Getting Started With OpenShift - Using Containers for SysOps and Engineering

Devops: Own from code to server

Infrastructure (Ops)
- Why openShift?
- Parts of OpenShift
- Planning your clusert
- Maintenace
- Troubleshoot common problems
OpenShift Usage (Dev)
- High level overview
- Step by Step
- Real world
Why
- Get started fast
  - Only as complex as you need it to be
- Kubernetes under the hood
- Infrastructure as YAML/JSON
- Ease of Use
  - Interface
  - Tagging
- Containers all the way down
Parts of OpenShift
- Master Nodes
  - Manage the cluser itself
  - Kubernetes APIs/Scheduler
  - etcd
  - Webconsole
- Infrastructure notes
  - Routers
  - Shared services
  - Monitoring, registry
Compute nodes
- Where your apps will go

Planning your 1st cluster

OpenShift 3.11 is latest stable
Operating System
- Nodes
- An "Atomic Distribution"
- Hypervisor
Upfront considerations
- Consider carefully
- Physical Layout
- Network Plugin
  - osm_cluster_network_cidr
  - This will cause you to run out of IPs if you don't doo this right
- Storage
  - Type
  - Location
  - (Gluster (triplicates data), OpenS doubles)
Strict separation between nodes, so that they dev and prod can be separated
Can configure to limit who can talk to shom

Maintenance

Cleanup/Pruning
- Registry (docker)
- Projects
  - Can "spin down", not gone, just not running
Backups
- etcd node
- configs
Monitoring
- Alerts sent somewhere YOU WILL WATCH!
Upgrading nodes
- If using ansible, git pulll branch, and run upgrade

troubleshooting Common Issues

The Events Page
- First place to look
Cattle not pets
- All applicatins like cattle
- Development environment
- If you used atomic and the node is dead...
- Delete the node, reload, and scale-up
  - GlusterFS

Developer

High Level Overview

Docker Image
- What is it?
  - The operating system
  - (And sometimes more!)
- Based on an Upstream Image
- Why?
  - Upstream updates
  - Security Fixes/Patches
Build Config
- Recipes for making an images
- Docker Build
  - Got root?
- Install rpms and other server applications
  - Anything you need to run yout app
- Setting up the s2i Scripts
Image Stream
- Builder
  - git for completed builds
    - Collection of builds
  - Tagged
    - Latest
    - Version Numbers
  - Watchable
    - Trigger downstram events
Source Build Config
- s21
- Incorporates Source Code
- Runs as unprivileged user
- Puts stuff in the right place
  - Produces a runnable image
Source Image Stream
- Deployable Image
- Managed using tags
  - Development
    - Dev secrets
  - Staging
    - Prod secrets
    - Not customer accissible
  - Production
    - Prod secrets
    - Customer Accessible
Deployment Config
- Container(s)
  - s2i run
- Mounts
  - Secrets
    - mounted to the filesystem
  - Config
    - In the environment
  - Volumes (data)
- Environment
- POD
  - Really the application
- Resource Allocation
  - CPU
  - Memory
- Health Checks
  - Liveness Probe
    - Kill and reload
  - Readiness Probe
    - Load balance
- Triggerable
- Versioned
Service (Networking)
- Internal Connectivity
- Internal Load Balancer
- Proxy to Pods
Route
- External Connectivity
- Exposes a Service
  - via a hostname
  - Only for somethnig that understands a hostname
    - OpenShift doesn't listen on sockets, routes by hostname
- TLS Termination

Learnings

Started at production worked backward
- May not have been the best way
- Focus on how devs work and then make work production
Resistance to moving into Dockerized approach
- Security
- Engineering/Operations leadership
  - Dev time
  - Hardware
- Engineers
  - Can't work directly on prod
    - Not comfortable with building the whole
  - Agile

The presentation is available as a PowerPoint deck.

We had 10 people attending this month. As always, we'd like to thank cPanel, L.L.C for providing the meeting space and food for the group.