Installation Guide

This guide describes everything you need to deploy Git MultiSite:

• Pre-installation requirements
• A standard installation
• Node configuration

1. Before you install

Before installing Git MultiSite, make sure that you have sufficient hardware and that all required software is configured appropriately.

1.1 Skills requirements

This section describes the knowledge and technical requirements for deployment and operation of the WANdisco software. You should ensure that each of these sections is addressed before you begin the deployment.

If you're not confident about handling any of these tasks, you can request a supported installation from WANdisco.

A single administrator can manage all the systems running MultiSite, although it's a good idea to have someone at each site who is familiar with MultiSite Basics.

1.2 Deployment overview

As with any software implementation you should deploy WANdisco SVN MultiSite following a well-defined plan. This helps you keep control, understand the product, and find and fix any issues before production. We recommend including the following steps:

1. Pre-deployment planning: Identify the requirements, people and skills needed for deployment and operation. Agree a schedule and milestones. Highlight any assumptions, constraints, dependencies and risks to a successful deployment.

2. Deployment preparation: Prepare and identify server specifications, locations, node configuration, repository set-up, replication architecture, and the server and software configurations.

3. Testing phase: Actions for an initial installation and testing in a non-production environment, executing test cases, and verifying deployment readiness.

4. Production deployment: Actions to install, configure, test, and deploy the production environment.

5. Post-deployment operations and maintenance: Actions including environment monitoring, system maintenance, training and in-life technical support.

1.3 System requirements

This section describes how to prepare your Git servers for replication. You need to ensure that you've got a suitable platform, with sufficient hardware and compatible versions of the equired software that is configured appropriately. View this information as a set of guidelines, not as a fixed set of requirements.

1.3.1 Hardware recommendations

1.3.2 Storage tips

• Use separate physical disks for Git and Git MultiSite.
• Use the fastest possible disks for storage. Disk IO is the critical path to improve repository responsiveness.
• We recommend that you use RAID-1 or RAID-2 solutions. We do not recommend RAID-0.
  Knowledgebase
  For more information about calculating storage capacity requirements, read the Knowledgebase article, Hardware Sizing Guide.

1.3.3 Processor tips

• Git MultiSite can run on a single 2GHz CPU, but for production you should run fast multi-core CPUs and scale the number of physical processors based on your peak concurrent usage.
• Aim to have no more than 15 concurrent Git users per CPU and 7 concurrent users per CPU core.
  Example 1: A server with 4 physical single core processors is expected to support (15x1x4) = 60 concurrent users.
  Example 2: A server with 4 physical processors, each being a quad core is expected to support (7x4x4) = 112 concurrent users.

1.3.4 Setup requirements

This is a summary of requirements. You must also check the more detailed Pre-installation checklist.

MultiSite servers require:

• The same operating system
• Java and Python installed
• A browser with network access to all servers
• A command line compression utility
• A unique license key file (provided by WANdisco: you will need one for each node and you may need to provide the server IP addresses)

Git installations require:

• WANdisco's modified distribution of Git, 1.8.5 or later

  Make sure you don't overwrite the WANdisco git binaries with system versions. The WANdisco versions are required for replication to work correctly.

• Matching file and directory-level permissions on repositories

2. Installation checklist

Though you may have referred to the checklist before evaluating Git MultiSite, we strongly recommend that you reread it before deployment to confirm that your system still meets all requirements.

ulimit -u unlimited && ulimit -f unlimited && ulimit -n 64000

# Default limit for number of user's processes to prevent
  # accidental fork bombs.
  # See rhbz #432903 for reasoning.
  * soft nproc 1024   <- Increase this limit or ulimit -u will be reset to 1024
  # The asterisk changes values for all users. If you want to change for a specific user, replace it with the username:
  gitms soft nproc 65000
  gitms hard nproc 65000
  gitms soft nofile 65000
  gitms hard nofile 65000
  gitms soft 

  gitms           soft    nofile  65000
  gitms           hard    nofile  65000
  gitms           soft    nproc   65000
  gitms           hard    nproc   65000

session  required  pam_limits.so

session  required  pam_limits.so

3. Installation procedure

This Installation Guide describes setting up Git MultiSite for the first time. If you are upgrading from an earlier version of Git MultiSite you should also follow this procedure. Git MultiSite is a completely new class of product so it's not possible to follow a shortcut upgrade procedure.

3.1 Installation overview

This is an overview of the process:

1. Double-check the Pre-installation checklist. Take time to make sure that you have everything set up and ready. This avoids problems during installation. In particular, check:
   • Git authentication: Git installed, and using authentication.
   • JDK: You need to run an Oracle JDK. We recommend JDK 7, but 6 works, with warnings.
   • Java memory settings: The Java process on which Git MultiSite runs is assigned a minimum and maximum amount of system memory. By default it gets 128MB at startup and 4GB maximum.
   • System resources: Ensure that your system is going to operate with a comfortable margin.
2. Ensure that your repositories are copied into place on all nodes.
3. Download and copy the MultiSite files into place.
4. Run the setup, then complete the installation from a web browser.

3.2 Before you start

1. Check through the Pre-installation checklist
2. Ensure that you have WANdisco's latest Git binaries pre-installed. Git MultiSite edition requires FSFSWD libraries that are built into WANdisco's version of Git
3. Repositories need to be created using the file system switch (--fs-type fsfswd)
4. Ensure that the system user used for installing Git MultiSite has access to Java, the installation will otherwise fail.

 export LOG_FILE="opt/wandiscoscp/log/file.file"

3.3 Start the installation

1. Extract the setup file.
2. Save the wandisco-git-multisite.sh installer file to your Installation site.
3. Make the script executable, e.g. enter the command:

   chmod a+x wandisco-git-multisite.sh

4. Run the setup script.

   
       [root@redhat6 ~]# chmod a+x git-multisite.sh
       [root@redhat6 ~]# ./git-multisite.sh
       Verifying archive integrity... All good.
       Uncompressing WANdisco MultiSite .......
           ::   ::  ::     #     #   ##    ####  ######   #   #####   #####   ##### 
          :::: :::: :::    #     #  #  #  ##  ## #     #  #  #     # #     # #     # 
         ::::::::::: :::   #  #  # #    # #    # #     #  #  #       #       #     # 
        ::::::::::::: :::  # # # # #    # #    # #     #  #   #####  #       #     # 
         ::::::::::: :::   # # # # #    # #    # #     #  #        # #       #     # 
          :::: :::: :::    ##   ##  #  ## #    # #     #  #  #     # #     # #     # 
           ::   ::  ::     #     #   ## # #    # ######   #   #####   #####   #####  
   
   
       INFO: Using the following Memory settings:
   
       INFO: UI:         -Xms128m -Xmx1024m
       INFO: Replicator: -Xms1024m -Xmx4096m
   
       Do you want to use these settings for the installation? (Y/n) 
       
       

5. Enter "Y" and click enter.

   Which port should the MultiSite UI listen on? [8080]:

   Running Gerrit?
   If you are going to integrate Git MultiSite with Gerrit then make sure that you select a port that will not conflict. Gerrit also defaults to port 8080.

6. Confirm the port you wish to run the admin interface on

   We strongly advise against running Git MultiSite as the root user.
   
       Which user should Git MultiSite run as?

7. Confirm the user who will run Git MultiSite.

   This user will need to have read and write access to your git repos

8. Which group should Git MultiSite run as?

   Confirm the group of the user running Git MultiSite

   Installing with the following settings:
       
       MultiSite user:    gitms
       MultiSite group:   gitms
       MultiSite UI Port: 8080
       MultiSite UI Minimum memory: 128
       MultiSite UI Maximum memory: 1024
       MultiSite Replicator Minimum memory: 1024
       MultiSite Replicator Maximum memory: 4096
   
       Do you want to continue with the installation? (Y/n)

9. Confirm the configuration settings and enter Y to finish the install. In our example, our server runs as gitms with a group of gitms.

10. Open a browser and go to the provided URL. If your server's DNS isn't running you can go to the next step at the following address:

    http://<IP_Adress>:<admin port>/multisite-local

    e.g.
    http://10.0.100.252:8080/
    
    

Flush your browser cache
If you are reinstalling and using SSL then you should clear your browser cache before you continue. Previous SSL details are stored in the cache and will cause SSL errors if they are not flushed.

11. The web installer begins with the Welcome screen Welcome to the installation of Git MultiSite.
    
    

    Set up > Start

    Welcome to Git MultiSite.
    
        You're about to run through the installation, which should only take a couple of minutes.
    
    
        If you run into difficulties on the way, check our documentation or talk to our support team through the Customer Support Website.
    
    
        Before you click Next, make sure you Read the Installation Checklist

    
    Click Next to begin the installation.
12. The next (Terms & Conditions) screen contains the WANdisco Master Subscription Agreement. To continue the installation click the I Agree button.
    

    Set up > License agreement

13. On the next (License Upload) screen you are prompted to browse for your product license key file. Click the Browse button and locate your file. You will have been sent this by the WANdisco sales team, contact them if you have any problems locating or using your license file.
    

    Set up > license.key file

14. On the Administrator Setup screen enter the username plus an associated password that you will use to log in to Git MultiSite's UI. This information is only added during the installation of the first "inductor" node.
    

    Set up > Admin settings, entered or uploaded in the users.properties file

    Username

    The administrator's username.

    Password

    The administrator's password.

    Confirm Password

    Enter your password again to confirm that it's been typed in correctly.

    User Interface HTTP Port

    You entered the port during the first part of the installation, it's now possible to choose an alternate port here.
    This port is sometimes referred to as the jetty port.

    
    For all subsequent node installations you should provide the users.properties file.
    
    Dealing with the user.properites file
    

    This properties file stores the unique information for the default admin user account. It is essential that this information exactly matches up between nodes. For this reason, it is only entered once during a deployment and then subsequently copied to all other nodes (in the form of the users.properties file).

    The default location of the file is here:

    /opt/wandisco/git-multisite/replicator/properties/users.properties

    If something goes wrong and you don't have a valid users.properties file in your deployment, Git MultiSite can automatically create a new one if you follow the procedure to Create a new users.properties file.

    

    Set up > user.properties file for all nodes after the first node.

    
    
15. The last screen in the setup process covers Server Settings.
    

    Set up > Server Settings.

    
    

    Node ID

    The default name for this node.

    Temporary limitation
    Node names can not contain spaces or ".".

    Node IP/Host

    The node's IP or hostname. If the server is multi-homed, you can select the IP to which you want Git MultiSite to be associated.
    

    Enter FQDN in this field
    We strongly recommend that you use fully qualified domain names for IP addresses. This can avoid SSL certification problems.

    Replication Port

    Select the port that will be used for replicated Git repository data. (Default: 6444)

    Content Server Port

    Select the port that will be used to transfer replicated content (repository changes). (Default: 4321)This is different from the port used by WANdisco's DConE² agreement engine.

    Content Node Count

    This setting gives you the ability to enforce a degree of resiliance. The value represents the number of nodes within a membership that must receive the content before a proposal is submitted for agreement. If the value is greater than the total learners in the current membership, it is adjusted to total learners in the current membership. The proposing node is not considered in the calculation.

    Minimum Content Nodes Required

    Ticking this checkbox will enforce the Content Node Count as a prerequisite for replication.

    REST API Port

    The port to be used for Git MultiSite's REST-based API. (Default: 8082)

    REST API UI Using SSL

    Check box for enabling the use of SSL for all API traffic.

    REST API SSL Port

    The port to be used for Git MultiSite's REST-based API when traffic is secured using SSL encryption. (Default: 8445)

    UI Port

    The port for HTTP access to the MultiSite administrative interface. (Default: 8080)

    UI SSL Port

    The port for HTTPS encrypted access to the MultiSite administrative interface. (Default: 8443)

    SSL Certificate Alias

    The name of your SSL Certificate file.

    SSL Key Password

    The password for your HTTPS service.

    SSL Key Store

    The name of the keystore file. The keystore contains the public keys of authorized users.

    SSL Key Store Password

    The password associated with the keystore.

    SSL Trust Store

    The location of your trust store file. The Truststore contains CA certifcates to trust. If your server's certificate is signed by a recognized Certification Authority (CA), the default truststore that ships with the JRE will already trust it (because it already trusts trustworthy CAs), so you don't need to build your own, or to add anything to the one from the JRE.

    SSL Trust Store Password

    The password for your trust store.

    A word about trust stores and key stores
    

    You might be familiar with the Public-key system that allows two parties to use encryption to keep their communications with each other private (incomprehensible to an intercepting third-party).

    The keystore is used to store the public and private keys that are used in this system. However, iIn isolation, however, the system remains susceptible to the hijacking of the public key file, where an end user may receive a fake public key and be unaware that it will enable communication with an impostor.

    Enter Certificate Authorities (CAs). These trusted third parties issue digital certificates that verify that a given public key matches with the expected owner. These digital certificates are kept in the truststore. An SSL implementation that uses both keystore and truststore files offers a more secure SSL solution.

16. Click FINISH when you have entered everything. The installer will now complete the configuration. Once that's all done a START USING MULTISITE button will appear. Click the button to login for the first time.
    
    
17. Time to login. Enter the username and password during step 12. Then click FINISHED - LET'S GO!.
18. The first time you view the dashboard, it will contain mostly blank areas. You can view the reference section to learn what all the buttons and options mean.

3.4 Repeat the installation process at all sites

Now repeat the installation process for every node that you wish to share your Git repositories.
You may benefit from creating an image of your initial server, with the repositories in place and using this as a starting point on your other sites. This helps ensure that your replicas are in exactly the same state.

4. Node induction

After installing Git MultiSite at all sites, you'll need to make the sites aware of each other through the node induction process. There's a particular way that you need to run through this process so get another coffee and don't skip this section.

4.1 Membership induction

It's important that nodes are connected together in specific sequence. Run through the following steps to ensure that your sites are all able to talk to each other:

1. When Git MultiSite is installed on all your sites, select one node to be your Inductor. This node will accept requests for membership and share its existing membership information. It doesn't matter which node you select.
   
2. Log in to this Inductor's admin console (http://<Inductor's IP>:8080/multisite-local/) and gather the following information, most is available from the Settings tab.
   
   All your remaining sites are now classed as Inductees.
3. Select one of your remaining Inductee sites. Connect to its web admin console (http://<Inductee1:8080/multisite-local/) and go to the Nodes tab.
4. Click on the CONNECT TO NODE button and enter the details that you collected from your Inductor node.
   
   

   Node Node ID *

   The name of the inductor node - you can verify this from the NODE ID entry on the Inductor node's Settings tab (see step 2, above.)

   Node Location ID *

   The reference code that is used to define the inductor node's location -you can verify this from the NODE ID entry on the Inductor node's SETTINGS tab (see step 2, above).

   Node IP Address *

   The IP address of the inductor node server.

   Node Port No *

   The DConE Port number (6444 by default), defined on the inductor node's SETTINGS tab.

   When these details are entered, click the SEND CONNECTION REQUEST button. The inductor node will accept the request and add the inductee to its membership. You will need to refresh your browser to see that this has happened..

5. Go back to step 3 and select one of your remaining inductees. Repeat this process until all the sites that you want to be included in the current membership have been connected to the inductor.

4.2 Create a replication group

Git MultiSite lets you share specific repositories between selected sites. This is done by creating Replication Groups that contain a list of sites and the specific repositories they will share.

This illustration shows a collection of four sites that are running two replication groups. Replication Group one replicates Repo1 across all four sites, whilst Replication Group 2 replicates repo2 across a subset of sites.

Follow this procedure to create a Replication Group. You can create as many replication groups as you like. However, each repository can only be part of one active replication group at a time.

1. When you have sites defined, click on the REPLICATION GROUPS tab. Then click on the CREATE REPLICATION GROUP button.
   
   

   Create Replication Group

   
   
   Local node automatically made the first member
   It's not possible to create a replication group remotely - the node on which you are creating the group must itself be an member. For this reason, when creating a replication group, the first node is added automatically.
2. Enter a name for your Replication Group in the Replication Group Name field. Then enter an existing Node name in the Add Sites field - any existing sites that match your entry will appear and can be selected with a click. Instead of typing in a name you can click on the drop-down button and choose from a list of existing sites (that are not already members of the new group).
   
   You can select any number of available Sites. Those sites that you select will appear as clickable buttons in the Add Node field.
   

   Enter a name and add some node.

3. New sites are added as Active Voters (denoted with "AV"). You can change the type of a node by clicking on its label. For an explanation of what each node type does, view the Reference Section - Node Types
   

   Change node type

   Once you have added all sites and configured their type, click CREATE REPLICATION GROUP to see a group's details.
4. Replication Groups that you create will be listed on the REPLICATION GROUPS tab.
   

   Groups boxes, click QUICK VIEW view your options.

4.3 Add repositories

When you have added at least one Replication Group you will be able to add repositories to your node. Here's how:

1. Click the REPOSITORIES tab. Click on the ADD button.
   
   

   Repositories > ADD

2. Enter the Repository's name, the file system path (full path to the repository) and use the drop-down to select the replication group. You can set the repository to be Read-only by ticking the Global Ready-only You can deselect this later. Click ADD REPO.
   
   

   Repositories > Enter details then click ADD REPO

Alert If a repository that you added gets stuck in the deploying state - you'll see this on the Dashboard, in the Replicator Tasks window - you can cancel the deployment and try adding the repository again. To cancel a deployment, go to the Replicator Tasks window and click on the Cancel Task link.
3. Click the REPOSITORIES tab to see a list of the repositories added.
   
   

   Repositories listed

   
   

   The repositories list shows:

   Name

   The name of the repository - this will be the same as the folder name in the Git directory.

   Path

   The full path to the Repository.

   Replication Group

   The Replication Group in which the repository may be replicated.

   Size

   The file size of the repository.
   

Table columns describe master branch, not the whole repository

The following columns of information describe the master branch.

4. Youngest Rev
   The youngest (latest) revision in the repository. Comparing the youngest revisions between replicas is a quick test that a repository is in the same state on all sites.
   Last Modified
   The timestamp for the last revision, which provides a quick indicator for the last time a Git user made a change.
   Global RO
   Checkbox that indicates whether the repository is globally Read-only, that is Read-only at all sites.
   Local RO
   Checkbox that indicates whether the repository is locally Read-only, that is Read-only to users at this node. The repository receives updates from the replicas on other sites, but never instigates changes itself.

4.4 Using Git sub-modules

If you use sub-modules, they are typically defined using the full URL of the repository, for example:

git add submodule test2 git@192.168.1.30:/home/wandisco/repos/subrepo.git

This adds the following into your .gitmodules file:

[submodule "test2"]
path = test2
url = git@192.168.1.30:/home/wandisco/repos/subrepo.git

It is possible to use them in this way, but this means that submodule activity will occur against a specific Git server. If the repository used as a submodule is being replicated through Git MultiSite, you will lose the benefits of using the repository on a local node.

To maintain the benefits of the replicated environment, specify the relationship to the sub-module using a relative path, such as:

git submodule add REPONAME ../RELATIVE-PATH-TO-REPO

For example:

git submodule add ../subrepo.git test2

This would then add the following entry to your .gitmodules file:

[submodule "test2"]
path = test2
url = ../subrepo.git

Note: If you're using external sub-modules, you can continue to specify them using full URLs. This is only applicable to local sub-modules you want replicated.