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Kubernetes Multinode on OpenStack

Launch Login Node

Prepare User Data

When launching a login node it is worth considering what user data options to provide. While it is not required, user data can provide powerful customisation at launch that can further streamline the cluster build process.

There are several options that can be added to change how a compute node will contact nodes on startup.

  • Sharing public ssh key to clients:
    • Instead of manually obtaining and sharing the root public SSH key (passwordless root ssh is required for flight profile) this can be shared over the local network with SHAREPUBKEY=true
  • Add an auth key:
    • Add the line AUTH_KEY=<string>. This means that the node will only accept incoming flight hunter nodes that provide a matching authorisation key
An example of all mentioned lines in a single cloud init script.
#cloud-config
write_files:
  - content: |
      SHAREPUBKEY=true
      AUTH_KEY=banana
    path: /opt/flight/cloudinit.in
    permissions: '0644'
    owner: root:root
  - content: |
      /opt/flight/bin/flight profile prepare openflight-kubernetes-multinode
    path: /var/lib/firstrun/scripts/00-prepare-profile.bash
    permissions: '0600'
    owner: root:root

Note

The section that writes the /var/lib/firstrun/scripts/00-prepare-profile.bash file sets up the necessary dependencies for Kubernetes automatically when the login node is launched

Info

More information on available user data options for Flight Solo via the user data documentation

Deploy

To set up a cluster, you will need to import a Flight Solo image.

Before setting up a cluster on Openstack, there are several required prerequisites:

  • Your own keypair
  • A network
  • A router
    • With an interface both on the External Gateway network and an Internal Interface on the previously created network
  • A security group that allows traffic is given below (if creating the security group through the web interface then the "Any" protocol will need to be 3 separate rules for "All ICMP", "All TCP" and "All UDP")
Protocol Direction CIDR Port Range
Any egress 0.0.0.0/0 any
Any ingress Virtual Network CIDR any
ICMP ingress 0.0.0.0/0 any
SSH ingress 0.0.0.0/0 22
TCP ingress 0.0.0.0/0 80
TCP ingress 0.0.0.0/0 443
TCP ingress 0.0.0.0/0 5900-5903
TCP ingress 0.0.0.0/0 8888

Note

The "Virtual Network CIDR" is the subnet and netmask for the network that the nodes are using. For example, a node on the 11.11.11.0 network with a netmask of 255.255.255.0 would have a network CIDR of 11.11.11.0/24.

The documentation includes instructions for importing an image to Openstack, and guides for setting up the other prerequisites can be found in the Openstack documentation

To set up a cluster:

  1. Go to the Openstack instances page.

  2. Click "Launch Instance", and the instance creation window will pop up.

  3. Fill in the instance name, and leave the number of instances as 1, then click next.

  4. Choose the desired image to use by clicking the up arrow at the end of its row. It will be displayed in the "Allocated" section when selected.

  5. Choose the desired instance size by clicking the up arrow at the end of its row. It will be displayed in the "Allocated" section when selected.

  6. Choose a network in the same way as an image or instance size. Note that all nodes in a cluster must be on the same network.

  7. Choose a security group in the same way as an image or instance size. Note that all nodes in a cluster must be in the same security group.

  8. Choose the keypair in the same way as an image or instance size.

  9. In the "Configuration" section, there is a "Customisation Script" section with a text box. This will be used to set your user data

  10. When all options have been selected, press the "Launch Instance" button to launch. If the button is greyed out, then a mandatory setting has not been configured.

  11. Go to the "Instances" page in the "Compute" section. The created node should be there and be finishing or have finished creation.

  12. Click on the down arrow at the end of the instance row. This will bring up a drop-down menu.

  13. Select "Associate Floating IP", this will make the ip management window pop up.

  14. Associate a floating IP, either by using an existing one or allocating a new one.

    1. To use an existing floating IP:

      1. Open the IP Address drop-down menu.

      2. Select one of the IP Addresses.

      3. Click "Associate" to finish associating an IP.

    2. To allocate a new floating IP:

      1. Click the "+" next to the drop-down arrow to open the allocation menu.

      2. Click "Allocate IP".

  15. Click "Associate" to finish associating an IP.

Launch Compute Nodes

Prepare User Data

Setting up compute nodes is done slightly differently than a login node. The basic steps are the same except subnets, networks and security groups need to match the ones used for the login node.

This is the smallest amount of cloud init data necessary. It allows the login node to find the compute nodes as long as they are on the same network, and ssh into them from the root user (which is necessary for setup).

#cloud-config
users:
  - default
  - name: root
    ssh_authorized_keys:
      - <Content of ~/.ssh/id_alcescluster.pub from root user on login node>

Tip

The above is not required if the SHAREPUBKEY option was provided to the login node. If this was the case then the SERVER option provided to the compute node will be enough to enable root access from the login node.

There are several options that can be added to change how a compute node will contact nodes on startup.

  • Sending to a specific server:
    • Instead of broadcasting across a range, add the line SERVER=<private server IP> to send to specifically that node, which would be your login node.
  • Add an auth key:
    • Add the line AUTH_KEY=<string>. This means that the compute node will send it's flight hunter packet with this key. This must match the auth key provided to your login node
An example of all mentioned lines in a single cloud init script.
#cloud-config
write_files:
  - content: |
      SERVER=10.10.0.1
      AUTH_KEY=banana
    path: /opt/flight/cloudinit.in
    permissions: '0644'
    owner: root:root
  - content: |
      /opt/flight/bin/flight profile prepare openflight-kubernetes-multinode
    path: /var/lib/firstrun/scripts/00-prepare-profile.bash
    permissions: '0600'
    owner: root:root
users:
  - default
  - name: root
    ssh_authorized_keys:
      - <Content of ~/.ssh/id_alcescluster.pub from root user on login node>

Note

The section that writes the /var/lib/firstrun/scripts/00-prepare-profile.bash file sets up the necessary dependencies for Kubernetes automatically when the compute node is launched

Info

More information on available user data options for Flight Solo via the user data documentation

Deploy

  1. Go to the Openstack instances page.

  2. Click "Launch Instance", and the instance creation window will pop up.

  3. Fill in the instance name, and set the number of instances to create, then click next.

  4. Choose the desired image to use by clicking the up arrow at the end of its row. It will be displayed in the "Allocated" section when selected.

  5. Choose the desired instance size by clicking the up arrow at the end of its row. It will be displayed in the "Allocated" section when selected.

  6. Choose a network in the same way as an image or instance size. Note that this should be the same network as the login node.

  7. Choose a security group in the same way as an image or instance size. Note that this should be the same network as the login node.

  8. Choose the keypair in the same way as an image or instance size.

  9. In the "Configuration" section, there is a "Customisation Script" section with a text box. This will be used to set user data script prepared earlier

  10. When all options have been selected, press the "Launch Instance" button to launch. If the button is greyed out, then a mandatory setting has not been configured.

General Configuration

Create Node Inventory

  1. Parse your node(s) with the command flight hunter parse.

    1. This will display a list of hunted nodes, for example

      [flight@login-node.novalocal ~]$ flight hunter parse
      Select nodes: (Scroll for more nodes)  login-node.novalocal - 10.10.0.1
         compute-node-1.novalocal - 10.10.101.1
      

    2. Select the desired node to be parsed with Space, and you will be taken to the label editor

      Choose label: login-node.novalocal
      

    3. Here, you can edit the label like plain text

      Choose label: login1
      

      Tip

      You can clear the current node name by pressing Down in the label editor.

    4. When done editing, press Enter to save. The modified node label will appear next to the ip address and original node label.

      Select nodes: login-node.novalocal - 10.10.0.1 (login1) (Scroll for more nodes)  login-node.novalocal - 10.10.0.1 (login1)
         compute-node-1.novalocal - 10.10.101.1
      

    5. From this point, you can either hit Enter to finish parsing and process the selected nodes, or continue changing nodes. Either way, you can return to this list by running flight hunter parse.

    6. Save the node inventory before moving on to the next step.

      Tip

      See flight hunter parse -h for more ways to parse nodes.

Add genders

  1. Optionally, you may add genders to the newly parsed node. For example, in the case that the node should have the gender cluster and all then run the command:
    flight hunter modify-groups --add cluster,all login1
    

Kubernetes Multinode Configuration

  1. Configure profile

    flight profile configure
    
    1. This brings up a UI, where several options need to be set. Use up and down arrow keys to scroll through options and enter to move to the next option. Options in brackets coloured yellow are the default options that will be applied if nothing is entered. - Cluster type: The type of cluster setup needed, in this case Openflight Kubernetes Multinode. - Cluster name: The name of the cluster. - Default user: The user that you log in with. - IP range of compute nodes: The IP range of the compute nodes used, remember to add the netmask. E.g. 172.31.16.0/20 - IP range of Kubernetes pods: The IP range that the kubernetes pods should use, make sure this is different from the IP range of the compute nodes, and remember to add the net mask. E.g. 192.168.0.0/16

  2. Apply identities by running the command flight profile apply

    1. First apply an identity to the login node
      flight profile apply login1 master
      
    2. Wait for the login node identity to finish applying. You can check the status of all nodes with flight profile list.

      Tip

      You can watch the progress of the application with flight profile view login1 --watch

    3. Apply an identity to the each of the compute nodes. E.g.

      flight profile apply node01,node02 worker
      

      Tip

      You can check all available identities for the current profile with flight profile identities

Success

Congratulations, you've now created a Kubernetes Multinode environment! Learn more about Kubernetes in their documentation.

Verifying Functionality

Check Nodes Running/Ready

  1. As the default_username (unless this was changed, it will be flight) check nodes are "Ready"
    kubectl get nodes
    

Launching a "Pod"

  1. Get test yaml file for the VM

    flight silo file pull openflight:kubernetes/pod-launch-test.yaml
    

  2. Launch a pod (this will create an ubuntu VM that sleeps for 10 minutes then exits)

    kubectl apply -f pod-launch-test.yaml
    

  3. Check that the pod is running

    kubectl get pods -o wide
    

  4. The pod should be running without issues.

Perform Network Test

  1. Create yaml file for a php-apache service
    flight silo file pull openflight:kubernetes/php-apache.yaml
    
  2. Launch pod service
    kubectl apply -f php-apache.yaml
    
  3. Get yaml file for VM to verify connection from
    flight silo file pull openflight:kubernetes/busybox-wget.yaml
    
  4. Launch pod
    kubectl apply -f busybox-wget.yaml
    
  5. View output of wget pod (this should show OK!)
    kubectl logs busybox-wget