Jenkins

Available Environment Variables

//See a list of environment variables
https://jenkins.mycomany.dev/env-vars.html/

//access environment variable in Jenksfile
build = "Build:${BUILD_NUMBER}"

See work place

cd /home/jenkins/workspace 

Check which docker image used by stack

In template file, image is mapped to BuildVersion.

• go to Cloudformation
• find the stack
• click parameters
• check BuildVersion

withCredentials explained

When the withCredentials block is executed, the specified credentials are made available only within that block by injecting enviornment variables. Once the block execution is complete, the environment variables are no longer available, ensuring the secrets are not exposed outside the block

stages {
        stage('Example') {
            steps {
                // Wrap steps with the credentials
                withCredentials([usernamePassword(credentialsId: 'my-credentials-id', 
                                                  usernameVariable: 'USER', 
                                                  passwordVariable: 'PASS')]) {
                    // Use the credentials. It shows we can access env variables USER and PASS
                    // because these two env variables have been injected by withCredentials
                    // in real life, you will not echo these credentials, but use it in your codes
                    sh 'echo "Username: $USER"'
                    sh 'echo "Password: $PASS"'
                }
            }
        }
    }

To manage credentials in Jenkins, go to Manage Jenkins; go to Manage Credentials

Run bash in Jenkins

sh "rm -rf composer/composer.json composer/composer.lock composer/vendor"
sh "composer.phar require aws/aws-sdk-php ^3.69 --ignore-platform-reqs --working-dir=composer"

Debug

Stuck because of low free disk space

#show space in machine
df -h

# spaces used by docker
docker system df

# show folders under var
sudo du -xhd1 /var | sort -h

# show folders under /var/log
sudo du -xhd1 /var/log | sort -h

# Human-readable sizes of files/folders directly under /var/log
sudo du -sh /var/log/* | sort -h

To clean up

#Remove old rotated message logs (already historical)
sudo rm -f /var/log/messages-20*

#optional. Do not do it if already have enough spaces (truncate -s 0: set file size to exactly 0 bytes.)
sudo truncate -s 0 /var/log/messages

Can not clone remote repository

ERROR: Error cloning remote repo 'origin' .... stderr: No RSA host key is known for git-codecommit.us-west-2.amazonaws..

It is because Jenkin container restarted. To fix it

1. Log into jenkin container

   docker exec -it ecs-sandbox-jenkins-worker-1-1-jenkins-slaves-1-xxxxxxxxx bash

2. ssh git-codecommit.us-west-2.amazonaws.com
3. when asked to add known host, type yes

Magic function __invoke

In PHP, __invoke() method is called when a script tries to call an object as a function

//example 1
<?php
class CallableClass
{
    public function __invoke($x)
    {
        var_dump($x);
    }
}
$obj = new CallableClass;

//treat object as function. Here var dump 5
$obj(5);

//will get true
var_dump(is_callable($obj));

//example 2
<?php
class CallableClass
{
    public function __invoke($x)
    {
        return $x + 100;
    }
}
$obj = new CallableClass;

$ans = $obj(5);

//Here var dump 105
var_dump($ans);