feat: implement the Casbin Cloud Storage Adapter (#1)

* chore: ignore .vscode folder from repo

* feat: implement basic adapter

* doc: add example

* ci: add semantic configuration

* ci: add Github Actions config

* doc: update README

* fix: add missing .releaserc.json file

* refactor: change ports to be sure that they are unused

.github/semantic.yml

@@ -0,0 +1,2 @@
+# Always validate all commits, and ignore the PR title
+commitsOnly: true

.github/workflows/default.yml

@@ -0,0 +1,48 @@
+name: Default
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: [ 1.13, 1.14 ]
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Run tests
+        run:  make test
+
+  benchmark:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: [ 1.13, 1.14 ]
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Benchmark code
+        run:  make benchmark
+
+  semantic-release:
+    needs: [test]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Run semantic-release
+        if: github.repository == 'qurami/casbin-cloud-storage-adapter' && github.event_name == 'push'
+        run: make release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -13,3 +13,6 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+# IDE-specific
+.vscode

.releaserc.json

@@ -0,0 +1,16 @@
+{
+    "debug": true,
+    "branches": [
+        "+([0-9])?(.{+([0-9]),x}).x",
+        "main",
+        {
+            "name": "beta",
+            "prerelease": true
+        }
+    ],
+    "plugins": [
+        "@semantic-release/commit-analyzer",
+        "@semantic-release/release-notes-generator",
+        "@semantic-release/github"
+    ]
+}

Makefile

@@ -0,0 +1,14 @@
+SHELL = /bin/bash
+export PATH := $(shell yarn global bin):$(PATH)
+
+default: test
+
+test:
+	go test -race -cover -v .
+
+benchmark:
+	go test -bench=.
+
+release:
+	yarn global add semantic-release@17.2.4
+	semantic-release

README.md

@@ -1,2 +1,77 @@
-# casbin-cloud-storage-adapter
-Casbin adapter implementation for GCP Cloud Storage
+# Casbin Cloud Storage Adapter
+
+[![Go Report Card](https://goreportcard.com/badge/github.com/qurami/casbin-cloud-storage-adapter)](https://goreportcard.com/report/github.com/qurami/casbin-cloud-storage-adapter)
+[![Build Status](https://travis-ci.com/casbin/casbin.svg?branch=master)](https://travis-ci.com/casbin/casbin)
+[![Coverage Status](https://coveralls.io/repos/github.com/qurami/casbin-cloud-storage-adapter/badge.svg?branch=master)](https://coveralls.io/github.com/qurami/casbin-cloud-storage-adapter?branch=master)
+[![Godoc](https://godoc.org/github.com/qurami/casbin-cloud-storage-adapter?status.svg)](https://pkg.go.dev/github.com/qurami/casbin-cloud-storage-adapter/v1)
+
+---
+
+[Casbin](https://casbin.org/) adapter implementation for GCP Cloud Storage.
+With this library, Casbin can load or save policies from/to Google Cloud Storage buckets.
+
+## Installation
+
+```
+go get github.com/qurami/casbin-cloud-storage-adapter/v1
+```
+
+## Example Usage
+
+```go
+package main
+
+import (
+	"context"
+	"log"
+
+	"cloud.google.com/go/storage"
+	"github.com/casbin/casbin/v2"
+	cloudstorageadapter "github.com/qurami/casbin-cloud-storage-adapter/v1"
+)
+
+func main() {
+	// Initialize a Google Cloud Storage client
+	// There are many ways, this is the quickest one.
+	// You could need a different one according to your configuration,
+	// please see https://pkg.go.dev/cloud.google.com/go/storage
+	cloudStorageClient, err := storage.NewClient(context.Background())
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Create a new cloudstorageadapter.Adapter
+	adapter, err := cloudstorageadapter.NewAdapter(
+		cloudStorageClient,
+		"myBucketName",
+		"path/to/policies.csv",
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Use the adapter in the casbin.NewEnforcer constructor
+	enforcer, err := casbin.NewEnforcer("rbac_model.conf", adapter)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Use the enforcer as usual
+	roles, err := enforcer.GetImplicitRolesForUser("alice")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println(roles)
+}
+```
+
+The same file with the corresponding RBAC model is available in the [examples](examples) folder.
+
+## Missing Features
+
+This version is missing the _autosave_ features, so please remember to manually execute the `enforcer.SavePolicy` method when using this adapter.
+
+## License
+
+This project is under MIT License. See the [LICENSE](LICENSE) file for the full license text.

adapter.go

@@ -0,0 +1,125 @@
+package cloudstorageadapter
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"sync"
+
+	"cloud.google.com/go/storage"
+	"github.com/casbin/casbin/v2/model"
+	"github.com/casbin/casbin/v2/persist"
+	"github.com/casbin/casbin/v2/util"
+)
+
+// Adapter implements casbin/persist.Adapter
+// storing policy configuration on a Google Cloud Storage Bucket
+type Adapter struct {
+	client     *storage.Client
+	bucketName string
+	objectKey  string
+	context    context.Context
+	mutex      *sync.Mutex
+}
+
+// NewAdapter creates new Adapter
+//
+// Parameters:
+// - client
+//     A cloud.google.com/go/storage.Client object
+// - bucketName
+//     Name of the bucket where the policy configuration file is stored on
+// - objectKey
+//     Key (name) of the object that contains policy configuration
+func NewAdapter(client *storage.Client, bucketName string, objectKey string) (*Adapter, error) {
+	ctx := context.Background()
+	_, err := client.Bucket(bucketName).Attrs(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	adapter := Adapter{
+		client:     client,
+		bucketName: bucketName,
+		objectKey:  objectKey,
+		context:    ctx,
+		mutex:      new(sync.Mutex),
+	}
+	return &adapter, nil
+}
+
+// LoadPolicy loads policy from database.
+func (a *Adapter) LoadPolicy(model model.Model) error {
+	a.mutex.Lock()
+	defer a.mutex.Unlock()
+
+	fileReader, err := a.client.Bucket(a.bucketName).Object(a.objectKey).NewReader(a.context)
+	if err != nil {
+		return err
+	}
+	defer fileReader.Close()
+
+	buf := bufio.NewReader(fileReader)
+	for {
+		line, err := buf.ReadString('\n')
+		line = strings.TrimSpace(line)
+		persist.LoadPolicyLine(line, model)
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return err
+		}
+	}
+	return nil
+}
+
+// SavePolicy saves all policy rules to the storage.
+func (a *Adapter) SavePolicy(model model.Model) error {
+	a.mutex.Lock()
+	defer a.mutex.Unlock()
+
+	fileWriter := a.client.Bucket(a.bucketName).Object(a.objectKey).NewWriter(a.context)
+	defer fileWriter.Close()
+
+	for ptype, assertion := range model["p"] {
+		for _, rule := range assertion.Policy {
+			_, err := fileWriter.Write([]byte(fmt.Sprintf("%s, %s\n", ptype, util.ArrayToString(rule))))
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	for ptype, assertion := range model["g"] {
+		for _, rule := range assertion.Policy {
+			_, err := fileWriter.Write([]byte(fmt.Sprintf("%s, %s\n", ptype, util.ArrayToString(rule))))
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// AddPolicy adds a policy rule to the storage.
+// This is part of the Auto-Save feature.
+func (a *Adapter) AddPolicy(sec string, ptype string, rule []string) error {
+	return errors.New("not implemented")
+}
+
+// RemovePolicy removes a policy rule from the storage.
+// This is part of the Auto-Save feature.
+func (a *Adapter) RemovePolicy(sec string, ptype string, rule []string) error {
+	return errors.New("not implemented")
+}
+
+// RemoveFilteredPolicy removes policy rules that match the filter from the storage.
+// This is part of the Auto-Save feature.
+func (a *Adapter) RemoveFilteredPolicy(sec string, ptype string, fieldIndex int, fieldValues ...string) error {
+	return errors.New("not implemented")
+}