Here's an easy to use tool that downloads issues from SonarQube and outputs them in CSV format

sonar-csv.js

#!/usr/bin/env node

/*
 * Downloads open issues from SonarQube and outputs them as a CSV file
 */

var request = require("request");
var json2csv = require("json2csv");
var util = require("util");

var current_page = 1;
var pages = Number.MAX_VALUE;

var handle_response = function(error, response, data) {
    if (error || response.statusCode !== 200) {
        throw error || response.statusCode;
    }

    json2csv({ data: data.issues, hasCSVColumnTitle: false }, function(err, csv) {
      if (err) {
          throw err;
      }
      console.log(csv);
    });

    if(pages > current_page) {
        current_page++;
        request_issues(current_page);
    }
};

var handle_first_page_response = function(error, response, data) {
    if(error || response.statusCode !== 200) {
        throw error || response.statusCode;
    }

    pages = data.paging.pages;

    var fields = Object.keys(data.issues[0]);

    json2csv({ data: data.issues, fields: fields }, function(err, csv) {
      if (err) {
          throw err;
      }
      console.log(csv);
    });

    if(pages > current_page) {
        current_page++;
        request_issues(current_page);
    }
};

var request_issues = function(page) {
    var url = util.format(
            "%s/api/issues/search?componentRoots=%s&resolved=false&pageSize=-1&pageIndex=%d",
            sonar,
            projects,
            page
        );

    var handler = (page === 1 ? handle_first_page_response : handle_response);

    request({
        url: url,
        json: true
    }, handler);
};

if (process.argv.length < 4) {
    console.log('Usage: sonar-csv sonar-url project-key-1 project-key-2 ...');
    console.log('   eg: sonar-csv http://sonar.example.com abc-my-project');
    process.exit(1);
}

var sonar = process.argv[2];
var projects = process.argv.slice(3).join(',');

request_issues(current_page);

sonar-csv.php

#!/usr/bin/env php
<?php
/*
 * Downloads open issues from SonarQube and outputs them as a CSV file
 */

if (count($argv) < 3) {
    echo 'Usage: sonar-csv sonar-url project-key-1 project-key-2  ...' . PHP_EOL;
    echo '       e.g. http://sonarqube.example.com my-project' . PHP_EOL . PHP_EOL;
    exit;
}

array_shift($argv);

$sonarUrl = array_shift($argv);
$repos = implode(',', $argv);

$url = $sonarUrl . '/api/issues/search?componentRoots=' . $repos .
    '&resolved=false&pageSize=-1&pageIndex=%d';

$pages = PHP_INT_MAX;
$currentPage = 1;

$haveOutputtedHeaders = false;
$out = fopen('php://output', 'w');

while($currentPage <= $pages) {
    $raw = file_get_contents(sprintf($url, $currentPage));
    $data = json_decode($raw, true);

    $pages = $data['paging']['pages'];

    foreach ($data['issues'] as $issue) {

        if(!$haveOutputtedHeaders) {
            fputcsv($out, array_keys($issue));
            $haveOutputtedHeaders = true;
        }

        fputcsv($out, array_values($issue));
    }

    $currentPage++;
}

fclose($out);