First, some background: we have 15 different methods to get a logger in
Elasticsearch but they can be broken down into three broad categories
based on what information is provided when building the logger.
Just a class like:
```
private static final Logger logger = ESLoggerFactory.getLogger(ActionModule.class);
```
or:
```
protected final Logger logger = Loggers.getLogger(getClass());
```
The class and settings:
```
this.logger = Loggers.getLogger(getClass(), settings);
```
Or more information like:
```
Loggers.getLogger("index.store.deletes", settings, shardId)
```
The goal of the "class and settings" variant is to attach the node name
to the logger. Because we don't always have the settings available, we
often use the "just a class" variant and get loggers without node names
attached. There isn't any real consistency here. Some loggers get the
node name because it is convenient and some do not.
This change makes the node name available to all loggers all the time.
Almost. There are some caveats are testing that I'll get to. But in
*production* code the node name is node available to all loggers. This
means we can stop using the "class and settings" variants to fetch
loggers which was the real goal here, but a pleasant side effect is that
the ndoe name is now consitent on every log line and optional by editing
the logging pattern. This is all powered by setting the node name
statically on a logging formatter very early in initialization.
Now to tests: tests can't set the node name statically because
subclasses of `ESIntegTestCase` run many nodes in the same jvm, even in
the same class loader. Also, lots of tests don't run with a real node so
they don't *have* a node name at all. To support multiple nodes in the
same JVM tests suss out the node name from the thread name which works
surprisingly well and easy to test in a nice way. For those threads
that are not part of an `ESIntegTestCase` node we stick whatever useful
information we can get form the thread name in the place of the node
name. This allows us to keep the logger format consistent.
The existing log rotation configuration allowed the index
and search slow log to grow unbounded. This commit removes the
date based rotation and adds the same size based rotation, that
the depreciation log already has.
In 5.0, the search slow log switched to the multi-line format with no option to get back to the origin single-line format that was used prior to 5.0 by default. This commit removes the reformat option from the search slow log and returns the search slow log back to the single-line format.
Closes#21711
This commit fixes two issues with the slow log docs:
- clarifies that these settings are per index
- updates index slow log configuration for Log4j 2
Relates #20976
Instead of logging the entire `_source` in the indexing slowlog we log by
default just the first 1000 characters - this is controlled by the
`index.indexing.slowlog.source` settings and can be set to `true` to log the
whole `_source`, `false` to log none of it, and a number to log at most that
many characters.
Closes#4485
Nik Everett
Jason Tedor
Alexander Reelsen
Igor Motov
Sakthipriyan Vairamani
Clinton Gormley
Kouhei Sutou
Lee Hinman