keeping-track-of-nodes.asciidoc

Keeping track of nodes

Creating a Node

A Node can be instantiated by passing it a Uri

var node = new Node(new Uri("http://localhost:9200"));
node.Uri.Should().NotBeNull();
node.Uri.Port.Should().Be(9200);

By default master eligible and holds data is presumed to be true *

node.MasterEligible.Should().BeTrue();
node.HoldsData.Should().BeTrue();

Is resurrected is true on first usage, hints to the transport that a ping might be useful

node.IsResurrected.Should().BeTrue();

Building a Node path

passing a node with a path should be preserved. Sometimes an Elasticsearch node lives behind a proxy

var node = new Node(new Uri("http://test.example/elasticsearch"));

node.Uri.Port.Should().Be(80);
node.Uri.AbsolutePath.Should().Be("/elasticsearch/");

We force paths to end with a forward slash so that they can later be safely combined

var combinedPath = new Uri(node.Uri, "index/type/_search");
combinedPath.AbsolutePath.Should().Be("/elasticsearch/index/type/_search");

which is exactly what the CreatePath method does on Node

combinedPath = node.CreatePath("index/type/_search");
combinedPath.AbsolutePath.Should().Be("/elasticsearch/index/type/_search");

Marking Nodes

var node = new Node(new Uri("http://localhost:9200"));
node.FailedAttempts.Should().Be(0);
node.IsAlive.Should().BeTrue();

every time a node is marked dead, the number of attempts should increase and the passed datetime should be exposed.

for(var i = 0; i<10;i++)
{
    var deadUntil = DateTime.Now.AddMinutes(1);
    node.MarkDead(deadUntil);
    node.FailedAttempts.Should().Be(i + 1);
    node.IsAlive.Should().BeFalse();
    node.DeadUntil.Should().Be(deadUntil);
}

however when marking a node alive, the DeadUntil property should be reset and FailedAttempts reset to 0

node.MarkAlive();
node.FailedAttempts.Should().Be(0);
node.DeadUntil.Should().Be(default(DateTime));
node.IsAlive.Should().BeTrue();

Node Equality

Nodes are considered equal if they have the same endpoint, no matter what other metadata is associated

var node = new Node(new Uri("http://localhost:9200")) { MasterEligible = false };
var nodeAsMaster = new Node(new Uri("http://localhost:9200")) { MasterEligible = true };

(node == nodeAsMaster).Should().BeTrue();
(node != nodeAsMaster).Should().BeFalse();

var uri = new Uri("http://localhost:9200");
(node == uri).Should().BeTrue();

var differentUri = new Uri("http://localhost:9201");
(node != differentUri).Should().BeTrue();

node.Should().Be(nodeAsMaster);