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.
By default, Elasticsearch binds to loopback addresses for HTTP and transport (internal) communication. This is fine for downloading and playing with Elasticsearch as well as 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 via a non-loopback address, a node must bind transport to a non-loopback address 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 via a non-loopback address, and is otherwise in production mode if it can join a cluster via non-loopback addresses.
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.
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.