Jenkins Copy Artifact unable to find folder/multiProjectPipeline/branchWithSlash - jenkins

Question

I have Jenkins LTS 2.60.2 on Windows Server 2016 and using these plugins:
Folders plugin (6.1.0)
Copy Artifact plugin (1.38.1)
Pipeline plugin (2.5) + all dependent pipeline sub-plugins
Various other dependent plugins...
See Pipeline to use artifacts from 2 projects associated by the same git branch name for more details about my setup, but to sum it up I have these items:
playground (a folder created with the Folders plugin to group all these following items)
frontend (multibranch pipeline)
backend (multibranch pipeline)
configure (pipeline with a parameter called BRANCH_NAME)
The frontend and backend git repos, both have a branch called master and one called release/2017.2.
The idea is to call the configure pipeline automatically after each successful build, passing the git branch name. Automatically triggering the configure pipeline works.
What doesn't work and I need your help to fix, is the step inside the configure pipeline to copy the artifacts from a multibranchPipeline/specificBranch.
If for the BRANCH_NAME parameter (or the upstream pipeline) is master it works. If BRANCH_NAME is: release/2017.2 I get this error:
ERROR: Unable to find project for artifact copy:
playground/frontend/release%2f2017.2 This may be due to incorrect project
name or permission settings; see help for project name in job
configuration. Finished: FAILURE
The configure pipeline looks like this:
node {
stage('Prepare') {
def projectname = "playground/frontend/" + "${BRANCH_NAME}".replace("/", "%2f")
step([$class: 'CopyArtifact', projectName: "${projectname}", selector: [$class: 'StatusBuildSelector', stable: false]])
}
stage('Archive') {
archiveArtifacts '**'
}
}
As you can see I already replace / with %2f (it's needed).
If I don't use the "playground" folder (all my pipelines as is, not inside a folder item), it works. If I use the folder and use the master branch, it works. It doesn't work if I use the folder and a branch name like 2017.2. What am I doing wrong? Can you help making it work? Of well if it's a bug (I searched in https://issues.jenkins-ci.org and found some bugs where a similar setup with folder doesn't work, but they have been fixed... so I really wonder...) in the copy artifact plugin, please file the bug and share the link here, so we can all monitor its progress...
Thank you.

Answer 1

I finally found the issue. The configure pipeline was failing to find a branch with a slash because the encoding was incorrect.
So, in my question, in the configure pipeline:
this (replace / with %2f) is wrong and generates the error:
def projectname = "playground/frontend/" + "${BRANCH_NAME}".replace("/", "%2f")
this is the proper way to encode the slash, and it works:
def projectname = "playground/frontend/" + URLEncoder.encode("${BRANCH_NAME}", "UTF-8").replace("+", "%20")
Credits to: http://www.pipegrep.se/copy-artifacts-from-jenkins-pipeline-jobs.html
UPDATE: actually, I investigated a bit further and added echo "${projectname}" just before step, with the previous and fixed projectname, and I noticed that the difference was %2f lowercase.
Uppercase, like this: %2F works:
def projectname = "playground/frontend/" + "${BRANCH_NAME}".replace("/", "%2F")
So, the fixed configure pipeline looks like this (I kept my replace function, which was enough for my case):
node {
stage('Prepare') {
def projectname = "playground/frontend/" + "${BRANCH_NAME}".replace("/", "%2F")
step([$class: 'CopyArtifact', projectName: "${projectname}", selector: [$class: 'StatusBuildSelector', stable: false]])
}
stage('Archive') {
archiveArtifacts '**'
}
}

Answer 2

I created a sample project to try and recreate what you were seeing, and I was able to do so, after a fashion, except that the build that I was having trouble on was master instead of release/2017.2. Eventually, I realized that I was doing the build job incorrectly from the frontend project, and it was giving me the same error as you because I hadn't ever completed a successful build of the frontend/master branch (I had completed a successful build of the release/2017.2 branch because I didn't have it triggering the configure build initially, so it didn't give me the same error once I did configure it to trigger the configure build).
What worked was changing the build job in the frontend Jenkinsfile to this:
build job: 'playground/configure', parameters: [[$class: 'StringParameterValue', name: 'BRANCH_NAME', value: env.BRANCH_NAME]], quietPeriod: 2, wait: false
Adding in the quietPeriod gives a couple seconds of quiet time between completing the previous job (I'm not certain that this is critical, but it seems like it might be a nice fail-safe, to try and make sure there's enough time for the build to complete), but the important part is the wait: false, which instructs Jenkins that this build shouldn't wait for the triggered build to complete. Once I changed that, the frontend/master branch completed successfully, and the configure build that it triggered also completed successfully.
Hopefully this helps. I was able to get both my master and release/2017.2 branches to build properly, so I don't believe there's any intrinsic problem with the / in the project name. You can see my simple Jenkinsfiles in the referenced repo, and I used the same pipeline script as you posted in your question.