# Pre-requirements

- Be comfortable with the UNIX command line

  - navigating directories

  - editing files

  - a little bit of bash-fu (environment variables, loops)

- Some Docker knowledge

  - `docker run`, `docker ps`, `docker build`

  - ideally, you know how to write a Dockerfile and build it
    <br/>
    (even if it's a `FROM` line and a couple of `RUN` commands)

- It's totally OK if you are not a Docker expert!

---

class: title

*Tell me and I forget.*
<br/>
*Teach me and I remember.*
<br/>
*Involve me and I learn.*

Misattributed to Benjamin Franklin

[(Probably inspired by Chinese Confucian philosopher Xunzi)](https://www.barrypopik.com/index.php/new_york_city/entry/tell_me_and_i_forget_teach_me_and_i_may_remember_involve_me_and_i_will_lear/)

---

## Hands-on sections

- The whole workshop is hands-on

- We are going to build, ship, and run containers!

- You are invited to reproduce all the demos

- All hands-on sections are clearly identified, like the gray rectangle below

.exercise[

- This is the stuff you're supposed to do!

- Go to @@SLIDES@@ to view these slides

<!-- ```open @@SLIDES@@``` -->

]

---

class: in-person

## Where are we going to run our containers?

---

class: in-person, pic

![You get a cluster](images/you-get-a-cluster.jpg)

---

class: in-person

## You get a cluster of cloud VMs

- Each person gets a private cluster of cloud VMs (not shared with anybody else)

- Get yours on https://2020-10-docberlin.container.training/vms

- They'll remain up for the duration of the workshop

- You should have a little card with login+password+IP addresses

- You can automatically SSH from one VM to another

- The nodes have aliases: `node1`, `node2`, etc.

---

class: in-person

## Why don't we run containers locally?

- Installing this stuff can be hard on some machines

  (32 bits CPU or OS... Laptops without administrator access... etc.)

- *"The whole team downloaded all these container images from the WiFi!
  <br/>... and it went great!"* (Literally no-one ever)

- All you need is a computer (or even a phone or tablet!), with:

  - an internet connection

  - a web browser

  - an SSH client

---

class: in-person

## SSH clients

- On Linux, OS X, FreeBSD... you are probably all set

- On Windows, get one of these:

  - [putty](http://www.putty.org/)
  - Microsoft [Win32 OpenSSH](https://github.com/PowerShell/Win32-OpenSSH/wiki/Install-Win32-OpenSSH)
  - [Git BASH](https://git-for-windows.github.io/)
  - [MobaXterm](http://mobaxterm.mobatek.net/)

- On Android, [JuiceSSH](https://juicessh.com/)
  ([Play Store](https://play.google.com/store/apps/details?id=com.sonelli.juicessh))
  works pretty well

- Nice-to-have: [Mosh](https://mosh.org/) instead of SSH, if your internet connection tends to lose packets

---

class: in-person, extra-details

## What is this Mosh thing?

*You don't have to use Mosh or even know about it to follow along.
<br/>
We're just telling you about it because some of us think it's cool!*

- Mosh is "the mobile shell"

- It is essentially SSH over UDP, with roaming features

- It retransmits packets quickly, so it works great even on lossy connections

  (Like hotel or conference WiFi)

- It has intelligent local echo, so it works great even in high-latency connections

  (Like hotel or conference WiFi)

- It supports transparent roaming when your client IP address changes

  (Like when you hop from hotel to conference WiFi)

---

class: in-person, extra-details

## Using Mosh

- To install it: `(apt|yum|brew) install mosh`

- It has been pre-installed on the VMs that we are using

- To connect to a remote machine: `mosh user@host`

  (It is going to establish an SSH connection, then hand off to UDP)

- It requires UDP ports to be open

  (By default, it uses a UDP port between 60000 and 61000)
