initial addition of policies

pkg/broker/policy/policy.go

@@ -0,0 +1,93 @@
+// Copyright 2019 the Service Broker Project Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package policy
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// Conditions are a set of values that can be compared with a base truth and
+// return true if all of the facets of the condition match.
+//
+// Blank facets are assumed to match everything.
+type Condition struct {
+	ServiceId   string `json:"service_id"`
+	ServiceName string `json:"service_name"`
+}
+
+// AppliesTo returns true if all the facets of this condition match the given
+// truth.
+func (cond *Condition) AppliesTo(truth Condition) bool {
+	if cond.ServiceId != "" && cond.ServiceId != truth.ServiceId {
+		return false
+	}
+
+	if cond.ServiceName != "" && cond.ServiceName != truth.ServiceName {
+		return false
+	}
+
+	return true
+}
+
+// Policy combines a condition with several sets of values that are set if
+// the condition holds true.
+type Policy struct {
+	Comment   string    `json:"//"`
+	Condition Condition `json:"if"`
+
+	Actions map[string]interface{} `json:"then"`
+}
+
+type PolicyList struct {
+	Policies   []Policy `json:"policy"`
+	Assertions []Policy `json:"assert"`
+}
+
+// CheckAssertions tests each assertion in the Assertions list against the
+// policies list. The conditoin is used as the ground truth and the
+// actions are used as the expected output. If the actions don't match then
+// an error is returned.
+func (pl *PolicyList) CheckAssertions() error {
+	for i, assertion := range pl.Assertions {
+		expected := assertion.Actions
+		actual := pl.Apply(assertion.Condition)
+
+		if !reflect.DeepEqual(actual, expected) {
+			return fmt.Errorf("Error in assertion %d, comment: %q, expected: %v, actual: %v", i+1, assertion.Comment, expected, actual)
+		}
+	}
+
+	return nil
+}
+
+// Apply runs through the list of policies, first to last, and cascades the
+// values of each if they match the given condition, returning the merged
+// map at the end.
+func (pl *PolicyList) Apply(groundTruth Condition) map[string]interface{} {
+	out := make(map[string]interface{})
+
+	for _, policy := range pl.Policies {
+		if !policy.Condition.AppliesTo(groundTruth) {
+			continue
+		}
+
+		for k, v := range policy.Actions {
+			out[k] = v
+		}
+	}
+
+	return out
+}

pkg/broker/policy/policy_test.go

@@ -0,0 +1,80 @@
+// Copyright 2019 the Service Broker Project Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package policy
+
+import "testing"
+
+func TestCondition_AppliesTo(t *testing.T) {
+	cases := map[string]struct {
+		Condition Condition
+		Truth     Condition
+		Expected  bool
+	}{
+		"matches everything": {
+			Condition: Condition{},
+			Truth:     Condition{},
+			Expected:  true,
+		},
+	}
+
+	for tn, tc := range cases {
+		t.Run(tn, func(t *testing.T) {
+			actual := tc.Condition.AppliesTo(tc.Truth)
+
+			if tc.Expected != actual {
+				t.Errorf("Expected condition to apply? %t but was: %t", tc.Expected, actual)
+			}
+		})
+	}
+}
+
+const examplePolicy = `
+{
+  "policies":[
+    {
+      "//":"always applies",
+      "if":{},
+      "then":{
+        "cascade-true": true,
+        "cascade-false": true
+
+      }
+    },
+    {
+      "//":"some comment here",
+      "if":{
+        "service_name": "cloud-storage"
+      },
+      "then":{
+        "cascade-false": false
+      }
+    }
+  ],
+  "assert":[
+  {
+    "//":"cascading works correctly",
+    "if":{
+      "service_name": "cloud-storage"
+    },
+    "then":{
+      "cascade-true": true,
+      "cascade-false": false
+    }
+  }
+
+
+  ],
+}
+`