SafeLock

SafeLock is a golang package for locking files used by distributed services.

Use SafeLock when distributed processes act on the same file on a local or remote filesystem and require exclusive access to that file. SafeLock should not be used to protect access in non-distributed systems as better mechanisms exist.

To use this module add import "github.com/deptofdefense/safelock" to your package.

Example

To use the lock in AWS S3 you could use this code:

svcS3 := s3.NewFromConfig(cfg)
bucket := "bucket"
key := "key"
kmsKeyArn := "kmsKeyArn"
l := safelock.NewS3ObjectLock(bucket, key, kmsKeyArn, &svcS3)

// Wait for the lock to become available
l.WaitForLock()

// Lock the object and defer unlocking
l.Lock()
defer l.Unlock()

// Do work on the object that was locked

This can also be accomplished with a local filesystem:

fs := afero.NewOsFs()
filename := "file.txt"
l := safelock.NewFileLock(filename, fs)

SafeLock also provides a primitive to build your own lock named SafeLock.

Testing

Testing can be done using the Makefile targets make test and make test_coverage.

Development

Development for this has been geared towards MacOS users. Install dependencies to get started:

brew install circleci go golangci-lint pre-commit shellcheck

Install the pre-commit hooks and run them before making pull requests:

pre-commit install
pre-commit run -a

License

This project constitutes a work of the United States Government and is not subject to domestic copyright protection under 17 USC § 105. However, because the project utilizes code licensed from contributors and other third parties, it therefore is licensed under the MIT License. See LICENSE file for more information.