Multi-Server Installation

This section describes a Carbonio Multi-Server installation, that is, a Carbonio installation spread across multiple nodes, each playing one or more Roles.

Rather than giving fixed installation instructions, with some functionality installed on any node, we present an installation scenario that can be adapted to the different needs of Carbonio users, who use a different number of nodes. For this reason, we introduce the notion of Role: a Carbonio functionality that is considered atomic and consists of one or more packages.

A Role can be installed on any node of the cluster, therefore the scenario we describe below can be modified at will by installing a Role on a different node (or even on a dedicated node).

Six Nodes Scenario

Carbonio Multi-Server is the only supported method of installation in a production environment, especially for large production system, because it is more scalable in case of a growth of the infrastructure and the communication across all nodes is set up and secured automatically by Carbonio Mesh, which also adds fault detection and dynamic routing between components of the infrastructure.

In the suggested scenario we will set up a Carbonio Multi-Server environment, composed by six nodes (that we will denote as SRV1, …, SRV6) as follows:

SRV1 features a dedicated installation of Postgres
SRV2 represents the core infrastructure of Carbonio and installs Directory Server, Carbonio Mesh, and DB connection
SRV3 is equipped with MTA, the mail server
SRV4 hosts the Proxy, which allows web access to all components, and Carbonio VideoServer, which provides the video-conference features and includes the ability to record meetings
SRV5 is an AppServer which installs Carbonio Files & Carbonio Docs, that provide sharing and collaborative editing of documents
SRV6 is another AppServer and consists of Carbonio Preview, Carbonio's ability to preview snippets or thumbnails of a document, the User Management, and some advanced service

In our scenario, we start Carbonio installation from six nodes equipped with Ubuntu 20.04 LTS. The instructions are valid for six nodes which are installed with RHEL 8: the only difference is the command for the package installation, while the commands to configure the nodes are the same.

We also assume that the IP address of each node is 172.16.0.1X, with X the n-th node. In other words, IPs will be in the range 172.16.0.11 (SRV1) 172.16.0.16 (second AppServer). These values will be used in configuration files that need to be manually modified during the installation or upgrade procedures.

In most Multi-Server scenarios, it proves useful to install a Replica Directory Server in a Master/Slave setup for improved reliability and load-balancing. We describe in a dedicated section the procedure to install the Replica on a dedicated node, SRV7 (which must be equipped with the same OS as the other six). However, you can install the Replica on any node other than SRV2, following the same procedure.

Requirements

Each node of a Multi-Server must satisfy the Single-Server’s Software Requirements and also System Requirements are valid, but take into account the following advices:

By dividing the services and therefore the load on more nodes, less resources per node are needed. We recommend at least 4GB of RAM on each node, though.

Additional Requirements

Ubuntu

No additional requirement is necessary.

RHEL

The following additional requirements are needed.

An active subscription (you must be able to fetch from BaseOS and the other main repositories):
```
# subscription-manager repos --enable=rhel-8-for-x86_64-appstream-rpms
```

The CodeReady repository enabled:

# subscription-manager repos --enable codeready-builder-for-rhel-8-x86_64-rpms

Some more remarks:

Acquaintance with the use of CLI is necessary. All carbonio commands must be executed as the zextras user (these commands will feature a zextras$ prompt), while all other commands must be issued as the root user, unless stated otherwise.
Give meaningful names to the nodes. For example, call them proxy.example.com, mta.example.com, and so on. Replace example.com with your domain name.
During the installation procedure, you will need to write down some configuration options and their value, because they will be needed in the setup of the next nodes. These information are summarised at the end of each node’s installation: copy them to a safe place and keep them at hand until the end of the installation. Example of values include: the IP address (public or private) of a node or the password of a database user.

Preliminary Tasks

Before starting with the actual installation, carry out the following two tasks on each of the six nodes.

Task 1: Configure repositories

Repository and Channels

The following are important information concerning the packages repository Carbonio and its content. Please read them carefully, as they might save you some time in case of installation or upgrade problems and help you to provide more precise bug reports.

The repository hosts simultaneously packages of two channels:

Release Candidate (RC). Packages in this channel are made available as soon as they are built by Zextras development and tested by the QA team. While they are stable, they are not suitable for a use in a production environment, because they might still contain some bug, new functionalities that have not yet reached a production-level quality, or some broken dependencies might be introduced.

Usually these problems are fixed within days or even hours, so in case just try again before you report some problem.

Use this channel and its packages for testing (or demo) installations only.
RELEASE. This channel contains only packages that are stable and suitable for a production environment.

Hint

When reporting a problem or opening a ticket, remember to always add the channel if you are using, as this helps us to analyse the problem quickly.

FAQ

I want to help testing things, which channel should I use?

RC channel.
I need to install Carbonio in a production environment which channel should I use?

RELEASE channel.
How will we be informed about new RC packages?

There will be no notification, because RC channel is updated continuously.
How will we be informed about a potential new release incoming?

A red message on the homepage of the documentation site will notify you of the release of a new stable version. You may also be informed through other means of communication such as email and social media.
Could there be bugs in the packages downloaded from the RC channel?

Yes, RC versions have a risk of containing bugs (which in some cases could lead to data loss). If you find a bug in an RC package we kindly ask you to report it on the appropriate community page. We will try to resolve it as quickly as possible.

Task 2: Setting Hostname

Carbonio needs a valid FQDN as hostname and a valid entry in the /etc/hosts file. To configure them, execute these two commands. First, set the hostname

# hostnamectl set-hostname mail.example.com

then update /etc/hosts with IP and hostname

# echo "172.16.0.10 mail.example.com mail" >> /etc/hosts

You can also simply get the current IP and hostname and save them:

# echo "$(hostname -I) $(hostname -f)"

Hint

Replace 172.16.0.10 with the actual management IP to be assigned to the server.

It is mandatory to configure the hostname, especially on the Directory-Server node, otherwise the services will not be able to bind to the correct address, leading to a disruption in Carbonio's functionality.

RHEL 8-only Preliminary Tasks

A few task are required for the installation of Carbonio on RHEL 8 systems, they concern the configuration of SELinux and the firewall.

SELinux and Firewall

SELinux

Must be set to disabled or permissive in file /etc/selinux/config. You can check the current profile using the command

# sestatus

Firewall

All the ports needed by Carbonio are open on the firewall or the firewall is disabled. To disable the firewall, issue the commands

# systemctl stop firewalld.service
# systemctl disable firewalld.service

Centralised Logging Configuration

The log system in Carbonio is rsyslog, which supports a centralised setup: in other words, all log files produced by Carbonio can be sent to a unique host server (we call it “Log Server”), that is appropriately configured to receive log files, which is particularly useful in a Multi-Server installation.

In the instructions below, we elect the Log Server to be SRV-6.

Centralised Logging Setup

On SRV-6, open file /etc/rsyslog.conf, find the following lines, and uncomment them (i.e., remove the # character at the beginning of the line).

$ModLoad imudp
$UDPServerRun 514

$ModLoad imtcp
$TCPServerRun 514

Then, restart the rsyslog service.

# systemctl restart rsyslog

Finally, specify the host server that will receive logs. Since is the SRV-6 node, we need SRV6_hostname.

zextras$ carbonio prov mcf zimbraLogHostname SRV6_hostname

Note

Since zimbraLogHostname is a global attribute, this command must be run only once on one node.

Other Nodes Setup

Once the Log Server node has properly been initialised, on all other nodes, execute

# /opt/zextras/libexec/zmsyslogsetup  && service rsyslog restart

Install a Directory Server Replica

In this section we explain how to install a Directory Server Replica, i.e., a second instance of a Directory Server in Master/Slave setup, which proves useful whenever the load on the Directory server is continuously high.

Indeed, in this set up the Master Directory Server will remain authoritative for storing and managing both user information and server configuration, but will delegate to the Replica all the queries coming from the other infrastructure nodes. Therefore, whenever some data is updated on the master, they are immediately copied to the slave and available for queries. The bottom line is that the two server will split their tasks, reducing thus the load on the main instance.

Preliminaries

Before attempting to install a Directory Server Replica, please read carefully the whole procedure in this page and make sure the following requirements are satisfied.

In the remainder, we show how to install one Replica on a dedicated node, but it is possible to install it also on existent node in the cluster.

A Multi-Server Carbonio is already operating correctly
A new node is available, on which to install the Replica, which satisfies the Multi Server Requirements and on which the Preliminary Tasks have already been executed. We will call this node SRV7.

Note

In case you plan to install the Replica on an existent node, execute all commands on that node instead of on SRV7.
Except for the one in the Installation section, all commands must be executed as the zextras user
Give the new node a meaningful name/FQDN. We will use ds-replica.example.com whenever necessary. Remember to replace it with the name you give.
Have CLI access to the Main and Replica Directory Servers, as you need to execute commands on both servers

Installation

The installation requires to execute this command on SRV7.

# apt install carbonio-directory-server service-discover-agent

Note

As an alternative. you may install the package service-discover-server if you plan to have multiple Carbonio Mesh server. In this case, however, please refer to section Set up Multiple Carbonio Mesh Servers for detailed directions.

Configuration

Configuration of the Replica Directory server requires a few steps.

Step 1: Activate replica

On SRV2 activate the replica by executing

$ /opt/zextras/libexec/zmldapenablereplica

Step 2: Retrieve passwords from SRV2

Then, retrieve a few passwords that you will need on the Replica to configure the connection and access to SRV2

$ zmlocalconfig -s zimbra_ldap_password
$ zmlocalconfig -s ldap_replication_password
$ zmlocalconfig -s ldap_postfix_password
$ zmlocalconfig -s ldap_amavis_password
$ zmlocalconfig -s ldap_nginx_password

Note

By default, these password are the same and coincide with zimbra_ldap_password. If you did not change them, use the same password in the next step.

Step 3: Bootstrap Carbonio on Replica

After the command completed successfully, log in to SRV7 and bootstrap Carbonio. You will need to configure a number of options, so make sure to have all available.

$ carbonio-bootstrap

Step 4: Configure Replica

You will asked to properly configure a couple of options in the Common configuration and Ldap configuration menus. In the first menu, provide these values:

Ldap configuration

   1) Hostname: The hostname of the Director Server Replica.
   2) Ldap master host: The hostname of SRV2
   3) Ldap port: 389
   4) Ldap Admin password: The zimbra_ldap_password

Exit this menu and go to the second:

Ldap configuration

   1) Status: Enabled
   2) Create Domain: do not change
   3) Domain to create: example.com
   4) Ldap root password: The zimbra_ldap_password
   5) Ldap replication password: The ldap_replication_password
   6) Ldap postfix password: The ldap_postfix_password
   7) Ldap amavis password: The ldap_amavis_password
   8) Ldap nginx password: The ldap_nginx_password

Hint

Remember to always use the zimbra_ldap_password in case you did not change the other passwords.

Step 5: Complete the installation

You can now continue the bootstrap process and after a while the installation will be successfully completed and immediately after, the copy of the Directory Server on SRV2 will be copied over to the Replica on SRV7.

Testing

In order to test whether the Replica works correctly after the installation was completed successfully, you can make a quick test as follows.

Log in to the Master (SRV2) and create a test user with a password:
```
$ carbonio prov ca john.doe@example.com MySecretPassword
```
Log in to the replica and check that all account have been copied over from the Master:
```
$ carbonio prov -l gaa
```
Among the results, the john.doe@example.com must be present.

Hint

You can pipe the previous command to grep to check only the new account (or any given account): carbonio prov -l gaa | grep "john.doe@example.com"

Set up Replica to Answer Queries

It is now time to configure the Replica to answer queries in place of the Master, which requires to reconfigure the value of the ldap_url parameter and let it point to the Replica. You can achieve this set up with a few commands on the Master.

Values used in this step

You need to keep at hand the following data

SRV2_hostname: the hostname on which the Directory Server Master is installed
SRV7_hostname: the hostname on which the Directory Server Replica is installed, e.g., ds-replica.example.com

Hint

To retrieve the hostname, use the hostname on the Master and Replica nodes.

Stop all Carbonio services
```
$ zmcontrol stop
```
Update the value of ldap_url
```
$ zmlocalconfig -e \
  ldap_url="ldap://SRV7_hostname ldap://SRV2_hostname"
```
If you plan to install multiple Replica Directory Servers, you can install all of them and then execute the above-mentioned command once for all Replicas, making sure that their hostnames precede the Master’s hostname. For example, provided you installed two Replica Directory Servers on SRV4 and SRV5, execute:
```
$ zmlocalconfig -e \
  ldap_url="ldap://SRV7_hostname ldap://SRV4_hostname \
  ldap://SRV5_hostname ldap://SRV2_hostname"
```
The Replica instance to query first is the first listed in the command.

Uninstall a Replica

To remove a Replica, you need to carry out two tasks:

On each node of the Multiple-Server installation, execute the following command, which will use only the Master for the queries
```
$ zmlocalconfig -e ldap_url="ldap://SRV2_hostname"
```
In case you had configured multiple Replicas, the above command will redirect all queries to the Master. If you want to remove only some of the Replicas, simply omit its hostname from the list. For example, to remove SRV5, use the command
```
$ zmlocalconfig -e \
  ldap_url="ldap://SRV7_hostname ldap://SRV4_hostname \
  ldap://SRV2_hostname"
```
Execute, only on the MTA node the command
```
$ /opt/zextras/libexe/zmmtainit
```
This command will update the configuration of postfix with new ldap_url.

Multi-Server Installation

Six Nodes Scenario

Requirements

Additional Requirements

Preliminary Tasks

RHEL 8-only Preliminary Tasks

Node Installation

SRV1: Postgres

SRV2: Directory Server, DB connection, and Carbonio Mesh Server

SRV3: MTA

SRV4: Proxy and Carbonio VideoServer

SRV5: Advanced, AppServer, Files, and Docs

SRV6: Advanced, AppServer, and Preview

Centralised Logging Configuration

Install a Directory Server Replica

Preliminaries

Installation

Configuration

Testing

Set up Replica to Answer Queries

Uninstall a Replica