add content for pre training post

Author: Tamás Hódi

01_intro.md

@@ -8,3 +8,12 @@ Install:
 In nutshell:
 - docker
 - kubernetes
+
+
+Containers
+
+Application containerization is an OS-level virtualization method used to deploy and run distributed applications without launching an entire virtual machine (VM) for each app.
+Containers work on bare-metal systems, cloud instances and virtual machines, across Linux and select Windows and Mac OSes.
+
+
+Docker

install_osx.sh

@@ -3,6 +3,11 @@
 # virtualBox
 brew cask install virtualbox
 
+# docker
+brew cask install docker
+open /Applications/Docker.app
+sudo docker run hello-world
+
 # kubectl
 curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/darwin/amd64/kubectl && chmod +x ./kubectl && sudo mv ./kubectl /usr/local/bin/kubectl
 kubectl version
@@ -12,10 +17,5 @@ brew cask install minikube
 minikube version
 minikube start
 
-# docker
-brew cask install docker
-open /Applications/Docker.app
-sudo docker run hello-world
-
 # jq
 brew install jq

post.md

@@ -0,0 +1,45 @@
+# Intro
+- microservices architecture shifts complexity from the space of code design and implementation into system operations
+- pushing the complexity from one place (software design and development) to another (operations) is just like hiding some tricky parts in somewhere else
+- k8s lets you to automate things and solve the problems easily
+
+![alt text](https://martinfowler.com/bliki/images/microservicePrerequisites/sketch.png "MS meme by Martin Fowler")
+
+# Problems
+
+## Change management
+- rapid provisioning of new resources
+- services can come and go
+- should be able to deploy a new service quickly
+
+### Deployment strategies
+- k8s deployment `.spec.strategy.type==Recreate` will kill all pods before new ones are created
+- 0 downtime deployment - `.spec.strategy.type==RollingUpdate` controls the process with `maxUnavailable` and `maxSurge`
+- blue/green
+- canary
+
+### Bootstrapping
+- graceful start / shutdown
+
+## Communication
+
+### Slow communication
+- use cache for GET
+- fail fast when POST, PUT, DEL
+
+### Direct communication
+- client never calls the service
+- use API gateway
+
+### + Scaling
+- persistent problem for MS and monoliths
+- HPA
+- heapster
+- rate limitation
+
+### Monitoring
+- loosely-coupled services collaborating
+- detect serious problems
+
+envoy
+- caching server + client? invalidate manually?