Duplicate Hosts

As of SingleStore Toolbox 1.4.4, a check for duplicate hosts is performed before SingleStore is deployed, and will display a message similar to the following if more than one host has the same SSH host key:

✘ Host check failed.host 172.26.212.166 has the same ssh
host keys as 172.16.212.165, toolbox doesn't support
registering the same host twice

Confirm that all specified hosts are indeed different and aren’t using identical SSH host keys. Identical host keys can be present if you have instantiated your host instances from images (AMIs, snapshots, etc.) that contain existing host keys. When a host is cloned, the host key (typically stored in /etc/ssh/ssh_host_<cipher>_key) will also be cloned.

As each cloned host will have the same host key, an SSH client cannot verify that it is connecting to the intended host. The script that deploys SingleStore will interpret a duplicate host key as an attempt to deploy to the same host twice, and the deployment will fail.

The following steps demonstrate a potential remedy for the duplicate hosts message. Please note these steps may slightly differ depending on your Linux distribution and configuration.

sudo root
ls -al /etc/ssh/
rm /etc/ssh/<your-ssh-host-keys>
ssh-keygen -f /etc/ssh/<ssh-host-key-filename> -N '' -t rsa1
ssh-keygen -f /etc/ssh/<ssh-host-rsa-key-filename> -N '' -t rsa
ssh-keygen -f /etc/ssh/<ssh-host-dsa-key-filename> -N '' -t dsa

For more information about SSH host keys, including the equivalent steps for Ubuntu-based systems, refer to Avoid Duplicating SSH Host Keys.

As of SingleStore Toolbox 1.5.3, sdb-deploy setup-cluster supports an --allow-duplicate-host-fingerprints option that can be used to ignore duplicate SSH host keys.

Network Configuration

Depending on the host and its function in deployment, some or all of the following port settings should be enabled on hosts in your cluster.

These routing and firewall settings must be configured to:

• Allow database clients (e.g. your application) to connect to the SingleStore aggregators

• Allow all nodes in the cluster to talk to each other over the SingleStore protocol (3306)

• Allow you to connect to management and monitoring tools

The service port values are configurable if the default values cannot be used in your deployment environment. For more information on how to change them, see:

• The cluster file template provided in this guide

• The SingleStore configuration file

• The sdb-toolbox-config register-host command

We also highly recommend configuring your firewall to prevent other hosts on the Internet from connecting to SingleStore.

Notes on Users and Groups

The user that deploys SingleStore via SingleStore Toolbox must be able to SSH to each host in the cluster. When singlestoredb-server is installed via an RPM or Debian package when deploying SingleStore, a memsql user and group are also created on each host in the cluster.

This memsql user does not have a shell, and attempting to log in or SSH as this user will fail. The user that deploys SingleStore is added to the memsql group. This group allows most Toolbox commands to run without sudo privileges, and members of this group can perform many Toolbox operations without the need to escalate to sudo. Users who desire to run SingleStore Toolbox commands must be added to the memsql group on each host in the cluster. They must also be able to SSH to each host.

Manually creating a memsql user and group is only recommended in a sudo-less environment when performing a tarball-based deployment of SingleStore. In order to run SingleStore Toolbox commands against a cluster, this manually-created memsql user must be configured so that it can SSH to each host in the cluster.

Minimal Deployment

SingleStore has been designed to be deployed with at least two nodes:

• A Master Aggregator node that runs SQL queries and aggregates the results, and

• A single leaf node, which is responsible for storing and processing data

These two nodes can be deployed on a single host (via the cluster-in-box option), or on two hosts, with one SingleStore node on each host.

While additional aggregators and nodes can be added and removed as required, a minimal deployment of SingleStore always consists of at least these two nodes.

Start the UI

Run the following command to start the UI.

1. Run the following on the command line.

   Shell

   Copy

   sdb-deploy ui

This command will display a link with a secure token that you can use to deploy SingleStore via the UI.

For additional options that can be used with sdb-deploy ui, refer to the associated reference page.

Access the UI

Copy and paste this link into a Chrome or Firefox browser to access the UI.

Note: You may need to modify the URL by changing localhost to a hostname or IP address depending on how and where you installed SingleStore Tools. The hostname or IP address must be that of the main deployment host, which is typically the Master Aggregator.

Create a YAML File Using the UI and Deploy a Cluster

In lieu of deploying a cluster immediately, a cluster can be configured using the UI and the configuration saved to a YAML file. The YAML file can then be used to deploy a cluster by copying the YAML file to the Master Aggregator and running the following command.

sdb-deploy setup-cluster --cluster-file </path/to/cluster-file>

Troubleshooting

• Message: unknown command "ui" for "sdb-deploy"

  Solution: Confirm that SingleStore Toolbox v1.6 or later has been installed on the main deployment host.

• Message: sdb-deploy ui is not currently supported by SingleStore.

  Solution: The installed version of SingleStore Toolbox does not support deploying SingleStore via the UI. Please select another deployment option.

• Message: Registered hosts detected. SingleStore Toolbox supports managing only one cluster per instance. To view them, run 'sdb-toolbox-config list-hosts'. To remove them, run 'sdb-toolbox-config unregister-host'

  Solution: SingleStore Toolbox can only manage a single instance of SingleStore.

Additional Deployment Options