private SolrClient createSolrClient() throws TikaConfigException {
        if (solrUrls == null || solrUrls.isEmpty()) {
            //TODO -- there's more that we need to pass through, including ssl etc.
            Http2SolrClient.Builder http2SolrClientBuilder = new Http2SolrClient.Builder();
            if (!StringUtils.isBlank(httpClientFactory.getUserName())) {
                http2SolrClientBuilder.withBasicAuthCredentials(httpClientFactory.getUserName(), httpClientFactory.getPassword());
            }
            http2SolrClientBuilder
                    .withRequestTimeout(httpClientFactory.getRequestTimeout(), TimeUnit.MILLISECONDS)
                    .withConnectionTimeout(connectionTimeout, TimeUnit.MILLISECONDS);


            Http2SolrClient http2SolrClient = http2SolrClientBuilder.build();
            return new CloudSolrClient.Builder(solrZkHosts, Optional.ofNullable(solrZkChroot))
                    .withHttpClient(http2SolrClient)
                    .build();

        }
        return new LBHttpSolrClient.Builder()
                .withConnectionTimeout(connectionTimeout)
                .withSocketTimeout(socketTimeout)
                .withHttpClient(httpClientFactory.build())
                .withBaseSolrUrls(solrUrls.toArray(new String[]{}))
                .build();
    }
You can specify solrUrls, or you can specify solrZkHosts and use use zookeeper to determine the solr server urls.
tika-pipes/tika-pipes-iterators/tika-pipes-iterator-solr/src/main/java/org/apache/tika/pipes/pipesiterator/solr/SolrPipesIterator.java