Installing the NetApp Docker Volume Plugin on CoreOS

In this blog I will provide the steps to install the NetApp Docker Volume Plugin (nDVP) on CoreOS manually and automatically with cloud-config.

First, some introductions:

• NetApp Docker Volume Plugin (nDVP):
  • Provides direct integration with the Docker ecosystem for NetApp storage including ONTAP, E-Series, and SolidFire. The nDVP allows for Docker integrated storage management including provisioning/deprovisioning, attaching/detaching, and cloning of NetApp storage. The nDVP software (a single binary) must be installed on the container host and reads its configuration from a JSON formatted config file when it is started. Each config file describes the connection with a single storage array config; multiple arrays == multiple nDVP daemons, each with a unique config file.
    
• CoreOS:
  • A barebones linux distribution designed specifically to run containers at scale. Some common linux features like the OS installer and a package manager are absent. On the other hand, container ecosystem software like docker, rkt, and etcd are pre-installed. CoreOS is also self-updating and does so for all components in an atomic manner using an A/B partition strategy which causes the /usr filesystem to be read-only. Given CoreOS is a bit unique in how it works installing software on it needs some special care.

Install nDVP manually

To install manually follow these steps:

1. Become root:

   sudo -i
   

2. If you will use iSCSI connected storage start the iSCSI service:

   systemctl start iscsid
   

3. Create a nDVP configuration file for your storage array type.

   • Copy a template from nDVP Github site for your platform and customize to match your site details.
     
   • Validate the JSON using JSONlint to avoid a syntax error that will prevent the driver from starting

   • Save this file to your container host. There are no requirements about name or directory location but for standardization the following filenames (matching the driver name) are suggested:

     Storage Driver	Full Path to Config file
     SolidFire iSCSI	/etc/netappdvp-solidfire-san.json
     ONTAP NFS	/etc/netappdvp-ontap-nas.json
     ONTAP iSCSI	/etc/netappdvp-ontap-san.json
     E-Series iSCSI	/etc/netappdvp-eseries-iscsi.json

4. Download, install, and start the plugin.

   • Replace the FULL-PATH-TO-CONFIG-FILENAME with the name of your config file

   • Replace the version of netappdvp with your desired version

     # Make a directory for the nDVP
     mkdir -p /opt/netappdvp
     
     # Download and install the software
     wget https://github.com/NetApp/netappdvp/releases/download/v1.3.3/netappdvp-1.3.3.tar.gz -O /tmp/netappdvp-1.3.3.tar.gz
     tar -zxvf /tmp/netappdvp-1.3.3.tar.gz -C /opt/netappdvp
     chown root:root /opt/netappdvp/netappdvp
     chmod 755 /opt/netappdvp/netappdvp
     
     # Start the nDVP passing the full path to your config file, and put it to the background
     /opt/netappdvp/netappdvp --config=CONFIG-FILENAME &
     

5. You should now be able to use docker volume COMMAND -d netapp commands to manage persistent storage.

Install nDVP with cloud-config

To install using cloud-config you need to add a few new snippets. These instructions assume you will distribute using a Config Drive and a user_data file:

1. Create a cloud-config file named user_data in the current working directory.

2. Create a nDVP configuration file for your storage array type.

   • Copy a template from nDVP Github site for your platform into a text editor and customize to match your site details. It will be added to the cloud-config in the next step.
   • Validate the JSON using JSONlint to avoid a syntax error that will prevent the driver from starting

3. Add a write_files definition to user_data so your nDVP config file will be saved on the container host:

   • There are no requirements about name or directory location but for standardization the following filenames (matching the driver name) are suggested:

   Storage Driver	Full Path to Config file
   SolidFire iSCSI	/etc/netappdvp-solidfire-san.json
   ONTAP NFS	/etc/netappdvp-ontap-nas.json
   ONTAP iSCSI	/etc/netappdvp-ontap-san.json
   E-Series iSCSI	/etc/netappdvp-eseries-iscsi.json

   • Replace FULL-PATH-TO-CONFIG-FILENAME with the name of your nDVP config file including the full path (example: /etc/netappdvp-solidfire-san.json)

     # Write out nDVP config files
     write_files:
     - path: "FULL-PATH-TO-CONFIG-FILENAME"
     permissions: "0644"
     owner: "root"
     content: |
       # Paste your nDVP config JSON snippet here; indentation in YAML matters!
     

4. If you will use iSCSI connected storage start the iSCSI service by adding a new unit definition to your user_data:

   coreos:
     units:
       # Start iSCSI
       - name: iscsid.service
         command: start
   

5. Add a unit definition to download, install, and start the nDVP.

   • Remove the coreos: and units: lines if you already have this header.
   • Remove the After=iscsid.service line if you are not using iSCSI
   • Replace FULL-PATH-TO-CONFIG-FILENAME with the name of your nDVP config file including the full path (example: /etc/netappdvp-solidfire-san.json)

   • Replace the version of netappdvp with your desired version

     coreos:
     units:
     # Install and start ndvp service
     - name: "ndvp.service"
       command: "start"
     content: |
       [Unit]
       Description=nDVP service
       After=iscsid.service
     
       [Service]
       Restart=always
       ExecStartPre=-/usr/bin/mkdir -p /opt/netappdvp
       ExecStartPre=-/usr/bin/wget https://github.com/NetApp/netappdvp/releases/download/v1.3.3/netappdvp-1.3.3.tar.gz -O /tmp/netappdvp-1.3.3.tar.gz
       ExecStartPre=-/usr/bin/tar -zxvf /tmp/netappdvp-1.3.3.tar.gz -C /opt/netappdvp
       ExecStart=/opt/netappdvp/netappdvp --config=FULL-PATH-TO-CONFIG-FILENAME
     

6. Deploy! You should be able to use docker volume COMMAND -d netapp commands to manage persistent storage.

Troubleshooting

1. The nDVP daemon must be running for it to manage NetApp storage. Check that it is running with:

   ps -ef | grep netappdvp
   

2. Check the nDVP logfile for status or error messages:

   tail /var/log/netappdvp/*
   

3. Enable debug logging, try the action again, and then check the log. Enable debug logging in one of two ways:

   (a) Edit your nDVP config JSON to include and then restart the nDVP:

   "debug": true,
   

   or (b) [Re]start the netappdvp with the -debug flag:

   /opt/netappdvp/netappdvp --config=FULL-PATH-TO-CONFIG-FILENAME  -debug
   

As always, comments are welcome!