15. Running the Website from a Container

UNDER DEVELOPMENT

In this chapter, you will learn how to set up an application consisting of a gateway that lets tasks run in the Docker containers you created in the previous chapter. In chapter 15, we will extend the functionality with a web interface, for which we will use the Julia package Bukdu.jl. This choice is not entirely voluntary. Originally we thought to use Genie.jl as Julia Web Framework, but we discovered that Distributed Computing was a problem.

                web
                 ⇵
              gateway
         ________⇵________
         ⇵               ⇵
     test_sshd2      test_sshd
     (GeneralLedger)  AppliAR

Fig 1: The three containers that make up the application

15. Running the Website from a Container

Activity 15.1: Create the Gateway Container
Activity 15.2: Restart the Containers and Enable SSH for the Container gateway

Activity 15.1: Create the Gateway Container

The Gateway container runs the software where actors perform different tasks on the other Docker containers. For communication between the different containers with Julia, the condition is that they have passwordless SSH connections.

With the Rocket.jl package you can set up an infrastructure based on actors. You can communicate with actors utilizing messages.

Prerequisites

Your system has Ubuntu 20.04 that runs on an Intel x86 processor.
You have installed Docker.
You have performed the activities and exercise of chapter 13.
The Docker image eg_sshd exists.

In this activity you will:

Create the gateway container.
SSH enable the container.
Install Julia.
Add the packages AppliSales, AppliAR, AppliGeneralLedger, Rocket, DataFrames, and Query.
SSH enable the container.
Create SSH keys for the container.
Add the files testwithactors.jl and actors.jl

Step 1: Create the `gateway` container

You create the container gateway from the image eg_sshd.

Step	Action	Comment
1	$ docker run -d -p 2224:22 -p 8004:8000 --name gateway eg_sshd	Create a container gateway.
2	$ docker exec -it gateway bash	Enter the container
3	# adduser rob
4	# apt-get update	Download package information
5	# apt-get install sudo	You act as root when you precede your commands with `sudo.` It is not installed yet in this minimized container.
6	# usermod -aG sudo rob	Give user administrator rights.
7	Ctrl-D	Leave the container.

Step 2: SSH enable the container

You copy the public key you created in activity 13.1 to the container for passwordless authentication.

Step	Action	Comment
1	$ docker stop test_sshd test_sshd2 gateway	Stop the containers.
2	$ docker start test_sshd test_sshd2 gateway	Start the containers.
3	$ docker ps	Check whether the containers are running.
4	$ docker inspect gateway \| grep "IPAddress"	Find internal IP address of the container:$\\$172.17.0.4
5	$ ssh-copy-id rob@172.17.0.4	Copy id to container for passwordless login.

You get the next message:

The authenticity of host '172.17.0.4 (172.17.0.4)' can't be established.
ECDSA key fingerprint is SHA256:0qEmNoH8hb1OC73Hcecf4iY44vKAnLYOc6jNsdkkM2U.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes

Type yes and enter your password.

Step 3: Install Julia

Step	Action	Comment
1	$ docker start test_sshd test_sshd2 gateway	Ensure all containers are running.
2	$ docker cp ~/Downloads/julia-1.5.3-linux-x86_64.tar.gz gateway:/home/rob	Copy the downloaded file to the container.
3	$ docker exec -it gateway bash	Enter the container.
4	# su rob	Switch to user rob.
5	$ cd ~	Go to home directory of the user.
6	$ sudo mkdir julia	Create folder julia. OS asks for yur password.
7	$ sudo mv julia-1.5.3-linux-x86_64.tar.gz julia	Move file to folder.
8	$ cd julia	Enter the folder
9	$ sudo tar -zxvf julia-1.5.3-linux-x86_64.tar.gz	Extract the file.
10	$ cd julia-1.5.3/bin/	We will test Julia.
11	$ ./julia	Start Julia. You get the next response:
12	julia> Ctrl-D	Leave Julia.
13	cd ~	To home directory.
14	$ sudo ln -s /home/rob/julia/julia-1.5.3/bin/julia /usr/local/bin/julia	Create link.
15	$ julia	Start Julia.
16	julia> Ctrl-D	Leave Julia.
17	$ Ctrl-D	Return to root.
18	# Ctrl-D	Leave container.

Activity 15.2: Restart the Containers and Enable SSH for the Container `gateway`

Prerequisites:

Activity 15.1.
You have the three containers test_sshd,test_sshd2, and gateway. You created test_sshd, and test_sshd2in chapter 13, Create the Container.
Run Docker commands without sudo.

In this activity you will:

Start the containers and check their Docker internal IP-address.
Use SSH to Connect from gateway to test_sshd and test_sshd 2 and install the packages.

Step 1: Start the containers and check their Docker internal IP-address

Step	Action	Comment
2	$ docker restart test_sshd test_sshd2 gateway	Start the containers.
3	$ docker ps	Check whether the containers are running.
4	$ docker inspect -f "{{ .NetworkSettings.IPAddress }}" test_sshd	e.g. 172.17.0.2
5	$ docker inspect -f "{{ .NetworkSettings.IPAddress }}" test_sshd2	e.g. 172.17.0.3
6	$ docker inspect -f "{{ .NetworkSettings.IPAddress }}" gateway	e.g. 172.17.0.4

Step 2: Use SSH to Connect from gateway to test_sshd and test_sshd 2 and install the packages

Step	Action	Comment
1	$ ssh rob@172.17.0.4
2	$ sudo apt-get update
3	$ sudo apt-get install openssh-client	Install ssh client in container.
4	$ ssh-keygen -t rsa -b 4096 -C "your_email@domain.com"	Generate the key.
8	$ ssh-copy-id rob@172.17.0.2	Copy id to container test_sshd for passwordless login.
9	$ ssh-copy-id rob@172.17.0.3	Copy id to container test_sshd2 for passwordless login.
10	$ ssh rob@172.17.0.2	Check paswordless login.
11	$ Ctrl-D	Leave container.
12	$ ssh rob@172.17.0.3	Check paswordless login.
13	$ Ctrl-D	Leave container.
14	$ julia	Start Julia in the container gateway.
15	julia> ]	Activate the package manager.
16	pkg> add AppliSales AppliGeneralLedger Rocket DataFrames Query	Add the packages.
17	pkg> add https://github.com/rbontekoe/AppliAR.jl
18	pkg> precompile	Precompile all the project dependencies.
19	pkg> instantiate	Downloads all the dependencies for the project.
20	pkg> <Backspace>	Leave package manager.
21	julia> Ctrl-D	Leave Julia.
22	$ ssh rob@172.17.0.2	Enter the container test_sshd.
23	$ julia	Start Julia in the container.
24	julia> ]	Activate the package manager.
25	pkg> add AppliSales AppliGeneralLedger AppliAR DataFrames Query	Add the packages.
26	pkg> add https://github.com/rbontekoe/AppliAR.jl
27	pkg> precompile	Precompile all the project dependencies.
28	pkg> instantiate	Downloads all the dependencies for the project.
29	pkg> <Backspace>	Leave package manager.
30	julia> Ctrl-D	Leave Julia.
31	$ Ctrl-D	Leave the container test_ssh.
32	$ ssh rob@172.17.0.3	Enter the container test_sshd2.
33	Repeat the steps 22 untill 31 for the container test_sshd2 (172.17.0.3)