Post on 20-May-2020
DevOps di applicazioni Python(e non solo) su OpenShiftFrancesco Fiore, System ArchitectPyCon Nove, 20 aprile 2018
2
Agenda
• Cos’è OpenShift• Cenni sull’architettura• Setup di una semplice applicazione• OpenShift per applicazioni Python: source-to-image
• Dietro le quinte: API objects• Parametrizzare il setup di applicazioni usando i Template
• Git, OpenShift e Jenkins: integrazione nativa per la CI/CD• Application lifecycle management• Application promotion• Strategie di deployment
3
OpenShift overview
• Platform as a Service di Red Hat• OpenShift Origin è un progetto opensource• Basato su:
– Kubernetes (CaaS)– Docker– Atomic
• Add-on rispetto a k8s– API objects– Web console– Software Defined Network– Docker registry– logging centralizzato
• Focus su application lifecycle management e automation• Red Hat OpenShift Container Platform
4
OpenShift vs Kubernetes
Source to Image (S2I)
IntegratedRegistry
BuildConfiguration Image Stream Deployment
Configuration
PersistentVolume Claims
Replication Controller Replica Sets Daemon Sets Persistent
Volumes
Secrets Config Maps Services RoutesSoftware Defined
Network (SDN)
Web console Users and Groups Projects Namespaces
OpenShift Kubernetes
5
OpenShift: architettura
6
Setup di una applicazione
oc new-project demooc new-app https://github.com/ffiore/devops-on-openshift-demo.git
--context-dir samples/flask--name flask-sample
• OpenShift rileva automaticamente qual è la strategy di build– if Jenkinsfile -> Pipeline strategy– elif Dockerfile -> Docker strategy– else -> Source strategy
File Linguaggio
requirements.txt, setup.py python
pom.xml jee
app.json, package.json nodejs
Godeps, main.go golang
cpanfile, index.pl perl
composer.json, index.php php
Gemfile, Rakefile, config.ru ruby
build.sbt scala
• Se Source strategy, OpenShiftrileva il linguaggio
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Setup di una applicazione
oc new-app https://github.com/ffiore/devops-on-openshift-demo.git--context-dir samples/flask--name flask-sample--env WELCOME_MESSAGE=‘Hello Pycon9!’--build-env HTTP_PROXY=‘http://x.y.z.w:8080’
oc new-app python:2.7~https://github.com/ffiore/devops-on-openshift-demo.git
--context-dir samples/flask--name flask-sample-python27--env WELCOME_MESSAGE=‘Hello Pycon9!’
oc expose svc flask-sample
• Per esporre l’applicazione all’esterno (Route)
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Source-to-image: Python
• s2i è la modalità utilizzata con Source strategy
• Nessuna modifica all’applicazione– sufficiente requirements.txt
• 4 modalità di esecuzione– Gunicorn
• se in requirements.txt o in setup.py (install_requires)
• entrypoint: wsgi.py (wsgi:application) o APP_MODULE
– Django development server
– Python script• APP_FILE, default app.py
– Script file• APP_SCRIPT, default app.sh
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Setup di una applicazione: API objects
• BuildConfig– Build
• ImageStream– ImageStreamTag
• DeploymentConfig– ReplicationController
• Pod
• Service
spec:output:to:kind: ImageStreamTagname: flask-sample:latest
source:git:uri: https://github.com/ffiore/devops-on-
openshift-democontextDir: samples/flasktype: Git
strategy:sourceStrategy:from:kind: ImageStreamTagname: python:3.5namespace: openshift
type: Sourcetriggers:- github:
secret: iopmuY9undV5grr7Z8zVtype: GitHub
- generic:secret: QOhldIxeE2ciwomAgoY9
type: Generic- type: ConfigChange- type: ImageChange
apiVersion: v1kind: BuildConfigmetadata:annotations:openshift.io/generated-by: OpenShiftNewApp
labels:app: flask-sample
name: flask-samplenamespace: demo...
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Setup di una applicazione: API objects
• BuildConfig– Build
• ImageStream– ImageStreamTag
• DeploymentConfig– ReplicationController
• Pod
• Service
apiVersion: v1kind: ImageStreammetadata:annotations:openshift.io/generated-by: OpenShiftNewApp
labels:app: flask-sample
name: flask-samplenamespace: demo
spec: {}status:dockerImageRepository:
172.30.0.128:5000/demo/flask-sample
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Setup di una applicazione: API objects
• BuildConfig– Build
• ImageStream– ImageStreamTag
• DeploymentConfig– ReplicationController
• Pod
• Service
template: metadata:...labels:app: flask-sampledeploymentconfig: flask-sample
spec:containers:- image: flask-sample:latestimagePullPolicy: Alwaysname: flask-sampleports:- containerPort: 8080protocol: TCP
dnsPolicy: ClusterFirstrestartPolicy: AlwaysterminationGracePeriodSeconds: 30
triggers:- type: ConfigChange- imageChangeParams:
automatic: truecontainerNames:- flask-samplefrom:kind: ImageStreamTagname: flask-sample:latestnamespace: demo
type: ImageChange
apiVersion: v1kind: DeploymentConfigmetadata:name: flask-samplenamespace: demo
spec:replicas: 1strategy:rollingParams:...
type: Rolling
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Setup di una applicazione: API objects
• BuildConfig– Build
• ImageStream– ImageStreamTag
• DeploymentConfig– ReplicationController
• Pod
• Service
apiVersion: v1kind: Servicemetadata:annotations:openshift.io/generated-by: OpenShiftNewApp
labels:app: flask-sample
name: flask-samplenamespace: demo
spec:clusterIP: 172.30.82.11ports:- name: 8080-tcpport: 8080protocol: TCPtargetPort: 8080
selector:app: flask-sampledeploymentconfig: flask-sample
type: ClusterIP
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Creare un Template
• Aggiungere altri API object– ConfigMap
– Secret
– PersistentVolumeClaim
– ...
• Personalizzare gli oggetti– consumare ConfigMap, Secret, PVC, ecc.
– creare legami tra componenti applicativi (es. applicazione + database)
• Parametrizzare gli oggetti
• Riutilizzare il tutto– su project/ambienti diversi
– per applicazioni diverse
14
Usare i Template
oc process –f python-flask-sample-s2i.yaml
-p APPLICATION_NAME=‘welcome-app’
-p SOURCE_REPOSITORY_URL=‘https://github.com/ffiore/devops-on-openshift-demo’
-p CONTEXT_DIR=‘samples/flask’
-p WELCOME_MESSAGE=‘Hello Pycon9!’ –o yaml | oc create –f -
• Creare l’applicazione usando il Template
• Inserire un Template «a catalogo»
oc –n devops create –f django-postgresql-persistent.yaml
• Usare un Template «a catalogo»
oc –n devops process django-psql-persistent
-p NAME=‘django-app’
-p SOURCE_REPOSITORY_URL=‘https://github.com/sclorg/django-ex’
| oc –n demo create –f -
15
Automatizzare con Jenkins
• BuildConfig possono avere strategy jenkinsPipelineStrategy– jenkinsfile– webhook per il triggering da Git
• OpenShift si aspetta di trovare una istanza di Jenkins– creazione della pipeline in Jenkins– creazione di un Build
• In alternativa, jenkins-ephemeral• Jenkins
– autoconfigurazione al primo deploy• puntamenti a Kubernetes• provisioning pipeline esistenti
– openshift jenkins plugin (deprecato da OpenShift 3.7)– openshift jenkins client plugin (GA da OpenShift 3.7)
• Parametrizzare usando Template– automatic setup e CI/CD
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Lifecycle management
• git flow/gitlabflow/...
• github/genericwebhook
gitpush/merge
• build applicazione• unit test
(postCommit)• build image
build• setup/update
database (pre)• deploy applicazione• integration test
(post)
deploy
17
Lifecycle management e software promotion
gitpush/merge
•git flow/gitlab flow/...•github/generic webhook
build
•build applicazione•unit test (postCommit)•build image
deploy DEV
•setup/update database (pre)•deploy applicazione•functional/integration test (post)
deploySTAGING
•setup/update database (pre)•deploy applicazione•smoke test (post)
deployPRODUCTION
•setup/update database (pre)•deploy applicazione•smoke test (post)
18
Rolling deployment
• Rimpiazzare le istanze della vecchia versione con la nuova– readiness check– canary deployment– rollback automatico
• builtin in OpenShift• quando:
– no downtime– N-1 compatibility
• lifecycle hooks– pre– post
pre hook
scale in old rc
scale out new rc
repeatscaling
post hook
git push
build
deploy
19
Recreate deployment
• Rimpiazzare tutte le istanze della vecchia versione con la nuova– readiness check– rollback automatico
• builtin in OpenShift• quando:
– migrazione dati– no N-1 compatibility– RWO volume
• downtime• lifecycle hooks
– pre– mid– post
pre hook
scale in to 0
mid hook
scale out to N
post hook
git push
build
deploy
20
Blue-green deployment
• Obiettivo: testing prima dello switch del traffico– smoke test– integration test
• 2 versioni dell’applicazione– production– internal (release candidate)
• ‘internal’ può essere pubblica o privata
• 2 service• 2 deployment configuration• switch gestito da Jenkins• alternativa, API manager
– <public, staging, private> URL
• N-1 compatibility
git push
build
deploy
test
go live
21
Blue-green deployment
Pod
Service
Route app
app-blue
app-blue-1-x app-blue-1-y
app-green
app-green-2-z app-green-2-k
app.os.local.int
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Blue-green deployment
Pod
Service
Route app
app-blue
app-blue-1-x app-blue-1-y
app-green
app-green-2-z app-green-2-k
app.os.local.int
oc patch route app –p ‘{“spec”: {“to”: {“name”: “app-green”}}}’
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Canary deployment
• Obiettivo: ridurre il rischio di deploy di una nuova versione
• come blue/green, ma entrambeversioni online
• 1 service• 2 deployment configuration• molteplici shard• proxy shard
– scale out/in deployment configs -> traffic splitter (%)
• N-1 compatibility• gestito da Jenkins
git push
build
deploy
go live
test
scale out/in
24
Canary deployment
Pod
Service
Route app
app
app1-1-x app1-1-y app1-1-z app2-1-k
app.os.local.int
25
Canary deployment
Pod
Service
Route app
app
app1-1-x app1-1-y app2-1-k app2-1-t
app.os.local.int
oc scale --replicas=2 dc app2 && oc scale --replicas=2 dc app1
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Canary deployment
Pod
Service
Route app
app
app2-1-k app2-1-t app2-1-j app2-1-w
app.os.local.int
oc scale --replicas=4 dc app2 && oc scale --replicas=0 dc app1
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A/B deployment
• Obiettivi:– testing di 2 (o più) versioni
contemporaneamente– 2 (o più) configurazioni, stessa
versione (es. più region)
• come A/B testing, ma codice + config
• 1 service• 2 (o più) deployment configuration• molteplici shard
• proxy shard– scale out/in deployment configs ->
traffic splitter (%)
• N-1 compatibility• gestito da Jenkins
git push
build
deploy
go live
test
scale out/in
28
A/B deployment
Pod
Service
Route app
app
app-1-x app-1-k app-a-1-y app-b-2-z
app.os.local.int
29
A/B deployment
Pod
Service
Route app
app
app-1-x app-a-1-y app-b-2-z app-b-2-k
oc scale --replicas=2 dc app-b && oc scale --replicas=1 dc app
app.os.local.int
30
A/B deployment
Pod
Service
Route app
app
app-a-1-y app-a-1-t app-b-2-z app-b-2-k
oc scale --replicas=2 dc app-a && oc scale --replicas=0 dc app
app.os.local.int
31
A/B deployment
Pod
Service
Route app
app
app-b-2-z app-b-2-k app-b-2-t app-b-2-w
oc scale --replicas=4 dc app-b && oc scale --replicas=0 dc app-a
app.os.local.int
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Grazie per l’attenzione!
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