📃Update Dockerfile exercise instructions

slides/containers/Exercise_Dockerfile_Basic.md

@@ -2,4 +2,99 @@
 
 Let's write Dockerfiles for an existing application!
 
-The code is at: https://github.com/jpetazzo/wordsmith
+1. Check out the code repository
+
+2. Read all the instructions
+
+3. Write Dockerfiles
+
+4. Build and test them individually
+
+<!--
+5. Test them together with the provided Compose file
+-->
+
+---
+
+## Code repository
+
+Clone the repository available at:
+
+https://github.com/jpetazzo/wordsmith
+
+It should look like this:
+```
+├── LICENSE
+├── README
+├── db/
+│   └── words.sql
+├── web/
+│   ├── dispatcher.go
+│   └── static/
+└── words/
+    ├── pom.xml
+    └── src/
+```
+
+---
+
+## Instructions
+
+The repository contains instructions in English and French.
+<br/>
+For now, we only care about the first part (about writing Dockerfiles).
+<br/>
+Place each Dockerfile in its own directory, like this:
+```
+├── LICENSE
+├── README
+├── db/
+│   ├── `Dockerfile`
+│   └── words.sql
+├── web/
+│   ├── `Dockerfile`
+│   ├── dispatcher.go
+│   └── static/
+└── words/
+    ├── `Dockerfile`
+    ├── pom.xml
+    └── src/
+```
+
+---
+
+## Build and test
+
+Build and run each Dockerfile individually.
+
+For `db`, we should be able to see some messages confirming that the data set
+was loaded successfully (some `INSERT` lines in the container output).
+
+For `web` and `words`, we should be able to see some message looking like
+"server started successfully".
+
+That's all we care about for now!
+
+Bonus question: make sure that each container stops correctly when hitting Ctrl-C.
+
+???
+
+## Test with a Compose file
+
+Place the following Compose file at the root of the repository:
+
+
+```yaml
+version: "3"
+services:
+  db:
+    build: db
+  words:
+    build: words
+  web:
+    build: web
+    ports:
+    - 8888:80
+```
+
+Test the whole app by bringin up the stack and connecting to port 8888.