Core: Default node.name to the hostname #33677

nik9000 · 2018-09-13T16:16:59Z

Changes the default of the node.name setting to the hostname of the
machine on which Elasticsearch is running. Previously it was the first 8
characters of the node id. This had the advantage of producing a unique
name even when the node name isn't configured but the disadvantage of
being unrecognizable and not being available until fairly late in the
startup process. Of particular interest is that it isn't available until
after logging is configured. This forces us to use a volatile read
whenever we add the node name to the log.

Using the hostname is available immediately on startup and is generally
recognizable but has the disadvantage of not being unique when run on
machines that don't set their hostname or when multiple elasticsearch
processes are run on the same host. I believe that, taken together, it
is better to default to the hostname.

Running multiple copies of Elasticsearch on the same node is a fairly
advanced feature. We do it all the as part of the elasticsearch build
for testing but we make sure to set the node name then.
That the node.name defaults to some flavor of "localhost" on an
unconfigured box feels like it isn't going to come up too much in
production. I expect most production deployments to at least set the
hostname.

As a bonus, production deployments need no longer set the node name in
most cases. At least in my experience most folks set it to the hostname
anyway.

Changes the default of the `node.name` setting to the hostname of the machine on which Elasticsearch is running. Previously it was the first 8 characters of the node id. This had the advantage of producing a unique name even when the node name isn't configured but the disadvantage of being unrecognizable and not being available until fairly late in the startup process. Of particular interest is that it isn't available until after logging is configured. This forces us to use a volatile read whenever we add the node name to the log. Using the hostname is available immediately on startup and is generally recognizable but has the disadvantage of not being unique when run on machines that don't set their hostname or when multiple elasticsearch processes are run on the same host. I believe that, taken together, it is better to default to the hostname. 1. Running multiple copies of Elasticsearch on the same node is a fairly advanced feature. We do it all the as part of the elasticsearch build for testing but we make sure to set the node name then. 2. That the node.name defaults to some flavor of "localhost" on an unconfigured box feels like it isn't going to come up too much in production. I expect most production deployments to at least set the hostname. As a bonus, production deployments need no longer set the node name in most cases. At least in my experience most folks set it to the hostname anyway.

elasticmachine · 2018-09-13T16:17:01Z

Pinging @elastic/es-core-infra

nik9000 · 2018-09-13T16:31:32Z

I've marked this as discuss because I bunch of us talked about this and thought it was a good idea but we are aware that other contributors have thought otherwise in the past and might still not like this idea.

jasontedor · 2018-09-13T20:31:07Z

We discussed this during Fix-it-Thursday and have consensus to move ahead with this proposal.

nik9000 · 2018-09-13T22:11:30Z

We discussed this during Fix-it-Thursday and have consensus to move ahead with this proposal.

❤️

nik9000 · 2018-09-13T22:15:07Z

The test failure is mine. I'm looking into it.

I still need to go through the docs some more. And write a breaking changes note for this.

rjernst

LGTM, one suggestion.

rjernst · 2018-09-13T22:16:02Z

docs/reference/setup/important-settings/node-name.asciidoc

+Elasticsearch uses `node.name` as a human readable identifier for a
+particular instance of Elasticsearch so it is included in the response
+of many APIs. It defaults to the hostname that the machine has when
+Elasticsearch starts. If you'd prefer a different identifier then you


I would word this a little less colloquially:

It defaults to the hostname of the machine when Elasticsearch starts, but can be configured explicitly in elasticsearch.yml as follows:

nik9000 · 2018-09-13T22:24:56Z

I think I need to do some testing work on this before it is ready. I'm seeing a few things I hadn't thought about.

nik9000

@rjernst could you have another look at this? Mostly I cleaned up testing things since you last looked.

nik9000 · 2018-09-19T18:31:34Z

qa/evil-tests/src/test/java/org/elasticsearch/common/logging/EvilLoggerTests.java

-        final Settings settings = builder.build();
+        final Settings settings = Settings.builder()
+                .put("cluster.name", randomAlphaOfLength(16))
+                .put("node.name", randomAlphaOfLength(16))


node.name is always available at this point in the course of normal operation.

nik9000 · 2018-09-19T18:32:16Z

qa/evil-tests/src/test/java/org/elasticsearch/common/logging/EvilLoggerTests.java

    }

    public void testNoNodeNameInPatternWarning() throws IOException, UserException {
+        String nodeName = randomAlphaOfLength(16);
+        LogConfigurator.setNodeName(nodeName);


Since we automatically add a node name to the pattern we need to configure one or else the NodeNamePatternConverter will refuse to be built.

nik9000 · 2018-09-19T18:32:39Z

...gured-node-name/src/test/java/org/elasticsearch/unconfigured_node_name/NodeNameInLogsIT.java

@@ -43,11 +48,4 @@ protected BufferedReader openReader(Path logFile) throws IOException {
            }
        });
    }
-
-    public void testDummy() {


I'm glad to remove this!

rjernst

LGTM, one nit.

rjernst · 2018-09-19T18:39:38Z

docs/reference/migration/migrate_7_0/settings.asciidoc

+==== The default for `node.name` is now the hostname
+
+`node.name` now defaults to the hostname at the time when Elasticsearch
+is started. We hope that this is a more generally useful default than


I would replace the second sentence with:

Previously the default node name was the first eight characters of the node id. It can still be configured explicitly in elasticsearch.yml.

bleskes · 2018-09-23T18:05:21Z

@nik9000 was it discussed whether we should prevent joins of nodes with a name that clashes with an existing node in the cluster?

nik9000 · 2018-09-24T14:23:26Z

@nik9000 was it discussed whether we should prevent joins of nodes with a name that clashes with an existing node in the cluster?

I wasn't around for the discussion. I'm not sure where I come down on the issue. It does feel like a sign of a configuration problem though so I think it'd be fair to prevent such joins.

nik9000 · 2018-09-24T14:24:36Z

I think it'd be fair to prevent such joins.

I suppose what I mean is that I think it'd be a good check to do and the argument to prevent joins where the node names match is pretty good. I'm not 100% sure it is worth implementing it but I feel like I could be convinced.

nik9000 added >breaking :Core/Infra/Core Core issues without another label v7.0.0 labels Sep 13, 2018

Update docs

605ce74

nik9000 added the discuss label Sep 13, 2018

jasontedor removed the discuss label Sep 13, 2018

rjernst approved these changes Sep 13, 2018

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nik9000 added 8 commits September 13, 2018 18:30

Breaking changes doc

5efba9e

Clean up InternalSettingsPreparer

d240e66

Remove extra ctor

ae00663

More cleanup

eb04e04

Fix test

31707dc

Fixup logger tests

81a0594

erge branch 'master' into node_name_defaults_to_host_name

d2257d1

Make compile again

1384762

nik9000 commented Sep 19, 2018

View reviewed changes

rjernst approved these changes Sep 19, 2018

View reviewed changes

Fixup asciidoc

74618d5

nik9000 merged commit 26c4f1f into elastic:master Sep 19, 2018

gwbrown mentioned this pull request Nov 29, 2018

Update Deprecation Info API for 7.0 breaking changes #36024

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colings86 added v7.0.0-beta1 and removed v7.0.0 labels Feb 7, 2019

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Core: Default node.name to the hostname #33677

Core: Default node.name to the hostname #33677

nik9000 commented Sep 13, 2018

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Core: Default node.name to the hostname #33677

Core: Default node.name to the hostname #33677

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