Drastic
This is a shared library for sharing functionality between various components in a running Drastic system. It is intended to be included by the drastic-web and drastic-agent components.
Configuration
Configuration is specified with the DRASTIC_CONFIG environment variable
export DRASTIC_CONFIG=settings
The file at settings.py only needs to be changed should the Cassandra Keyspace name change. By default the keyspace is called Drastic.
Functionality provided
Models
Activity
Blob
Collection
Group
Node
Resource
Search
User
Errors
This module contains Drastic model-specific exceptions to be handled if problems occur when writing to the database, such as UniqueError to be raised when an attempt is made to write a new Collection with the name of an existing one.
Drivers
The shared drivers (drastic.drivers.CassandraDriver and drastic.drivers.FileSystemDriver) provide functions for returning a previous added file in chunks. The drivers are loaded by called drastic.drivers.get_driver() and passing either a cassandra:// URL or a file:// URL. By default the chunk size is 1Mb.
Metadata Validation
The drastic.metadata.MetadataValidator class provides a mechanism for validating collection/resource metadata when submitted via a webform. Once the CDMI layer is complete it is expected that it will use the same mechanism.
Command Line Interface
Whenever drastic is installed in a sub-component’s virtualenv, the drastic command is available from inside the activated virtualenv to interact with the system.
Create the database
Creates/Syncs the database defined in configuration with the latest models.
drastic create
Reset the database
Deletes the entire database (defined in config), and is irreversible. Should only be used during development.
drastic zap
Create a user
Provides a guided interface to create a new user. You will be asked if this is an administrative user, their password and their email address.
drastic user-create
List all users
Displays a list of all known users within the current drastic system.
drastic user-list
Create a group
Creates a new group within the system. Requires the name of the group and the name of the owning user.
drastic group-create GROUP_NAME OWNING_USERNAME
List all groups
List all currently known groups
drastic group-list
Add user to group
Adds a user to a group by specifying the group name and the username
drastic group-add-user GROUP_NAME USER_NAME
Delete a group
Deletes the specified group
drastic group-delete GROUP_NAME
Ingest data
The ingest command is used to import existing data into the Drastic system. By providing a directory the command will walk the files and sub-folders within that directory adding them as collections and resources in Drastic. The created collection structure will mirror the provided local directory.
This command needs at least 3 arguments, they are:
- group - The group name which will be given ownership of the newly created resources and collections
- user - The user who will be used to create the resources and collections.
- folder - The local folder to be ingested.
By default, all created resources are stored in Cassandra (the system default), and are created with URLs that point to a Blob in the Cassandra DB. It is possible to create the collections and resources but without uploading any files - this will mean that the created resource URLs will point to the local agent (which will then deliver the content). To perform this type of import the noimport and localip are required. The first is a boolean flag, the second a string with the IP address of the local agent.
Examples
Import a local folder into Cassandra
Imports all of the folders and resources under /data into Cassandra.
drastic ingest --group TEST_GROUP--user TEST_USER --folder /data
Import into Drastic but leave the resources on disk
In this case it is important that the agent is configured to point to /data for its disk storage as the URLs created will be relative to this. So a local file /data/test/somedata.csv will be given the URL file://192.168.10.10/test/somedata.csv.
drastic ingest --group TEST_GROUP--user TEST_USER --folder /data --localip 192.168.10.10 --noimport
