"info()"

    $response = $e->nodes->info(
        node_id => $node_id | \@node_ids       # optional
        metric  => $metric  | \@metrics        # optional
    );

The "info()" method returns static information about the nodes in the cluster, such as the configured maximum number of file handles, the maximum configured heap size or the threadpool settings.

Allowed metrics are: "http", "jvm", "network", "os", "plugin", "process", "settings", "thread_pool", "timeout", "transport"

Query string parameters: "error_trace", "flat_settings", "human"

See the node_info docs <http://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-nodes-info.html> for more information.

"stats()"

    $response = $e->nodes->stats(
        node_id      => $node_id    | \@node_ids       # optional
        metric       => $metric     | \@metrics        # optional
        index_metric => $ind_metric | \@ind_metrics    # optional
    );

The "stats()" method returns statistics about the nodes in the cluster, such as the number of currently open file handles, the current heap memory usage or the current number of threads in use.

Stats can be returned for all nodes, or limited to particular nodes with the "node_id" parameter. By default all metrics are returned, but these can be limited to those specified in the "metric" parameter.

Allowed metrics are: "_all", "breaker", "fs", "http", "include_segment_file_sizes", "indices", "jvm", "network", "os", "process", "thread_pool", "timeout", "transport"

If the "indices" metric (or "_all") is specified, then indices_stats information is returned on a per-node basis. Which indices stats are returned can be controlled with the "index_metric" parameter:

    $response = $e->nodes->stats(
        node_id       => 'node_1',
        metric        => ['indices','fs']
        index_metric  => ['docs','fielddata']
    );

Allowed index metrics are: "_all", "completion" "docs", "fielddata", "filter_cache", "flush", "get", "id_cache", "indexing", "merge", "percolate", "query_cache", "refresh", "search", "segments", "store", "warmer"

Query string parameters: "completion_fields", "error_trace", "fielddata_fields", "fields", "groups", "human", "level", "types"

See the stats docs <http://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-nodes-stats.html> for more information.

"hot_threads()"

    $response = $e->nodes->hot_threads(
        node_id => $node_id | \@node_ids       # optional
    )

The "hot_threads()" method is a useful tool for diagnosing busy nodes. It takes a snapshot of which threads are consuming the most CPU.

Query string parameters: "error_trace", "human", "ignore_idle_threads", "interval", "snapshots", "threads", "timeout", "type"

See the hot_threads docs <http://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-nodes-hot-threads.html> for more information.

"usage()"

    $response = $e->nodes->usage(
        node_id => $node_id | \@node_ids       # optional
        metric  => $metric  | \@metrics        # optional
    )

The "usage()" API retrieve sinformation on the usage of features for each node.

Query string parameters: "error_trace", "human", "timeout"

See the nodes_usage docs <https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-nodes-usage.html> for more information.