OpenSearch/watcher/docs/reference/java/put-watch.asciidoc

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[[api-java-put-watch]]
==== PUT Watch API
The PUT watch API either registers a new watch in Watcher or update an existing one. Once registered, a new document
will be added to the `.watches` index, representing the watch, and the watch's trigger will immediately be registered
with the relevant trigger engine (typically the scheduler, for the `schedule` trigger).
IMPORTANT: Putting a watch must be done via this API only. Do not put a watch directly to the `.watches` index
using Elasticsearch's Index API. When integrating with Shield, a best practice is to make sure
no `write` privileges are granted to anyone over the `.watches` API.
The following example adds an watch with the `my-watch` id that has the following qualities:
* The watch schedule triggers every minute.
* The watch search input finds any 404 HTTP responses that occurred in the past five minutes.
* The watch condition checks the search results for 404s.
* The watch action sends an email if there are any 404s.
[source,java]
--------------------------------------------------
WatchSourceBuilder watchSourceBuilder = WatchSourceBuilders.watchBuilder();
// Set the trigger
watchSourceBuilder.trigger(TriggerBuilders.schedule(Schedules.cron("0 0/1 * * * ?")));
// Create the search request to use for the input
SearchRequest request = Requests.searchRequest("idx").source(searchSource()
.query(filteredQuery(matchQuery("response", 404), boolFilter()
.must(rangeFilter("date").gt("{{ctx.trigger.scheduled_time}}"))
.must(rangeFilter("date").lt("{{ctx.execution_time}}")))));
// Set the input
watchSourceBuilder.input(new SearchInput(request, null));
// Set the condition
watchSourceBuilder.condition(new ScriptCondition(Script.inline("ctx.payload.hits.total > 1").build()));
// Create the email template to use for the action
EmailTemplate.Builder emailBuilder = EmailTemplate.builder();
emailBuilder.to("someone@domain.host.com");
emailBuilder.subject("404 recently encountered");
EmailAction.Builder emailActionBuilder = EmailAction.builder(emailBuilder.build());
// Add the action
watchSourceBuilder.addAction("email_someone", emailActionBuilder.build());
PutWatchResponse putWatchResponse = watcherClient.preparePutWatch("my-watch")
.setSource(watchSourceBuilder)
.get();
--------------------------------------------------
While the above snippet flashes out all the concrete classes that make our watch, using the
available builder classes along with static imports can significantly simplify and compact
your code:
[source,java]
--------------------------------------------------
PutWatchResponse putWatchResponse = watcherClient.preparePutWatch("my-watch")
.setSource(watchBuilder()
.trigger(schedule(cron("0 0/1 * * * ?")))
.input(searchInput(searchRequest("idx").source(searchSource()
.query(filteredQuery(matchQuery("response", 404), boolFilter()
.must(rangeFilter("date").gt("{{ctx.trigger.scheduled_time}}"))
.must(rangeFilter("date").lt("{{ctx.execution_time}}")))))))
.condition(scriptCondition("ctx.payload.hits.total > 1"))
.addAction("email_someone", emailAction(EmailTemplate.builder()
.to("someone@domain.host.com")
.subject("404 recently encountered"))))
.get();
--------------------------------------------------
* Use `TriggerBuilders` and `Schedules` classes to define the trigger
* Use `InputBuilders` class to define the input
* Use `ConditionBuilders` class to define the condition
* Use `ActionBuilders` to define the actions