UiPath Orchestrator

Installation

Installation of the High Availability add-on (HAA) for your Orchestrator instance can be done via a Docker image, Amazon Web Services AMI, or a .tar Installation package. This guide provides the steps for downloading and installing HAA using the package file.

For this installation, three CentOS 7 Virtual Machines, each with 4 vCPUs, 16GB memory, 64GB of storage, and Static IP addresses were used. For additional details, see here.

Prerequisites

Note:

You must be the root user or have access to sudo to the root user to install HAA.

The following conditions must be met before proceeding with your installation:

  1. Be sure your machines are up to date by running the yum update -y command.
  2. Turn off swap by running the swapoff -a command. To persist this change across reboots, you must comment the swap entry in the /etc/fstab file.
  3. Install the wget package, used for downloading the RS installation file, by running the yum install wget command.

Note:

During installation, HAA downloads and installs the following dependency packages: cyrus-sasl-scram, boost-program-options, cyrus-sasl, cyrus-sasl-plain, boost-serialization, and cyrus-sasl-md5. If the machine where you are installing RS does not have an internet connection, you must manually download and install these packages.

Installation

  1. Create the directory where HAA is to be downloaded and extracted, for example: mkdir haa.
  2. Change to the newly created directory using the command: cd /<path-to>/haa/.
  3. Download the installation package by running wget https://s3.amazonaws.com/redis-enterprise-software-downloads/5.4.0/redislabs-5.4.0-19-rhel7-x86_64.tar.
  4. Extract the package by running tar vxf redislabs-5.4.0-19-rhel7-x86_64.tar.
  5. Start the installation with the command ./install.sh.
  6. During the installation process you are prompted to confirm the:
    • Setup of NTP time synchronization for the cluster, enter Y;
    • Opening the firewall for ports used by RS, enter Y;
    • Running of rlcheck to confirm the proper configuration, enter Y.

You can automatically accept these defaults by adding the -y parameter to the install command, such as ./install.sh -y.

Configuration

Before you can create and configure your HAA cluster, there are several entries that must be created on your DNS server. You can do this manually, or by running the Powershell script below:

[CmdletBinding()]
Param
(
    [Parameter(Mandatory = $true,
        HelpMessage = "Name of the DNS zone:")]
    [string]$DNSZone,
    [Parameter(Mandatory = $true,
        HelpMessage = "Name of the Redis cluster(Not FQDN):")]
    [string]$RedisClusterName,
    [Parameter(Mandatory = $true,
        HelpMessage = "Redis node ip")]
    [string []]$RedisNodeIP
)

    Write-Host "Using DNS zone:"$DNSZone
    Write-Host "Using Redis cluster name:"$RedisClusterName

    for ($i = 1; $i -le $RedisNodeIP.Length; $i++) {
        $redisNodeName = Read-Host "Please enter the name of the Redis node (in order of the IP provided earlier): "
        $nodeFQDN = $redisNodeName + ".$DNSZone"
        Add-DnsServerResourceRecordA -Name $redisNodeName -ZoneName $DNSZone -IPv4Address $RedisNodeIP -AllowUpdateAny
        Add-DnsServerZoneDelegation -Name $DNSZone -ChildZoneName $RedisClusterName -NameServer $nodeFQDN -IPAddress $RedisNodeIP -PassThru
    }

Enter values specific to your environment for these variables:

  • $DNSZone - the name of the DNS zone dedicated for this purpose;
  • $RedisClusterName - a custom name for your RS cluster. Must be of type "NAMESERVER" (NS) inside the DNS zone;
  • $RedisNodeIP - the names and IP addresses of all nodes to be included in the cluster.

Note:

You must have DNS administrative rights to create these entries.

Creating the Cluster

Follow these steps to create your HAA cluster:

  1. Access the Redis Web application by navigating your browser to https://<machine-ip>:8443. For example, if the node is installed on a machine with the 10.10.24.192 IP address, you have to navigate to https://10.10.24.192:8443.
  2. Click Setup. The Node Configuration page appears.
  3. Open the Cluster Configuration tab and:
    a. select the Create new cluster radio button;
    b. in the Cluster name (FQDN) field, enter the childZoneName created by the DNS server Powershell script above;
    c. select the Enable rack-zone awareness check box. When enabled, this feature alters the placement of database shards and endpoints. See here for details.
    d. In the Rack-zone ID field, enter an ID for the node, for example RZ1. Each node must have a unique ID.
  4. Click Next. The Cluster authentication page appears.
  5. Enter your cluster key and click Next. The Set admin credentials page appears.
  6. Enter your email address and set a password. These are used to manage the cluster.
  7. Click Next. The cluster is created and you are redirected to the login page.

Adding a Node

Once you have created the cluster, follow these steps to join any additional nodes:

  1. Navigate to the management UI using the address: https://<new_node_IP>:8443.
    For example, if the node is installed on a machine with the 10.10.25.192 IP address, you have to navigate to https://10.10.25.192:8443.
  2. Click Setup. The Node Configuration page appears.
  3. Open the Cluster Configuration tab and:
    a. select the Join cluster radio button;
    b. in the IP address of a node in the cluster field, enter the IP address of any node in the cluster;
    c. in the Verify cluster admin credentials fields, enter the email and password used when creating the cluster.
  4. Click Next. The Set rack-zone ID page appears.
  5. In the Rack-zone ID field, enter an ID for the node, for example RZ2. Each node must have a unique ID.
  6. Click Next. The node is added to the cluster and the management UI appears.

Creating the Database

A complete overview of the available options and configurations for your HAA database is beyond the scope of this section. For full details, see here.
Here we provide the steps to create a single region database, with replication enabled to provide high availability:

  1. Navigate to the management UI.
  2. Click the Databases tab. If no database exists, the Create new database window automatically appears. If there are existing databases, click the + button to open the Create new database window.
  3. Select Redis database and, in the Deployment drop-down, select Single Region.
  4. Click Next. The Create database window is displayed.
  5. In the Name field, enter your desired name for the database.
  6. In the Memory limit field, set the desired limit for the database. The total available memory in the cluster is displayed next to the field.
  7. Select the Replication check box. The Rack-zone awareness check box is displayed.
  8. Select the Rack-zone awareness check box. This enables a more advanced logic for determining the master and slave nodes used for replication.
  9. In the Redis password field, you can optionally set a password for the database.
  10. Click Activate. The database is initialized and the Configuration screen is displayed.
  11. Note the Endpoint as that is the address used to access the database.

Your HAA cluster is now ready, and you can proceed with the Orchestrator installation, as described here.

Updated 2 months ago



Installation


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