Goal of this walkthrough is to demonstrate how to install a simple example application, an HTTP server, on Kubernetes with kapp-controller. We will use examples/simple-app-git directory as our YAML configuration.
You can use kubectl (or another tool) to deploy YAML examples below. We've chosen kapp.
-
Start by installing kapp-controller onto cluster
-
Install examples/simple-app-git/1.yml App CR. It specifies how to fetch, template, and deploy our example application.
$ kapp deploy -a simple-app -f https://raw.githubusercontent.com/k14s/kapp-controller/master/examples/simple-app-git/1.yml
# or... kubectl apply -f https://raw.githubusercontent.com/k14s/kapp-controller/master/examples/simple-app-git/1.yml
Changes
Namespace Name Kind Conds. Age Op Wait to Rs Ri
default simple-app App - - create reconcile - -
Op: 1 create, 0 delete, 0 update, 0 noop
Wait to: 1 reconcile, 0 delete, 0 noop
Continue? [yN]: y
5:20:27PM: ---- applying 1 changes [0/1 done] ----
5:20:27PM: create app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:20:27PM: ---- waiting on 1 changes [0/1 done] ----
5:20:27PM: ongoing: reconcile app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:20:33PM: ok: reconcile app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:20:33PM: ---- applying complete [1/1 done] ----
5:20:33PM: ---- waiting complete [1/1 done] ----
Succeeded-
Check out
kubectl get appoutput to see that app is deployed. -
Additionally, let's check status of our App CR. It shows overall status of the application, including latest deploy output (
status.deploy.stdout), and latest inspect output (status.inspect.stdout). Based on inspect output we can see that our app included aDeploymentand aService.
$ kapp inspect -a simple-app --status
# or... kubectl get app simple-app -oyaml
Resources in app 'simple-app'
Namespace default
Name simple-app
Kind App
Status conditions:
- status: "True"
type: ReconcileSucceeded
deploy:
exitCode: 0
finished: true
startedAt: "2019-12-02T22:20:28Z"
stdout: |-
Changes
Namespace Name Kind Conds. Age Op Wait to Rs Ri
default simple-app Deployment - - create reconcile - -
^ simple-app Service - - create reconcile - -
Op: 2 create, 0 delete, 0 update, 0 noop
Wait to: 2 reconcile, 0 delete, 0 noop
10:20:28PM: ---- applying 2 changes [0/2 done] ----
10:20:28PM: create service/simple-app (v1) namespace: default
10:20:28PM: create deployment/simple-app (apps/v1) namespace: default
10:20:29PM: ---- waiting on 2 changes [0/2 done] ----
10:20:29PM: ok: reconcile service/simple-app (v1) namespace: default
10:20:29PM: ongoing: reconcile deployment/simple-app (apps/v1) namespace: default
10:20:29PM: ^ Waiting for 1 unavailable replicas
10:20:29PM: L ok: waiting on replicaset/simple-app-6fb57f844b (apps/v1) namespace: default
10:20:29PM: L ongoing: waiting on pod/simple-app-6fb57f844b-jk7d8 (v1) namespace: default
10:20:29PM: ^ Pending: ContainerCreating
10:20:29PM: ---- waiting on 1 changes [1/2 done] ----
10:20:31PM: ok: reconcile deployment/simple-app (apps/v1) namespace: default
10:20:31PM: ---- applying complete [2/2 done] ----
10:20:31PM: ---- waiting complete [2/2 done] ----
Succeeded
updatedAt: "2019-12-02T22:20:31Z"
fetch:
exitCode: 0
startedAt: "2019-12-02T22:20:27Z"
updatedAt: "2019-12-02T22:20:27Z"
inspect:
exitCode: 0
stdout: |-
Resources in app 'simple-app-ctrl'
Namespace Name Kind Owner Conds. Rs Ri Age
default simple-app Deployment kapp 2/2 t ok - 4s
default L simple-app-6fb57f844b ReplicaSet cluster - ok - 4s
default L.. simple-app-6fb57f844b-jk7d8 Pod cluster 4/4 t ok - 4s
default simple-app Service kapp - ok - 4s
default L simple-app Endpoints cluster - ok - 4s
Rs: Reconcile state
Ri: Reconcile information
5 resources
Succeeded
updatedAt: "2019-12-02T22:20:32Z"
observedGeneration: 2
template:
exitCode: 0
updatedAt: "2019-12-02T22:20:28Z"
1 resources
Succeeded- Update simple-app App CR to reconfigure simple-app. In this example we are changing data values for ytt templates.
$ kapp deploy -a simple-app -f https://raw.githubusercontent.com/k14s/kapp-controller/master/examples/simple-app-git/2.yml -c
# or... kubectl apply -f https://raw.githubusercontent.com/k14s/kapp-controller/master/examples/simple-app-git/2.yml
--- update app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
...
23, 23 template:
24 - - ytt: {}
24 + - ytt:
25 + inline:
26 + pathsFrom:
27 + - secretRef:
28 + name: simple-app-values
25, 29 status:
26, 30 conditions:
--- create secret/simple-app-values (v1) namespace: default
0 + apiVersion: v1
1 + kind: Secret
2 + metadata:
3 + labels:
4 + kapp.k14s.io/app: "1575325198404867000"
5 + kapp.k14s.io/association: v1.7a671029ad7db07aa797301eac59e9ad
6 + name: simple-app-values
7 + namespace: default
8 + stringData:
9 + values2.yml: |
10 + #@data/values
11 + ---
12 + hello_msg: updated
13 +
Changes
Namespace Name Kind Conds. Age Op Wait to Rs Ri
default simple-app App 1/1 t 2m update reconcile ok -
^ simple-app-values Secret - - create reconcile - -
Op: 1 create, 0 delete, 1 update, 0 noop
Wait to: 2 reconcile, 0 delete, 0 noop
Continue? [yN]: y
5:23:13PM: ---- applying 2 changes [0/2 done] ----
5:23:13PM: update app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:23:13PM: create secret/simple-app-values (v1) namespace: default
5:23:14PM: ---- waiting on 2 changes [0/2 done] ----
5:23:14PM: ongoing: reconcile app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:23:14PM: ok: reconcile secret/simple-app-values (v1) namespace: default
5:23:14PM: ---- waiting on 1 changes [1/2 done] ----
5:23:17PM: ok: reconcile app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:23:17PM: ---- applying complete [2/2 done] ----
5:23:17PM: ---- waiting complete [2/2 done] ----
Succeeded- Delete simple-app App CR
$ kapp delete -a simple-app
# or... kubectl delete -f https://raw.githubusercontent.com/k14s/kapp-controller/master/examples/simple-app-git/2.yml
Changes
Namespace Name Kind Conds. Age Op Wait to Rs Ri
default simple-app App 1/1 t 6m delete delete ok -
^ simple-app-values Secret - 3m delete delete ok -
Op: 0 create, 2 delete, 0 update, 0 noop
Wait to: 0 reconcile, 2 delete, 0 noop
Continue? [yN]: y
5:26:25PM: ---- applying 2 changes [0/2 done] ----
5:26:25PM: delete secret/simple-app-values (v1) namespace: default
5:26:25PM: delete app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:26:26PM: ---- waiting on 2 changes [0/2 done] ----
5:26:26PM: ok: delete secret/simple-app-values (v1) namespace: default
5:26:26PM: ongoing: delete app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:26:26PM: ---- waiting on 1 changes [1/2 done] ----
5:26:30PM: ok: delete app/simple-app (kappctrl.k14s.io/v1alpha1) namespace: default
5:26:30PM: ---- applying complete [2/2 done] ----
5:26:30PM: ---- waiting complete [2/2 done] ----
Succeeded