2018-04-04 at CNCF Paris
How do you develop a Kubernetes app, that is, how do you write and test an app that is supposed to run on Kubernetes? In this talk Michael will discuss the challenges as well as review potential tools (incl. Telepresence, ksync, and kubed-sh) you want to be aware of to successfully write Kubernetes apps.
The demo app used throughout here is kubernauts/dok-example-us.
Install ksync. Then:
kubectl create namespace dok
cd ~/Desktop/ParisCNCF
mkdir -p $(pwd)/ksync
ksync init -n dok
ksync create -n dok --selector=app=stock-con $(pwd)/ksync /app# deploy app:
kubectl -n=dok apply -f https://raw.githubusercontent.com/kubernauts/dok-example-us/master/stock-gen/app.yaml
kubectl -n=dok apply -f https://raw.githubusercontent.com/kubernauts/dok-example-us/master/stock-con/app.yaml
# start watching changes:
ksync watch -n dok
ksync get -n dok
# forward port of stock-con service for local consumption:
kubectl get -n dok po --selector=app=stock-con \
-o=custom-columns=:metadata.name --no-headers | \
xargs -IPOD kubectl -n dok port-forward POD 9898:9898
# check current state of response in another terminal:
watch http localhost:9898/healthz
###############################################################################
# dev iteration
# change stuff in `ksync/` folder, for example update /healthz code in service.js
# clean up:
kubectl delete ns dokBased on this local dev setup by Abhishek Tiwari which configures via minikube docker-env the Minikube-internal Docker daemon for building images locally.
kubectl create namespace dok
cd ~/Desktop/ParisCNCF
git clone https://github.com/kubernauts/dok-example-us.git && cd dok-example-us
eval $(minikube docker-env)# deploy app:
kubectl -n=dok apply -f stock-gen/app.yaml
kubectl -n=dok apply -f stock-con/app.yaml
# forward port of stock-con service for local consumption:
kubectl -n dok get po --selector=app=stock-con \
-o=custom-columns=:metadata.name --no-headers | \
xargs -IPOD kubectl -n dok port-forward POD 9898:9898
###############################################################################
# dev iteration
cd stock-con
docker build -t stock-con:dev -f Dockerfile .
kubectl -n dok set image deployment/stock-con *=stock-con:dev
# check current state of response in another terminal:
watch http localhost:9898/healthz
# clean up:
kubectl delete ns dokNote: See also how to mount host directories into Minikube.
Recording in dok-openshift-s2i.mov.
oc new-project dok-test
# stock-gen app:
oc new-app --docker-image=quay.io/mhausenblas/stock-gen:0.3 \
--name=stock-gen \
--env=DOK_STOCKGEN_PORT=9999 \
--env=DOK_STOCKGEN_CRASHEPOCH=100
oc expose dc/stock-gen --port=9999
# stock-con app:
oc new-app https://github.com/kubernauts/dok-example-us \
--strategy=source \
--name=stock-con \
--context-dir=stock-con \
--env=DOK_STOCKGEN_HOSTNAME=stock-gen \
--env=DOK_STOCKGEN_PORT=9999
oc get svc
oc patch svc stock-con \
--type=merge \
--patch='{"spec": {"ports": [ { "name": "http", "port": 9898, "protocol": "TCP", "targetPort": 9898 } ] } }'
oc expose svc stock-con --port=9898
http http://stock-con-dok-test.b9ad.pro-us-east-1.openshiftapps.com/average/NYSE:RHT
# in stock-con pod do:
curl localhost:9898/healthz
###############################################################################
# dev iteration
# create a Webhook in GitHub for the stock-con build.
# alternatively manually with `oc start-build stock-con` to trigger build.
# check current state of response in another terminal:
watch http localhost:9898/healthz
# change stuff in the code, for example update /healthz code in service.js
# in stock-con pod do:
curl localhost:9898/healthz