Exploring the cloud with AWS Free Tier (2)

In the first part of this “diary” I found a cloud provider for my developer’s testing needs – Amazon’s AWS. This time we will mention some hiccups one may encounter when doing some basic operations around their EC2 instance. Finally, we will prepare some Docker image for ourselves, although this is not really AWS specific – at least not in our basic scenario case.

Shut it down!

When you shutdown your desktop computer, you see what it does. I’ve been running Windows for some years although being a Linux guy before (blame gaming and music home recording). On servers, no doubt, I prefer Linux every time. But I honestly don’t remember what happens if I enter shutdown now command without further options.

If I see the computer going on and on although my OS is down already, I just turn it off and remember to use -h switch the next time. But when “my computer” runs far away and only some dashboard shows what is happening, you simply don’t know for sure. There is no room for “mechanical sympathy”.

Long story short – always use shutdown now -h on your AMI instance if you really want to stop it. Of course, check instance’s Shutdown Behavior setup – by default it’s Stop and that’s probably what you want (Terminate would delete the instance altogether). With magical -h you’ll soon see that the state of the instance goes through stopping to stopped – without it it just hangs there running, but not really reachable.

Watch those volumes

When you shut down your EC2 instances they will stop taking any “instance-hours”. On the other hand, if you spin up 100 t2.micro instances and run them for an hour, you’ll spend 100 of your 750 limit for a month. It’s easy to understand this way of “spending”.

However, volumes (disk space for your EC2 instance) work a bit differently. They are reserved for you and they are billed for all the time you have them available – whether the instance runs or not. Also, how much of it you really use is NOT important. Your reserved space (typically 8 GiB for t2.micro instance if you use defaults) is what counts. Two sleeping instances for the whole month would not hit the limit, but three would – and 4 GiB above 20GiB/month would be billed to you (depending on the time you are above limit as well).

In any case, Billing Management Console is your friend here and AWS definitely provides you with all the necessary data to see where you are with your usage.

Back to Docker

I wanted to play with Docker before I decided to couple it with cloud exploration. AWS provides so called EC2 Container Service (ECS) to give you more power when managing containers, but today we will not go there. We will create Docker image manually right on our EC2 instance. I’d rather take baby steps than skip some “maturity levels” without understanding the basics.

When I want to “deploy” a Java application in a container, I want to create some Java base image for it first. So let’s connect to our EC2 instance and do it.

Java 32-bit base image

Let’s create our base image for Java applications first. Create a dir (any name will do, but something like java-base sounds reasonable) and this Dockerfile in it:

FROM ubuntu:14.04
MAINTAINER virgo47

# We want WGET in any case
RUN apt-get -qqy install wget

# For 32-bit Java we need to enable 32-bit binaries
RUN dpkg --add-architecture i386
RUN apt-get -qqy update
RUN apt-get -qqy install libc6:i386 libncurses5:i386 libstdc++6:i386

ENV HOME /root

# Install 32-bit JAVA
WORKDIR $HOME
RUN wget -q --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebac kup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u60-b27/jdk-8u60-linux-i586.tar.gz
RUN tar xzf jdk-8u60-linux-i586.tar.gz
ENV JAVA_HOME $HOME/jdk1.8.0_60
ENV PATH $JAVA_HOME/bin:$PATH

Then to build it (you must be in the directory with Dockerfile):

$ docker build -t virgo47/jaba .

Jaba stands for “java base”. And to test it:

$ docker run -ti virgo47/jaba
root@46d1b8156c7c:~# java -version
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) Client VM (build 25.60-b23, mixed mode)
root@46d1b8156c7c:~# exit

My application image

Now I want to run my HelloWorld application in that base image. That means creating another image based on virgo47/jaba. Create another directory (myapp) and the following Dockerfile:

FROM virgo47/jaba
MAINTAINER virgo47

WORKDIR /root/
COPY HelloWorld.java ./
RUN javac HelloWorld.java
CMD java HelloWorld

Easy enough, but before we can build it we need that HelloWorld.java too. I guess anybody can do it, but for the sake of completeness:

public class HelloWorld {
        public static void main(String... args) {
                System.out.println("Hello, world!");
        }
}

Now let’s build it:

$ docker build -t virgo47/myapp .

And to test it:

$ docker run -ti virgo47/myapp
Hello, world!

So it actually works! But we should probably deliver JAR file directly into the image build and not compiling it during the build. Can we automate it? Sure we can, but maybe in another post.

To wrap up…

I hope I’ll get to Amazon’s ECS later, because the things above are working, are kinda Docker(file) practice, but they definitely are not for real world. You may at least run it all from your local machine as a combination of scp/ssh, instead of creating Dockerfiles and other sources on the remote machine – because that doesn’t make sense, of course. We need to build Docker image as part of our build process, publish it somewhere and just download it to the target environment. But let’s get away from Docker and back to AWS.

In the meantime one big AWS event occurred – AWS re:Invent 2015. I have to admit I wasn’t aware of this at all until now, I just got email notifications about the event and the keynotes as an AWS user. I am aware of other conferences, I’m happy enough to attend some European Sun TechDays (how I miss those :-)), TheServerSide Java Symposiums (miss those too) and one DEVOXX – but just judging from the videos, the re:Invent was really mind-blowing.

I don’t know what more to say, so I’m over and out for now. It will probably take me another couple of weeks to get more of concrete impressions about AWS, but I plan to add the third part – hopefully again loosely coupled to Docker.

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About virgo47
Java Developer by profession in the first place. Gamer and amateur musician. And father too. Naive believer in brighter future. Step by step.

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