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#Cloud Files™ (storage)
This document explains how to get started using Cloud Files with Fog. It assumes you have read the Getting Started with Fog and the Rackspace Open Cloud document.
Starting irb console
Start by executing the following command:
irb
Once irb has launched you need to require the Fog library.
If using Ruby 1.8.x execute:
require 'rubygems'
require 'fog'
If using Ruby 1.9.x execute:
require 'fog'
Create Service
Next, create a connection to Cloud Files.
Using a US based account:
service = Fog::Storage.new({
:provider => 'Rackspace', # Rackspace Fog provider
:rackspace_username => RACKSPACE_USER_NAME, # Your Rackspace Username
:rackspace_api_key => RACKSPACE_API, # Your Rackspace API key
:rackspace_region => :ord # Defaults to :dfw
:connection_options => {} # Optional
})
Using a UK based account:
service = Fog::Storage.new({
:provider => 'Rackspace', # Rackspace Fog provider
:rackspace_username => RACKSPACE_USER_NAME, # Your Rackspace Username
:rackspace_api_key => RACKSPACE_API, # Your Rackspace API key
:rackspace_auth_url => Fog::Rackspace::UK_AUTH_ENDPOINT
:rackspace_region => :lon
:connection_options => {} # Optional
})
To learn more about obtaining cloud credentials refer to the Getting Started with Fog and the Rackspace Open Cloud document.
By default Fog::Storage will authenticate against the US authentication endpoint and connect to the DFW region. You can specify alternative authentication endpoints using the key :rackspace_auth_url. Please refer to Alternate Authentication Endpoints for a list of alternative Rackspace authentication endpoints.
Alternative regions are specified using the key :rackspace_region . A list of regions available for Cloud Files can be found by executing the following:
identity_service = Fog::Identity({
:provider => 'Rackspace', # Rackspace Fog provider
:rackspace_username => RACKSPACE_USER_NAME, # Your Rackspace Username
:rackspace_api_key => RACKSPACE_API, # Your Rackspace API key
:rackspace_auth_url => Fog::Rackspace::UK_AUTH_ENDPOINT # Not specified for US Cloud
})
identity_service.service_catalog.display_service_regions :cloudFiles
Rackspace Private Cloud installations can skip specifying a region and directly specify their custom service endpoints using the key :rackspace_storage_url and :rackspace_cdn_url.
Note: AFog::Storage instance is needed for the desired region.
Optional Service Parameters
The Storage service supports the following additional parameters:
| Key | Description |
|---|---|
| :rackspace_servicenet | If set to true, the service will access Cloud Files using the internal Rackspace ServiceNet. This option should only be used for internal network connections. |
| :rackspace_cdn_ssl | If set to true, the public_url method will return the SSL based URLs. |
| :persistent | If set to true, the service will use a persistent connection. |
| :rackspace_storage_url | The endpoint for the Cloud Files service. By default, Fog::Storage will pick the appropriate endpoint for region. This option will typically only be used for Rackspace Private Cloud Access. |
| :rackspace_cdn_url | The endpoint for the CDN service. By default, Fog::Storage pick the appropriate endpoint for region. This option will typically only be used for Rackspace Private Cloud Access. |
| :chunk_size | The chunk size in bytes used for block transfers. By default, Fog uses 1 MB chunks. |
Optional Connection Parameters
Fog supports passing additional connection parameters to its underlying HTTP library (Excon) using the :connection_options parameter.
| Key | Description |
|---|---|
| :connect_timeout | Connection timeout (default: 60 seconds) |
| :read_timeout | Read timeout for connection (default: 60 seconds) |
| :write_timeout | Write timeout for connection (default: 60 seconds) |
| :proxy | Proxy for HTTP and HTTPS connections |
| :ssl_ca_path | Path to SSL certificate authorities |
| :ssl_ca_file | SSL certificate authority file |
| :ssl_verify_peer | SSL verify peer (default: true) |
Fog Abstractions
Fog provides both a model and request abstraction. The request abstraction provides the most efficient interface and the model abstraction wraps the request abstraction to provide a convenient ActiveModel like interface.
Request Layer
The request abstraction maps directly to the Cloud Files API. It provides the most efficient interface to the Rackspace Open Cloud.
To see a list of requests supported by the storage service:
service.requests
This returns:
:copy_object, :delete_container, :delete_object, :get_container, :get_containers, :get_object, :get_object_https_url, :head_container, :head_containers, :head_object, :put_container, :put_object, :put_object_manifest, :post_set_meta_temp_url_key
To see a list of requests supported by the CDN service:
service.cdn.requests
This returns:
:get_containers, :head_container, :post_container, :put_container, :delete_object
Example Request
To request a view account details:
response = service.head_containers
This returns in the following Excon::Response:
#<Excon::Response:0x10283fc68 @headers={"X-Account-Bytes-Used"=>"2563554", "Date"=>"Thu, 21 Feb 2013 21:57:02 GMT", "X-Account-Meta-Temp-Url-Key"=>"super_secret_key", "X-Timestamp"=>"1354552916.82056", "Content-Length"=>"0", "Content-Type"=>"application/json; charset=utf-8", "X-Trans-Id"=>"txe934924374a744c8a6c40dd8f29ab94a", "Accept-Ranges"=>"bytes", "X-Account-Container-Count"=>"7", "X-Account-Object-Count"=>"5"}, @status=204, @body="">
To view the status of the response:
response.status
Note: Fog is aware of the valid HTTP response statuses for each request type. If an unexpected HTTP response status occurs, Fog will raise an exception.
To view response headers:
response.headers
This will return:
{"X-Account-Bytes-Used"=>"2563554", "Date"=>"Thu, 21 Feb 2013 21:57:02 GMT", "X-Account-Meta-Temp-Url-Key"=>"super_secret_key", "X-Timestamp"=>"1354552916.82056", "Content-Length"=>"0", "Content-Type"=>"application/json; charset=utf-8", "X-Trans-Id"=>"txe934924374a744c8a6c40dd8f29ab94a", "Accept-Ranges"=>"bytes", "X-Account-Container-Count"=>"7", "X-Account-Object-Count"=>"5"}
To learn more about Fog::Storage request methods refer to rdoc. To learn more about Excon refer to Excon GitHub repo.
Model Layer
Fog models behave in a manner similar to ActiveModel. Models will generally respond to create, save, destroy, reload and attributes methods. Additionally, fog will automatically create attribute accessors.
Here is a summary of common model methods:
| Method | Description |
|---|---|
| create |
Accepts hash of attributes and creates object. Note: creation is a non blocking call and you will be required to wait for a valid state before using resulting object. |
| save | Saves object. Note: not all objects support updating object. |
| destroy |
Destroys object. Note: this is a non blocking call and object deletion might not be instantaneous. |
| reload | Updates object with latest state from service. |
| attributes | Returns a hash containing the list of model attributes and values. |
| identity |
Returns the identity of the object. Note: This might not always be equal to object.id. |
The remainder of this document details the model abstraction.
Note: Fog refers to Rackspace Cloud containers as directories.
List Directories
To retrieve a list of directories:
service.directories
This returns a collection of Fog::Storage::Rackspace::Directory models:
<Fog::Storage::Rackspace::Directories
[
<Fog::Storage::Rackspace::Directory
key="blue",
bytes=434266,
count=1,
cdn_cname=nil
>,
<Fog::Storage::Rackspace::Directory
key="brown",
bytes=761879,
count=1,
cdn_cname=nil
>,
...
Get Directory
To retrieve a specific directory:
service.directories.get "blue"
This returns a Fog::Storage::Rackspace::Directory instance:
<Fog::Storage::Rackspace::Directory
key="blue",
bytes=434266,
count=1,
cdn_cname=nil
>
Create Drectory
To create a directory:
service.directories.create :key => 'backups'
To create a directory utilizing CDN:
service.directories.create :key => 'web-assets', :public => true
Additional Parameters
The create method also supports the following key values:
| Key | Description |
|---|---|
| :metadata | Hash containing directory metadata. |
Update Directory
Cloud Files supports updating the public attribute to enable/disable CDN.
To update this attribute:
directory.public = false
directory.save
Delete Directory
To delete a directory:
directory.destroy
Note: Directory must be empty before it can be deleted.
List Files
To list files in a directory:
directory.files
Note: File contents is not downloaded until body attribute is called.
Upload Files
To upload a file into a directory:
file = directory.files.create :key => 'space.jpg', :body => File.open "space.jpg"
Additional Parameters
The create method also supports the following key values:
| Key | Description |
|---|---|
| :content_type | The content type of the object. Cloud Files will attempt to auto detect this value if omitted. |
| :access_control_allow_origin | URLs can make Cross Origin Requests. Format is http://www.example.com. Separate URLs with a space. An asterisk (*) allows all. Please refer to CORS Container Headers for more information. |
| :origin | The origin is the URI of the object's host. |
| :etag | The MD5 checksum of your object's data. If specified, Cloud Files will validate the integrity of the uploaded object. |
| :metadata | Hash containing file metadata. |
Download Files
The most efficient way to download files from a private or public directory is as follows:
File.open('downloaded-file.jpg', 'w') do | f |
directory.files.get("my_big_file.jpg") do | data, remaining, content_length |
f.syswrite data
end
end
This will download and save the file in 1 MB chunks. The chunk size can be changed by passing the parameter :chunk_size into the :connection_options hash in the service constructor.
Note: The body attribute of file will be empty if a file has been downloaded using this method.
If a file object has already been loaded into memory, you can save it as follows:
File.open('germany.jpg', 'w') {|f| f.write(file_object.body) }
Note: This method is more memory intensive as the entire object is loaded into memory before saving the file as in the example above.
Accessing Files Through CDN
The CDN service offers several different URLs to access your files.
The simplest is with the default container URL. This can be accessed as follows:
file.public_url
For a more user-friendly URL, you can create a CNAME DNS record pointing to the URL generated by the public_url method. Then set the CNAME on the Directory object using the attribute cdn_cname. Note, that the cdn_cname attribute does not persist and will need to be specified every time a directory object is retrieved.
To access the file using SSL, you need to specify the option :rackspace_cdn_ssl => true when creating Fog::Storage service. This will cause the public_url method to return the SSL-secured URL.
To stream content use the following:
file.streaming_url
To stream video for iOS devices without needing to convert your video use the following:
file.ios_url
Metadata
You can access metadata as an attribute on both Fog::Storage::Rackspace::Directory and Fog::Storage::Rackspace::File.
This example demonstrates how to iterate through a directory's metadata:
directory.metadata.each_pair {|metadatum| puts "#{metadatum.key}: #{metadatum.value}" }
You can update and retrieve metadata in a manner similar to a hash:
directory.metadata[:thumbnails]
file.metadata[:environment] = "development"
Directory metadata is saved when the directory is saved and file metadata is set when the file is saved:
directory.save
file.save
Metadata is reloaded when directory or file is reloaded:
directory.reload
file.reload
Copy File
Cloud Files supports copying files. To copy files into a container named "trip" with a name of "europe.jpg" do the following:
file.copy("trip", "europe.jpg")
To move or rename a file, perform a copy operation and then delete the old file:
file.copy("trip", "germany.jpg")
file.destroy
Delete File
To delete a file:
file.destroy
CDN Purge
To immediately remove a file from the CDN network use the following:
file.purge_from_cdn
You may only purge up to 25 objects per day and thus this should only be used in situations where there could be serious personal, business, or security consequences if the object remained in the CDN. To purge a directory, please contact Rackspace support.
Note: You may only PURGE up to 25 objects per day. Any attempt to purge more than this will result in a 498 status code error (Rate Limited).
Account Information
To view Cloud Files usage execute the following:
service.account
This returns a response similar to the following:
<Fog::Storage::Rackspace::Account
meta_temp_url_key="lkkl23jl2j3",
container_count=13,
bytes_used=2563554,
object_count=5
>