The flockerctl Command

This page describes one of our experimental projects, developed to less rigorous quality and testing standards than the mainline Flocker distribution. It is not built with production-readiness in mind.

flockerctl is a CLI for controlling the Flocker Control Service, with commands for listing nodes, creating volumes, and moving them around. flockerctl supports supplying metadata such as size, name and Flocker Storage Profiles.

Install & Configure

Run the following command to install flockerctl:

curl -sSL https://get.flocker.io |sh

You will need to set some environment variables which define the address and credentials that flockerctl will use to connect to the Flocker control service:

  • FLOCKER_CERTS_PATH - typically /etc/flocker if you're running flockerctl from a node in the cluster, otherwise, where your certificates are stored.
  • FLOCKER_USER - the name of a flocker user which has .key and .crt file in the certs path. See Generating an API Client Certificate.
  • FLOCKER_CONTROL_SERVICE - the address (DNS name or IP address) of the control service. The name you use should match up with the name you specified when creating the cluster certificates.

Running the CLI

The command for the CLI tool is flockerctl. If you run this command in the same folder as your cluster.yml file - it will use the settings in the file. If you run it from elsewhere - you need to tell the CLI some additional options.

Here is the output of the flockerctl --help command, where you can see the supported options:

$ flockerctl --help
Usage: flockerctl [options]
Options:
      --cluster-yml=      Location of cluster.yml file (makes other options
                          unnecessary) [default: ./cluster.yml]
      --certs-path=       Path to certificates folder [default: .]
      --user=             Name of user for which .key and .crt files exist
                          [default: user]
      --cluster-crt=      Name of cluster cert file [default: cluster.crt]
      --control-service=  Hostname or IP of control service
      --control-port=     Port for control service REST API [default: 4523]
      --version           Display Twisted version and exit.
      --help              Display this help and exit.
Commands:
    create          create a flocker dataset
    destroy         mark a dataset to be deleted
    list            list flocker datasets
    list-nodes      show list of nodes in the cluster
    move            move a dataset from one node to another
    version         show version information

So - to test that the CLI is installed properly - we can do this command:

flockerctl --version

Listing Nodes

You can list the nodes in your cluster using this command:

flockerctl list-nodes

It will produce output like this:

SERVER     ADDRESS
1acbab49   172.16.70.251
5d74f5be   172.16.70.250

This shows short ID's for the nodes. To show the full ID's for each node:

flockerctl list-nodes -l

It will produce output like this:

SERVER                                 ADDRESS
1acbab49-877c-40d4-80c6-a78ba581df7a   172.16.70.251
5d74f5be-0422-433f-8c6e-dc31f9d89565   172.16.70.250

Here is the output of the help for list-nodes

flockerctl list-nodes --help

It will produce output like this:

Options:
-l, --long     Show long UUIDs
    --version  Display Twisted version and exit.
    --help     Display this help and exit.

Creating a Volume

To create a volume you tell the CLI the ID of the node you want it attached to, the maximum size and some optional metadata.

Here is an example of a CLI command to create a volume:

flockerctl create \
    --node 1acbab49 \
    --size 50Gb \
    --metadata "name=apples,size=medium"

The above command will create a volume that is targeted to the 172.16.70.251 node (using it's ID).

The node property instructs Flocker to attach the volume to the given node, use the ID of the node you want the volume attached to. The size property can either be a number (meaning bytes) or you can use Gb or Mb. The metadata property is a comma-separated string of key=value pairs.

Here is the output of the help for create

flockerctl create --help

It will produce output like this:

Usage: flockerctl [options] create [options]
Options:
  -n, --node=      Initial primary node for dataset (any unique prefix of node
                   uuid, see flockerctl list-nodes)
  -m, --metadata=  Set volume metadata ("a=b,c=d")
  -s, --size=      Set size in bytes (default), k, M, G, T
      --version    Display Twisted version and exit.
      --help       Display this help and exit.

Listing Volumes

To list the volumes in your cluster - use the list command:

$ flockerctl list
DATASET                                SIZE      METADATA                  STATUS         SERVER
9026a6f5-8c74-485d-84a9-a8b41e5b8e66   50.00G    name=apples,size=medium   attached       1acbab49 (172.16.70.251)
b180f7bb-71f4-4acd-82c7-20f4bbd80a21   100.00G   name=apples               attached       1acbab49 (172.16.70.251)

Here is the output of the help for list

flockerctl list --help

It will produce output like this:

Usage: flockerctl [options] list [options]
Options:
  -d, --deleted  Show deleted datasets
  -l, --long     Show long UUIDs
  -h, --human    Human readable numbers
      --version  Display Twisted version and exit.
      --help     Display this help and exit.

Moving Volumes

To move a volume from one node to another - use the move command.

flockerctl move \
    --dataset 9026a6f5 \
    --target 5d74f5be

This command would move the 9026a6f5 dataset onto node 5d74f5be

Here is the output of the help for move

flockerctl move --help

It will produce output like this:

Usage: flockerctl [options] move [options]
Options:
  -d, --dataset=      Dataset to move (uuid)
  -t, --destination=  New primary node (uuid) to move the dataset to
      --version       Display Twisted version and exit.
      --help          Display this help and exit.

Destroying Volumes

To mark a volume as destroyed - use the destroy command.

flockerctl destroy \
    --dataset 9026a6f5

This command would destroy the 9026a6f5 dataset.

Here is the output of the help for destroy.

flockerctl destroy --help

It will produce output like this:

Usage: flockerctl [options] destroy [options]
Options:
  -d, --dataset=  Dataset to destroy
      --version   Display Twisted version and exit.
      --help      Display this help and exit.