Example of using WordPress Core's HTTP API to call a microservice

post-to-microservice.php

<?php

/*
 * There are many different actions you might
 * hook into to trigger a post to your microservice
 */
add_action( 'sample_action', 'post_to_microservice', 10 );

function post_to_microservice() {

	$response = wp_remote_post(
		'http://your-url.test',
		array(
			'headers' => array(
				/**
				* You might include authorization here,
				* depending on your microservice's setup
				*/
			),
			'body' => array(
				/**
				* This is where you would pass any data
				* needed for your microservice to consume
				*/
				'data' => 'Test data',
			),
		)
	);

	if ( is_wp_error( $response ) ) {
		// Handle the error here
		sample_handle_error( $response );
		return;
	}

	// Handle a successful response here
	sample_handle_success( $response );
	return;

}