Slides from my presentation to the Sydney Jenkins Meetup on Declarative Pipeline. Video of the presentation available at https://www.youtube.com/watch?v=3R5xh4oeDg0&feature=youtu.be

1. Declarative
Pipeline
Malcolm
Groves
malcolm@code-­‐partners.com
@malgroves

2. Training,
Consulting
and
Services
across
the
whole
Development
and
Deployment
lifecycle.

3. What’s
Pipeline?

4. Pipeline
• Pipeline
as
Code
• Versioned
with
rest
of
application
source
• Pipelines
can
be
restarted!
Yay!
• Initially
specified
in
Groovy-­‐based
language
:
Scripted
Pipelines
• Very
flexible,
it’s
code!
• Shared
Objects

5. Sounds
Awesome.
What’s
the
problem?

6. “Problem”
is
probably
too
harsh,
but:
• Some
barrier
to
adopting
(even
if
perceived
barrier)
• “I
don’t
know
Groovy”
• Structure
of
code
doesn’t
always
communicate
what
pipeline
does
• Tough
to
catch
errors
without
running
pipeline
• Visual
Tooling
challenging.

7. What’s
Declarative
Pipeline?

8. Declarative
Pipeline
• Alternative
to
Scripted
Pipeline
• More
approachable,
no
need
to
know
any
Groovy
• More
readable
• Structure
communicates
what
is
happening
• Visual,
two-­‐way
Editor
• Still
Jenkinsfile-­‐based

9. Hello
World
of
Declarative
Pipelines

10. Declarative
Pipeline
Sections

11. Basic
Structure pipeline {
agent any
environment {
Foo = 'Bar’
Fred = 'Flintstone’
}
stages {
stage('Build') {
steps {
bat 'echo %Foo%’
}
}
}
}
• Whole
file
wrapped
in
a
pipeline
section
• stages specifies
what
will
run
• 1
or
more
stage
directives
• Each
stage
contains
1
or
more
steps

12. agent pipeline {
agent any
environment {
Foo = 'Bar’
Fred = 'Flintstone’
}
stages {
stage('Build') {
steps {
bat 'echo %Foo%’
}
}
}
}
• agent
specifies
where
pipeline
will
be
run:
• any,
none,
label,
docker,
dockerfile
• Can
specify
per
stage
as
well

13. agent
pipeline {
agent none
stages {
stage('Example Build') {
agent {docker 'maven:3-­‐alpine'}
steps {
echo 'Hello, Maven’
sh 'mvn -­‐-­‐version'
}
}
stage('Example Test') {
agent {docker 'openjdk:8-­‐jre'}
steps {
echo 'Hello, JDK'
sh 'java -­‐version'
}
}
}
}
• Example
of
per-­‐stage
agent
directive
• Needs
pipeline-­‐level
agent
directive
to
be
none

14. Stages pipeline {
agent any
stages {
stage('Example Build') {
steps {
echo 'Hello World’
}
}
stage('Example Deploy') {
when {branch 'production'}
echo 'Deploying’
}
}
}
• “When”
directive
allows
conditional
execution
of
stages
• Conditions:
• branch
– match
to
branch
name
• environment
– match
to
environment
variables
• expression
– Groovy
expression
evaluates
to
true

15. Steps
pipeline {
agent any
stages {
stage(’Test') {
steps {
archive ‘*/target/**/*’
junit‘*/target/reports/*.xml’
}
}
}
}
• The
actual
work
to
be
performed
inside
this
stage
• Individual
Steps
can
be:
• Any
pipeline
build
step.

16. Steps
pipeline {
agent any
stages {
stage(’Audits') {
steps {
parallel(
“code analysis”: {
bat: ‘echo do stuff’
},
“security scan”: {
bat: ‘echo do stuff’
},
)
}
}
}
}
• The
actual
work
to
be
performed
inside
this
stage
• Individual
Steps
can
be:
• Any
pipeline
build
step.
• parallel

17. Steps
pipeline {
agent any
stages {
stage(’Audits') {
steps {
echo 'Hello World’
script {
def browsers = ['chrome', 'firefox']
for (int i = 0; i < browsers.size(); ++i) {
echo "Testing the ${browsers[i]} browser"
}
}
}
}
}
}
• The
actual
work
to
be
performed
inside
this
stage
• Individual
Steps
can
be:
• Any
pipeline
build
step.
• Parallel
• Script

18. Environment
pipeline {
agent any
environment {
CC = 'clang’
}
stages {
stage('Example') {
environment {
MY_KEY = credentials('my-­‐secret-­‐text')
}
steps {
sh 'printenv’
}
}
}
}
• Name
=
value
pairs
that
will
be
defined
as
environment
variables
• Variables
are
scoped:
• to
whole
pipeline,
or
• to
just
an
individual
stage
if
defined
at
stage
level
• Helper
function
to
access
Credentials
defined
in
Jenkins

19. Post
pipeline {
agent any
stages {
stage('Example') {
steps {
echo 'Hello World’
}
}
}
post {
always {
archive ‘*/target/**/*’
junit‘*/target/reports/*.xml’
}
failure {
echo ‘yikes, build broke!’
}
}
}
• Defines
steps
to
run
at
end
of
pipeline
(or
stage)
• Conditions:
• Always
• Failure
• Success
• Unstable
• Changed

20. A
few
other
sections
• Options
• Options
for
whole
pipeline,
eg.
Timeout,
skipDefaultCheckout,
etc
• Tools
• Install
pre-­‐defined
tools
• Triggers
• alternative
triggers
for
pipeline,
eg.
Schedule,
poll,
etc
• Parameters
• Define
parameters
that
will
be
prompted
for
at
run
time
https://jenkins.io/doc/book/pipeline/syntax/

21. Declarative
Pipelines
are
for
making
most
things
easier.
For
corner-­‐cases,
you
have
Scripted
Pipelines

22. The
Dev
workflow
I’ve
shown
is
a
bit
cumbersome
Let’s
fix
that

23. Tools
and
Resources
Links
• Pipeline
Syntax
https://jenkins.io/doc/book/pipeline/syntax/
• Steps
Reference
https://jenkins.io/doc/pipeline/steps/
Tools
• Replay
https://jenkins.io/doc/book/pipeline/development/#replay
• Linter
https://jenkins.io/doc/book/pipeline/development/#linter
• Unit
Testing
(3rd Party)
https://github.com/lesfurets/JenkinsPipelineUnit

24. Questions?

25. Thank
You
malcolm@code-­‐partners.com
@malgroves