feat: implement exec-with-secret command

LICENSE.txt

@@ -0,0 +1,8 @@
+Copyright 2020 nomeaning777
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

README.md

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+# exec-with-secret
+
+Run commands with secrets from GCP Secret Manager.
+This program resolves environment variables that starts with `secretmanager://`.
+
+## Usage
+
+```shell
+$ NON_SECRET=not_secret SECRET=secretmanager://<PROJECT_NAME>/<SECRET_NAME>/<VERSION> ./exec-with-secret sh -c 'echo $NON_SECRET $SECRET'
+not_secret very_important_secret
+```
+
+## License
+MIT

auto/auto.go

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+package auto
+
+import (
+	"github.com/nomeaning777/exec-with-secret"
+	"log"
+)
+
+func init() {
+	if err := secret.InjectSecretToEnvironment(); err != nil {
+		log.Fatal(err)
+	}
+}

cmd/exec-with-secret/main.go

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+package main
+
+import (
+	"fmt"
+	_ "github.com/nomeaning777/exec-with-secret/auto"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"syscall"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Fprintf(os.Stderr, "usage: %s <command> <arguments>\n", filepath.Base(os.Args[0]))
+		os.Exit(1)
+	}
+	binary, err := exec.LookPath(os.Args[1])
+	if err != nil {
+		panic(err)
+	}
+	if err := syscall.Exec(binary, os.Args[1:], os.Environ()); err != nil {
+		panic(err)
+	}
+}

go.mod

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+module github.com/nomeaning777/exec-with-secret
+
+go 1.13
+
+require (
+	cloud.google.com/go v0.53.0
+	google.golang.org/genproto v0.0.0-20200225123651-fc8f55426688
+)

secret_env.go

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+package secret
+
+import (
+	secretmanager "cloud.google.com/go/secretmanager/apiv1beta1"
+	"context"
+	"fmt"
+	secretmanagerpb "google.golang.org/genproto/googleapis/cloud/secretmanager/v1beta1"
+	"net/url"
+	"os"
+	"strings"
+)
+
+type secretPath struct {
+	Project string
+	Secret  string
+	Version string
+}
+
+func getSecret(client *secretmanager.Client, path secretPath) (string, error) {
+	req := &secretmanagerpb.AccessSecretVersionRequest{
+		Name: fmt.Sprintf("projects/%s/secrets/%s/versions/%s", path.Project, path.Secret, path.Version),
+	}
+	resp, err := client.AccessSecretVersion(context.Background(), req)
+	if err != nil {
+		return "", fmt.Errorf("failed to access secret version: %w", err)
+	}
+	return string(resp.Payload.Data), nil
+}
+
+func parseSecretUrl(key string) (secretPath, error) {
+	secretUrl, err := url.Parse(key)
+	if err != nil {
+		return secretPath{}, fmt.Errorf("failed to parse secretUrl: %w", err)
+	}
+	projectName := secretUrl.Host
+	secretName := secretUrl.Path[1:]
+	version := "latest"
+	if strings.Contains(secretName, "/") {
+		splitSecretName := strings.SplitN(secretName, "/", 2)
+		secretName = splitSecretName[0]
+		version = splitSecretName[1]
+	}
+	return secretPath{
+		Project: projectName,
+		Secret:  secretName,
+		Version: version,
+	}, nil
+}
+
+func isSecretUrl(value string) bool {
+	return strings.HasPrefix(value, "secretmanager://")
+}
+
+func InjectSecretToEnvironment() error {
+	client, err := secretmanager.NewClient(context.Background())
+	if err != nil {
+		return fmt.Errorf("failed to create secret manager client: %w", err)
+	}
+
+	for _, env := range os.Environ() {
+		pair := strings.SplitN(env, "=", 2)
+		if len(pair) != 2 {
+			continue
+		}
+
+		if !isSecretUrl(pair[1]) {
+			continue
+		}
+
+		path, err := parseSecretUrl(pair[1])
+		if err != nil {
+			return fmt.Errorf("parse failed to environment variable %s: %w", pair[0], err)
+		}
+
+		secret, err := getSecret(client, path)
+		if err != nil {
+			return fmt.Errorf("get secret failed to environemnt variable %s: %w", pair[0], err)
+		}
+
+		if err := os.Setenv(pair[0], secret); err != nil {
+			return fmt.Errorf("failed to setenv to %s: %+v", pair[0], err)
+		}
+	}
+	return nil
+}