Automating Stateful Applications with Kubernetes Operators

Transcript

1. Automating Stateful Applications
   with Kubernetes Operators
   Jan Kleinert
   jan.kleinert@redhat.com
   September 23, 2019
   

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   Jan Kleinert
   Developer Advocate, Red Hat
   twitter/github: @jankleinert
   Hello!
   

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   What is Kubernetes?
   An open source orchestration system for
   managing containerized workloads across
   a cluster of nodes.
   

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   Pod
   Deployment
   DaemonSet
   ReplicaSet
   StatefulSet
   Job
   Kubernetes objects are persistent entities that represent the state
   of your cluster that you can manage with the K8s API
   EndPoints
   Ingress
   Service
   ConfigMap
   Secret
   StorageClass
   Namespace
   NetworkPolicy
   PersistentVolume
   Role
   RoleBinding
   ServiceAccount
   Understanding Kubernetes objects
   

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   Kubernetes Object Definitions
   kind: Pod
   apiVersion: v1
   metadata:
   name: example-app
   spec:
   containers:
   - name: example
   image: quay.io/my/app:v1.2.0
   [...]
   

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   Why should you care about operators?
   

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   Scaling stateless apps: easy
   

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   $ kubectl scale deploy/staticweb --replicas=3
   

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   scale up
   count=1
   desired=3
   ReplicaSet
   

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    start
    count=3
    desired=3
    ReplicaSet
    

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    What about apps that store data?
    

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    Creating a database is easy
    

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    $ kubectl run db --image=quay.io/my/db
    

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    Running a database over time is harder
    

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    ⏣ Resize/Upgrade
    ⏣ Reconfigure
    ⏣ Backup
    ⏣ Healing
    

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    Every application on any platform must
    be installed, configured, managed, and
    upgraded over time
    Patching is critical to security
    

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    Anything not automated is slowing you down
    

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    If only Kubernetes knew...
    

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    Operators are automated software
    managers that deal with installation and
    lifecycle of Kubernetes applications
    

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    1. Application-specific custom controllers
    2. Custom resource definitions (CRD)
    Extending the Kubernetes API
    

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    The Operator Pattern
    K8S API CUSTOM
    RESOURCE & MY
    APP STATE
    WATCH
    EVENTS
    RECONCILE MY K8S
    APPLICATION
    Controller
    

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    Application-Specific Controllers
    

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    Custom Resource Definition (CRD)
    kind: ProductionReadyDatabase
    apiVersion: database.example.com/v1alpha1
    metadata:
    name: my-production-ready-database
    spec:
    clusterSize: 3
    readReplicas: 2
    version: v4.0.1
    [...]
    

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    {
    }
    

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    What is etcd?
    Example: etcd Operator
    ● distributed key-value store
    ● primary datastore of
    Kubernetes
    ● stores and replicates all
    Kubernetes cluster state
    

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    Example: etcd Operator
    kind: EtcdCluster
    apiVersion: etcd.database.coreos.com/v1beta2
    metadata:
    name: example-etcd-cluster
    spec:
    size: 3
    version: "3.1.0"
    

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    Example: etcd Operator
    

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    https://learn.openshift.com/operatorframework/
    Try It! Hands-On Operator Tutorials
    

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    Use Operators Today
    OperatorHub.io is a home
    for the Kubernetes
    community to share
    Operators.
    Find an existing Operator
    or list your own today.
    

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    https://github.com/operator-framework
    

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    Operator Maturity Model
    Phase I Phase II Phase III Phase IV Phase V
    Basic Install
    Automated application
    provisioning and
    configuration management
    Seamless Upgrades
    Patch and minor version
    upgrades supported
    Full Lifecycle
    App lifecycle, storage
    lifecycle (backup, failure
    recovery)
    Deep Insights
    Metrics, alerts, log
    processing and workload
    analysis
    Auto Pilot
    Horizontal/vertical scaling,
    auto config tuning, abnormal
    detection, scheduling tuning
    

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    https://github.com/operator-framework
    https://coreos.com/operators/
    https://operatorhub.io
    https://coreos.com/blog/introducing-operator-framework
    https://learn.openshift.com/operatorframework/
    Resources
    

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