Apache: Capturing an Image to run in a Xen VM and Creating a Tier

Intended for use with Cassatt Active Response V5.0.

This blueprint describes how to deploy Apache in a Xen VM within the Cassatt Active Response environment. If you haven't read Understanding the Cross Virtualization Manager and Understanding Blueprints for Deploying Applications, read that first for background and context.

Prerequisites

	Software requirements: Red Hat ELAS 4.1 or 4.4: Set up a Red Hat installation server as described in Appendix E of the XenEnterprise user guide, Getting Started With XenEnterprise. Apache Web Server XenEnterprise Administrator Console 3.2: Follow the installation instructions provided in the XenEnterprise user guide, Getting Started With XenEnterprise, to install the XenEnterprise Administrator Console on a workstation outside the Cassatt Active Response environment. You will need the Administrator Console to create a VM to use as the virtual image host.
	Image host requirements: XenEnterprise installed; see XenEnterprise: Capturing an Image and Creating a Tier.
	Capture/deployment method: This blueprint includes two methods for capturing and deploying Apache in XenEnterprise VMs—both methods leverage Xen storage mechanisms: virtual block device (VBD) file and NFS root. Use the method that works best for your site based on how Cassatt Active Response serves the images:   Advantages Disadvantages VBD: Cassatt Active Response copies the entire file into the VM each time a VM is booted. Fast disk IO Volatility: Any changes made to the VBD file are lost when the guest VM is rebooted (and when the host application node is rebooted, since rebooting the host also reboots the VMs) Power on is slow because the entire VBD image (possibly multiple gigabytes in size) is copied from the image matrix every time a VM is powered on NFS root: Cassatt Active Response serves the image in the usual way via NFS. Persistence: Any changes made to the image are saved and used across VM (and host node) reboots. Fast boot Slower net IO
	Tier Settings: SLAs: Determine the capacity settings for the Apache tier. To understand how to determine capacity levels, see Understanding Tier Configuration and Personalization. Tier Dependencies: select at least one Xen host tier as a tier dependency to ensure that VMs are available for this tier. For more information, see the sidebar Tier Dependencies: What You Should Know.
	Network Requirements: XenEnterprise does not support VLAN interfaces within VMs, and Xen VMs are limited to three NICs. Consequently, this tier is limited to a primary network plus two additional networks, which must have dedicated NICs. In addition, Xen guest tiers are limited to those networks you selected for the XenEnterprise host tier. From the networks selected for the host tier, select a primary network and up to two additional networks.

The blueprint steps

This blueprint differs somewhat from the standard high-level blueprint steps.

• For this blueprint, reserving the physical image host is a prerequisite because XenEnterprise must already be running before starting this blueprint. Instead, you must create a XenEnterprise VM to serve as the virtual image host.
• Installing Apache is part of installing the operating system.
• This blueprint includes two capture methods: virtual block device (VBD) file and NFS root.
  

Step 1: Create a XenEnterprise VM to be the virtual image host

1. Log into the XenEnterprise Administrator Console on your workstation using the IP address of your physical image host for the XenEnterprise Server.
2. Install a XenEnterprise VM using the instructions provided in the XenEnterprise user guide, Getting Started With XenEnterprise.
3. In the Install From field, select your preferred Red Hat Enterprise Linux repository (4.1 or 4.4).
4. Use your own values for all other fields.

The VM you create in this step serves only as a container; the VM itself is not copied during image capture. Values you specify during VM creation are used only while installing the operating system and configuring Apache.

Step 2: Install the operating system

When the Red Hat installation begins, use the following settings; for fields not listed, use values appropriate for your site:

• IP configuration: use the static IP address from the last step and the default gateway and DNS server for your Cassatt Active Response environment
• Packages: make sure the GNU Compiler and Apache Web Server are installed

Step 3: Configure your software

Follow these steps to set up the Apache configuration on the virtual image host.

1. Log into the VM:
   1. Connect to the physical image host via ssh.
   2. List the VMs:
      
      xm list
   3. Identify your VM ID (only one should be listed) and log in:
      
      xm console ID
2. Set the firewall to off:
   
   

   chkconfig iptables off

3. To facilitate http monitoring, configure Apache to start automatically when the system is rebooted, as follows:

   chkconfig httpd on

4. If you have web content ready to deploy, do so now.
   
   If you do not have web content to deploy, you need to put a placeholder index.html file in /var/www/html for Cassatt Active Response to use in monitoring the Apache service. A simple way to create a blank file that serves this function is to navigate to /var/www/html:
   
   cd /var/www/html
   
   Then issue the touch command to create a blank file called index.html:
   
   touch index.html
5. Edit the network configuration as follows, deleting the lines for HWADDR, NETMASK, IPADDR, and GATEWAY:

   vi /etc/sysconfig/network-scripts/ifcfg-eth0

   DEVICE=eth0
   BOOTPROTO=dhcp
   TYPE=Ethernet
   ONBOOT=yes

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Step 4: Capture the image

In this step, you will capture the base image from the image host using the cccapture command—an interactive script. Although you can change the values later, it is most efficient to supply valid values now.

NFS root capture

Follow these steps:

1. Using the XenEnterprise Administrator Console, check to make sure your VM is running.
2. Log into the active Cassatt Active Response control node as root.
3. Enter the following command to start the capture of the base image from the image host:
   
   /opt/cassatt/bin/cccapture
4. Answer each prompt.
   
   The next table lists suggested values for the Apache blueprint; unless you have site-specific reasons, you can accept the default values for other cccapture prompts.
   
   For names, descriptions, and other discretionary fields, use values that are meaningful to you. In the image name, do not use spaces or characters (for example, /) special to Unix-based file systems such as Linux.
   
   For file system selection: selecting unneeded file systems wastes space but is otherwise harmless.
   
   

   At this prompt...	Enter...	Notes
   Enter the image type (linux, vmhost, xenhost, xenguest, windows, solaris):	xenguest
   Enter the IP address or hostname of the image host:	ipaddress	Use the IP address of the XenEnterprise VM you created as the virtual image host.
   OS Monitoring Options Specify the operating system monitoring that will be used for this image (at least one monitoring option must be configured): Monitor via SNMP? [n]	y
   Monitor via ping? [n] Ping Timeout (seconds): [15]	y 30

   
   
5. In the Controller, release the image host back to the free pool by selecting the node using the checkbox, then select Node Actions > Release from Image Capture.

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VBD capture

Follow these steps:

1. Using the XenEnterprise Administrator Console, shut down your VM.
2. Log into the active control node as root.
3. Enter the following command to start the capture of the base image from the image host:
   
   /opt/cassatt/bin/cccapture
4. Answer each prompt.
   
   The next table lists suggested values for the Apache blueprint; unless you have site-specific reasons, you can accept the default values for other cccapture prompts.
   
   For names, descriptions, and other discretionary fields, use values that are meaningful to you. In the image name, do not use spaces or characters (for example, /) special to Unix-based file systems such as Linux.
   
   

   At this prompt...	Enter...	Notes
   Enter the image type (linux, vmhost, xenhost, xenguest, windows, solaris):	xenguest
   Enter the IP address or hostname of the image host:	ipaddress	Use the IP address of the physical image host.
   OS Monitoring Options Specify the operating system monitoring that will be used for this image (at least one monitoring option must be configured): Monitor via SNMP? [n]	y
   Monitor via ping? [n] Ping Timeout (seconds): [15]	y 30

5. In the Controller, release the image host back to the free pool by selecting the node using the checkbox, then select Node Actions > Release from Image Capture.

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Step 5: Create the tier

Return to the Controller to define the Apache tier. Cassatt Active Response prepopulates tier values with the parameters you set during image capture. If necessary, you can change them during tier creation.

1. On the left navigation pane, click Tiers to display the Tier List.
2. On the Tier List page, click the New Tier button (on the right).
3. On the Properties page, set the properties for the Apache tier. The next table lists the suggested values for the Apache blueprint; unless you have site-specific reasons, you can accept the defaults in other fields.
   
   

   At this prompt...	Enter...	Notes
   Email Alerts	On
   Email On: Tier Critical Tier Non-Critical		Select all choices
   Reboot on failure	On
   Automatic move to maintenance pool	On
   Harvest priority	High
   Allow harvest	On

4. On the Requirements page, set the hardware requirements for the tier.
   
   

   At this prompt...	Enter...	Notes
   Operational Target	TargetNodes
   Minimum Nodes	MinNodes
   Maximum Nodes	MaxNodes
   Dependencies	XenHostTier	Note: If you select more than one tier, every tier you select must be activated for this tier to activate.

5. On the networks page, select a primary network. Select up to two additional networks, and select the Dedicated checkbox for the additional networks. Make sure all networks you select are assigned to the host tier that is providing the VMs.
6. On the IPs and Hostnames page, assign IP addresses or host names, or accept the default settings.
7. You can close the Creating Tier Progress page and continue with the next section.

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Step 6: Personalize the image instances

The blueprint does not require personalization.

Do not personalize images captured as VBD files: all changes are lost when the VMs are rebooted.

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Step 7: Allocate nodes and activate the tier

Follow these steps to allocate nodes and activate the tier.

1. From the Tiers table on the Domain page, select the checkbox for the Apache tier.
2. From the Tier Actions dropdown menu, select Allocate Nodes. Click Allocate Nodes on the confirmation page.
   
   Cassatt Active Response allocates nodes and displays the Tiers table.
3. Again, select the checkbox for the Apache tier.
4. From the Tier Actions dropdown menu, select Activate. Click Activate on the confirmation page.
   
   Cassatt Active Response starts the operating system and the applications on each node in the tier.

This completes the procedure to create and deploy an Apache image.

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