config: allow HCL2 experiment opt-in (build-time flag to enable)

Use the new HCL2 config loader when the opt-in comment #terraform:hcl2 is
present in a .tf file.

For now this is disabled for "normal" builds and enabled only if
explicitly configured via a linker flag during build. This is because it's
not yet in a good state to be released: the HCL2 loader produces RawConfig
objects that the validator and interpolator can't yet deal with, and so
using HCL2 for anything non-trivial currently causes Terraform to crash
in real use.
This commit is contained in:
Martin Atkins 2017-09-28 15:15:14 -07:00
parent b0215fcd0f
commit d91327eaa0
5 changed files with 143 additions and 4 deletions

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@ -1,8 +1,10 @@
package config
import (
"bufio"
"fmt"
"io"
"os"
)
// configurable is an interface that must be implemented by any configuration
@ -27,15 +29,52 @@ type importTree struct {
// imports.
type fileLoaderFunc func(path string) (configurable, []string, error)
// Set this to a non-empty value at link time to enable the HCL2 experiment.
// This is not currently enabled for release builds.
//
// For example:
// go install -ldflags="-X github.com/hashicorp/terraform/config.enableHCL2Experiment=true" github.com/hashicorp/terraform
var enableHCL2Experiment = ""
// loadTree takes a single file and loads the entire importTree for that
// file. This function detects what kind of configuration file it is an
// executes the proper fileLoaderFunc.
func loadTree(root string) (*importTree, error) {
var f fileLoaderFunc
switch ext(root) {
case ".tf", ".tf.json":
f = loadFileHcl
default:
// HCL2 experiment is currently activated at build time via the linker.
// See the comment on this variable for more information.
if enableHCL2Experiment == "" {
// Main-line behavior: always use the original HCL parser
switch ext(root) {
case ".tf", ".tf.json":
f = loadFileHcl
default:
}
} else {
// Experimental behavior: use the HCL2 parser if the opt-in comment
// is present.
switch ext(root) {
case ".tf":
// We need to sniff the file for the opt-in comment line to decide
// if the file is participating in the HCL2 experiment.
cf, err := os.Open(root)
if err != nil {
return nil, err
}
sc := bufio.NewScanner(cf)
for sc.Scan() {
if sc.Text() == "#terraform:hcl2" {
f = globalHCL2Loader.loadFile
}
}
if f == nil {
f = loadFileHcl
}
case ".tf.json":
f = loadFileHcl
default:
}
}
if f == nil {

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@ -0,0 +1,81 @@
package config
import (
"testing"
)
func TestImportTreeHCL2Experiment(t *testing.T) {
// Can only run this test if we're built with the experiment enabled.
// Enable this test by passing the following option to "go test":
// -ldflags="-X github.com/hashicorp/terraform/config.enableHCL2Experiment=true"
// See the comment associated with this flag variable for more information.
if enableHCL2Experiment == "" {
t.Skip("HCL2 experiment is not enabled")
}
t.Run("HCL not opted in", func(t *testing.T) {
// .tf file without opt-in should use the old HCL parser
imp, err := loadTree("test-fixtures/hcl2-experiment-switch/not-opted-in.tf")
if err != nil {
t.Fatal(err)
}
tree, err := imp.ConfigTree()
if err != nil {
t.Fatalf("unexpected error loading not-opted-in.tf: %s", err)
}
cfg := tree.Config
if got, want := len(cfg.Locals), 1; got != want {
t.Fatalf("wrong number of locals %#v; want %#v", got, want)
}
if cfg.Locals[0].RawConfig.Raw == nil {
// Having RawConfig.Raw indicates the old loader
t.Fatal("local has no RawConfig.Raw")
}
})
t.Run("HCL opted in", func(t *testing.T) {
// .tf file with opt-in should use the new HCL2 parser
imp, err := loadTree("test-fixtures/hcl2-experiment-switch/opted-in.tf")
if err != nil {
t.Fatal(err)
}
tree, err := imp.ConfigTree()
if err != nil {
t.Fatalf("unexpected error loading opted-in.tf: %s", err)
}
cfg := tree.Config
if got, want := len(cfg.Locals), 1; got != want {
t.Fatalf("wrong number of locals %#v; want %#v", got, want)
}
if cfg.Locals[0].RawConfig.Body == nil {
// Having RawConfig.Body indicates the new loader
t.Fatal("local has no RawConfig.Body")
}
})
t.Run("JSON ineligible", func(t *testing.T) {
// .tf.json file should always use the old HCL parser
imp, err := loadTree("test-fixtures/hcl2-experiment-switch/not-eligible.tf.json")
if err != nil {
t.Fatal(err)
}
tree, err := imp.ConfigTree()
if err != nil {
t.Fatalf("unexpected error loading not-eligible.tf.json: %s", err)
}
cfg := tree.Config
if got, want := len(cfg.Locals), 1; got != want {
t.Fatalf("wrong number of locals %#v; want %#v", got, want)
}
if cfg.Locals[0].RawConfig.Raw == nil {
// Having RawConfig.Raw indicates the old loader
t.Fatal("local has no RawConfig.Raw")
}
})
}

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@ -0,0 +1,5 @@
{
"locals": {
"foo": "baz"
}
}

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@ -0,0 +1,7 @@
# The use of an equals to assign "locals" is something that would be rejected
# by the HCL2 parser (equals is reserved for attributes only) and so we can
# use it to verify that the old HCL parser was used.
locals {
foo = "bar"
}

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@ -0,0 +1,7 @@
#terraform:hcl2
locals {
# This direct expression is something that would be rejected by the old HCL
# parser, so we can use it as a marker that the HCL2 parser was used.
foo = 1 + 2
}