Allow for configuration policies

Summary:
Implements a rough interface for validating configuration against
arbitrary policy rules. Policies are provided as YAML and passed via the
command line as file paths or remote URIs.

The format of policies is:

    enforcements:
      - path: <path>
        rule: <rule>

Where `<path>` is a YAML-ish path to a config field and `<rule>` is any
expression our config validator understands (expressions built in by the
validator library and custom tags defined in `config.validation.go`).

Example policy:

    enforcements:
      - path: variants.production.base
        rule: oneof=debian:jessie debian:stretch
      - path: variants.production.runs.as
        rule: ne=foo
      - path: variants.production.node.dependencies
        rule: isfalse

Command flag parsing was implemented in `main.go` to support the new
`--policy=uri` flag and improve existing handling of `--version` and the
usage statement.

Test Plan: Run `go test ./...`.

Reviewers: thcipriani, demon, hashar, mmodell, #release-engineering-team

Reviewed By: thcipriani, #release-engineering-team

Tags: #release-engineering-team

Differential Revision: https://phabricator.wikimedia.org/D999

1 files changed, 23 insertions, 62 deletions

diff --git a/vendor/gopkg.in/go-playground/validator.v9/validator_instance.go b/vendor/gopkg.in/go-playground/validator.v9/validator_instance.go
index d3a1543..e84b452 100644
--- a/vendor/gopkg.in/go-playground/validator.v9/validator_instance.go
+++ b/vendor/gopkg.in/go-playground/validator.v9/validator_instance.go
@@ -370,39 +370,37 @@ func (v *Validate) StructPartialCtx(ctx context.Context, s interface{}, fields .
 	typ := val.Type()
 	name := typ.Name()
 
-	if fields != nil {
-		for _, k := range fields {
+	for _, k := range fields {
 
-			flds := strings.Split(k, namespaceSeparator)
-			if len(flds) > 0 {
+		flds := strings.Split(k, namespaceSeparator)
+		if len(flds) > 0 {
 
-				vd.misc = append(vd.misc[0:0], name...)
-				vd.misc = append(vd.misc, '.')
-
-				for _, s := range flds {
+			vd.misc = append(vd.misc[0:0], name...)
+			vd.misc = append(vd.misc, '.')
 
-					idx := strings.Index(s, leftBracket)
+			for _, s := range flds {
 
-					if idx != -1 {
-						for idx != -1 {
-							vd.misc = append(vd.misc, s[:idx]...)
-							vd.includeExclude[string(vd.misc)] = struct{}{}
+				idx := strings.Index(s, leftBracket)
 
-							idx2 := strings.Index(s, rightBracket)
-							idx2++
-							vd.misc = append(vd.misc, s[idx:idx2]...)
-							vd.includeExclude[string(vd.misc)] = struct{}{}
-							s = s[idx2:]
-							idx = strings.Index(s, leftBracket)
-						}
-					} else {
+				if idx != -1 {
+					for idx != -1 {
+						vd.misc = append(vd.misc, s[:idx]...)
+						vd.includeExclude[string(vd.misc)] = struct{}{}
 
-						vd.misc = append(vd.misc, s...)
+						idx2 := strings.Index(s, rightBracket)
+						idx2++
+						vd.misc = append(vd.misc, s[idx:idx2]...)
 						vd.includeExclude[string(vd.misc)] = struct{}{}
+						s = s[idx2:]
+						idx = strings.Index(s, leftBracket)
 					}
+				} else {
 
-					vd.misc = append(vd.misc, '.')
+					vd.misc = append(vd.misc, s...)
+					vd.includeExclude[string(vd.misc)] = struct{}{}
 				}
+
+				vd.misc = append(vd.misc, '.')
 			}
 		}
 	}
@@ -520,36 +518,18 @@ func (v *Validate) VarCtx(ctx context.Context, field interface{}, tag string) (e
 		return nil
 	}
 
-	// find cached tag
-	ctag, ok := v.tagCache.Get(tag)
-	if !ok {
-		v.tagCache.lock.Lock()
-		defer v.tagCache.lock.Unlock()
-
-		// could have been multiple trying to access, but once first is done this ensures tag
-		// isn't parsed again.
-		ctag, ok = v.tagCache.Get(tag)
-		if !ok {
-			ctag, _ = v.parseFieldTagsRecursive(tag, "", "", false)
-			v.tagCache.Set(tag, ctag)
-		}
-	}
-
+	ctag := v.fetchCacheTag(tag)
 	val := reflect.ValueOf(field)
-
 	vd := v.pool.Get().(*validate)
 	vd.top = val
 	vd.isPartial = false
-
 	vd.traverseField(ctx, val, val, vd.ns[0:0], vd.actualNs[0:0], defaultCField, ctag)
 
 	if len(vd.errs) > 0 {
 		err = vd.errs
 		vd.errs = nil
 	}
-
 	v.pool.Put(vd)
-
 	return
 }
 
@@ -590,36 +570,17 @@ func (v *Validate) VarWithValueCtx(ctx context.Context, field interface{}, other
 	if len(tag) == 0 || tag == skipValidationTag {
 		return nil
 	}
-
-	// find cached tag
-	ctag, ok := v.tagCache.Get(tag)
-	if !ok {
-		v.tagCache.lock.Lock()
-		defer v.tagCache.lock.Unlock()
-
-		// could have been multiple trying to access, but once first is done this ensures tag
-		// isn't parsed again.
-		ctag, ok = v.tagCache.Get(tag)
-		if !ok {
-			ctag, _ = v.parseFieldTagsRecursive(tag, "", "", false)
-			v.tagCache.Set(tag, ctag)
-		}
-	}
-
+	ctag := v.fetchCacheTag(tag)
 	otherVal := reflect.ValueOf(other)
-
 	vd := v.pool.Get().(*validate)
 	vd.top = otherVal
 	vd.isPartial = false
-
 	vd.traverseField(ctx, otherVal, reflect.ValueOf(field), vd.ns[0:0], vd.actualNs[0:0], defaultCField, ctag)
 
 	if len(vd.errs) > 0 {
 		err = vd.errs
 		vd.errs = nil
 	}
-
 	v.pool.Put(vd)
-
 	return
 }