In principle, this can already be done with a shell script step from a workflow (using, e.g., the ssh interface to gerrit), but that can be a bit tedious. But a feature that is not currently possible is to influence how the voting happens after the build finishes. See JENKINS-32692 for some background.

One solution on the Gerrit Trigger side, which would probably provide a better integration in the long run, would be to provide a workflow step that can be used to influence the final vote: e.g., to set the Url to Post option, or the message to write (this could also replace the ability to pass Unsuccessful Message File, which is not possible from a workflow).

I can create a separate issue for this if you prefer.

I have drafted an initial implementation for setting a custom URL or a custom unsuccessful message from a workflow step for the final vote. I don't have any prior experience from developing for Jenkins, so I might have missed some things, but at least existing tests pass, as does my one new test. I haven't tested whether the workflow snippetizer works. I'll push it to GitHub once I have a bit more time.

For now, I used this DSL syntax:

gerritReview customUrl: 'myUrl', unsuccessfulMessage: 'message'

This could possibly be extended to also post immediately without much confusion to cover more of this feature request, but alternative suggestions are welcome.

Code changed in jenkins
User: Teemu Murtola
Path:
pom.xml
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ToGerritRunListener.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep.java
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep/config.jelly
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep/help-unsuccessfulMessage.html
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep/help.html
src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/hudsontrigger/WorkflowTest.java
http://jenkins-ci.org/commit/gerrit-trigger-plugin/427d422b5c1ed7c3d69bfb0d6db4c89b6f760d8f
Log:
Workflow step for setting unsuccessful message

Add a workflow step that allows setting the unsuccessful message from a
workflow build. config.jelly is currently missing.

Dependency to the workflow plugin is optional.

Implements a limited part of JENKINS-26103.

Code changed in jenkins
User: Teemu Murtola
Path:
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ParameterExpander.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ToGerritRunListener.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/model/BuildMemory.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep.java
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep/config.jelly
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/GerritReviewStep/help-customUrl.html
src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/hudsontrigger/WorkflowTest.java
http://jenkins-ci.org/commit/gerrit-trigger-plugin/3e31f724712d5a6f43605f18f601ca0d18d63423
Log:
Allow setting custom url in workflow

Extend the gerritReview workflow step to also allow setting the URL to
post. Use the existing mechanism (BuildMemory) for storing the value
while the build is running.

Implements a limited part of JENKINS-26103.

Code changed in jenkins
User: Robert Sandell
Path:
pom.xml
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ParameterExpander.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ToGerritRunListener.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/model/BuildMemory.java
src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/SetGerritReviewStep.java
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/SetGerritReviewStep/config.jelly
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/SetGerritReviewStep/help-customUrl.html
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/SetGerritReviewStep/help-unsuccessfulMessage.html
src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/workflow/SetGerritReviewStep/help.html
src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ParameterExpanderTest.java
src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/gerritnotifier/ToGerritRunListenerTest.java
src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/hudsontrigger/WorkflowTest.java
http://jenkins-ci.org/commit/gerrit-trigger-plugin/b7ab5892c183e6ca91ce00325f009d9f1571a8b8
Log:
Merge pull request #274 from teemumurtola/workflow-steps

Partial implementation for JENKINS-26103

Compare: https://github.com/jenkinsci/gerrit-trigger-plugin/compare/64d7d8aa16c1...b7ab5892c183