the for_each depends on.`,
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Subject: expr.Range().Ptr(),
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})
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}
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return forEachMap, diags
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}
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// evaluateResourceForEachExpressionKnown is like evaluateResourceForEachExpression
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// except that it handles an unknown result by returning an empty map and
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// a known = false, rather than by reporting the unknown value as an error
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// diagnostic.
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func evaluateResourceForEachExpressionKnown(expr hcl.Expression, ctx EvalContext) (forEach map[string]cty.Value, known bool, diags tfdiags.Diagnostics) {
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if expr == nil {
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return nil, true, nil
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}
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forEachVal, forEachDiags := ctx.EvaluateExpr(expr, cty.DynamicPseudoType, nil)
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diags = diags.Append(forEachDiags)
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if diags.HasErrors() {
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return nil, true, diags
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}
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switch {
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case forEachVal.IsNull():
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diags = diags.Append(&hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Invalid for_each argument",
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Detail: `The given "for_each" argument value is unsuitable: the given "for_each" argument value is null. A map, or set of strings is allowed.`,
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Subject: expr.Range().Ptr(),
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})
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return nil, true, diags
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case !forEachVal.IsKnown():
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return map[string]cty.Value{}, false, diags
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}
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if !forEachVal.CanIterateElements() || forEachVal.Type().IsListType() || forEachVal.Type().IsTupleType() {
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diags = diags.Append(&hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Invalid for_each argument",
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Detail: fmt.Sprintf(`The given "for_each" argument value is unsuitable: the "for_each" argument must be a map, or set of strings, and you have provided a value of type %s.`, forEachVal.Type().FriendlyName()),
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Subject: expr.Range().Ptr(),
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})
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return nil, true, diags
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}
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// If the map is empty ({}), return an empty map, because cty will return nil when representing {} AsValueMap
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// This also covers an empty set (toset([]))
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if forEachVal.LengthInt() == 0 {
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return map[string]cty.Value{}, true, diags
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}
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if forEachVal.Type().IsSetType() {
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if forEachVal.Type().ElementType() != cty.String {
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diags = diags.Append(&hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Invalid for_each set argument",
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Detail: fmt.Sprintf(`The given "for_each" argument value is unsuitable: "for_each" supports maps and sets of strings, but you have provided a set containing type %s.`, forEachVal.Type().ElementType().FriendlyName()),
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Subject: expr.Range().Ptr(),
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})
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return nil, true, diags
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}
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// A set may contain unknown values that must be
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// discovered by checking with IsWhollyKnown (which iterates through the
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// structure), while for maps in cty, keys can never be unknown or null,
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// thus the earlier IsKnown check suffices for maps
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if !forEachVal.IsWhollyKnown() {
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return map[string]cty.Value{}, false, diags
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}
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// A set of strings may contain null, which makes it impossible to
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// convert to a map, so we must return an error
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it := forEachVal.ElementIterator()
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for it.Next() {
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item, _ := it.Element()
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if item.IsNull() {
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diags = diags.Append(&hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Invalid for_each set argument",
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Detail: fmt.Sprintf(`The given "for_each" argument value is unsuitable: "for_each" sets must not contain null values.`),
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Subject: expr.Range().Ptr(),
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})
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return nil, true, diags
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}
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}
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}
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return forEachVal.AsValueMap(), true, nil
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}
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