cloudstorageapi

Cloud storage client library abstracts provider details and gives uniform C++ API to multiple cloud storages. Inspired by google-cloud-cpp.

Supported cloud storages

Storage service	Version
Google drive	v3

Supported platforms

• Windows, Linux and coming on macOS
• C++20 compilers. Tested with GCC(12.1.0), MSVC(>=2019)
• CMake builds

Documentation

Detailed header comments in public .h files

Quickstart

The quickstart/ directory contains a minimal environment to get started using this client library in a larger project. The following "Hello World" program is used in this quickstart, and should give you a taste of this library.

#include "cloudstorageapi/cloud_storage_client.h"
#include <iostream>

int main(int argc, char* argv[])
{
    if (argc != 2)
    {
        std::cerr << "Missing file name.\n";
        std::cerr << "Usage: quickstart <file-name>\n";
        return 1;
    }
    std::string const file_name = argv[1];

    // Create a client to communicate with Google Drive. This client
    // uses the default configuration for authentication.
    csa::StatusOrVal<csa::CloudStorageClient> client =
        csa::CloudStorageClient(csa::Options{}.Set<csa::ProviderOption>(csa::EProvider::GoogleDrive));
    if (!client)
    {
        std::cerr << "Failed to create cloud storage client, status=" << client.GetStatus() << std::endl;
        return 1;
    }

    auto root_meta = client->GetFolderMetadata("root");
    if (!root_meta)
    {
        std::cerr << "Failed to get root folder metadata: " << root_meta.GetStatus().Message();
    }

    auto writer = client->WriteFile(root_meta->GetCloudId(), file_name);
    writer << "Hello World!";
    writer.Close();
    if (writer.GetMetadata())
    {
        std::cout << "Successfully created object: " << *writer.GetMetadata() << "\n";
    }
    else
    {
        std::cerr << "Error creating object: " << writer.GetMetadata().GetStatus() << "\n";
        return 1;
    }

    auto file_id = writer.GetMetadata().Value().GetCloudId();
    auto reader = client->ReadFile(file_id);
    if (!reader)
    {
        std::cerr << "Error reading object: " << reader.GetStatus() << "\n";
        return 1;
    }

    std::string contents{std::istreambuf_iterator<char>{reader}, {}};
    std::cout << contents << "\n";

    return 0;
}

Dependencies

• libcurl
• openssl
• spdlog
• gtest
• nlohmann/json

Building on Windows (static library)

Prerequisites:

• CMake
• Git
• Visual Studio 2019 or greater
• vcpkg

  > git clone https://github.com/microsoft/vcpkg
  > .\vcpkg\bootstrap-vcpkg.bat

Building instructions:

> [path to vcpkg] install curl gtest nlohmann-json openssl spdlog --triplet=x64-windows-static-md
> git clone --recursive https://github.com/awkv/cloudstorageapi.git
> mkdir cloudstorageapi\build
> cd cloudstorageapi\build
> cmake -G "Visual Studio 16 2019" -A x64 -S .. -DCMAKE_TOOLCHAIN_FILE=[path to vcpkg]/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=x64-windows-static-md
> cmake --build .

Binaries can be found in cloudstorageapi\build\binaries

Run the tests

> ctest -C Release

Building on Linux (static library)

Prerequisites:

• tools

  > sudo apt update
  > sudo apt install -y build-essential cmake git gcc g++ cmake

• vcpkg

  > VCPKG_ROOT=~/projects/vcpkg
  > git clone https://github.com/microsoft/vcpkg "${VCPKG_ROOT}"
  > ${VCPKG_ROOT}/bootstrap-vcpkg.sh

Building instructions:

> "${VCPKG_ROOT}/vcpkg" install curl gtest nlohmann-json openssl spdlog --triplet=x64-linux
> git clone --recursive https://github.com/awkv/cloudstorageapi.git
> mkdir cloudstorageapi/build
> cd cloudstorageapi/build
> cmake -S .. -DCMAKE_TOOLCHAIN_FILE="${VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake" -DVCPKG_TARGET_TRIPLET=x64-linux
> cmake --build . -- -j $(nproc)

Binaries can be found in cloudstorageapi/build/binaries

Run the tests

> ctest

Authentication

Usually cloud storages require that your application authenticates with the service before accessing any data. The library supports OAuth 2.0 credentials. You can either use the CSA_CREDENTIALS environment variable or write code to pass the account key to the library.

For example (on Windows)

• via environment variable

  > set CSA_CREDENTIALS="C:\Users\username\Downloads\account-file.json"

• using code

  auto cred = csa::auth::CredentialFactory::CreateAuthorizedUserCredentialsFromJsonContents(csa::EProvider::GoogleDrive, <json-credentials-string>, "");
  auto client = csa::CloudStorageClient(csa::Options{}.Set<csa::ProviderOption>(csa::EProvider::GoogleDrive).Set<Oauth2CredentialsOption>(cred));

Credentials file or credential string is the following json structure:

{
  "client_id": "<cloud-storage-client_id>",
  "client_secret": "<cloud-storage-client-secret>",
  "refresh_token": "<cloud-storage-refresh-token>",
  "token_type": "Bearer"
}

Licensing

Apache 2.0; see LICENSE for details.