feat: add license header policy (siderolabs#105)

Signed-off-by: Andrew Rynhard <andrew@andrewrynhard.com>

.conform.yaml

@@ -16,3 +16,8 @@ policies:
     scopes:
     - policy
     - '*'
+- type: license
+  spec:
+    includeSuffixes:
+    - .go
+    headerFile: ./hack/LICENSE_HEADER.txt

README.md

@@ -23,6 +23,7 @@ Some of the policies included are:
   - Developer Certificate of Origin
   - GPG signature
 - **Conventional Commits**: Enforce [conventional commits](https://www.conventionalcommits.org) for all commit messages.
+- **License Headers**: Enforce license headers on source code files.
 
 ## Getting Started
 
@@ -41,12 +42,23 @@ policies:
       - "type"
     scopes:
       - "scope"
+- type: license
+  spec:
+    includeSuffixes:
+    - .ext
+    excludeSuffixes:
+    - .exclude-ext-prefix.ext
+    headerFile: ./hack/LICENSE_HEADER.txt
 ```
 
 In the same directory, run:
 
 ```bash
-conform enforce
+$ conform enforce
+POLICY                    STATUS        MESSAGE
+commit                    PASS          <none>
+conventionalCommit        PASS          <none>
+license                   PASS          <none>
 ```
 
 ### License

cmd/enforce.go

@@ -1,15 +1,6 @@
-// Copyright © 2017 NAME HERE <EMAIL ADDRESS>
-// 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.
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package cmd
 

cmd/root.go

@@ -1,15 +1,6 @@
-// Copyright © 2017 NAME HERE <EMAIL ADDRESS>
-// 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.
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package cmd
 

cmd/version.go

@@ -1,15 +1,6 @@
-// Copyright © 2017 NAME HERE <EMAIL ADDRESS>
-// 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.
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package cmd
 

hack/LICENSE_HEADER.txt

@@ -0,0 +1,3 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

internal/constants/constants.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package constants
 
 const (

internal/enforcer/enforcer.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package enforcer
 
 import (
@@ -9,6 +13,7 @@ import (
 	"github.com/autonomy/conform/internal/policy"
 	"github.com/autonomy/conform/internal/policy/commit"
 	"github.com/autonomy/conform/internal/policy/conventionalcommit"
+	"github.com/autonomy/conform/internal/policy/license"
 	"github.com/mitchellh/mapstructure"
 	"github.com/pkg/errors"
 
@@ -31,6 +36,7 @@ type PolicyDeclaration struct {
 var policyMap = map[string]policy.Policy{
 	"commit":             &commit.Commit{},
 	"conventionalCommit": &conventionalcommit.Conventional{},
+	"license":            &license.License{},
 	// "version":    &version.Version{},
 }
 

internal/git/git.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package git
 
 import (

internal/policy/commit/commit.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package commit
 
 import (

internal/policy/conventionalcommit/conventionalcommit.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package conventionalcommit
 
 import (

internal/policy/conventionalcommit/conventionalcommit_test.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package conventionalcommit
 
 import (

internal/policy/license/license.go

@@ -0,0 +1,81 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package license
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/autonomy/conform/internal/policy"
+	"github.com/pkg/errors"
+)
+
+// License implements the policy.Policy interface and enforces source code
+// license headers.
+type License struct {
+	// IncludeSuffixes is the regex used to find files that the license policy
+	// should be applied to.
+	IncludeSuffixes []string `mapstructure:"includeSuffixes"`
+	// ExcludeSuffixes is the Suffixes used to find files that the license policy
+	// should not be applied to.
+	ExcludeSuffixes []string `mapstructure:"excludeSuffixes"`
+	// LicenseHeaderFile is the path to the license header file.
+	LicenseHeaderFile string `mapstructure:"headerFile"`
+}
+
+// Compliance implements the policy.Policy.Compliance function.
+func (l *License) Compliance(options *policy.Options) (report policy.Report) {
+	var err error
+
+	report = policy.Report{}
+
+	var value []byte
+	if value, err = ioutil.ReadFile(l.LicenseHeaderFile); err != nil {
+		report.Errors = append(report.Errors, errors.Errorf("Failed to open %s", l.LicenseHeaderFile))
+	}
+
+	err = filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.Mode().IsRegular() {
+			// Skip excluded suffixes.
+			for _, suffix := range l.ExcludeSuffixes {
+				if strings.HasSuffix(info.Name(), suffix) {
+					continue
+				}
+			}
+			// Check files matching the included suffixes.
+			for _, suffix := range l.IncludeSuffixes {
+				if strings.HasSuffix(info.Name(), suffix) {
+					var contents []byte
+					if contents, err = ioutil.ReadFile(path); err != nil {
+						report.Errors = append(report.Errors, errors.Errorf("Failed to open %s", path))
+						return nil
+					}
+					ValidateLicenseHeader(&report, info.Name(), contents, value)
+				}
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		report.Errors = append(report.Errors, errors.Errorf("Failed to walk directory: %v", err))
+	}
+
+	return report
+}
+
+// ValidateLicenseHeader checks the header of a file and ensures it contains the
+// provided value.
+func ValidateLicenseHeader(report *policy.Report, name string, contents, value []byte) {
+	if bytes.HasPrefix(contents, value) {
+		return
+	}
+	report.Errors = append(report.Errors, errors.Errorf("File %s does not contain a license header", name))
+}

internal/policy/policy.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package policy
 
 // Report summarizes the compliance of a policy.

internal/policy/policy_options.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package policy
 
 // Option is a functional option used to pass in arguments to a Policy.

internal/policy/version/version.go

@@ -1,3 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
 package version
 
 // Version defines the version policy to use and the options specific to the

main.go

@@ -1,15 +1,6 @@
-// Copyright © 2017 NAME HERE <EMAIL ADDRESS>
-// 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.
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package main