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‫So let's go ahead and

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‫create some health checks.

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‫So on the left hand side,

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‫I'm going to go into the health checks, and we're going to

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‫create health checks for all our EC2 instances.

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‫So we're going to check three health checks.

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‫So the first one is going to be from an

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‫instance in US east one, and is going to be an end point.

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‫And then you'd just specify either an IP address or a

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‫domain name.

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‫So we'll keep it as an IP address.

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‫And my instance in US east one is right here.

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‫So we'll paste that in. We have to specify a port,

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‫so we'll keep it as 80, because this is the HTTP port.

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‫And for path,

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‫we're just going to be keeping the path as slash because

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‫while this is the same as the IP slash,

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‫which is the root of our website,

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‫if we had a real application,

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‫sometimes it is very common to have a path slash health,

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‫for example,

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‫which responds with the health of the endpoint itself.

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‫Okay, so we have this ready,

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‫so I'll just remove the slash health.

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‫And then we can look at some advanced configuration.

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‫So we can have either have a standard

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‫every thirty seconds or a

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‫fast every ten seconds health check.

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‫We'll keep it as standard because this is

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‫otherwise more expensive.

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‫How many times does it need to fail

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‫before being considered as a failure?

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‫Do you want to do string matching so do you want to look for

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‫a string in the first 5,120 bytes? Yes or no?

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‫Do we want a latency graph,

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‫to see how latency evolves over time?

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‫Do we want to invert the health check status.

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‫Do we want to be healthy and vise-versa.

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‫Or disable it.

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‫And then do you want to customize the regions of

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‫the health checkers?

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‫Or do you want to use the recommended and we'll just keep it

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‫as is with using recommended?

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‫So every option is pretty much as default.

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‫And do we want to be notified whenever this health check

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‫fails? Yes or no by creating alarm?

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‫I will just say no for now.

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‫So we have created our first health check.

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‫Now let's create our second health check and it's going to

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‫be for AP Southeast one. So AP Southeast one,

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‫and then IP address right here,

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‫not host name. And then next and create.

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‫And the last health check is for EU central one.

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‫So let's create this health check and I will name it

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‫EU central one.

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‫And then here is the IP address and click on next and

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‫create health check.

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‫Okay. So our health checks are created.

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‫And what I'm going to do is I'm going to go to one of my

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‫instances, for example,

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‫the one in Singapore and for the security group,

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‫I'm going to start blocking the port 80, removing this rule.

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‫And the idea is that I want to get a failing health check.

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‫So I'm going to go into the security group right here.

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‫I will do action and end it's the inbound rules,

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‫and it will delete my HTTP based rules.

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‫And what this will do is that's the one health check

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‫for AP Southeast one should give me a unhealthy status.

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‫So let me wait a little bit for the health checkers to do

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‫their thing, and then we'll get back to you.

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00:02:43,470 --> 00:02:45,823
‫Okay. So as we can see, we have three health checkers,

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‫and one of them is unhealthy,

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‫obviously because I locked at the security group and the

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‫other two healthy because I don't see any

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‫security group event.

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00:02:52,820 --> 00:02:55,719
‫So we can have a look at the health checkers and to give you

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‫some information around when it was last checked and so on.

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‫And for the unhealthy one, we can view the error status.

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‫So if we look at view last failed check,

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‫we can see that there was a connection timeout,

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‫and maybe the requests are being blocked by my firewall and

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00:03:09,260 --> 00:03:11,990
‫firewall is your security group. So that makes sense.

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‫So at least it gives us some information and they are

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‫working just as expected.

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00:03:16,013 --> 00:03:18,450
‫And one last thing and you can create is a calculated

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‫health check.

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‫And this one is going to be a calculated health check,

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‫Cal-cu-lated. Here we go.

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00:03:25,070 --> 00:03:27,960
‫And this going to check for the status of

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00:03:27,960 --> 00:03:29,130
‫other health checks.

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‫And now we can specify which health checks

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‫we want to monitor.

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00:03:33,500 --> 00:03:34,333
‫And okay,

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00:03:34,333 --> 00:03:37,410
‫we're saying maybe you want to report healthy when one of

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00:03:37,410 --> 00:03:39,268
‫the three health checks are healthy or when 2,

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00:03:39,268 --> 00:03:41,110
‫or when all of them are healthy.

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00:03:41,110 --> 00:03:44,080
‫So this is an AND or one or more health checks are healthy.

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00:03:44,080 --> 00:03:45,160
‫So this is,

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00:03:45,160 --> 00:03:47,150
‫so we can definitely create as complicated rule.

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00:03:47,150 --> 00:03:50,310
‫So I would just keep it as this should be healthy when all

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00:03:50,310 --> 00:03:52,880
‫of my health checks are healthy and then

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00:03:52,880 --> 00:03:55,810
‫click on next, next.

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00:03:55,810 --> 00:03:58,950
‫And we have created a calculated health check and the last

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00:03:58,950 --> 00:04:01,220
‫kind of a health check we can create is to monitor the

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00:04:01,220 --> 00:04:02,750
‫state of a CloudWatch alarm.

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00:04:02,750 --> 00:04:04,740
‫In which case we need to specify the region

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00:04:04,740 --> 00:04:06,270
‫the alarm is going to be in,

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00:04:06,270 --> 00:04:08,310
‫and then this alarm could be monitoring.

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00:04:08,310 --> 00:04:10,770
‫Obviously the state have a private EC2 instance

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‫for example.

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00:04:11,603 --> 00:04:13,590
‫And this is how we would link the health check,

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00:04:13,590 --> 00:04:15,250
‫the health of a private resource

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00:04:15,250 --> 00:04:17,970
‫into a route 53 health check. Okay.

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00:04:17,970 --> 00:04:19,450
‫But I can't create it right now because I don't have

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00:04:19,450 --> 00:04:22,040
‫an alarm available for us. Okay.

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00:04:22,040 --> 00:04:22,873
‫Okay.

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00:04:22,873 --> 00:04:24,790
‫So my calculated health check is now reported unhealthy

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00:04:24,790 --> 00:04:26,550
‫because well, one of the health checks,

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00:04:26,550 --> 00:04:28,640
‫I'm trying to monitor is unhealthy,

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00:04:28,640 --> 00:04:29,910
‫and this is how we define it.

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00:04:29,910 --> 00:04:31,520
‫So that really shows you the power of health checks.

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00:04:31,520 --> 00:04:33,810
‫And in the next lecture, we'll be using them of course,

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00:04:33,810 --> 00:04:35,641
‫alongside records in route 53.

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00:04:35,641 --> 00:04:38,320
‫So I hope you liked this lecture and I will see you in the

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00:04:38,320 --> 00:04:39,153
‫next lecture.