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5.2. Managing Volumes using Heketi

Heketi provides a RESTful management interface which can be used to manage the lifecycle of Red Hat Gluster Storage volumes. With Heketi, cloud services like OpenStack Manila, Kubernetes, and OpenShift can dynamically provision Red Hat Gluster Storage volumes with any of the supported durability types. Heketi will automatically determine the location for bricks across the cluster, making sure to place bricks and its replicas across different failure domains. Heketi also supports any number of Red Hat Gluster Storage clusters, allowing cloud services to provide network file storage without being limited to a single Red Hat Gluster Storage cluster.
With Heketi, the administrator no longer manages or configures bricks, disks, or trusted storage pools. Heketi service will manage all hardware for the administrator, enabling it to allocate storage on demand. Any disks registered with Heketi must be provided in raw format, which will then be managed by it using LVM on the disks provided.

Note

  • The replica 3 volume type is the default and the only supported volume type that can be created using Heketi.
Heketi Architecture
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Heketi Architecture

Figure 5.1. Heketi Architecture

Heketi can be configured and executed using the CLI or the API. The sections ahead describe configuring Heketi using the CLI.

5.2.1. Prerequisites
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Heketi requires SSH access to the nodes that it will manage. Hence, ensure that the following requirements are met:
  • SSH Access

    • SSH user and public key must be setup on the node.
    • SSH user must have password-less sudo.
    • Must be able to run sudo commands from SSH. This requires disabling requiretty in the /etc/sudoers file
  • Start the glusterd service after Red Hat Gluster Storage is installed.
  • Disks to be registered with Heketi must be in the raw format.

5.2.2. Installing Heketi
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Note

Heketi is supported only on Red Hat Enterprise Linux 7.
After installing Red Hat Gluster Storage 3.2, execute the following command to install the heketi-client: 
 # yum install heketi-client
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heketi-client has the binary for the heketi command line tool.
Execute the following command to install heketi: 
# yum install heketi
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For more information about subscribing to the required channels and installing Red Hat Gluster Storage, see the Red Hat Gluster Storage Installation Guide.

5.2.3. Starting the Heketi Server
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Before starting the server, ensure that the following prerequisites are met:
  • Generate the passphrase-less SSH keys for the nodes which are going to be part of the trusted storage pool by running the following command: 
    # ssh-keygen -f /etc/heketi/heketi_key -t rsa -N ''
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  • Change the owner and the group permissions for the heketi keys using the following command: 
    # chown heketi:heketi /etc/heketi/heketi_key*
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  • Set up password-less SSH access between Heketi and the Red Hat Gluster Storage servers by running the following command: 
    # ssh-copy-id -i /etc/heketi/heketi_key.pub root@server
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  • Setup the heketi.json configuration file. The file is located in /etc/heketi/heketi.json. The configuration file has the information required to run the Heketi server. The config file must be in JSON format with the following settings:
    • port: string, Heketi REST service port number
    • use_auth: bool, Enable JWT Authentication
    • jwt: map, JWT Authentication settings
      • admin: map, Settings for the Heketi administrator
        • key: string,
        • user: map, Settings for the Heketi volume requests access user
        • key: string, t
    • glusterfs: map, Red Hat Gluster Storage settings
      • executor: string, Determines the type of command executor to use. Possible values are:
        • mock: Does not send any commands out to servers. Can be used for development and tests
        • ssh: Sends commands to real systems over ssh
      • db: string, Location of Heketi database
      • sshexec: map, SSH configuration
        • keyfile: string, File with private ssh key
        • user: string, SSH user
    Following is an example of the JSON file: 
    {
  "_port_comment": "Heketi Server Port Number",
  "port": "8080",

  "_use_auth": "Enable JWT authorization. Please enable for deployment",
  "use_auth": false,

  "_jwt": "Private keys for access",
  "jwt": {
    "_admin": "Admin has access to all APIs",
    "admin": {
      "key": "My Secret"
    },
    "_user": "User only has access to /volumes endpoint",
    "user": {
      "key": "My Secret"
    }
  },

  "_glusterfs_comment": "GlusterFS Configuration",
  "glusterfs": {
    "_executor_comment": [
      "Execute plugin. Possible choices: mock, ssh",
      "mock: This setting is used for testing and development.",
      "      It will not send commands to any node.",
      "ssh:  This setting will notify Heketi to ssh to the nodes.",
      "      It will need the values in sshexec to be configured.",
      "kubernetes: Communicate with GlusterFS containers over",
      "            Kubernetes exec api."
    ],
    "executor": "ssh",

    "_sshexec_comment": "SSH username and private key file information",
    "sshexec": {
      "keyfile": "path/to/private_key",
      "user": "sshuser",
      "port": "Optional: ssh port.  Default is 22",
      "fstab": "Optional: Specify fstab file on node.  Default is /etc/fstab"
    },

    "_kubeexec_comment": "Kubernetes configuration",
    "kubeexec": {
      "host" :"https://kubernetes.host:8443",
      "cert" : "/path/to/crt.file",
      "insecure": false,
      "user": "kubernetes username",
      "password": "password for kubernetes user",
      "namespace": "OpenShift project or Kubernetes namespace",
      "fstab": "Optional: Specify fstab file on node.  Default is /etc/fstab"
    },

    "_db_comment": "Database file name",
    "db": "/var/lib/heketi/heketi.db",

    "_loglevel_comment": [
      "Set log level. Choices are:",
      "  none, critical, error, warning, info, debug",
      "Default is warning"
    ],
    "loglevel" : "debug"
  }
}
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    Note

    The location for the private SSH key that is created must be set in the keyfile setting of the configuration file, and the key should be readable by the heketi user.

5.2.3.1. Starting the Server
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For Red Hat Enterprise Linux 7

  1. Enable heketi by executing the following command: 
    # systemctl enable heketi
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  2. Start the Heketi server, by executing the following command: 
    # systemctl start heketi
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  3. To check the status of the Heketi server, execute the following command: 
    # systemctl status heketi
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  4. To check the logs, execute the following command: 
    # journalctl -u heketi
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Note

After Heketi is configured to manage the trusted storage pool, gluster commands should not be run on it, as this will make the heketidb inconsistent, leading to unexpected behaviors with Heketi.

5.2.3.2. Verifying the Configuration
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To verify if the server is running, execute the following step:
If Heketi is not setup with authentication, then use curl to verify the configuration: 
# curl http://<server:port>/hello
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You can also verify the configuration using the heketi-cli when authentication is enabled: 
# heketi-cli --server http://<server:port> --user <user> --secret <secret> cluster list
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5.2.4. Setting up the Topology
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Setting up the topology allows Heketi to determine which nodes, disks, and clusters to use.

5.2.4.1. Prerequisites
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You have to determine the node failure domains and clusters of nodes. Failure domains is a value given to a set of nodes which share the same switch, power supply, or anything else that would cause them to fail at the same time. Heketi uses this information to make sure that replicas are created across failure domains, thus providing cloud services volumes which are resilient to both data unavailability and data loss.
You have to determine which nodes would constitute a cluster. Heketi supports multiple Red Hat Gluster Storage clusters, which gives cloud services the option of specifying a set of clusters where a volume must be created. This provides cloud services and administrators the option of creating SSD, SAS, SATA, or any other type of cluster which provide a specific quality of service to users.

Note

Heketi does not have a mechanism today to study and build its database from an existing system. So, a new trusted storage pool has to be configured that can be used by Heketi.

5.2.4.2. Topology Setup
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The command line client loads the information about creating a cluster, adding nodes to that cluster, and then adding disks to each one of those nodes.This information is added into the topology file. To load a topology file with heketi-cli, execute the following command:

Note

A sample, formatted topology file (topology-sample.json) is installed with the ‘heketi-templates’ package in the /usr/share/heketi/ directory. 
# export HEKETI_CLI_SERVER=http://<heketi_server:port>
# heketi-cli load --json=<topology_file>
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Where topology_file is a file in JSON format describing the clusters, nodes, and disks to add to Heketi. The format of the file is as follows:
clusters: Array of clusters
  • Each element on the array is a map which describes the cluster as follows
    • nodes: Array of nodes in a cluster
      Each element on the array is a map which describes the node as follows
      • node: Same as Node Add, except there is no need to supply the cluster ID.
      • devices: Name of each disk to be added
      • zone: The value represents failure domain on which the node exists.
For example:
  1. Topology file: 
    {
    "clusters": [
        {
            "nodes": [
                {
                    "node": {
                        "hostnames": {
                            "manage": [
                                "10.0.0.1"
                            ],
                            "storage": [
                                "10.0.0.1"
                            ]
                        },
                        "zone": 1
                    },
                    "devices": [
                        "/dev/sdb",
                        "/dev/sdc",
                        "/dev/sdd",
                        "/dev/sde",
                        "/dev/sdf",
                        "/dev/sdg",
                        "/dev/sdh",
                        "/dev/sdi"
                    ]
                },
                {
                    "node": {
                        "hostnames": {
                            "manage": [
                                "10.0.0.2"
                            ],
                            "storage": [
                                "10.0.0.2"
                            ]
                        },
                        "zone": 2
                    },
                    "devices": [
                        "/dev/sdb",
                        "/dev/sdc",
                        "/dev/sdd",
                        "/dev/sde",
                        "/dev/sdf",
                        "/dev/sdg",
                        "/dev/sdh",
                        "/dev/sdi"
                    ]
                },

.......
.......
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  2. Load the Heketi JSON file: 
    # heketi-cli topology load --json=topology_libvirt.json
Creating cluster ... ID: a0d9021ad085b30124afbcf8df95ec06
        Creating node 192.168.10.100 ... ID: b455e763001d7903419c8ddd2f58aea0
                Adding device /dev/vdb ... OK
                Adding device /dev/vdc ... OK
…….
        Creating node 192.168.10.101 ... ID: 4635bc1fe7b1394f9d14827c7372ef54
                Adding device /dev/vdb ... OK
                Adding device /dev/vdc ... OK
………….
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  3. Execute the following command to check the details of a particular node: 
    # heketi-cli node info b455e763001d7903419c8ddd2f58aea0
Node Id: b455e763001d7903419c8ddd2f58aea0
Cluster Id: a0d9021ad085b30124afbcf8df95ec06
Zone: 1
Management Hostname: 192.168.10.100
Storage Hostname: 192.168.10.100
Devices:
Id:0ddba53c70537938f3f06a65a4a7e88b   Name:/dev/vdi            Size (GiB):499     Used (GiB):0       Free (GiB):499
Id:4fae3aabbaf79d779795824ca6dc433a   Name:/dev/vdg            Size (GiB):499     Used (GiB):0       Free (GiB):499
…………….
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  4. Execute the following command to check the details of the cluster: 
    # heketi-cli cluster info a0d9021ad085b30124afbcf8df95ec06
Cluster id: a0d9021ad085b30124afbcf8df95ec06
Nodes:
4635bc1fe7b1394f9d14827c7372ef54
802a3bfab2d0295772ea4bd39a97cd5e
b455e763001d7903419c8ddd2f58aea0
ff9eeb735da341f8772d9415166b3f9d
Volumes:
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  5. To check the details of the device, execute the following command: 
    # heketi-cli device info 0ddba53c70537938f3f06a65a4a7e88b
Device Id: 0ddba53c70537938f3f06a65a4a7e88b
Name: /dev/vdi
Size (GiB): 499
Used (GiB): 0
Free (GiB): 499
Bricks:
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5.2.5. Creating a Volume
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After Heketi is set up, you can use the CLI to create a volume.
  1. Execute the following command to check the various option for creating a volume: 
    # heketi-cli volume create --size=<size in Gb> [options]
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  2. For example: After setting up the topology file with two nodes on one failure domain, and two nodes in another failure domain, create a 100Gb volume using the following command: 
    # heketi-cli volume create --size=100
Name: vol_0729fe8ce9cee6eac9ccf01f84dc88cc
Size: 100
Id: 0729fe8ce9cee6eac9ccf01f84dc88cc
Cluster Id: a0d9021ad085b30124afbcf8df95ec06
Mount: 192.168.10.101:vol_0729fe8ce9cee6eac9ccf01f84dc88cc
Mount Options: backupvolfile-servers=192.168.10.100,192.168.10.102
Durability Type: replicate
Replica: 3
Snapshot: Disabled

Bricks:
Id: 8998961142c1b51ab82d14a4a7f4402d
Path: /var/lib/heketi/mounts/vg_0ddba53c70537938f3f06a65a4a7e88b/brick_8998961142c1b51ab82d14a4a7f4402d/brick
Size (GiB): 50
Node: b455e763001d7903419c8ddd2f58aea0
Device: 0ddba53c70537938f3f06a65a4a7e88b
 …………….
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  3. To check the details of the device, execute the following command: 
    # heketi-cli device info 0ddba53c70537938f3f06a65a4a7e88b
Device Id: 0ddba53c70537938f3f06a65a4a7e88b
Name: /dev/vdi
Size (GiB): 499
Used (GiB): 201
Free (GiB): 298
Bricks:
Id:0f1766cc142f1828d13c01e6eed12c74   Size (GiB):50      Path: /var/lib/heketi/mounts/vg_0ddba53c70537938f3f06a65a4a7e88b/brick_0f1766cc142f1828d13c01e6eed12c74/brick
Id:5d944c47779864b428faa3edcaac6902   Size (GiB):50      Path: /var/lib/heketi/mounts/vg_0ddba53c70537938f3f06a65a4a7e88b/brick_5d944c47779864b428faa3edcaac6902/brick
Id:8998961142c1b51ab82d14a4a7f4402d   Size (GiB):50      Path: /var/lib/heketi/mounts/vg_0ddba53c70537938f3f06a65a4a7e88b/brick_8998961142c1b51ab82d14a4a7f4402d/brick
Id:a11e7246bb21b34a157e0e1fd598b3f9   Size (GiB):50      Path: /var/lib/heketi/mounts/vg_0ddba53c70537938f3f06a65a4a7e88b/brick_a11e7246bb21b34a157e0e1fd598b3f9/brick
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5.2.6. Deleting a Volume
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To delete a volume, execute the following command: 
# heketi-cli volume delete <volname>
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For example: 
$ heketi-cli volume delete 0729fe8ce9cee6eac9ccf01f84dc88cc
Volume 0729fe8ce9cee6eac9ccf01f84dc88cc deleted
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