Narrator: So let's go ahead and
create some health checks.
So on the left hand side,
I'm going to go into the health checks, and we're going to
create health checks for all our EC2 instances.
So we're going to check three health checks.
So the first one is going to be from an
instance in US east one, and is going to be an end point.
And then you'd just specify either an IP address or a
domain name.
So we'll keep it as an IP address.
And my instance in US east one is right here.
So we'll paste that in. We have to specify a port,
so we'll keep it as 80, because this is the HTTP port.
And for path,
we're just going to be keeping the path as slash because
while this is the same as the IP slash,
which is the root of our website,
if we had a real application,
sometimes it is very common to have a path slash health,
for example,
which responds with the health of the endpoint itself.
Okay, so we have this ready,
so I'll just remove the slash health.
And then we can look at some advanced configuration.
So we can have either have a standard
every thirty seconds or a
fast every ten seconds health check.
We'll keep it as standard because this is
otherwise more expensive.
How many times does it need to fail
before being considered as a failure?
Do you want to do string matching so do you want to look for
a string in the first 5,120 bytes? Yes or no?
Do we want a latency graph,
to see how latency evolves over time?
Do we want to invert the health check status.
Do we want to be healthy and vise-versa.
Or disable it.
And then do you want to customize the regions of
the health checkers?
Or do you want to use the recommended and we'll just keep it
as is with using recommended?
So every option is pretty much as default.
And do we want to be notified whenever this health check
fails? Yes or no by creating alarm?
I will just say no for now.
So we have created our first health check.
Now let's create our second health check and it's going to
be for AP Southeast one. So AP Southeast one,
and then IP address right here,
not host name. And then next and create.
And the last health check is for EU central one.
So let's create this health check and I will name it
EU central one.
And then here is the IP address and click on next and
create health check.
Okay. So our health checks are created.
And what I'm going to do is I'm going to go to one of my
instances, for example,
the one in Singapore and for the security group,
I'm going to start blocking the port 80, removing this rule.
And the idea is that I want to get a failing health check.
So I'm going to go into the security group right here.
I will do action and end it's the inbound rules,
and it will delete my HTTP based rules.
And what this will do is that's the one health check
for AP Southeast one should give me a unhealthy status.
So let me wait a little bit for the health checkers to do
their thing, and then we'll get back to you.
Okay. So as we can see, we have three health checkers,
and one of them is unhealthy,
obviously because I locked at the security group and the
other two healthy because I don't see any
security group event.
So we can have a look at the health checkers and to give you
some information around when it was last checked and so on.
And for the unhealthy one, we can view the error status.
So if we look at view last failed check,
we can see that there was a connection timeout,
and maybe the requests are being blocked by my firewall and
firewall is your security group. So that makes sense.
So at least it gives us some information and they are
working just as expected.
And one last thing and you can create is a calculated
health check.
And this one is going to be a calculated health check,
Cal-cu-lated. Here we go.
And this going to check for the status of
other health checks.
And now we can specify which health checks
we want to monitor.
And okay,
we're saying maybe you want to report healthy when one of
the three health checks are healthy or when 2,
or when all of them are healthy.
So this is an AND or one or more health checks are healthy.
So this is,
so we can definitely create as complicated rule.
So I would just keep it as this should be healthy when all
of my health checks are healthy and then
click on next, next.
And we have created a calculated health check and the last
kind of a health check we can create is to monitor the
state of a CloudWatch alarm.
In which case we need to specify the region
the alarm is going to be in,
and then this alarm could be monitoring.
Obviously the state have a private EC2 instance
for example.
And this is how we would link the health check,
the health of a private resource
into a route 53 health check. Okay.
But I can't create it right now because I don't have
an alarm available for us. Okay.
Okay.
So my calculated health check is now reported unhealthy
because well, one of the health checks,
I'm trying to monitor is unhealthy,
and this is how we define it.
So that really shows you the power of health checks.
And in the next lecture, we'll be using them of course,
alongside records in route 53.
So I hope you liked this lecture and I will see you in the
next lecture.