Adding rule for azurerm resource missing tags

[guybartal]

Resolves #133 based on the work done in terraform-linters/tflint#617 for AWS.

this PR allows you to get notified for resources with missing required tags:

rule "azurerm_resource_missing_tags" {
  enabled = true
  exclude = [] (list of resource types to exclude, optional)
  tags = ["Environment", "Department"]
}

[guybartal]

@wata727 , @hattan can you please review?

[wata727]

Nice! Added integration test would be very helpful :)

Left some comments, but mostly looks good. If you can check and fix it, I would like to merge this PR.

[wata727]

runner.EmitIssue returns an error, so handle the error in this function and handle it in the caller.
https://pkg.go.dev/github.com/terraform-linters/tflint-plugin-sdk/tflint#Runner.EmitIssue

[guybartal]

error handled both in this function and in the caller using runner.EnsureNoError

[wata727]

The EnsureNoError is a helper function for handling warnings returned by EvaluateExpr. So, there is no need to use it here. Return an error and check it in the caller as follows:

diff --git a/rules/azurerm_resource_missing_tags.go b/rules/azurerm_resource_missing_tags.go
index c6fc048..07bcbc7 100644
--- a/rules/azurerm_resource_missing_tags.go
+++ b/rules/azurerm_resource_missing_tags.go
@@ -87,15 +87,16 @@ func (r *AzurermResourceMissingTagsRule) Check(runner tflint.Runner) error {
 				wantType := cty.Map(cty.String)
 				err := runner.EvaluateExpr(attribute.Expr, &resourceTags, &tflint.EvaluateExprOption{WantType: &wantType})
 				err = runner.EnsureNoError(err, func() error {
-					r.emitIssue(runner, resourceTags, config, attribute.Expr.Range())
-					return nil
+					return r.emitIssue(runner, resourceTags, config, attribute.Expr.Range())
 				})
 				if err != nil {
 					return err
 				}
 			} else {
 				logger.Debug("checking", "resource type", resource.Labels[0], "resource name", resource.Labels[1])
-				r.emitIssue(runner, map[string]string{}, config, resource.DefRange)
+				if err := r.emitIssue(runner, map[string]string{}, config, resource.DefRange); err != nil {
+					return err
+				}
 			}
 		}
 	}
@@ -103,7 +104,7 @@ func (r *AzurermResourceMissingTagsRule) Check(runner tflint.Runner) error {
 	return nil
 }
 
-func (r *AzurermResourceMissingTagsRule) emitIssue(runner tflint.Runner, tags map[string]string, config azurermResourceTagsRuleConfig, location hcl.Range) {
+func (r *AzurermResourceMissingTagsRule) emitIssue(runner tflint.Runner, tags map[string]string, config azurermResourceTagsRuleConfig, location hcl.Range) error {
 	var missing []string
 	for _, tag := range config.Tags {
 		if _, ok := tags[tag]; !ok {
@@ -114,8 +115,9 @@ func (r *AzurermResourceMissingTagsRule) emitIssue(runner tflint.Runner, tags ma
 		sort.Strings(missing)
 		wanted := strings.Join(missing, ", ")
 		issue := fmt.Sprintf("The resource is missing the following tags: %s.", wanted)
-		runner.EmitIssue(r, issue, location)
+		return runner.EmitIssue(r, issue, location)
 	}
+	return nil
 }
 
 func stringInSlice(a string, list []string) bool {

[guybartal]

got it, thanks!
fixed.

[wata727]

It would be nice if go generate could easily update the list of resources by adding a line like this:

//go:generate go run -tags generators ./generator/main.go

[guybartal]

go generate comment was added,
I had to put it after the package declaration, otherwise golint asks for special comment format Package tags...
by the way I've noticed that golint is deprecated and should be replaced (golang/go#38968)

[wata727]

Yeah, we'll need to replace it with golangci-lint or simply turn it off. For rulesets, godoc is not so important, so we may not need to enforce this rule.

[guybartal]

Nice! Added integration test would be very helpful :)

Left some comments, but mostly looks good. If you can check and fix it, I would like to merge this PR.

Thanks for the feedback @WATA72 😊
I'll fix the code based on your comments and will update you so you could merge.

[wata727]

Good, please check the error handling lastly.

[guybartal]

Good, please check the error handling lastly.

did I fix it correctly?

[wata727]

Perfect. Thanks!

[guybartal]

Perfect. Thanks!

Can you please create a new release so we could use this rule?

[wata727]

Sure. I'm planning to release a new version within a few days.