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Merge pull request #673 from ryanbreen/watches

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Very minor tweaks to docs/agent/watches
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Armon Dadgar 2015-02-05 09:43:54 -08:00
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1 changed files with 26 additions and 25 deletions
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@ -3,19 +3,18 @@ layout: "docs"
page_title: "Watches" page_title: "Watches"
sidebar_current: "docs-agent-watches" sidebar_current: "docs-agent-watches"
description: |- description: |-
Watches are a way of specifying a view of data (list of nodes, KV pairs, health checks, etc) which is monitored for any updates. When an update is detected, an external handler is invoked. A handler can be any executable. As an example, you could watch the status of health checks and notify an external system when a check is critical. Watches are a way of specifying a view of data (e.g. list of nodes, KV pairs, health checks) which is monitored for updates. When an update is detected, an external handler is invoked. A handler can be any executable. As an example, you could watch the status of health checks and notify an external system when a check is critical.
--- ---
# Watches # Watches
Watches are a way of specifying a view of data (list of nodes, KV pairs, Watches are a way of specifying a view of data (e.g. list of nodes, KV pairs, health
health checks, etc) which is monitored for any updates. When an update checks) which is monitored for updates. When an update is detected, an external handler
is detected, an external handler is invoked. A handler can be any is invoked. A handler can be any executable. As an example, you could watch the status
executable. As an example, you could watch the status of health checks and of health checks and notify an external system when a check is critical.
notify an external system when a check is critical.
Watches are implemented using blocking queries in the [HTTP API](/docs/agent/http.html). Watches are implemented using blocking queries in the [HTTP API](/docs/agent/http.html).
Agents automatically make the proper API calls to watch for changes, Agents automatically make the proper API calls to watch for changes
and inform a handler when the data view has updated. and inform a handler when the data view has updated.
Watches can be configured as part of the [agent's configuration](/docs/agent/options.html), Watches can be configured as part of the [agent's configuration](/docs/agent/options.html),
@ -23,27 +22,28 @@ causing them to run once the agent is initialized. Reloading the agent configura
allows for adding or removing watches dynamically. allows for adding or removing watches dynamically.
Alternatively, the [watch command](/docs/commands/watch.html) enables a watch to be Alternatively, the [watch command](/docs/commands/watch.html) enables a watch to be
started outside of the agent. This can be used by an operator to inspect data in Consul, started outside of the agent. This can be used by an operator to inspect data in Consul
or to easily pipe data into processes without being tied to the agent lifecycle. or to easily pipe data into processes without being tied to the agent lifecycle.
In either case, the `type` of the watch must be specified. Each type of watch In either case, the `type` of the watch must be specified. Each type of watch
supports different parameters, both required and optional. These options are specified supports different parameters, some required and some optional. These options are specified
in a JSON body when using agent configuration, or as CLI flags for the watch command. in a JSON body when using agent configuration or as CLI flags for the watch command.
## Handlers ## Handlers
The watch specification specifies the view of data to be monitored. The watch configuration specifies the view of data to be monitored.
Once that view is updated the specified handler is invoked. The handler Once that view is updated, the specified handler is invoked. The handler
can be any executable. can be any executable.
A handler should read its input from stdin, and expect to read A handler should read its input from stdin and expect to read
JSON formatted data. The format of the data depends on the type of the JSON formatted data. The format of the data depends on the type of the
watch. Each watch type documents the format type, and because they watch. Each watch type documents the format type. Because they
map directly to an HTTP API, handlers should expect the input to map directly to an HTTP API, handlers should expect the input to
match the format of the API. match the format of the API.
Additionally, the `CONSUL_INDEX` environmental variable will be set. Additionally, the `CONSUL_INDEX` environment variable will be set.
This maps to the `X-Consul-Index` value from the [HTTP API](/docs/agent/http.html). This maps to the `X-Consul-Index` value in responses from the
[HTTP API](/docs/agent/http.html).
## Global Parameters ## Global Parameters
@ -56,7 +56,7 @@ are a few global parameters that all watches support:
## Watch Types ## Watch Types
The following types are supported, with more documentation below: The following types are supported. Detailed documentation on each is below:
* `key` - Watch a specific KV pair * `key` - Watch a specific KV pair
* `keyprefix` - Watch a prefix in the KV store * `keyprefix` - Watch a prefix in the KV store
@ -215,10 +215,11 @@ An example of the output of this command:
### Type: service ### Type: service
The "service" watch type is used to monitor the providers The "service" watch type is used to monitor the providers
of a single service. It requires the "service" parameter, of a single service. It requires the "service" parameter
but optionally takes "tag" and "passingonly". The "tag" parameter and optionally takes the parameters "tag" and "passingonly".
will filter by tag, and "passingonly" is a boolean that will The "tag" parameter will filter by tag, and "passingonly" is
filter to only the instances passing all health checks. a boolean that will filter to only the instances passing all
health checks.
This maps to the `/v1/health/service` API internally. This maps to the `/v1/health/service` API internally.
@ -281,10 +282,10 @@ An example of the output of this command:
The "checks" watch type is used to monitor the checks of a given The "checks" watch type is used to monitor the checks of a given
service or those in a specific state. It optionally takes the "service" service or those in a specific state. It optionally takes the "service"
parameter to filter to a specific service, or "state" to filter parameter to filter to a specific service or the "state" parameter to
to a specific state. By default, it will watch all checks. filter to a specific state. By default, it will watch all checks.
This maps to the `/v1/health/state/` API if monitoring by state, This maps to the `/v1/health/state/` API if monitoring by state
or `/v1/health/checks/` if monitoring by service. or `/v1/health/checks/` if monitoring by service.
An example of the output of this command: An example of the output of this command:
@ -308,7 +309,7 @@ An example of the output of this command:
The "event" watch type is used to monitor for custom user The "event" watch type is used to monitor for custom user
events. These are fired using the [consul event](/docs/commands/event.html) command. events. These are fired using the [consul event](/docs/commands/event.html) command.
It takes only a single optional "name" parameter, which restricts It takes only a single optional "name" parameter which restricts
the watch to only events with the given name. the watch to only events with the given name.
This maps to the `v1/event/list` API internally. This maps to the `v1/event/list` API internally.