Programming

basic programming

Deploying a Python app to Openshift 4 using s2i

By / 11 March 2022 / Openshift, Programming, Python / , , ,

S2I or Source to Image, is a way to deploy application from its sourcecode directly to Openshift. In this article, we try to build a Python apps with Flask framework and deploy it to Openshift.

So lets start with requirements.txt for storing required libraries 

flask

And a simple hello world app

from flask import Flask

app = Flask(__name__)

@app.route("/")
def index():
    return "<h1>Hello, World!</h1>"

app.run(host="0.0.0.0", port=8080)

Next is where the magic happens, it would build, containerized and push the whole apps to external registry by using below commands,

$ oc new-build . --name=hello-world-python --to-docker --to=docker.io/dockerusername/hello-world-python

$ oc start-build hello-world-python --from-dir=. --follow --wait

Once we push it to external registry, we can pull and run the apps in Openshift

$ oc new-app . --docker-image=dockerusername/hello-world-python --name=hello-world-python-app

And expose a secure URL for it,

$ oc create route edge --service=hello-world-python-app

Code for this can be accessed here,

https://github.com/edwin/hello-world-flask

How to Connect OpenShift BuildConfig to Docker Hub

By / 10 March 2022 / Openshift, Programming / , ,

On this article im trying to use Openshift as a Build Server to build a containerized image from a plain sourcecode and store the result in external Image Registry, in this case Docker Hub. The goal is to provide another options to build containerized image when we have limitation, especially we dont have any Docker command installed in our local laptop.

The concept is displayed in below image,

For this example, im using a simple PHP file.

<?php
    echo "hello world php";
?>

So lets start by creating a BuildConfig to containerized this PHP code in OpenShift, and trigger it by using our local PHP file,

 $ oc new-build . --name=hello-world-php --to-docker \ 
		--to=docker.io/dockerusername/hello-world-php

 $ oc start-build hello-world-php \ 
		--from-dir=. --follow --wait

But before we do that, we need to register our Docker Hub credentials into our OCP so that OCP can push the build image into Docker Hub.

 $ oc create secret docker-registry --docker-server=docker.io \ 
		--docker-username=dockerusername --docker-password=dockerpassword 
		--docker-email=your@email.com docker-login

 $ oc secret link builder docker-login --for=mount

In summary, there are multiple ways and strategies of deploying your app into OpenShift and this is one way of doing it.

Deploying a Java Apps and JBoss EAP into Openshift 4

By / 27 February 2022 / Java, Openshift, Programming / , , ,

Sometimes we still have to maintain an application which is still deployed on top of JBoss EAP and in a Virtual Machine, and planning in onboarding them into Openshift.

Deploying this kind of applications is almost the same as deploying a Spring Boot applications on Openshift. Only need one command for doing it.

So lets start with a basic maven file,

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edw</groupId>
    <artifactId>HelloWorldWar</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <optimize>true</optimize>
                    <debug>true</debug>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <warName>${project.name}</warName>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

Lets set the context root of this app,

<jboss-web>
    <context-root>/</context-root>
</jboss-web>

And a servlet for serving some content,

package com.edw;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name = "HelloServlet", urlPatterns = "/")
public class HelloServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");

        PrintWriter out = response.getWriter();
        out.println("<h1> Hello World </h1>");

    }
}

And make sure the structure of our project is like below,

+--- .gitignore
+--- pom.xml
+--- README.md
+--- src
|   +--- main
|   |   +--- java
|   |   |   +--- com
|   |   |   |   +--- edw
|   |   |   |   |   +--- HelloServlet.java
|   |   +--- webapp
|   |   |   +--- WEB-INF
|   |   |   |   +--- jboss-web.xml

We can deploy our code to test-project namespace in our Openshift by using below command,

$ oc new-app openshift/jboss-eap73-openjdk11-openshift:latest~. \ 
	--name=hello-world -n test-project

Code for this tutorial can be seen in below Github url

https://github.com/edwin/hello-world-jboss-eap

A Jenkins Agent with Helm 3 for Build and Deploying Java Application in Openshift 4

By / 17 February 2022 / Java, Openshift, Programming / , , ,

Basically im trying to create a Jenkins Agent base image, with the capability of building and deploying Java application. For building, i need to have a Maven installation within Jenkins Agent. But for deploying, im planning on exploring Helm 3.

Below is a Dockerfile to build a slave image than can be use for build and deploying Java applications. 

FROM registry.redhat.io/openshift4/ose-jenkins-agent-maven:latest
USER root

RUN curl -fsSL -o /tmp/get_helm.sh https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 \ 
    && chmod 700 /tmp/get_helm.sh  \
	&& cd /tmp/ && ./get_helm.sh  \ 
	&& rm -Rf /tmp/*
RUN helm version

USER 1001

We can build it by using below command,

docker build -t ose-jenkins-agent-maven-helm .

And as always, my code can be downloaded on below url

https://github.com/edwin/ose-jenkins-agent-maven-helm

How to Solve “Error from server (Forbidden): buildconfigs.build.openshift.io build-name is forbidden”

By / 7 February 2022 / Openshift, Programming / ,

I had this error while building an image on Jenkins from one Openshift namespace to another namespace. This happens mainly due to limited access that the corresponding Jenkins user have on the target namespace.

Error from server (Forbidden): buildconfigs.build.openshift.io "hello-world" is forbidden: 
User "system:serviceaccount:cicd:jenkins" 
cannot create resource "buildconfigs/instantiatebinary" in API group 
"build.openshift.io" in the namespace "apps"

How to solve it is actually quite easy, we are giving admin privilege to jenkins service account user.

oc policy add-role-to-user admin system:serviceaccount:cicd:jenkins -n apps