List Openstack container’s options with the swift command-line client – capabilities command

First, you need to install

swift command-line utility

and second, install the command-line tool to manage your account: Install OpenStack swift client only
With the capabilities command you may discover the following important policy and limits of your account like:

  • Listing limits – how many files (objects) will be in the output when using list command.
  • The maximum file size, which is supported by the server.
  • Maximum files (objects) for deletion per a single request. How many files you can delete with a single request, which is very convinient to put thousands of files per one requests, not to initiate an http(s) connection for each file (object), which could be thousands of files, or even millions!
  • Additinal plugins (in terms of Openstack – middleware), which are supported
  • Maximum container name length

and many more.

In general, you will need:

  1. username (–os-username) – Username
  2. password (–os-password) – Password
  3. authentication url (–os-auth-url) – The URL address, which authorize your requests, it generates a security token for your operations. Always use https!
  4. tenant name (–os-tenant-name) – Tenant is like a project.

All of the above information should be available from your OpenStack administrator.
Here an example output of the capabalities command:

myuser@myserver:~$ swift --os-username myusr --os-tenant-name myusr --os-password mypass --os-auth-url capabilities
Core: swift
  account_autocreate: True
  account_listing_limit: 20000
  allow_account_management: False
  container_listing_limit: 20000
  extra_header_count: 0
  max_account_name_length: 256
  max_container_name_length: 256
  max_file_size: 5368709122
  max_header_size: 8192
  max_meta_count: 90
  max_meta_name_length: 128
  max_meta_overall_size: 4096
  max_meta_value_length: 256
  max_object_name_length: 1024
  policies: [{'name': 'Policy-0', 'default': True}]
  strict_cors_mode: True
Additional middleware: bulk_delete
  max_deletes_per_request: 20000
Additional middleware: bulk_upload
  max_containers_per_extraction: 20000
  max_failed_extractions: 1000
Additional middleware: container_sync
  realms: {}
Additional middleware: crossdomain
Additional middleware: formpost
Additional middleware: keystoneauth
Additional middleware: slo
  max_manifest_segments: 1000
  max_manifest_size: 2097152
  min_segment_size: 1048576
Additional middleware: staticweb

You can see various middleware are activated with specific options – bulk_upload – to upload multiple files with one request (a list with files) and bulk_delete – to delete multiple files per one request and so on.

Install OpenStack swift client only

To manage files in the OpenStack cloud you need the swift client. This is not so tiny python tool (a lot of dependencies), which offers by means of files (as files are objects for the OpenStack):

  • delete – Delete files, directories and sub-directories. Be careful with a simple command you can delete all your files at once. “Delete a container or objects within a container.”
  • download – Download files to your local storage. “Download objects from containers.”
  • list – List all files in the main directory (i.e. the container), cannot be listed files in sub-directories. The output will be a file with path per line or you can enable extended output to show file size, time modified, the type of the file and the full file path. “Lists the containers for the account or the objects for a container.”
  • post – Creates containers and updates metadata, could create seurity keys for temporary urls – “Updates meta information for the account, container, or object; creates containers if not present.”
  • copy – Copy files to a new place within a container or to a different container. “Copies object, optionally adds meta”
  • stat – Display information for files, container and your account. No information is available per directory. Most typically you will read the file length, the type and modifcation date. “Displays information for the account, container, or object”
  • upload – uploads files and whole directories in a container – “Uploads files or directories to the given container.” You can read our article here – Upload files and directories with swift in OpenStack
  • capabilities – List the configuration options of your account like file size limits, file amount limits , limit requests per seconds and so on and which additional middleware your instance supports like bulk_delete, bulk_upload (the name are self-explainatory) – “List cluster capabilities.”
  • tempurl – Generate a temporary url for a file protected with time validity and a key – “Create a temporary URL.”
  • auth – Show your authentication token and storage url – “Display auth related environment variables.”

The text in the hyphens is from the swift help command. If you do not know what is a container with simple words these are the main sub-directories in your account if you use the list command without any argument (not adding a name after “list”):

myuser@myserver:~$ swift --os-username myusr --os-tenant-name myusr --os-password mypass --os-auth-url list

The best way is to install the swift client from the package system of your Linux Distribution. The package system ensures the programs you install and upgrade are consistent within dependencies upgrades.

When you install this package “python-swiftclient” it depends on multiple python packages, which might be upgraded later, too, but the package system of a Linux distribution ensure the programs of python-swiftclient will work with them

. On the contrary, if you install it manually even with “pip” as it is offered in OpenStack site it is unsure what will happen and even your client program from “python-swiftclient” could stop working because of an upgraded dependancy library. Of course, the packages from the official package system could be a little bit older (but probably more stable) than the manual installs from the OpenStack official site. Still if you would like to install it with “pip” here you can check how you can do it:
Keep on reading!