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Website: cleanup for intro/getting-started/checks.html.

pull/794/head
Ryan Breen 10 years ago
parent
commit
8920da59ee
  1. 2
      website/source/docs/agent/checks.html.markdown
  2. 40
      website/source/intro/getting-started/checks.html.markdown

2
website/source/docs/agent/checks.html.markdown

@ -31,7 +31,7 @@ There are three different kinds of checks:
It is possible to configure a custom HTTP check timeout value by specifying
the `timeout` field in the check definition.
* Time to Live (TTL) - These checks retain their last known state for a given TTL.
* <a name="TTL"></a>Time to Live (TTL) - These checks retain their last known state for a given TTL.
The state of the check must be updated periodically over the HTTP interface. If an
external system fails to update the status within a given TTL, the check is
set to the failed state. This mechanism, conceptually similar to a dead man's switch,

40
website/source/intro/getting-started/checks.html.markdown

@ -3,7 +3,7 @@ layout: "intro"
page_title: "Registering Health Checks"
sidebar_current: "gettingstarted-checks"
description: |-
We've now seen how simple it is to run Consul, add nodes and services, and query those nodes and services. In this section, we will continue our tour by adding health checks to both nodes and services. Health checks are a critical component of service discovery that prevents using services that are unhealthy.
We've now seen how simple it is to run Consul, add nodes and services, and query those nodes and services. In this step, we will continue our tour by adding health checks to both nodes and services. Health checks are a critical component of service discovery that prevent using services that are unhealthy.
---
# Health Checks
@ -11,29 +11,32 @@ description: |-
We've now seen how simple it is to run Consul, add nodes and services, and
query those nodes and services. In this section, we will continue our tour
by adding health checks to both nodes and services. Health checks are a
critical component of service discovery that prevents using services that
critical component of service discovery that prevent using services that
are unhealthy.
This page will build upon the previous page and assumes you have a
two node cluster running.
This step builds upon [the Consul cluster created previously](join.html).
At this point, you should have a two-node cluster running.
## Defining Checks
Similar to a service, a check can be registered either by providing a
[check definition](/docs/agent/checks.html) or by making the
appropriate calls to the [HTTP API](/docs/agent/http.html).
appropriate calls to the [HTTP API](/docs/agent/http/health.html).
We will use the check definition because, just like with services, definitions
are the most common way to set up checks.
We will use the check definition approach because, just like with
services, definitions are the most common way to set up checks.
Create two definition files in the Consul configuration directory of
the second node:
```text
$ echo '{"check": {"name": "ping", "script": "ping -c1 google.com >/dev/null", "interval": "30s"}}' >/etc/consul.d/ping.json
vagrant@n2:~$ echo '{"check": {"name": "ping", \
"script": "ping -c1 google.com >/dev/null", "interval": "30s"}}' \
>/etc/consul.d/ping.json
$ echo '{"service": {"name": "web", "tags": ["rails"], "port": 80,
"check": {"script": "curl localhost:80 >/dev/null 2>&1", "interval": "10s"}}}' >/etc/consul.d/web.json
vagrant@n2:~$ echo '{"service": {"name": "web", "tags": ["rails"], "port": 80,\
"check": {"script": "curl localhost >/dev/null 2>&1", "interval": "10s"}}}' \
>/etc/consul.d/web.json
```
The first definition adds a host-level check named "ping". This check runs
@ -46,7 +49,7 @@ request every 10 seconds via curl to verify that the web server is accessible.
As with the host-level health check, if the script exits with a non-zero exit code,
the service will be flagged unhealthy.
Now restart the second agent or send it a `SIGHUP` signal. You should now see the
Now, restart the second agent or send it a `SIGHUP` signal. You should see the
following log lines:
```text
@ -58,7 +61,7 @@ following log lines:
[WARN] Check 'service:web' is now critical
```
The first few log lines indicate that the agent has synced the new
The first few lines indicate that the agent has synced the new
definitions. The last line indicates that the check we added for
the `web` service is critical. This is because we're not actually running
a web server, so the curl test is failing!
@ -70,7 +73,7 @@ them. First, we can look for any failing checks using this command (note, this
can be run on either node):
```text
$ curl http://localhost:8500/v1/health/state/critical
vagrant@n1:~$ curl http://localhost:8500/v1/health/state/critical
[{"Node":"agent-two","CheckID":"service:web","Name":"Service 'web' check","Status":"critical","Notes":"","ServiceID":"web","ServiceName":"web"}]
```
@ -88,9 +91,14 @@ dig @127.0.0.1 -p 8600 web.service.consul
;web.service.consul. IN A
```
## Next Steps
In this section, you learned how easy it is to add health checks. Check definitions
can be updated by changing configuration files and sending a `SIGHUP` to the agent.
Alternatively, the HTTP API can be used to add, remove, and modify checks dynamically.
The API also allows for a "dead man's switch", a [TTL-based check](/docs/agent/checks.html).
TTL checks can be used to integrate an application more tightly with Consul, enabling
business logic to be evaluated as part of assessing the state of the check.
The API also allows for a "dead man's switch", a
[TTL-based check](/docs/agent/checks.html#TTL). TTL checks can be used to integrate an
application more tightly with Consul, enabling business logic to be evaluated as part
of assessing the state of the check.
Next, we will explore [Consul's K/V store](kv.html).

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