Running the xgtd server

Configuring xgtd

There are reasonable defaults provided for all of these configuration parameters. It is recommended that you override these default values only after running xGT with the default values. The only exceptions to this guidance is the security information: (i) the AWS credential information has no reasonable defaults for securely accessing data in S3 buckets, and (ii) to run with SSL encryption between the Python client and xgtd server the configuration parameters for ssl must be provided.

Configuring xgtd is done using key-value pairs. The pairs can be given either in configuration files written in JSON format or as command line arguments when launching xgtd.

There are two standard locations for the configuration file: /home/xgtd/.xgtd.conf and /etc/xgtd.conf. When launched, the xgtd application will first look for a configuration file at /home/xgtd/.xgtd.conf. If the file doesn't exist, the xgtd application will look at /etc/xgtd.conf. Only one of these configuration files will be read, and no message is given if neither of these files are found.

The xgtd application will next process configuration files given as program arguments. An arbitrary configuration file can be used by passing the following program argument to xgtd: -c /path/to/xgtd.conf.

Users may split configuration information into multiple files and repeat the -c argument. Users may also give a config file on the command line when a config file exists in one of the standard locations. A config file in the standard location is processed first, and then files given on the command line are processed in the order they are given (left to right). This results in later configuration for the same key overriding earlier configuration for that key.

xgtd also supports providing a single key-value configuration item in the form of a program argument: -Dkey=value or -Dkey:value. These -D options can appear multiple times and repeated keys are set to the latest appearance in the command line (left to right). Users can mix -c and -D options. They are collectively processed in a left to right manner.

The following keys for configuring xGT are supported:

An example file containing xgtd configuration file (/path/to/xgtd.conf:

  "system": {
    "worker_threads": 16,
    "io_threads": 10,
    "port": 4369

  "system.locale": "en_US.UTF-8"

Then, to launch xgtd, you may do this command that uses this base configuration and supplements that with a definition for

$ xgtd -c /path/to/xgtd.conf

To launch xgtd using the base configuration but overriding the worker_threads configuration value:

$ xgtd -c /path/to/xgtd.conf -Dsystem.worker_threads=8

To launch xgtd using multiple base configurations:

$ xgtd -c /path/to/xgtd_conf1.conf -Dsystem.port=4369 -c /path/to/xgtd_conf2.conf

Configuring xgtd the old way (deprecated)

Some parameters of xGT can be configured with the JSON-formatted configuration file xgtd.conf located on the computer where the server process is running.

The following variables for configuring xGT are supported:

Example xgtd.conf file:

  "worker_threads" : 4,
  "pin_threads" : false

To configure xGT on AWS, login to the server and create the file /etc/xgtd.conf or the file /home/xgtd/.xgtd.conf. The system will first look for the file /home/xgtd/.xgtd.conf, and if unsuccessful, it will look for the file /etc/xgtd.conf.

After creating or modifying the configuration file, the the xGT server must be restarted:

sudo systemctl restart xgtd

S3 credentials

When loading a file using the load method and an s3: protocol prefix, xGT will check the /home/xgtd/.aws/credentials file for the two variables aws_access_key_id and aws_secret_access_key. If the credentials file doesn't exist, xgt will check for the configuration variables aws.access_key_id and aws.secret_access_key. The online AWS Access Keys document explains what these keys are and contains references to learn how to create and manage them. (These values may also be specified at runtime in user code by passing them to a Connection object.)

When reading the /home/xgtd/.aws/credentials file, xGT also supports profile selection via the AWS_PROFILE environment variable. If no environment variable is found, xGT will use the default profile.

Using an SSL secure channel

By default xGT uses an insecure channel, but an admin or user can enable a secure channel using SSL certifcates. To run a secure server, pass the flags -s (or --ssl) and -d (or --ssl_root_dir) when starting the xgtd executable. The ssl_root_dir argument should be the path to the root directory that holds the server's SSL certificates and private keys. A user can also turn on the secure server by setting the configuration variable system.usessl to True. Setting the configuration variable system.ssl_root_dir is an alternative way to specify the root directory that holds the server's SSL certificates and private keys. xGT expects the following directory structure:

├── certs
│   ├── ca-chain.cert.pem
│   └── server.cert.pem
└── private
    └── server.key.pem

To connect to an xGT server using SSL, the client needs to pass the following flags to the xgt.Connection() method: ssl, ssl_root_dir, and ssl_server_cn. The ssl flag needs to be set to true. The ssl_root_dir flag should be set to the root directory containing the SSL certificates and private keys. The ssl_server_cn flag should be set to the common name for the server listed on the server side SSL certificate. The xGT client expects the following directory structure for SSL certificates and private keys:

├── certs
│   ├── ca-chain.cert.pem
│   └── client.cert.pem
└── private
    └── client.key.pem