I have a jenkins declarative pipeline which I am interested to be able to perform a stage only if a specific environment variable contains a specific substring(not fully equals to it, just contains it).
Does anyone got any idea on how can I implement it(maybe using the when condition if possible).
Thanks in advance,
Alon
As you mentioned, in declarative pipeline you can use the when directive to establish a condition in which the stage will be executed.
Among the built in condition options like triggeredBy,branch and tag there is the generic expression option, which allows you to run any groovy code and calculate the relevant Boolean value according to your needs.
So for your case for example you can just use the groovy contains methods to achieve what you want, something like:
pipeline {
agent any
stages {
stage('Conditional Stage') {
when {
expression { return env.MyParamter.contains('MySubstring') }
}
steps {
echo "Running the conditional stage"
}
}
}
}
Related
I am looking at a Jenkins Scripted Pipeline tutorial here https://www.jenkins.io/blog/2019/12/02/matrix-building-with-scripted-pipeline/ and found that I need to learn some Groovy to understand this.
I have been reading through Groovy documentation, but still and not understanding all of this code. I will list the areas of question.
1
List getMatrixAxes(Map matrix_axes) {
List axes = []
matrix_axes.each { axis, values ->
List axisList = []
values.each { value ->
axisList << [(axis): value]
}
axes << axisList
}
// calculate cartesian product
axes.combinations()*.sum()
}
In most of the Groovy documentation I have seen, it defines lists such as List axes = []. The syntax above looks more like a function which would return a List. If this is what this is, I don't see any return statement inside the curly brackets, which just confuses me.
2
node(nodeLabel) {
withEnv(axisEnv) {
stage("Build") {
echo nodeLabel
sh 'echo Do Build for ${PLATFORM} - ${BROWSER}'
}
stage("Test") {
echo nodeLabel
sh 'echo Do Build for ${PLATFORM} - ${BROWSER}'
}
}
}
I have seen this concept of node in Groovy scripts before, somethings with the parameter section, ie: node(nodelabel) {...} and sometimes without, ie: node {...}. Is this core Groovy or somehow something specific to Jenkins? What does it mean and where can I find documentation about it?
getMatrixAxes is a function. In Groovy return statement is optional. If you don't explicitly return something in a function, the last expression evaluated in the body of a method or a closure is returned. In your case, the output generated by the axes.combinations()*.sum() will be returned. In the example, it's generating a List. You can read more from here.
These constructs are something specific to Jenkins. Specifically the mentioned syntax is from Jenkins Scripted Pipeline Syntax. node {...} Simply means run on any agent. node(nodelabel) {...} means run on the agent with the label nodelabel. Jenkins has a new Job DSL called Declarative syntax which is preferred over Scripted Syntax. You can read more about both here.
I have the following declarative pipeline where I write a global build variable
during a parallel matrix, the write in stage Build Detection is probably (wasn't clear to me) a race condition but I am not sure. I have 3 questions regarding the below simple pipeline:
Is it correct that since Build-Detection uses the same agent (note only Build uses a different agent), it is definitely a race condition ?
If I would have one agent for each parallel line, it would not be a
race condition as the global build is different in each agent?
Is there a way to make a variable copy of build inside the stage such that its not global anymore?
How should we deal with global variable communicating stuff (for when steps etc)
and parallel matrix feature?
Map<String,Boolean> build
pipeline {
stages {
stage('Test') {
failFast false
matrix {
axes {
axis {
name 'CONTAINER'
values 'A', 'B'
}
}
stages {
stage('Build Detection') {
steps {
script {
build[CONTAINER] = CONATAINER == 'A'
echo "Should Build: ${build[CONTAINER]}"
}
}
}
stage('Build') {
agent {
kubernetes {
yamlFile '.jenkins/pods/build-kaniko.yaml'
}
}
when {
beforeAgent true
expression { return build[CONTAINER] }
}
steps {
echo "BUILDING....."
}
}
}
}
}
}
}
No, it has nothing to do with build agents. The JVM that's executing the compiled groovy code is running on the Jenkins master, not a build agent. Therefore, using a global variable is shared by each thread running in the Jenkins master JVM. Whether there's a possible race condition is not related to stages using the same or different build agents.
Same answer as 1.
Yes, simply define a variable using "def" or a specific type in the stage's script block. Just be sure to not reference a new variable without a type because in Groovy that causes it to be declared globally.
Using a map with a key that is specific to each thread like you're doing seems like a good way to me. If you really want to make sure there is no possibility of two unsafe thread operations modifying the map at the same time, then make sure that a threadsafe map is used. You could print out the class of the map to find out what implementation is getting instantiated. I would hope it's something threadsafe like ConcurrentHashMap.
I put this in the script section of a Jenkins UI job's configuration -
pipeline {
agent any
stages{
stage('Project') {
...
That works, however -
pipeline {
agent any
stages{
stage('Project ' + 'Josh') {
...
throws and displays an incorrect error message because the parser gets all confused due to the constructed string inside the stage.
Moreover,
String description = 'Project' + ' Josh'
pipeline {
agent any
stages{
stage(description) {
...
does not fail, but displays 'description' as the stage's description.
Now, if you try to load a groovy PaC file with this in it:
node {
stage('Project' + 'Josh') {
...
it works without a hitch.
Is it possible that there are two different Groovy parsers employed, one for the UI and another for loaded PaC's? This means that the UI one has this really horrible bug in it...
Ideas?
.a.
Your example has nothing to do with Jenkins UI. You have shown two different pipeline types - a declarative and scripted one.
Declarative pipeline
A declarative pipeline
pipeline {
agent any
stages {
stage('Build') {
steps {
// do something here
}
}
}
}
introduces more simplified, limited and opinionated syntax. This type of a pipeline sets boundaries for Groovy code execution - it is only available inside a dedicated script block, e.g.
pipeline {
agent any
stages {
stage('Build') {
steps {
script {
def name = 'Joe'
echo "My name is ${name}"
}
}
}
}
}
This is why stage block expects a literal and not a variable nor expression.
Scripted pipeline
The second example you have shown is a scripted pipeline. This kind of pipeline is more powerful comparing to a declarative pipeline - the whole pipeline script is more or less a Groovy script so you can put any code almost everywhere. A scripted pipeline starts with node block and it allows you to put any Groovy code inside this block. Consider following example:
node {
stage("Test") {
echo "1,2,3"
}
for (int i = 0; i < 5; i++) {
stage("Stage ${i}") {
echo "This is ${i}"
}
}
}
This pipeline script generates 6 stages:
As you can see there are actually no limits what kind of stuff you put inside node block. Declarative pipeline does not allow you doing that - its syntax is strict and you have to follow it directly.
Differences
As a final note I will quote Jenkins official docs:
Where they differ however is in syntax and flexibility. Declarative limits what is available to the user with a more strict and pre-defined structure, making it an ideal choice for simpler continuous delivery pipelines. Scripted provides very few limits, insofar that the only limits on structure and syntax tend to be defined by Groovy itself, rather than any Pipeline-specific systems, making it an ideal choice for power-users and those with more complex requirements. As the name implies, Declarative Pipeline encourages a declarative programming model. Whereas Scripted Pipelines follow a more imperative programming model.
Source: https://jenkins.io/doc/book/pipeline/syntax/#compare
The script you configured via UI is using declarative pipeline syntax, while the other uses the scripted node syntax. I'd say that's probably where the other parser comes in and would agree that the one for pipeline has a bug.
I have Jenkins Pipeline jobs, where the only difference between the jobs is a parameter, a single "name" value, I could even use the multibranch job name (though not what it's passing as JOB_NAME which is the BRANCH name, sadly none of the envs look suitable without parsing). It would be great if I could set this outiside of the Jenkinsfile, since then I could reuse the same jenkinsfile for all the various jobs.
Add this to your Jenkinsfile:
properties([
parameters([
string(name: 'myParam', defaultValue: '')
])
])
Then, once the build has run once, you will see the "build with parameters" button on the job UI.
There you can input the parameter value you want.
In the pipeline script you can reference it with params.myParam
Basically you need to create a jenkins shared library example name myCoolLib and have a full declarative pipeline in one file under vars, let say you call the file myFancyPipeline.groovy.
Wanted to write my examples but actually I see the docs are quite nice, so I'll copy from there. First the myFancyPipeline.groovy
def call(int buildNumber) {
if (buildNumber % 2 == 0) {
pipeline {
agent any
stages {
stage('Even Stage') {
steps {
echo "The build number is even"
}
}
}
}
} else {
pipeline {
agent any
stages {
stage('Odd Stage') {
steps {
echo "The build number is odd"
}
}
}
}
}
}
and then aJenkinsfile that uses it (now has 2 lines)
#Library('myCoolLib') _
evenOrOdd(currentBuild.getNumber())
Obviously parameter here is of type int, but it can be any number of parameters of any type.
I use this approach and have one of the groovy scripts that has 3 parameters (2 Strings and an int) and have 15-20 Jenkinsfiles that use that script via shared library and it's perfect. Motivation is of course one of the most basic rules in any programming (not a quote but goes something like): If you have "same code" at 2 different places, something is not right.
There is an option This project is parameterized in your pipeline job configuration. Write variable name and a default value if you wish. In pipeline access this variable with env.variable_name
I'm using declarative Jenkins pipelines to run some of my build pipelines and was wondering if it is possible to define multiple agent labels.
I have a number of build agents hooked up to my Jenkins and would like for this specific pipeline to be able to be built by various agents that have different labels (but not by ALL agents).
To be more concrete, let's say I have 2 agents with a label 'small', 4 with label 'medium' and 6 with label 'large'. Now I have a pipeline that is very resource-low and I want it to be executed on only a 'small'- or 'medium'-sized agent, but not on a large one as it may cause larger builds to wait in the queue for an unnecessarily long time.
All the examples I've seen so far only use one single label.
I tried something like this:
agent { label 'small, medium' }
But it failed.
I'm using version 2.5 of the Jenkins Pipeline Plugin.
You can see the 'Pipeline-syntax' help within your Jenkins installation and see the sample step "node" reference.
You can use exprA||exprB:
node('small||medium') {
// some block
}
EDIT: I misunderstood the question. This answer is only if you know
which specific agent you want to run for each stage.
If you need multiple agents you can declare agent none and then declare the agent at each stage.
https://jenkins.io/doc/book/pipeline/jenkinsfile/#using-multiple-agents
From the docs:
pipeline {
agent none
stages {
stage('Build') {
agent any
steps {
checkout scm
sh 'make'
stash includes: '**/target/*.jar', name: 'app'
}
}
stage('Test on Linux') {
agent {
label 'linux'
}
steps {
unstash 'app'
sh 'make check'
}
post {
always {
junit '**/target/*.xml'
}
}
}
stage('Test on Windows') {
agent {
label 'windows'
}
steps {
unstash 'app'
bat 'make check'
}
post {
always {
junit '**/target/*.xml'
}
}
}
}
}
This syntax appears to work for me:
agent { label 'linux && java' }
As described in Jenkins pipeline documentation and by Vadim Kotov one can use operators in label definition.
So in your case if you want to run your jobs on nodes with specific labels, the declarative way goes like this:
agent { label('small || medium') }
And here are some examples from Jenkins page using different operators
// with AND operator
agent { label('windows && jdk9 )') }
// a more complex one
agent { label('postgres && !vm && (linux || freebsd)') }
Notes
When constructing those definitions one just needs to consider following rules/restrictions:
All operators are left-associative
Labels or agent names can be surrounded with quotation marks if they contain characters that would conflict with the operator syntax
Expressions can be written without whitespace
Jenkins will ignore whitespace when evaluating expressions
Matching labels or agent names with wildcards or regular expressions is not supported
An empty expression will always evaluate to true, matching all agents
Create a another label call 'small-or-medium' that has 6 all agents. Then in Jenkinsfile:
agent { label 'small-or-medium' }