Collectively, we have a lot of experience with users suffering unexpected issues because they have not configured important settings. In previous versions of Elasticsearch, misconfiguration of some of these settings were logged as warnings. Understandably, users sometimes miss these log messages. To ensure that these settings receive the attention that they deserve, Elasticsearch has bootstrap checks upon startup.
These bootstrap checks inspect a variety of Elasticsearch and system settings and compare them to values that are safe for the operation of Elasticsearch. If Elasticsearch is in development mode, any bootstrap checks that fail appear as warnings in the Elasticsearch log. If Elasticsearch is in production mode, any bootstrap checks that fail will cause Elasticsearch to refuse to start.
There are some bootstrap checks that are always enforced to prevent Elasticsearch from running with incompatible settings. These checks are documented individually.
Development vs. production modeedit
By default, Elasticsearch binds to
localhost for HTTP and
transport (internal) communication. This is fine for
downloading and playing with Elasticsearch, and everyday development but it’s
useless for production systems. To join a cluster, an Elasticsearch node must be
reachable via transport communication. To join a cluster over an external
network interface, a node must bind transport to an external interface and not
be using single-node discovery. Thus, we consider an
Elasticsearch node to be in development mode if it can not form a cluster with
another machine over an external network interface, and is otherwise in
production mode if it can join a cluster over an external interface.
Note that HTTP and transport can be configured independently via
can be useful for configuring a single node to be reachable via HTTP for testing
purposes without triggering production mode.
We recognize that some users need to bind transport to an external interface for
testing their usage of the transport client. For this situation, we provide the
single-node (configure it by setting
single-node); in this situation, a node will elect itself master and will not
join a cluster with any other node.
Forcing the bootstrap checksedit
If you are running a single node in production, it is possible to evade the
bootstrap checks (either by not binding transport to an external interface, or
by binding transport to an external interface and setting the discovery type to
single-node). For this situation, you can force execution of the bootstrap
checks by setting the system property
(set this in Setting JVM options, or by adding
to the environment variable
ES_JAVA_OPTS). We strongly encourage you to do
this if you are in this specific situation. This system property can be used to
force execution of the bootstrap checks independent of the node configuration.