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Red Hat® OpenShift® Container Platform on Alibaba Cloud
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Red Hat® OpenShift® Container Platform on Alibaba Cloud
Red Hat® OpenShift® Container Platform on Alibaba Cloud
Nov 15, 2024 -p= --server= --insecure-
skip-tls-verify
With an OAuth token:
$ oc login --token=
With a web browser:
$ oc login --web
You can now create a project or issue other commands for managing your cluster.
Additional resources
oc login
oc logout
4.3. CREATING A NEW PROJECT
A project enables a community of users to organize and manage their content in isolation. Projects are
26CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
A project enables a community of users to organize and manage their content in isolation. Projects are
OpenShift Container Platform extensions to Kubernetes namespaces. Projects have additional features
that enable user self-provisioning.
Users must receive access to projects from administrators. Cluster administrators can allow developers
to create their own projects. In most cases, users automatically have access to their own projects.
Each project has its own set of objects, policies, constraints, and service accounts.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
Procedure
To create a new project, enter the following command:
$ oc new-project user-getting-started --display-name="Getting Started with OpenShift"
Example output
Now using project "user-getting-started" on server "https://openshift.example.com:6443".
Additional resources
oc new-project
4.4. GRANTING VIEW PERMISSIONS
OpenShift Container Platform automatically creates a few special service accounts in every project. The
default service account takes responsibility for running the pods. OpenShift Container Platform uses
and injects this service account into every pod that launches.
The following procedure creates a RoleBinding object for the default ServiceAccount object. The
service account communicates with the OpenShift Container Platform API to learn about pods, services,
and resources within the project.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
You must have cluster-admin or project-admin privileges.
Procedure
To add the view role to the default service account in the user-getting-started project, enter
the following command:
27OpenShift Container Platform 4.17 Getting started
$ oc adm policy add-role-to-user view -z default -n user-getting-started
Additional resources
Understanding authentication
RBAC overview
oc policy add-role-to-user
4.5. DEPLOYING YOUR FIRST IMAGE
The simplest way to deploy an application in OpenShift Container Platform is to run an existing container
image. The following procedure deploys a front-end component of an application called national-parks-
app. The web application displays an interactive map. The map displays the location of major national
parks across the world.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
Install the OpenShift CLI (oc).
Procedure
To deploy an application, enter the following command:
$ oc new-app quay.io/openshiftroadshow/parksmap:latest --name=parksmap -l
''app=national-parks-app,component=parksmap,role=frontend,app.kubernetes.io/part-
of=national-parks-app''
Example output
--> Found container image 0c2f55f (12 months old) from quay.io for
"quay.io/openshiftroadshow/parksmap:latest"
* An image stream tag will be created as "parksmap:latest" that will track this image
--> Creating resources with label app=national-parks-app,app.kubernetes.io/part-of=national-
parks-app,component=parksmap,role=frontend ...
imagestream.image.openshift.io "parksmap" created
deployment.apps "parksmap" created
service "parksmap" created
--> Success
Additional resources
oc new-app
4.5.1. Creating a route
External clients can access applications running on OpenShift Container Platform through the routing
28CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
External clients can access applications running on OpenShift Container Platform through the routing
layer and the data object behind that is a route. The default OpenShift Container Platform router
(HAProxy) uses the HTTP header of the incoming request to determine where to proxy the connection.
Optionally, you can define security, such as TLS, for the route.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
You must have cluster-admin or project-admin privileges.
Procedure
1. To retrieve the created application service, enter the following command:
$ oc get service
Example output
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
parksmap ClusterIP <123.456.789> 8080/TCP 8m29s
2. To create a route, enter the following command:
$ oc create route edge parksmap --service=parksmap
Example output
route.route.openshift.io/parksmap created
3. To retrieve the created application route, enter the following command:
$ oc get route
Example output
NAME HOST/PORT PATH SERVICES PORT
TERMINATION WILDCARD
parksmap parksmap-user-getting-started.apps.cluster.example.com parksmap
8080-tcp edge None
Additional resources
oc create route edge
oc get
29OpenShift Container Platform 4.17 Getting started
4.5.2. Examining the pod
OpenShift Container Platform leverages the Kubernetes concept of a pod, which is one or more
containers deployed together on one host, and the smallest compute unit that can be defined,
deployed, and managed. Pods are the rough equivalent of a machine instance, physical or virtual, to a
container.
You can view the pods in your cluster and to determine the health of those pods and the cluster as a
whole.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
1. To list all pods with node names, enter the following command:
$ oc get pods
Example output
NAME READY STATUS RESTARTS AGE
parksmap-5f9579955-6sng8 1/1 Running 0 77s
2. To list all pod details, enter the following command:
$ oc describe pods
Example output
Name: parksmap-848bd4954b-5pvcc
Namespace: user-getting-started
Priority: 0
Node: ci-ln-fr1rt92-72292-4fzf9-worker-a-g9g7c/10.0.128.4
Start Time: Sun, 13 Feb 2022 14:14:14 -0500
Labels: app=national-parks-app
app.kubernetes.io/part-of=national-parks-app
component=parksmap
deployment=parksmap
pod-template-hash=848bd4954b
role=frontend
Annotations: k8s.v1.cni.cncf.io/network-status:
[{
"name": "ovn-kubernetes",
"interface": "eth0",
"ips": [
"10.131.0.14"
],
"default": true,
30CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
"dns": {}
}]
k8s.v1.cni.cncf.io/network-status:
[{
"name": "ovn-kubernetes",
"interface": "eth0",
"ips": [
"10.131.0.14"
],
"default": true,
"dns": {}
}]
openshift.io/generated-by: OpenShiftNewApp
openshift.io/scc: restricted
Status: Running
IP: 10.131.0.14
IPs:
IP: 10.131.0.14
Controlled By: ReplicaSet/parksmap-848bd4954b
Containers:
parksmap:
Container ID: cri-
o://4b2625d4f61861e33cc95ad6d455915ea8ff6b75e17650538cc33c1e3e26aeb8
Image:
quay.io/openshiftroadshow/parksmap@sha256:89d1e324846cb431df9039e1a7fd0ed2ba0c51a
afbae73f2abd70a83d5fa173b
Image ID:
quay.io/openshiftroadshow/parksmap@sha256:89d1e324846cb431df9039e1a7fd0ed2ba0c51a
afbae73f2abd70a83d5fa173b
Port: 8080/TCP
Host Port: 0/TCP
State: Running
Started: Sun, 13 Feb 2022 14:14:25 -0500
Ready: True
Restart Count: 0
Environment:
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-6f844 (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-6f844:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional:
DownwardAPI: true
ConfigMapName: openshift-service-ca.crt
ConfigMapOptional:
QoS Class: BestEffort
Node-Selectors:
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
31OpenShift Container Platform 4.17 Getting started
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 46s default-scheduler Successfully assigned user-getting-
started/parksmap-848bd4954b-5pvcc to ci-ln-fr1rt92-72292-4fzf9-worker-a-g9g7c
Normal AddedInterface 44s multus Add eth0 [10.131.0.14/23] from ovn-
kubernetes
Normal Pulling 44s kubelet Pulling image
"quay.io/openshiftroadshow/parksmap@sha256:89d1e324846cb431df9039e1a7fd0ed2ba0c51
aafbae73f2abd70a83d5fa173b"
Normal Pulled 35s kubelet Successfully pulled image
"quay.io/openshiftroadshow/parksmap@sha256:89d1e324846cb431df9039e1a7fd0ed2ba0c51
aafbae73f2abd70a83d5fa173b" in 9.49243308s
Normal Created 35s kubelet Created container parksmap
Normal Started 35s kubelet Started container parksmap
Additional resources
oc describe
oc get
oc label
Viewing pods
Viewing pod logs
4.5.3. Scaling the application
In Kubernetes, a Deployment object defines how an application deploys. In most cases, users use Pod,
Service, ReplicaSets, and Deployment resources together. In most cases, OpenShift Container
Platform creates the resources for you.
When you deploy the national-parks-app image, a deployment resource is created. In this example, only
one Pod is deployed.
The following procedure scales the national-parks-image to use two instances.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
To scale your application from one pod instance to two pod instances, enter the following
command:
$ oc scale --current-replicas=1 --replicas=2 deployment/parksmap
32CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
Example output
deployment.apps/parksmap scaled
Verification
1. To ensure that your application scaled properly, enter the following command:
$ oc get pods
Example output
NAME READY STATUS RESTARTS AGE
parksmap-5f9579955-6sng8 1/1 Running 0 7m39s
parksmap-5f9579955-8tgft 1/1 Running 0 24s
2. To scale your application back down to one pod instance, enter the following command:
$ oc scale --current-replicas=2 --replicas=1 deployment/parksmap
Additional resources
oc scale
4.6. DEPLOYING A PYTHON APPLICATION
The following procedure deploys a back-end service for the parksmap application. The Python
application performs 2D geo-spatial queries against a MongoDB database to locate and return map
coordinates of all national parks in the world.
The deployed back-end service is nationalparks.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
1. To create a new Python application, enter the following command:
$ oc new-app python~https://github.com/openshift-roadshow/nationalparks-py.git --name
nationalparks -l ''app=national-parks-
app,component=nationalparks,role=backend,app.kubernetes.io/part-of=national-parks-
app,app.kubernetes.io/name=python'' --allow-missing-images=true
Example output
--> Found image 0406f6c (13 days old) in image stream "openshift/python" under tag "3.9-
33OpenShift Container Platform 4.17 Getting started
ubi9" for "python"
Python 3.9
----------
Python 3.9 available as container is a base platform for building and running various
Python 3.9 applications and frameworks. Python is an easy to learn, powerful programming
language. It has efficient high-level data structures and a simple but effective approach to
object-oriented programming. Python''s elegant syntax and dynamic typing, together with its
interpreted nature, make it an ideal language for scripting and rapid application development
in many areas on most platforms.
Tags: builder, python, python39, python-39, rh-python39
* A source build using source code from https://github.com/openshift-
roadshow/nationalparks-py.git will be created
* The resulting image will be pushed to image stream tag "nationalparks:latest"
* Use ''oc start-build'' to trigger a new build
--> Creating resources with label app=national-parks-
app,app.kubernetes.io/name=python,app.kubernetes.io/part-of=national-parks-
app,component=nationalparks,role=backend ...
imagestream.image.openshift.io "nationalparks" created
buildconfig.build.openshift.io "nationalparks" created
deployment.apps "nationalparks" created
service "nationalparks" created
--> Success
2. To create a route to expose your application, nationalparks, enter the following command:
$ oc create route edge nationalparks --service=nationalparks
Example output
route.route.openshift.io/parksmap created
3. To retrieve the created application route, enter the following command:
$ oc get route
Example output
NAME HOST/PORT PATH SERVICES
PORT TERMINATION WILDCARD
nationalparks nationalparks-user-getting-started.apps.cluster.example.com
nationalparks 8080-tcp edge None
parksmap parksmap-user-getting-started.apps.cluster.example.com
parksmap 8080-tcp edge None
Additional resources
oc new-app
4.7. CONNECTING TO A DATABASE
34CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
Deploy and connect a MongoDB database where the national-parks-app application stores location
information. Once you mark the national-parks-app application as a backend for the map visualization
tool, parksmap deployment uses the OpenShift Container Platform discover mechanism to display the
map automatically.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
To connect to a database, enter the following command:
$ oc new-app quay.io/centos7/mongodb-36-centos7 --name mongodb-nationalparks -e
MONGODB_USER=mongodb -e MONGODB_PASSWORD=mongodb -e
MONGODB_DATABASE=mongodb -e MONGODB_ADMIN_PASSWORD=mongodb -l
''app.kubernetes.io/part-of=national-parks-app,app.kubernetes.io/name=mongodb''
Example output
--> Found container image dc18f52 (8 months old) from quay.io for
"quay.io/centos7/mongodb-36-centos7"
MongoDB 3.6
-----------
MongoDB (from humongous) is a free and open-source cross-platform document-oriented
database program. Classified as a NoSQL database program, MongoDB uses JSON-like
documents with schemas. This container image contains programs to run mongod server.
Tags: database, mongodb, rh-mongodb36
* An image stream tag will be created as "mongodb-nationalparks:latest" that will track this
image
--> Creating resources with label app.kubernetes.io/name=mongodb,app.kubernetes.io/part-
of=national-parks-app ...
imagestream.image.openshift.io "mongodb-nationalparks" created
deployment.apps "mongodb-nationalparks" created
service "mongodb-nationalparks" created
--> Success
Additional resources
oc new-project
4.7.1. Creating a secret
The Secret object provides a mechanism to hold sensitive information such as passwords, OpenShift
Container Platform client configuration files, private source repository credentials, and so on. Secrets
decouple sensitive content from the pods. You can mount secrets into containers using a volume plugin
35OpenShift Container Platform 4.17 Getting started
or the system can use secrets to perform actions on behalf of a pod. The following procedure adds the
secret nationalparks-mongodb-parameters and mounts it to the nationalparks workload.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
1. To create a secret, enter the following command:
$ oc create secret generic nationalparks-mongodb-parameters --from-
literal=DATABASE_SERVICE_NAME=mongodb-nationalparks --from-
literal=MONGODB_USER=mongodb --from-literal=MONGODB_PASSWORD=mongodb --
from-literal=MONGODB_DATABASE=mongodb --from-
literal=MONGODB_ADMIN_PASSWORD=mongodb
Example output
secret/nationalparks-mongodb-parameters created
2. To update the environment variable to attach the mongodb secret to the nationalpartks
workload, enter the following command:
$ oc set env --from=secret/nationalparks-mongodb-parameters deploy/nationalparks
Example output
deployment.apps/nationalparks updated
3. To show the status of the nationalparks deployment, enter the following command:
$ oc rollout status deployment nationalparks
Example output
deployment "nationalparks" successfully rolled out
4. To show the status of the mongodb-nationalparks deployment, enter the following command:
$ oc rollout status deployment mongodb-nationalparks
Example output
deployment "nationalparks" successfully rolled out
deployment "mongodb-nationalparks" successfully rolled out
Additional resources
36CHAPTER 4. CREATING AND BUILDING AN APPLICATION USING THE CLI
Additional resources
oc create secret generic
oc set env
oc rollout status
4.7.2. Loading data and displaying the national parks map
You deployed the parksmap and nationalparks applications and then deployed the mongodb-
nationalparks database. However, no data has been loaded into the database.
Prerequisites
You must have access to an OpenShift Container Platform cluster.
You must have installed the OpenShift CLI (oc).
You have a deployed image.
Procedure
1. To load national parks data, enter the following command:
$ oc exec $(oc get pods -l component=nationalparks | tail -n 1 | awk ''{print $1;}'') -- curl -s
http://localhost:8080/ws/data/load
Example output
"Items inserted in database: 2893"
2. To verify that your data is loaded properly, enter the following command:
$ oc exec $(oc get pods -l component=nationalparks | tail -n 1 | awk ''{print $1;}'') -- curl -s
http://localhost:8080/ws/data/all
Example output (trimmed)
, {"id": "Great Zimbabwe", "latitude": "-20.2674635", "longitude": "30.9337986", "name":
"Great Zimbabwe"}]
3. To add labels to the route, enter the following command:
$ oc label route nationalparks type=parksmap-backend
Example output
route.route.openshift.io/nationalparks labeled
4. To retrieve your routes to view your map, enter the following command:
$ oc get routes
37OpenShift Container Platform 4.17 Getting started
Example output
NAME HOST/PORT PATH SERVICES PORT
TERMINATION WILDCARD
nationalparks nationalparks-user-getting-started.apps.cluster.example.com
nationalparks 8080-tcp edge None
parksmap parksmap-user-getting-started.apps.cluster.example.com parksmap
8080-tcp edge None
5. Copy and paste the HOST/PORT path you retrieved above into your web browser. Your browser
should display a map of the national parks across the world.
Figure 4.1. National parks across the world
Additional resources
oc exec
oc label
oc get
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