ConfD

What is ConfD?

ConfD is a low-level API that can be used to perform all administrative actions in Exasol. The ConfD API is available on all nodes in a deployment. You can interact with ConfD directly using the command-line tool confd_client, or indirectly through XML-RPC in your own Python programs.

Stages in a job pipeline

• submitted: The job ID has been received and the job is waiting in the queue to be scheduled.

• scheduled: The scheduler has examined the job and accepted it, assigned the configuration update (if necessary), and started execution in a dedicated worker thread.

• executed: The commands are being executed. A job may consist of multiple commands which are documented in their own sections within the job file, including the result and output.

• finished: All commands of the job have been executed and stored within the job file. This is the final stage for a read-only job.

• committed: All nodes have received the changes made by this job, and the updated configuration has been synchronized. This is the final stage for a job that modifies the database.

EXAConf

Each database node contains a configuration file /exa/etc/EXAConf that stores most of the configuration settings that are managed by ConfD jobs. Manual editing of this file is normally not necessary and is not recommended.

Do not edit the EXAConf file directly unless you have been requested to do so by Exasol Support.

Use confd_client

The command-line tool confd_client allows you to interact directly with ConfD on all active nodes in a deployment.

To use confd_client, connect to the cluster operating system (COS) using c4 connect -t <DEPLOYMENT>[.<NODE>]/cos. For example:

./c4 connect -t 1/cos

If you do not specify a node, c4 will connect to the first active node in the deployment. If the cluster is configured with an access node, the first node is the access node (usually n10). The command prompt in COS indicates which node you are connected to. For example:

[root@n10 ~]#

For more information about how to use c4 connect, see Connect to a deployment (AWS) or Connect to a deployment (on-premises).

To get help with confd_client, use confd_client --help once you are connected to COS.

ConfD jobs are executed with the user that is logged in to the node, which in most cases is root. There is no extra authentication step when using confd_client in this way.

Syntax of confd_client commands

You can use different syntax formats when submitting jobs in confd_client. Most jobs can be submitted using either of these formats. For more information about the accepted syntax for a specific ConfD job, refer to the respective job description in this reference.

In the following examples, the job db_start is submitted using different syntax formats in order to start the database Exasol:

confd_client db_start db_name: Exasol

confd_client -c db_start -a '{db_name: Exasol}'

Use XML-RPC in Python

You can interact with ConfD through XML-RPC in your own Python programs. By default, the XML-RPC interface is available on port 20003 on the first active node in the deployment. For AWS deployments deployed with an access node, the first node is the access node.

When using XML-RPC, you must authenticate with a user. For more details, see Authentication.

Example:

import xmlrpc.client
import requests, urllib3, ssl
import sys
import json
import pprint

# Disable SSL warnings
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

# Enter the public IP address of the first node in the deployment and the COS port (default port: 20003)
# If the deployment has an access node, the first node is the access node. 
database_host = '203.0.113.42:20003'

# Enter the username and password you are connecting with.
user = 'admin' 
pw = 'exasol'

connection_string = f'https://{user}:{pw}@{database_host}'

sslcontext = ssl._create_unverified_context()

# Establish connection 
conn = xmlrpc.client.ServerProxy(connection_string, context = sslcontext, allow_none=True)

Once you are connected, you can execute a job:

# Choose the job you want to run
job_name = 'db_start'

# Set the parameters for the chosen job
params = {'db_name': 'Exasol'}

# Execute the job and wait for it to finish and return the result
conn.job_exec(job_name, {'params': params})

For more examples on how you can interact with ConfD using XML-RPC, see the confd_xmlrpc script on GitHub.