Basics of containers and OpenShift.

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Introduction to Red Hat OpenShift

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Agenda
• Container Technologies: A Primer
▫ Virtual Machines v/s Container Technologies
▫ Evolution of Container Technologies
• Why Kubernetes?
• Why Red Hat OpenShift?
• Red Hat OpenShift Key Features

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Virtual Machines v/s Container Technologies
 Virtual Machines
 Rigid Partitioning of Hardware
▫ CPU
▫ Memory
▫ Hard Disk
 Overhead of Host Operating System
 Overhead of Guest Operating System
 Inefficient Distribution of Load
 Snapshots
 Container Technologies
 Soft Partitioning of Resources
▫ CPU
▫ Memory
▫ Disk I/O
▫ Network
 Runs Using Host Operating System Kernel
 No Overhead of Guest Operating System Except
for Base Image Containing Libraries
 Flexible Division of Load
 Image Layers• Common Features
• Sharing External Volumes/Drives
• Virtual Network

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Evolution of Container Technologies
• Some of the underlying technologies
▫ cgroups (Control Groups) in Linux Kernel for limiting CPU, Memory, Disk I/O, Network etc
▫ Namespaces for isolating cgroups, network, mounts, pids etc.
▫ Union File Systems - aufs, devicemapper, overlayfs
• Open Container Initiative (OCI)
▫ Image-Spec
▫ Runtime-Spec
• Container Runtimes
▫ runc
▫ lxc
• Container Runtime Interface (CRI)
▫ Docker
▫ Podman/Buildah (by Red Hat)
▫ Kubernetes CRI-O
• Container Network Interface (CNI)
 Union File System
Base Image (Ex: UBI7)
Layer(1) (Ex: Liberty)
Layer(N) (Ex: Application) Container 2
.
.
Container 1
->
->

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Why Kubernetes?
 Cluster Architecture
 Multi-Tenant
 Namespaces
 Orchestration
 Node Affinity/Anti-Affinity
Control
 HADR
 Deployment Replication
 Autoscaling
 Security (PSP, RBAC, SA)
 Services (ClusterIP, NodePort,
LoadBalancer)
 Ingress
 Monitoring/Management
(Grafana, ISTIO, ELK)
 Docker Registry
 Helm/Tiller for easier
Deployment

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Why Red Hat OpenShift?
 All of Kubernetes With Red Hat
Enterprise Support
 Certified Container Ecosystem
 Enhanced Security (SCC)
 Dashboard for Easier
Management
 Built-in
Monitoring/Management
Capabilities with Prometheus
 Enhanced Isolation Over
Namespaces via Projects
 Automated Builds (S2I)
 Image Streams for Automation
of Build/Deployment
 Built-in Secure Docker Registry
 CI/CD
 Routes for Exposing Services as
External Load-Balanced
Readable URLs
 Operators for
Packing/Deploying/Managing
Applications

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Source-to-Image

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OpenShift Build Strategies
 Source-to-Image Strategy
▫ Use a s2i base image with source repo in specified format for build and testing.
 Docker Strategy
▫ Use a dockerfile from a source repo to build new images
 Custom Strategy
▫ Use a custom base image with custom source repo structure
 Jenkins Pipeline
▫ Use jenkins pipeline to build new images as well as trigger additional actions/jobs

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Log Management With EFK
 EFK stack to aggregate logs for hosts and applications
▫ Elasticsearch: a search and analytics engine to store logs
▫ Fluentd: gathers logs and sends to Elasticsearch.
▫ Kibana: A web UI for Elasticsearch.
 Access control
▫ Cluster administrators can view all logs
▫ Users can only view logs for their projects
 Ability to send logs elsewhere
▫ External elasticsearch, Splunk, etc

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OpenShift Architecture