Kubernetes and the Potential for Higher Level Interfaces

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Kubernetes and the Potential for Higher Level Interfaces Puppet Labs Gareth Rushgrove Ecosystems, APIs and user needs

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Gareth Rushgrove @garethr

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Gareth Rushgrove

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Human and computer interfaces Concepts and demos Ecosystems and interoperability Gareth Rushgrove - - -

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The User Interface(s) of Kubernetes What do we mean by user and interface?

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The user context matters Gareth Rushgrove

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Creating Consuming Gareth Rushgrove - -

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Developers Operators Gareth Rushgrove - -

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Building something new Running in production Gareth Rushgrove - -

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Team size Regulation/compliance Multi-tenancy Infrastructure size Skills and experience Gareth Rushgrove - - - - -

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Gareth Rushgrove Gareth Rushgrove

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kubectl is a user interface Gareth Rushgrove

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YAML is a user interface Gareth Rushgrove

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Gareth Rushgrove Dashboard is a user interface Gareth Rushgrove

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The API is a user interface Gareth Rushgrove

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Client libraries are a user interface Gareth Rushgrove

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Different interfaces are useful in different contexts Gareth Rushgrove

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Different people might use different interfaces to achieve different tasks Gareth Rushgrove

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Out of the box Just enough user interface

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kubectl Gareth Rushgrove

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$ kubectl controls the Kubernetes cluster manager. Find more information at https://github.com/kubernetes/kubernetes. Usage: kubectl [flags] kubectl [command] Available Commands: get Display one or many resources describe Show details of a specific resource or group of resources create Create a resource by filename or stdin replace Replace a resource by filename or stdin. patch Update field(s) of a resource by stdin. delete Delete resources by filenames, stdin, resources and names, or by resources and label selector. edit Edit a resource on the server A universal interface for actions on a Kubernetes cluster Gareth Rushgrove

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Gareth Rushgrove

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YAML Gareth Rushgrove

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template: metadata: labels: app: guestbook tier: frontend spec: containers: - name: php-redis image: gcr.io/google_samples/gb-frontend:v4 resources: requests: cpu: 100m memory: 100Mi env: - name: GET_HOSTS_FROM value: dns # If your cluster config does not include a dns service, then to A data format describing desired state Gareth Rushgrove

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API wire format as user interface Gareth Rushgrove

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But isn’t YAML declarative? And other user interface tales

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Yes Gareth Rushgrove

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Code plus data has advantages over data alone Gareth Rushgrove

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The language to represent the data should be a simple, data-only format such as JSON or YAML, and programmatic modiﬁcation of this data should be done in a real programming language Gareth Rushgrove Borg, Omega, and Kubernetes, ACM Queue, Volume 14, issue 1 http://queue.acm.org/detail.cfm?id=2898444 “

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Avoid repetition Combine external inputs Correctness Abstractions Gareth Rushgrove - - - -

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So why are so many people hand writing YAML? Gareth Rushgrove

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Changes with kubectle patch diverge from the model $ kubectl patch --help Update field(s) of a resource using strategic merge patch JSON and YAML formats are accepted. Usage: kubectl patch (-f FILENAME | TYPE NAME) -p PATCH [flags] Examples: # Partially update a node using strategic merge patch kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}' Gareth Rushgrove

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$ kubectl apply --help Apply a configuration to a resource by filename or stdin. JSON and YAML formats are accepted. Usage: kubectl apply -f FILENAME [flags] Examples: # Apply the configuration in pod.json to a pod. $ kubectl apply -f ./pod.json And kubectl apply requires the full object serialisation Gareth Rushgrove

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A familiar Kubernetes Pod deﬁnition in YAML Gareth Rushgrove

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What happens if you run the same YAML ﬁle twice? Gareth Rushgrove

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How many times do you have to repeat the same label? Gareth Rushgrove

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kubectl is actually pretty low-level Gareth Rushgrove

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kubectl get pod mypod -o yaml \ | sed 's/$image: myimage$:.*$/\1:v4/' \ | kubectl replace -f - This is from the oﬃcial kubectl help. It pipes to sed. Gareth Rushgrove

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Declarative code with an idempotent runtime model Gareth Rushgrove

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Describe what you want Gareth Rushgrove

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Converge from any state Gareth Rushgrove

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The same Kubernetes Pod described in Puppet Gareth Rushgrove

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$ puppet apply examples/init.pp --test Info: Loading facts Notice: Compiled catalog for gareths in environment production in 1.24 seconds Info: Applying configuration version '1453298602' Info: Checking if sample-pod exists Info: Creating kubernetes_pod sample-pod Notice: /Stage[main]/Main/Kubernetes_pod[sample-pod]/ensure: created Notice: Applied catalog in 0.23 seconds Running without that Pod already existing will create it Gareth Rushgrove

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Running a second time, nothing changes because the Pod already exists Gareth Rushgrove $ puppet apply examples/init.pp --test Info: Loading facts Notice: Compiled catalog for garethr in environment production in 1.33 seconds Info: Applying configuration version '1453298688' Info: Checking if sample-pod exists Notice: Applied catalog in 0.15 seconds

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$ puppet resource kubernetes_pod sample-pod kubernetes_pod { 'sample-pod': ensure => 'present', metadata => { 'creationTimestamp' => '2016-01-20T14:03:23Z', 'name' => 'sample-pod', 'namespace' => 'default', 'resourceVersion' => '4579', 'selfLink' => '/api/v1/namespaces/default/pods/sample-pod’, 'uid' => '91c8a550-bf7e-11e5-816e-42010af001b1' }, spec => { 'containers' => [{ ‘image' => 'nginx', 'imagePullPolicy' => 'IfNotPresent', 'name' => ‘container-name', 'resources' => {'requests' => {'cpu' => '100m'}}, 'terminationMessagePat [{'mountPath' => '/var/run/secrets/kubernetes.io/serviceaccount', 'name' 'dnsPolicy' => 'ClusterFirst', 'nodeName' => 'gke-guestbook-dc15a31a-nod puppet resource allows for interrogating an existing Kubernetes installation Gareth Rushgrove

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$ kubectl describe pod sample-pod Name: sample-pod Namespace: default Image(s): nginx Node: gke-guestbook-dc15a31a-node-fyb6/10.240. Start Time: Wed, 20 Jan 2016 14:03:23 +0000 Labels: Status: Running Reason: Message: IP: 10.24.1.7 Replication Controllers: Containers: container-name: Container ID: docker://542389c5b2a98616ba3a8001029bc4a3f00d7c0 Image: nginx Image ID: docker://407195ab8b07 The same information is still accessible via other tooling Gareth Rushgrove

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Other programming languages exist Gareth Rushgrove

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DEMO

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Gareth Rushgrove More details on the oﬃcial Kubernetes blog Gareth Rushgrove

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Imperative Interfaces Pragmatism and familiarity

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Gareth Rushgrove

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Gareth Rushgrove Deis is an open source PaaS that provides a Heroku- inspired workﬂow, using Kubernetes under the hood Gareth Rushgrove

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Interactive CLI to login Gareth Rushgrove $ deis login http://deis.example.com username: deis password: Logged in as deis

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Create conﬁgs locally with the CLI Gareth Rushgrove $ deis create Creating application... done, created boring-huntress Git remote deis added

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$ git push deis master Counting objects: 95, done. Delta compression using up to 8 threads. Compressing objects: 100% (52/52), done. Writing objects: 100% (95/95), 20.24 KiB | 0 bytes/s, done. Total 95 (delta 41), reused 85 (delta 37) -----> Ruby app detected -----> Compiling Ruby/Rack -----> Using Ruby version: ruby-1.9.3 -----> Installing dependencies using 1.5.2 Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment Fetching gem metadata from http://rubygems.org/.......... Fetching additional metadata from http://rubygems.org/.. Using bundler (1.5.2) Installing tilt (1.3.6) Installing rack (1.5.2) The switch to Git for deployment Gareth Rushgrove

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Set conﬁg using CLI Gareth Rushgrove $ deis config:set FOO=1 BAR=baz && deis config:pull $ cat .env FOO=1 BAR=baz $ echo "TIDE=high" >> .env $ deis config:push Creating config... done, v4 === yuppie-earthman DEIS_APP: yuppie-earthman FOO: 1 BAR: baz TIDE: high

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$ deis scale web=8 Scaling processes... but first, coffee! done in 20s === boring-huntress Processes --- web: web.1 up (v2) web.2 up (v2) web.3 up (v2) web.4 up (v2) web.5 up (v2) web.6 up (v2) web.7 up (v2) web.8 up (v2) Scale using the CLI Gareth Rushgrove

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Replication Controllers, Services and Pods are implementation details Gareth Rushgrove

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Kubernetes is an implementation details from the point of view of the user Gareth Rushgrove

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Kubernetes is NOT an implementation details from the point of view of the administrator Gareth Rushgrove

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The advantages of familiarity Gareth Rushgrove

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The challenges of git as a user interface Gareth Rushgrove

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Ecosystems and Interoperability Everyone can play together

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Gareth Rushgrove

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Package management Gareth Rushgrove

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Gareth Rushgrove Helm, a package manager for Kubernetes Gareth Rushgrove

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$ helm install redis-cluster ---> Running `kubectl create -f` ... services/redis-sentinel pods/redis-master replicationcontrollers/redis replicationcontrollers/redis-sentinel ---> Done Help provides distribution tools, plus wraps kubectl Gareth Rushgrove

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Helm as a user interface Gareth Rushgrove

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Gareth Rushgrove Charts as a place to share low level descriptions Gareth Rushgrove

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name: jenkins home: https://jenkins-ci.org/ version: 0.2.0 description: The leading open-source continuous integration server. maintainers: - Matt Fisher details: Jenkins is the leading open-source continuous integration server. Chart.yaml metadata format Gareth Rushgrove

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Gareth Rushgrove Or, what is the Kubernetes equivalent to MPM metadata? Gareth Rushgrove

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The importance of sharing metadata Gareth Rushgrove

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Metadata as a ﬁrst class user interface Gareth Rushgrove

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If the API is the point of interoperability, how can it evolve safely? Gareth Rushgrove

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Gareth Rushgrove Swagger is a speciﬁcation for describing APIs Gareth Rushgrove

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Gareth Rushgrove Now being developed by the Open API Initiative Gareth Rushgrove

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"type": "integer", "format": "int32", "description": "The port on each node on which this service is exposed when type=NodePort or LoadBalancer. Usually assigned by the system. If specified, it will be allocated to the service if unused or else creation of the service will fail. Default is to auto-allocate a port if the ServiceType of this Service requires one. More info: http://releases.k8s.io/HEAD/docs/user- guide/services.md#type--nodeport" } } }, "v1.ServiceStatus": { "id": "v1.ServiceStatus", "description": "ServiceStatus represents the current status of a service.", "properties": { "loadBalancer": { "$ref": "v1.LoadBalancerStatus", "description": "LoadBalancer contains the current status of the load-balancer, if one is present." The Kubernetes API spec is ~14,000 lines of JSON Gareth Rushgrove

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Some client libraries, including the Puppet module, are generated from the Swagger spec Gareth Rushgrove

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Gareth Rushgrove

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Standards mean going slow in the right places Gareth Rushgrove

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So we can go fast everywhere else Gareth Rushgrove

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Conclusions Why Kubernetes as a platform

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Interoperable because of a stable set of APIs Gareth Rushgrove

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Platforms exposing high level interfaces, without limiting access to lower level ones Gareth Rushgrove

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Allow for different use-cases and different life-cycles on the same infrastructure Gareth Rushgrove

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Questions? And thanks for listening