S3 Object Store

Allow storing json objects in S3 easily

Goals:

• Map objects to a sensible s3 hierarchy
• Use json for fast-ish and flexible serialization and model updates + human readability
• Control the folder template name with options

Please see the Sandbox project, Program.cs which shows a simple example of using sessions.

Usage

Define an object that implements the IStorageObject interface:

/// <summary>
/// Example session object
/// </summary>
public sealed class Session : IStorageObject
{
    /// <summary>
    /// The session identifier, probably a guid
    /// </summary>
    [JsonPropertyName("k")]
    public string? Key { get; set; } = string.Empty;

    /// <summary>
    /// The account id the session belongs to, probably a guid. Can be null if no owner.
    /// </summary>
    [JsonPropertyName("o")]
    public string? Owner { get; set; }

    /// <summary>
    /// IP address
    /// </summary>
    [JsonPropertyName("i")]
    public string IPAddress { get; set; } = string.Empty;

    /// <summary>
    /// User agent
    /// </summary>
    [JsonPropertyName("a")]
    public string UserAgent { get; set; } = string.Empty;

    /// <summary>
    /// When the session expires
    /// </summary>
    [JsonPropertyName("e")]
    public DateTimeOffset Expires { get; set; }

    /// <summary>
    /// Could put permissions for the session here
    /// </summary>
    [JsonPropertyName("p")]
    public string Permissions { get; set; } = string.Empty;

    /// <inheritdoc />
    public override string ToString()
    {
        return $"{Key} {Owner} {IPAddress} {UserAgent} {Expires} {Permissions}";
    }
}

Using JsonPropertyName to shorten property names is highly recommended as it will save you on storage space.

The IStorageObject interface will return null for both Key and Owner by default.

In most cases, you will usually implement both the Key and Owner properties yourself and return Guid or some other identifier.

Exceptions to this case:

• You can return null for the Owner if your service options (see down below) do not have a format specifier for the owner in the folder template - {0}.
• You can return null for the Key if your service options specify that the folder format has the file name in it. By default, the Key is used as the file name, with a .json extension.

Create your s3 repository

// note disable signing is required for cloudflare r2
// set disable signing to false as long as your s3 provider works
var config = new S3Config(accessKey, secretKey, url, disableSigning);

// in production, deleting and creating buckets is not allowed for safety
// you can get both the environment and logger from `IServiceProvider` when using a full .net 6 app.
var repository = new S3StorageRepository(config, new FakeEnvironment(), new NullLogger<S3StorageRepository>());

Create your object service

var serviceOptions = new StorageObjectServiceOptions<Session>
{
    Bucket = "bucketname",

    // the folder format does not need a {0} if there is no owner for the object (owner is null)
    // by default the key will be appended to this folder with a .json extension
    FolderFormat = "users/{0}/sessions",

    // if your folder format contains the file name, for example to store a user profile, you could use:
    // users/{0}/profile.json, which would ignore the key as part of the file name
    FolderFormatIncludesFileName = false
};

// create s3 object service, wrapping the s3 repository
var service = new S3StorageObjectService<Session>(serviceOptions, repository);

Perform operations

The storage object service interface is as follows:

/// <summary>
/// Storage object service interface. Stores one or more objects (like sessions) with an owner (like a user).
/// </summary>
/// <typeparam name="T">Types of objects to work with, must be json serializable</typeparam>
public interface IStorageObjectService<T> where T : class, IStorageObject
{
    /// <summary>
    /// Get an object by key and owner
    /// </summary>
    /// <param name="key">Key</param>
    /// <param name="owner">Owner identifier</param>
    /// <returns>Object or null if not found</returns>
    Task<T?> GetObjectAsync(string key, string owner);

    /// <summary>
    /// Set an object. The key and owner properties are used to determine the folder path
    /// </summary>
    /// <param name="obj">Object</param>
    /// <returns>Task</returns>
    Task SetObjectAsync(T obj);

    /// <summary>
    /// Get all objects for the owner.
    /// </summary>
    /// <param name="owner">Owner identifier</param>
    /// <returns>Task of found objects</returns>
    Task<IReadOnlyCollection<T>> GetObjectsAsync(string owner);

    /// <summary>
    /// Get just the keys for the owner, much more lightweight operation
    /// </summary>
    /// <param name="owner">Owner</param>
    /// <returns>Task of keys</returns>
    Task<IReadOnlyCollection<string>> GetKeys(string owner);

    /// <summary>
    /// Delete object.
    /// </summary>
    /// <param name="key">Key</param>
    /// <param name="owner">Owner identifier</param>
    /// <returns>Task</returns>
    Task DeleteObjectAsync(string key, string owner);
}

Please email support@digitalruby.com if you have questions or feedback.

-- Jeff