Manage Application Servers

plication Server is a regular VS based on default CentOS template with pre-installed additional software. This software allows you to install and have up & running various PHP/Perl/Python frameworks (like Drupal, Joomla, Wordpress etc.) on a server using web interface. In this document you can find information on how to manage Application Servers in your cloud.  

  • To activate Application Server functionality you need to activate appropriate license at OnApp dashboard.
  • Application servers allow you to deploy different applications on your cloud. For more info refer to Applications.
  • The following field in OnApp configuration should be necessarily filled in, as system_email is used for proper configuration of application server: Control Panel > Admin > Settings > Configuration > System > Email > From.


View Application Servers



To view an application:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. The page that loads will show the list of application servers together with their: 
    • Operating system
    • Label. Click the label to see details.
    • IP Addresses
    • Disk Size
    • RAM
    • Backups - the number of backups and the space these backups take.
    • Compute Resource - the label of compute resource with which application server is associated
    • User- the owner of this application server. Click the user name to see the owner details.
    • Power status. Click the on/off buttons to change the status

      3. Click the Actions button next to the application server for the quick access to the list of application server actions (the list of actions displayed depends on the application server status):

    • Reboot 
    • Recovery reboot
    • Shutdown
    • Startup
    • Recovery startup
    • Unlock

If you are viewing the application servers list on a narrow screen, you can customize the way the table is displayed by clicking the actions icon at the top of the table. In the drop-down list that appears, check the columns you want to be displayed and click Apply. The narrower your screen is, the more unchecked columns will be hidden from the table. If your screen is too narrow to fit all the columns you have checked, a scrollbar will appear at the bottom of the application servers list. You can always alter you column selection later. Note that by default the VIP and Backups columns are not visible in the table on narrow screens.


Column selection is currently set for one browser. Iftheyou have checked some columns in one browser and open the list in some other browser, the column selection will be the default one for that other browser.


To search for a particular application server, click the Search icon at the top of the application server list. When the search box appears, type the text you want to search for and click the Search button:



View Application Server Details



To view details of a specific application server:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the application server you're interested in.
  3. The screen that appears loads the application server properties, application list, notes, activity log and tools for managing your application server.

Application Server Properties

Application server properties page gives a general overview of the server details:

  • Template this server is built on
  • Power status & On/Off/Reboot buttons.

    Clicking the OFF button performs a graceful shutdown and then powers off the application server after the timeout set in Configuration Settings.

  • FQDN (fully qualified domain name)
  • Compute resource. Click the compute resource name to see its details
  • Login credentials
  • Owner. Click the owner name to see its details.
  • Estimated Price per hour. This sum does not take into consideration the free limits for resources set in the bucket. Therefore, the final price for the server might differ from the sum indicated here.
  • Memory
  • CPU(s)
  • CPU priority or CPU units
  • Disk Size
  • Disk backups
  • Network Speed
  • IP Addresses. Only the first five IP addresses are displayed on the application server properties page. To view the list of all application server IP addresses, mouse over IP addresses area or go to the Networking > IP addresses tab.
  • Auto-backups - move the slider to enable/disable automatic backups for this application server. If the incremental backups are enabled in your cloud, you can set auto-backups per application server rather than per disk.

    If the automation options weren’t enabled during this application server creation, you’ll be redirected to the form where you can configure them.
  • Autoscale - move the slider to enable/disable the autoscaling rules set for this AS.

    • Until the autoscaling rules are configured the autoscaling itself will not start working.
    • If the Autoscale slider is greyed out that means that you have reached the autoscaling limit in a bucket (or the max is setas 0).

Applications

In this section, you can see the list of all applications deployed on this server.


Notes

The Notes section lists brief comments or reminders for an application server. You can add either Admin's or User's notes. The Admin's note will be available to cloud administrators. Click the Actions button in the Notes section of the page to add admin's or user's note.

Application Server Management

  • Click the Tools button to expand the Tools menu with the application server management options.
  • Use the top menu to manage your application servers' statistics/networking/storage options.


Edit Application Server



You can edit CPU and RAM resources for application servers. To adjust CPU & RAM resources:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the server you want to resize, to show its details screen.
  3. Click the Tools button and select the Edit Application Server link.
  4. Change label, CPU cores, CPU priority/units and RAM values, and click the Save button.


Rebuild/Build Application Server Manually



If you haven't checked the Build Application Server option during the application server creation process, you will have to do this manually after the application server has been created. Building an application server is the process of allocating physical resources to that application server.



To build an application server manually or rebuild the application server on the same (or another) template:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the application server you're interested in.
  3. On the screen that appears, click the Tools button and then click Rebuild Application Server.
  4. On the screen that pops up, use the drop-down menu to choose a template with which to build the application server.

  5. Move the Start AS after rebuild slider to the right if you want to have your application server started automatically after it is built.
  6. Click the Rebuild Application Server button to finish.
After you rebuild your template all data will be lost!

Migrate Application Server



You can migrate application servers using a hot or cold migration method:

  • Hot migration is the migration of application servers with or without disks between compute resources that share common data stores or data store zones.
  • Cold migration is the migration of application servers with disks between compute resources with local storage or across compute zones.

Hot Migration

Check if your Windows template supports hot migration at the Windows Templates.

You can migrate an online application server from one compute resource to another compute resource that are both utilizing local/shared/IS storage or across zones. There are two types of hot migration:

  • Compute Resource - migration of an application server from one compute resource to another
  • Compute Resource and Storage - migration of an application server with disk from one compute resource and data store to another

Compute Resource

To hot migrate an application server:

  1. Go to your Control Panel > Cloud > Application Servers.
  2. Click a label of an application server that you want to migrate.
  3. Click the Tools button and click the Migrate Application Server button.
  4. In the Migration Type box, select Compute Resource and click Next
  5. Select a Target compute resource from the box and click Next
  6. At the final step of the wizard, you can see the migration summary and select the following check boxes: 
    • Cold-migrate when hot-migration fails - select the check box to apply cold migration in case of the hot migration failure
    • Are you sure you want to migrate? - select the check box to confirm the hot migration
  7. When you are finished, click the Submit button.

Compute Resource and Storage

To hot migrate an application server:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the application server you want to migrate.
  3. Click the Tools button and click the Migrate Application Server button.
  4. In the Migration Type box, select Compute Resource and Storage (Hot) and click Next
  5. Select the following destination resources: 
    • Target compute zone - select a destination compute zone. The list includes compute zones that you have access to within the same network (i.e. KVM to KVM but not KVM to Xen). 
    • Target compute resource - select a destination compute resource
    • Target data store for disk - select a destination data store for each disk. The list includes available data stores associated with the compute zone and compute resource that you selected earlier.
  6. At the final step of the wizard, you can see the migration summary and select the following check boxes: 
    • Cold-migrate when hot-migration fails - select the check box to apply cold migration in case of the hot migration failure
    • Are you sure you want to migrate? - select the check box to confirm the hot migration
  7. When you are finished, click the Submit button.

After migration, the power status of your application server remains the same as before the migration. If you migrate an application server that's running, the whole process is almost unnoticeable. 

Cold Migration

Cold migration enables you to migrate application servers with disks between compute resources with local storage or across compute zones. To cold migrate an application server:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the application server you want to migrate.
  3. Click the Tools button and click the Migrate Application Server link.
  4. In the Migration Type box, select Compute Resource and Storage (Cold) and click Next
  5. Select the following destination resources: 
    • Target compute zone - select a destination compute zone. The list includes compute zones that you have access to within the same network (i.e. KVM to KVM but not KVM to Xen). 
    • Target compute resource - select a destination compute resource
    • Target data store for disk - select a destination data store for each disk. The list includes available data stores associated with the compute zone and compute resource that you selected earlier.
  6. At the final step of the wizard, you can see the migration summary and select the Are you sure you want to migrate? check box to confirm the migration.
  7. When you are finished, click the Submit button.

If you change the compute resource or data store zone, the billing will be changed according to the prices set for that new zone in the bucket. The new estimated price per hour for a VS is displayed at the bottom of the VS migration screen.

Autoscale Application Server



Application server autoscaling allows you to change the RAM, CPU, and disk size settings of an application server automatically. Application server resources scaling is based on rules you specify. For example, you can set up a rule that will add 1000MB of memory to an application server if RAM usage has been above 90% for the last 10 minutes - but add no more than 5000MB in total in 24 hours. You can set autoscaling down settings alongside with autoscaling up.

  • For Linux-based application servers only.
  • If you autoscale an application server's memory to a value greater than current application server RAM x 16 (which is a max_memory parameter in a configuration file and database), the application server will be rebooted anyway, regardless of the template it is built on.
  • Make sure an application server can be reached via SSH. Otherwise, the autoscaling client installation will fail.
  • Starting with version 4.2, OnApp uses Zabbix for autoscaling. Monitis will be used for autoscaling of servers built using OnApp versions previous to 4.2 until you switch autoscaling off for such server(s). If you decide to switch autoscaling back on, autoscaling will be implemented using Zabbix. Zabbix also will be used for autoscaling of newly created VSs.

To configure autoscaling settings:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the appropriate application server.
  3. On the page that follows, click the Overview tab, and then click Autoscaling.
  4. Press the required tab - Memory Usage, Disk Usage or CPU Usage - to see the statistics for each type of resources.
  5. Below you will see UP and DOWN autoscaling options. Move the slider to the right to add the autoscaling rule or move it to the left to remove the rule.
  6. Add autoscaling rules as explained below:

    Set autoscale up options:

    • If RAM usage is above X% for a specific time period, add Y MB – but no more than Z MB in a 24 hour period.
    • If CPU usage is above X % for a specific time period, add Y% - but no more than Z% in a 24 hour period.
    • If disk usage is above X % for a specific time period, add Y GB - but no more than Z GB in a 24 hour period.

    Set autoscale down options:

    • If RAM usage is below X% for a specific time period, remove Y MB.
    • If CPU usage is below X % for a specific time period, remove Y%.
    • If disk usage is below X % for a specific time period, remove Y GB.
  7. Click Apply.

Clicking the Apply button does not activate autoscaling if the Autoscale slider at the AS overview page is disabled. You can configure autoscaling rules, press the Apply button, these rules will be saved and will start working only after the Autoscale slider at VS overview page is enabled. Also, you can disable the Autoscale slider, autoscaling will stop working, but the configuration of rules will be saved in case you will want to activate them in future.

Set VIP Status for Application Server



If a Compute resource fails or reboots, the system migrates application servers to another Compute resource, one server at a time. The order servers are migrated in is random. However, you can give an application server "VIP" status, and this will give that server priority in the migration queue. 

To set or remove VIP status for an application server:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Use the VIP button next to a required application server to change its VIP status.


Segregate Application Server



To isolate one application server from another:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the application server you want to segregate.
  3. On the screen that appears, click the Tools button, then click Segregate Application Server.
  4. In the dialogue box that pops up, use the drop-down menu to choose an application server you want to keep away from.
  5. Click the Segregate VS button to finish.


Application Server Power Options



To manage an application server power options:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the required application server.
  3. Click the Tools button on the application server's screen to expand the Tools menu.
  4. The Tools menu enables you to perform the following power actions on application servers (the exact list shown depends on the application server status):
    • Reboot Application Server - powers off and then restarts the application server.
    • Suspend  - stops an application server, changes its status to suspended and disables all the other actions on application server, unless unsuspended.

    • Shut Down Application Server – pops up a dialogue box, where you can either Shut Down application server (terminates the application server gracefully), or Power Off application server (terminates the application server forcefully).
    • Startup Application Server - queues a start-up action for a application server that's currently powered off.


Application Server Administrative Options



To manage an application server power options:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. Click the label of the required application server.
  3. Click the Tools button on the application server's screen to expand the application server Tools menu.
  4. The Tools menu enables you to perform the following administrative actions on application servers:
    • Change Owner - pops up a dialogue box with a drop-down of all users on the system, enabling you to pass ownership of the application server to the user selected from the list. If you have any  backups for this application server, you will be also prompted to confirm if the backup should be moved to another user.


Delete Application Server



Shut down the application server before destroying it. If you are deleting an application server that is running, the application server will be deleted after the time set in Timeout Before Shutting Down application servers configuration parameter.
To remove the application server from the cloud:

  1. Go to your Control Panel > Cloud > Application Servers menu.
  2. On the screen that appears, you'll see the list of all application servers in the cloud. Click the label of the application server you want to delete.
  3. On the application server's screen, click the Tools button, then select Delete Application Server.
  4. Move the Move Last Backup to My Templates if it is present slider to the right if you want to save the last application server's backup as a template.
  5. Move the Destroy All Existing Backups slider to the right if you want to remove all existing backups of this application server.

    IMPORTANT:

    • You won't be able to restoreaapplication server after deleting it.
    • Deleting an application server removes all data stored on that application server. To save the data stored on the application server, back up your application server and tick the Destroy All Existing Backups box when following the instructions described in this section. 
  6. Press the Destroy button.