src/Ovh/Cloud/CloudClient.php
public function postInstanceSnapshot($serviceName, $idInstance, $snapshotName){
        if (!$serviceName)
            throw new BadMethodCallException('Missing parameter $serviceName (OVH Cloud Project).');
        if (!$idInstance)
            throw new BadMethodCallException('Missing parameter $idInstance (OVH Cloud Instance ID).');           
        if (!$snapshotName)
            throw new BadMethodCallException('Missing parameter $snapshotName (OVH Cloud Instance Snapshot Name).');          
        $post = array(
            'snapshotName' => $snapshotName
		);
         
        try {
            $r = $this->post('cloud/project/'.$serviceName.'/instance/'.$idInstance.'/snapshot', array('Content-Type' => 'application/json;charset=UTF-8'), json_encode($post))->send();
        }
        catch (\Exception $e) {
            throw new CloudException($e->getMessage(), $e->getCode(), $e);
        }
        return $r->getBody(true);
    }
public function postInstanceSnapshot($serviceName, $idInstance, $snapshotName){
        if (!$serviceName)
            throw new BadMethodCallException('Missing parameter $serviceName (OVH Cloud Project).');
        if (!$idInstance)
            throw new BadMethodCallException('Missing parameter $idInstance (OVH Cloud Instance ID).');           
        if (!$snapshotName)
            throw new BadMethodCallException('Missing parameter $snapshotName (OVH Cloud Instance Snapshot Name).');          
        $post = array(
            'snapshotName' => $snapshotName
		);
         
        try {
            $r = $this->post('cloud/project/'.$serviceName.'/instance/'.$idInstance.'/snapshot', array('Content-Type' => 'application/json;charset=UTF-8'), json_encode($post))->send();
        }
        catch (\Exception $e) {
            throw new CloudException($e->getMessage(), $e->getCode(), $e);
        }
        return $r->getBody(true);
    }
POST Snapshot Instance
POST /cloud/project/{serviceName}/instance/{instanceId}/snapshot

@return null
@throws \Ovh\Cloud\Exception\CloudException
@throws \Ovh\Common\Exception\BadMethodCallException