Google Cloud APIs for Julia

This module wraps Google Cloud Platform (GCP) APIs with Julia.

Currently only the Google Storage API has been added.

Quick Start

This Quick Start walks through the steps required to store and retrieve data from Google Cloud Storage.

Google Cloud Prerequisites

  1. If you don't already have a Google account, create one here.
  2. Sign in to the GCP console here.

  3. Create a new project by clicking on the Project drop-down menu at the top of the page. If you already have a GCP project, click on the drop-down menu at the top of the page and select Create project.

    A GCP project is a set of resources with common settings that is billed and managed separately from any resource outside the set. Thus a resource exists in exactly one project. Examples of resources include GCE instances, storage volumes and data on those volumes. A project's settings include ownership, users and their permissions, and associated GCP services. As a user anything you do on GCP happens within a project, including data storage, compute, messaging, logging, etc.

  4. Associated with your project are credentials that allow users to add, read and remove resources from the project. Get the credentials for your project as a JSON file from your GCP Credentials page:

    • Type credentials into the search bar at the top of the console.
    • Select Credentials API Manager from the search results.
    • Click on the Create credentials drop-down menu and select Service account key.
    • From the Service Account menu select New service account.
    • From Role select Storage > Storage Admin.
    • Ensure the key type is JSON.
    • Click Create.

    Credentials are then automatically downloaded in a JSON file. Save this file to your machine. In this tutorial we save the service account credentials to ~/credentials.json.

Interacting with the Storage API from Julia

Start Julia and install the GoogleCloud.jl package:

Pkg.add("GoogleCloud")
using GoogleCloud

Load the service account credentials obtained from Google:

creds = GoogleCredentials(expanduser("~/credentials.json"))

Now, create a session with the credentials, requesting any required scopes:

session = GoogleSession(creds, ["devstorage.full_control"])

Set the default session of an API using set_session!:

set_session!(storage, session)    # storage is the API root, exported from GoogleCloud.jl

List all existing buckets in your project. The list contains a default bucket:

bkts = storage(:Bucket, :list)    # storage(:Bucket, :list; raw=true) returns addition information

# Pretty print
for item in bkts
    display(item)
    println()
end

Create a bucket called a12345foo, for example. Note: The bucket name must be unique... across all buckets in GCP, so choose your own!

storage(:Bucket, :insert; data=Dict(:name => "a12345foo"))

# Verify the new bucket exists in the project
bkts = storage(:Bucket, :list)
for item in bkts
    display(item)
    println()
end

List all objects in the a12345foo bucket. The list is currently empty:

storage(:Object, :list, "a12345foo")

Upload an object to the a12345foo bucket:

# String containing the contents of test_image.jpg. The semi-colon avoids an error caused by printing the returned value.
file_contents = readstring(open("test_image.jpg", "r"));

# Upload
storage(:Object, :insert, "a12345foo";     # Returns metadata about the object
    name="image.jpg",           # Object name is "image.jpg"
    data=file_contents,         # The data being stored on your project
    content_type="image/jpeg"   # The contents are specified to be in JPEG format
)

# Verify that the object is in the bucket
obs = storage(:Object, :list, "a12345foo")    # Ugly print
map(x -> x[:name], obs)                       # Pretty print

Get the image.jpg object from the bucket:

s = storage(:Object, :get, "a12345foo", "image.jpg");
s == file_contents    # Verify that the retrieved data is the same as that originally posted

Delete the image.jpg object from the bucket:

storage(:Object, :delete, "a12345foo", "image.jpg")

# Verify that the bucket is now empty
storage(:Object, :list, "a12345foo")

Delete the bucket:

storage(:Bucket, :delete, "a12345foo")

# Verify that the bucket has been deleted
bkts = storage(:Bucket, :list)
for item in bkts
    display(item)
    println()
end

High-Level API

Low-Level API

Index