Self-Healing Applications with Kubernetes

My talk on building scalable, reliable, fault-tolerant, and self-healing applications using Kubernetes at DevFest Lahore 2019.

No matter what your language or framework of choice is, using strategies in this talk can help your application figure out if it's failing using custom-defined health checks that can automatically restart your app and try to bring it back to its last good state.

Video and more info: https://shyr.io/t/k8s-self-healing

Transcript

1. Self-Healing Applications
   with Kubernetes
   

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2. @sheharyarn ! " #
   Sheharyar Naseer
   

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3. Why do I care?
   • DevOps is hard
   
   • From 1 instance on your laptop to 100s in production
   
   • Something breaks
   
   • Requires monitoring and manual intervention
   
   • SSH'ing into production at 3am on a Saturday night
   

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4. Holy Grail of DevOps
   • Imagine: Your server constantly monitoring for issues
   
   • And automatically Hxing them
   
   • You no longer hate your job and yourself
   
   • And you can Hnally have a life (Maybe?)
   

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5. Kubernetes
   • Container automation framework
   
   • Open-sourced by Google in 2014
   
   • Monitors, Detects and RectiHes issues in your cluster
   
   • Declarative, not Imperative
   

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6. Imperative System
   • Give your system explicit instructions
   
   • It executes them to get to your desired state
   
   • You still need to monitor for changes
   
   • Give more instructions in case something goes
   down
   

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7. Declarative System
   • Desired State
   
   • Tell Kubernetes what you want,

   not what to do
   
   • If stuX breaks
   
   • Kubernetes will automatically Hx it
   
   • Will always go back to desired state
   

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8. Architecture
   • Containers
   
   • Pods
   
   • Deployment
   
   • Services, Volumes, ReplicaSets, etc.
   

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9. Container
   FROM openjdk:8-jdk-alpine
   VOLUME /tmp
   RUN mkdir /k8s-demo
   COPY . /k8s-demo
   WORKDIR /k8s-demo
   RUN /k8s-demo/gradlew build
   RUN mv /k8s-demo/build/libs/*.jar /app.jar
   ENTRYPOINT ["java","-jar","/app.jar"]
   Architecture
   apiVersion: apps/v1
   kind: Deployment
   metadata:
   name: app-deploy
   spec:
   replicas: 3
   ...
   template:
   spec:
   containers:
   - name: nginx
   image: nginx:1.7.9
   ports:
   - containerPort: 80
   - name: k8s-demo
   resources:
   limits:
   cpu: 6000m
   memory: 24Gi
   requests:
   cpu: 2000m
   memory: 10Gi
   Deployment
   

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10. Application Health
    • Pod Phases
    
    • Pending, Running, Succeeded, Failed, etc.
    
    • Health Checks
    
    • Readiness:

    Finished initializing and ready to accept requests
    
    • Liveness:

    Can process and respond to requests

    

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11. Application Health
    • Probes
    
    • Exec:

    Execute a command in the container
    
    • HTTP GET:

    Make a web request to check if a success response is returned
    
    • TCP Socket:

    Pe?orm a TCP check for an open poA
    

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12. Readiness
    readinessProbe:
    httpGet:
    path: /ready
    port: http
    initialDelaySeconds: 5
    timeoutSeconds: 1
    periodSeconds: 5
    failureThreshold: 3
    Self-Healing
    livenessProbe:
    httpGet:
    path: /healthy
    port: http
    initialDelaySeconds: 10
    timeoutSeconds: 10
    failureThreshold: 3
    Liveness
    

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13. Demo
    

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14. Outro
    Previous talk (Deployment with K8S):
    
    to.shyr.io/io19-k8s
    
    

    

    Find these slides at:
    
    to.shyr.io/k8s-self-healing
    !
    !
    #
    shyr.io
    hi@shyr.io
    sheharyarn
    

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