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Google NIO Filesystem Provider for Google Cloud Storage Client for Java

Java idiomatic client for NIO Filesystem Provider for Google Cloud Storage.

Note: This client is a work-in-progress, and may occasionally make backwards-incompatible changes.

Quickstart

If you are using Maven with BOM, add this to your pom.xml file

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>libraries-bom</artifactId>
      <version>22.0.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>google-cloud-nio</artifactId>
  </dependency>
</dependencies>

If you are using Maven without BOM, add this to your dependencies:

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-nio</artifactId>
  <version>0.123.10</version>
</dependency>

If you are using Gradle 5.x or later, add this to your dependencies

implementation platform('com.google.cloud:libraries-bom:23.0.0')

implementation 'com.google.cloud:google-cloud-nio'

If you are using Gradle without BOM, add this to your dependencies

implementation 'com.google.cloud:google-cloud-nio:0.123.10'

If you are using SBT, add this to your dependencies

libraryDependencies += "com.google.cloud" % "google-cloud-nio" % "0.123.10"

Authentication

See the Authentication section in the base directory's README.

Authorization

The client application making API calls must be granted authorization scopes required for the desired NIO Filesystem Provider for Google Cloud Storage APIs, and the authenticated principal must have the IAM role(s) required to access GCP resources using the NIO Filesystem Provider for Google Cloud Storage API calls.

Getting Started

Prerequisites

You will need a Google Cloud Platform Console project with the NIO Filesystem Provider for Google Cloud Storage API enabled.

Follow these instructions to get your project set up. You will also need to set up the local development environment by installing the Google Cloud SDK and running the following commands in command line: gcloud auth login and gcloud config set project [YOUR PROJECT ID].

Installation and setup

You'll need to obtain the google-cloud-nio library. See the Quickstart section to add google-cloud-nio as a dependency in your code.

About NIO Filesystem Provider for Google Cloud Storage

NIO Filesystem Provider for Google Cloud Storage provides a Google Cloud Storage extension for Java's NIO Filesystem.

See the NIO Filesystem Provider for Google Cloud Storage client library docs to learn how to use this NIO Filesystem Provider for Google Cloud Storage Client Library.

About Google Cloud Storage

Google Cloud Storage is a durable and highly available object storage service. Google Cloud Storage is almost infinitely scalable and guarantees consistency: when a write succeeds, the latest copy of the object will be returned to any GET, globally.

See the Google Cloud Storage docs for more details on how to activate Cloud Storage for your project.

About Java NIO Providers

Java NIO Providers is an extension mechanism that is part of Java and allows third parties to extend Java's normal File API to support additional filesystems.

Accessing files

The simplest way to get started is with Paths and Files:

Path path = Paths.get(URI.create("gs://bucket/lolcat.csv"));
List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);

If you know the paths will point to Google Cloud Storage, you can also use the direct formulation:

try (CloudStorageFileSystem fs = CloudStorageFileSystem.forBucket("bucket")) {
  Path path = fs.getPath("lolcat.csv");
  List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
}

Once you have a Path you can use it as you would a normal file. For example you can use InputStream and OutputStream for streaming:

try (InputStream input = Files.openInputStream(path)) {
  // ...
}

You can also set various attributes using CloudStorageOptions static helpers:

Files.write(csvPath, csvLines, StandardCharsets.UTF_8,
    withMimeType(MediaType.CSV_UTF8),
    withoutCaching());

Limitations

This library is usable, but not yet complete. The following features are not yet implemented:

Resuming upload or download
Generations
File attributes
(more - list is not exhaustive)

Some features are not on the roadmap: this library would be a poor choice to mirror a local filesystem onto the cloud because Google Cloud Storage has a different set of features from your local disk. This library, by design, does not mask those differences. Rather, it aims to expose the common subset via a familiar interface.

NOTE: Cloud Storage uses a flat namespace and therefore doesn't support real directories. So this library supports what's known as "pseudo-directories". Any path that includes a trailing slash, will be considered a directory. It will always be assumed to exist, without performing any I/O. Paths without the trailing slash will result in an I/O operation to check a file is present in that "directory". This allows you to do path manipulation in the same manner as you would with the normal UNIX file system implementation. Using this feature with buckets or "directory" paths that do not exist is not recommended, as at the time I/O is performed the failure may not be handled gracefully. You can disable this feature with CloudStorageConfiguration.usePseudoDirectories().

Complete source code

There are examples in google-cloud-nio-examples for your perusal.

Troubleshooting

To get help, follow the instructions in the shared Troubleshooting document.

Supported Java Versions

Java 7 or above is required for using this client.

Google's Java client libraries, Google Cloud Client Libraries and Google Cloud API Libraries, follow the Oracle Java SE support roadmap (see the Oracle Java SE Product Releases section).

For new development

In general, new feature development occurs with support for the lowest Java LTS version covered by Oracle's Premier Support (which typically lasts 5 years from initial General Availability). If the minimum required JVM for a given library is changed, it is accompanied by a semver major release.

Java 11 and (in September 2021) Java 17 are the best choices for new development.

Keeping production systems current

Google tests its client libraries with all current LTS versions covered by Oracle's Extended Support (which typically lasts 8 years from initial General Availability).

Legacy support

Google's client libraries support legacy versions of Java runtimes with long term stable libraries that don't receive feature updates on a best efforts basis as it may not be possible to backport all patches.

Google provides updates on a best efforts basis to apps that continue to use Java 7, though apps might need to upgrade to current versions of the library that supports their JVM.

Where to find specific information

The latest versions and the supported Java versions are identified on the individual GitHub repository github.com/GoogleAPIs/java-SERVICENAME and on google-cloud-java.

Versioning

This library follows Semantic Versioning.

It is currently in major version zero (0.y.z), which means that anything may change at any time and the public API should not be considered stable.

Contributing

Contributions to this library are always welcome and highly encouraged.

See CONTRIBUTING for more information how to get started.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. See Code of Conduct for more information.

License

Apache 2.0 - See LICENSE for more information.

CI Status

Java Version	Status
Java 7
Java 8
Java 8 OSX
Java 8 Windows
Java 11

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