How to use Throttle Concurrent Builds in Jenkins Scripted Pipelines - jenkins

I have a jenkins job used pipeline. But I found two problem:
the node setting not work. I have setting 2 nodes, but only one node of them will be used.
node('mac-m1||travis') {
stage('Prepare Code') {
//some task
}
stage('build') {
//some task
}
}
the throttle plugins setting like below, but the settings for per Node not work.
What I want is that a node can only execute one task, and different nodes can execute tasks concurrently. For example, mac-m1 and travis execute one task at the same time. But mac-m1 cannot execute two tasks at the same time.

Related

CI for a monorepo with Jenkins and BlueOcean

I'm trying to figure out what options do I have,
when trying to build a good pipeline for CICD for a monorepo,
I'm trying to have something like this (this is only a pseudo pipeline)
and not really what I'm using ATM in my monorepo (or what I will have).
Explanation:
Pre: understand what I should build, test, etc..
Build dynamically a parallel step which will give me the later explained capabilities.
Foo: run the parallel and comfortably wait:)
This is the only way I thought of getting this features:
* Build process among the P’s can be shared and I can generate some waitUntil statements
to make this works, I guess...
* Every P’s is independent from the other, if one Ut of P2 fails f.e, it doesn't affect the other progress
of the pipeline, or if I want, it's only a failFast configuration
* Every step within the way is again not related to the progress of other P’s,
so when Ut finishes in any of the P's it starts immediately it's St.
(thought this might changed according to some configuration I'll probably need)
The main problems with that is:
1. I'm losing the control the Restart single steps (since I can only restart Top level steps)
2. It requires me to do a lot more with Scripted Pipeline, which looks like the support of BlueOcean
(which is kind of critical to me), is questionable...
seems that BlueOcean is more supported within the scope of the Declarative Pipeline.
NOTE: It probably looks like I can split every P’s to a another jenkins job
but, this will require me to wait a lot of time in checkout workspace+preparation of the monorepo,
and like I said the "build" step may have shared between the P’s and it's more efficient to do this like that
I will appreciate every feedback or any suggestion:)
There's no problem whatsoever with doing what you want with a Declarative pipeline, since stage can have a stages child. So:
pipeline {
stages {
stage("Pre") { }
stage("Foo") {
parallel {
stage ("P1") {
stages {
stage("P1-Build") {}
stage("P1-Ut") {}
stage("P1-St") {}
}
}
stage ("P2") {
stages {
stage("P2-Build") {}
stage("P2-Ut") {}
}
}
// etc..
Stages P1..P4 will run in parallel but within each their Build-unittest-test stages will run sequentially.
You won't be able to restart separate stages but it's not a good feature anyway.

Jenkins pipeline queue gets full when all agents are offline

I am using a Jenkins pipeline script and when all nodes are offline, the builds keep on queuing up. How do I stop Jenkins from adding jobs to the queue while all slaves are offline?
pipeline {
triggers {
pollSCM('H/3 * * * 1-5')
}
}
Is your agent's availability configured to 'Keep this agent online as much as possible' ?
One way to tackle this situation is, run the below script on master node and build your pipeline(s) only if at least one of the nodes is online. You can pass the online node name to your downstream job as a parameter.
def axis = []
for (slave in jenkins.model.Jenkins.instance.getNodes()) {
if (slave.toComputer().isOnline()) {
axis += slave.getDisplayName()
}
}
return axis
Above script source: Jenkins: skip if node is offline
Other links that may help are:
Monitor and restart your slave nodes - https://wiki.jenkins.io/display/JENKINS/Monitor+and+Restart+Offline+Slaves
I found this script handy in some situations:
https://github.com/jenkinsci/jenkins-scripts/blob/master/scriptler/clearBuildQueue.groovy
I'm not into pipeline jobs, but for regular freestyle jobs, this kind of queueing will only happen if your builds are parameterized. Seperate builds are needed then to ensure that the project will run seperately for each and every parameter value (it does not matter whether the value is actually different).
So, removing build parameters in your project might solve the problem.

Jenkins upstreamProjects not starting jobs

I created a pipelined jobs in jenkins and want to get it triggered as another jobs ends.
I introduced into my pipeline this way:
pipeline {
agent any
triggers { upstream(upstreamProjects: "jobname" )}
...
}
It does not start when the first job ends. I tryed with the web interface build trigger section and it worked.
I wonder what am I missing to get it work in the pipeline code.
I also add "../folder/jobname" and "threshold: hudson.model.Result.SUCCESS".

Jenkins Pipeline "node inside stage" vs "stage inside node"

As both node step and stage step provide scoped {} syntax, what is the best practice for defining their topology inside groovy code?
Exhibit A
node ("NodeName") {
stage ("a stage inside node"){
// do stuff here
}
}
Exhibit B
stage ("a stage holding a node") {
node ("NodeName"){
// do stuff here
}
}
This depends on your actual needs.
As long as you can run your complete pipeline on a single node, I would wrap the stages in a node so that the pipeline is not blocked by busy executors.
As soon as you use the parallel step, then you don't really have a choice besides having stage around node allocations.
There are (at least for me) no issues around mixing that, i.e., have the first 2-3 stages executed on the same node and then one stage that executes on multiple nodes within parallel.
With node { stage { ... } } each stage will share the same working folder and all the files from the previous stage will be there for the next stage.
With stage { node { ... } } you need to stash/unstash files between each stage. If you have a large repository, and especially if you have a large folder of dependencies like node_modules, this repeated stash/unstash could end up being a significant, or even majority, or your build time.
IMO I would generally start with the first syntax, node { stage { ... } } as preferred. If you have individual build stages that take time and can benefit from parallelism, then switching to stage { node { ... } } might be better, as long as the time gained in parallelization is not lost in stashing.
Update:
I tested the exact effect of swapping nesting on one of our builds. with a bunch of stages inside a node, the total build time is just over one minute. With a node inside each stage, total build time is almost five minutes. Big difference.

Matrix configuration with Jenkins pipelines

The Jenkins Pipeline plugin (aka Workflow) can be extended with other Multibranch plugins to build branches and pull requests automatically.
What would be the preferred way to run multiple configurations? For example, building with Java 7 and Java 8. This is often called matrix configuration (because of the multiple combinations such as language version, framework version, ...) or build variants.
I tried:
executing them serially as separate stage steps. Good, but takes more time than necessary.
executing them inside a parallel step, with or without nodes allocated inside them. Works but I cannot use the stage step inside parallel for known limitations on how it would be visualized.
Is there a recommended way to do this?
TLDR: Jenkins.io wants you to use nodes for each build.
Jenkins.io: In pipeline coding contexts, a "node" is a step that does two things, typically by enlisting help from available executors on agents:
Schedules the steps contained within it to run by adding them to the Jenkins build queue (so that as soon as an executor slot is free on a node, the appropriate steps run)
It is a best practice to do all material work, such as building or running shell scripts, within nodes, because node blocks in a stage tell Jenkins that the steps within them are resource-intensive enough to be scheduled, request help from the agent pool, and lock a workspace only as long as they need it.
Vanilla Jenkins Node blocks within a stage would look like:
stage 'build' {
node('java7-build'){ ... }
node('java8-build'){ ... }
}
Further extending this notion Cloudbees writes about parallelism and distributed builds with Jenkins. Cloudbees workflow for you might look like:
stage 'build' {
parallel 'java7-build':{
node('mvn-java7'){ ... }
}, 'java8-build':{
node('mvn-java8'){ ... }
}
}
Your requirements of visualizing the different builds in the pipeline would could be satisfied with either workflow, but I trust the Jenkins documentation for best practice.
EDIT
To address the visualization #Stephen would like to see, He's right - it doesn't work! The issue has been raised with Jenkins and is documented here, the resolution of involving the use of 'labelled blocks' is still in progress :-(
Q: Is there documentation letting pipeline users not to put stages inside of parallel steps?
A: No, and this is considered to be an incorrect usage if it is done; stages are only valid as top-level constructs in the pipeline, which is why the notion of labelled blocks as a separate construct has come to be ... And by that, I mean remove stages from parallel steps within my pipeline.
If you try to use a stage in a parallel job, you're going to have a bad time.
ERROR: The ‘stage’ step must not be used inside a ‘parallel’ block.
I would suggest Declarative Matrix as a preferred way to run multiple configurations in Jenkins. It allows you to execute the defined stages for every configuration without code duplication.
Example:
pipeline {
agent none
stages {
stage('Test') {
matrix {
agent {
label "${NODENAME}"
}
axes {
axis {
name 'NODENAME'
values 'java7node', 'java8node'
}
}
stages {
stage('Test') {
steps {
echo "Do Test for ${NODENAME}"
}
}
}
}
}
}
}
Note that declarative Matrix is a native declarative Pipeline feature, so no additional Plugin installation needed.
Jenkins blog post about the matrix directive.
As noted by #StephenKing, Blue Ocean will show parallel branches better than the current stage view. A planned upcoming version of the stage view will be able to show all the branches, though it will not visually indicate any nesting structure (would look the same as if you ran the configurations serially).
In any event, the deeper issue is that you will essentially only get a pass/fail status for the build overall, pending a resolution to JENKINS-27395 and related requests.
In order to test each commit on several platforms, I've used this base Jenkinsfile skeleton:
def test_platform(label, with_stages = false)
{
node(label)
{
// Checkout
if (with_stages) stage label + ' Checkout'
...
// Build
if (with_stages) stage label + ' Build'
...
// Tests
if (with_stages) stage label + ' Tests'
...
}
}
/*
parallel ( failFast: false,
Windows: { test_platform("Windows") },
Linux: { test_platform("Linux") },
Mac: { test_platform("Mac") },
)
*/
test_platform("Windows", true)
test_platform("Mac", true)
test_platform("Linux", true)
With this it's relatively easy to switch from a sequential to a parallel execution, each of them having their pros and cons:
Parallel execution runs much faster, but it doesn't contain the stages labelling
Sequential execution is much slower, but you get a detailed report thanks to stages, labelled as "Windows Checkout", "Windows Build", "Windows Tests", "Mac Checkout", etc.)
I'm using the sequential execution for the time being, until I find a better solution.
It seems like there is relief coming at least with the BlueOcean UI. Here is what I got (the tk-* nodes are the parallel steps):

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