Jenkins: env in pipeline from Jenkinsfile is null - jenkins

Question

Please help. env is null.
Jenkinsfile:
node {
println "Your ENV:"
println env.dump
println "Your params:"
println params.dump
}
Jenkins output:
[Pipeline] properties
[Pipeline] node
Running on foobarquux in c:\workspace\123abc
[Pipeline] {
[Pipeline] echo
Your ENV:
[Pipeline] echo
null
[Pipeline] echo
Your params:
[Pipeline] echo
null
I expect that my environment variables will not be null. I expect env.dump not to be null and to see something beyond Your ENV: when println env.dump executes.
After reading very helpful comments from #mkobit, I realized I needed parentheses for dump, and even with them Jenkins throws a security exception.

Answer 1

${WORKSPACE} only works if it is used in an agent (node)! Otherwise it comes out as null.
I have agent none at the top of my pipeline because I have a few input steps that i don't want use heavyweight executors for. And I was setting an environment variable in the top-level environment {} block that used ${WORKSPACE}. For the life of me I couldn't figure out why it was being set to null. Some other thread mentioned the workspace on an agent, so i moved that definition into a step on an agent, and lo and behold, when you set a var with WORKSPACE while running on an agent, it all works as expected.
The sidebar here is that if you are using a top-level agent none, the environment and presumably other pre-stages blocks are not running in an agent. So anything that relies on an agent will behave unexpectedly.

Answer 2

Groovy's optional parenthesis requires at least one parameter, which is different than Ruby.
Method calls can omit the parentheses if there is at least one parameter and there is no ambiguity:
So, to call the dump() method you would do env.dump() or params.dump(). However, this method will not be whitelisted and you will get a security exception (if you are running in the sandbox or using any sort of Jenkins security) because this would print out all fields of the object.

Answer 3

Thanks to StephenKing for pointing out, i check again with a new fresh Jenkins instance. see comments inside
Assuming the job has 2 parameters [str1=val1, bool1=true] :
node {
// Print the value of a job parameter named "str1"
// output: val1
println "${params.str1}"
// Calling the dump() function to print all job parameters (keys/vals)
// NOTE: calling this method should be approved by Jenkins admin
// output: .... m=[str1:val1, bool1:true] ...
println params.dump()
// Same as the above.
// output: .... m=[str1:val1, bool1:true] ...
println "${params.dump()}"
// SYNTAX ERROR, the '$' is not expected here by the parser
//println ${params.dump()};
// This appears in the question, but it seems like this is not
// what the author meant. It tries to find a param named "dump"
// which is not available
// output: null
println params.dump
}