1. Container technology, Microservices, and DevOps
Digital Innovation Workshop
April 2019
Henrik Bærbak Christensen

2. Henrik Bærbak Christensen
Exercise 0
Create a Dockerfile that only
Is based upon ‘henrikbaerbak/jdk8-gradle’
Sets WORKDIR to /root/cave
Copies ‘build.gradle’ into that directory
Now execute your image like
‘docker run -ti (yourimage) bash’
And validate that the file is in the right place...
Henrik Bærbak Christensen

3. Henrik Bærbak Christensen
Exercise 1
Using Docker to containerize the ‘daemon’
Create an image using Dockerfile that
Contains the SkyCave case code, expose port 4567, and issue a command to start the daemon (‘gradle daemon –Pcpf=http.cpf’)
When ‘docker run’ed will start a daemon using the HTTP protocol exposed on port 4567
Test
run your daemon container portmapped to localhost:4567
docker run –d –p 4567:4567 (yourimage)
Run your cmd against it from M51 (and/or open browser on localhost:4567/info)
Henrik Bærbak Christensen

4. Henrik Bærbak Christensen
Hint
As base image you will need a linux with Java 8 and gradle installed
You should my image: ‘henrikbaerbak/jdk8-gradle’ as base
Do it the simple and ‘incorrect’ way (include the src)
Just copy the source code and build.gradle, CPF files, etc.
And issue the ‘gradle daemon –Pcpf=(…).cpf’
Will pull dependencies, compile, and then run the daemon
Do not oversimplify 
Just copy ”/cave” project will copy ALSO all derived files (.class files) which is may cause problems…
Henrik Bærbak Christensen

5. Henrik Bærbak Christensen
Hint!
My own matra for development is take small steps !!!
How to climb a 4 meter high wall?
Use a vaulting pole? Fast – if you do not break your neck
Use a ladder? Slow – but faster than being hospitalized
So, use the debugging tips, and grow the dockerfile rather than use ‘big bang integration’...
Make the ‘copy source code’ part first, create the image, use ‘docker run –ti (image) bash’ to run a shell inside the container and inspect the file system
Add more stuff and repeat 
Henrik Bærbak Christensen

6. Henrik Bærbak Christensen
Anatomy of an Image
State your base image
FROM
Identify yourself
Copy your software
WORKDIR set working directory in container
COPY (src) (dest)
copy from src to dest (src: relative to current dir, dest: rel. to workdir)
Configure
EXPOSE expose port to the outside
Execute
CMD state defaults for process to be run
Imhotep
Henrik Bærbak Christensen

7. Henrik Bærbak Christensen
Hint: Clean up
You will soon have 10s of dead containers 
docker ps –a
Shows even dead containers
docker rm –f (containername)
Kill that dead container
Henrik Bærbak Christensen

8. Henrik Bærbak Christensen
Exercise 2
Context
No persistent storage is running for the daemon 
The cpf ‘digiinno-storage.cpf’ configures daemon for storing data in a running memcached instances on localhost:11211
Exercise
Run the skycave server using docker container ‘memcached:1.4’ port mapped to on localhost
Test
Start daemon, dig a room, kill server, test that room did survive server restart…
Henrik Bærbak Christensen

9. Henrik Bærbak Christensen
Hint
This exercise is much about networking
The three approaches:
1) Reuse the host’s network (you can now use ‘localhost’ in CPF)
2) Create a docker network, and use node names in CPF
docker run --name (thenodename)
3) Reuse an existing container’s network
Use the --network container:(containername)
Henrik Bærbak Christensen

10. Henrik Bærbak Christensen
Exercise 3
Create a container using Dockerfile multistage that
In step 1 creates a container that will build a deployment unit (Java Fat JAR file)
(See hint next slide on how to do that)
In step 2 creates a container that contains the fat jar and will start it when ‘docker run’ed
Again, HTTP protocol on port 4567
Henrik Bærbak Christensen

11. Henrik Bærbak Christensen
Hint
Gradle supports creating ‘fat jar’.
Insert the following into your ‘build.gradle’
The CMD line now has to obey ”java –jar” syntax:
java -jar cave.jar whatevercpf.cpf
Henrik Bærbak Christensen