LibraryConfiguration: defaultedVersion(): check for BRANCH_NAME first; and then it is safer to check getSCMs() not for WorkflowRun, but for the FlowDefinition from WorkflowJob [JENKINS-69731]

Author: jimklimov

src/main/java/org/jenkinsci/plugins/workflow/libs/LibraryConfiguration.java

@@ -38,6 +38,8 @@
 import hudson.scm.SCM;
 import hudson.util.FormValidation;
 import jenkins.model.Jenkins;
+import org.jenkinsci.plugins.workflow.flow.FlowDefinition;
+import org.jenkinsci.plugins.workflow.job.WorkflowJob;
 import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
@@ -196,18 +198,64 @@ public LibraryCachingConfiguration getCachingConfiguration() {
 
             // without a runParent we can't validateVersion() anyway
             if (runParent != null) {
-                // First ask SCM source of the pipeline (if any),
-                // as the most authoritative source of the branch
-                // name we want:
+                // First, check if envvar BRANCH_NAME is defined?
+                // Trust the plugins and situations where it is set.
                 try {
-                    if (run instanceof WorkflowRun) {
-                        // This covers both "Multibranch Pipeline"
-                        // and "Pipeline script from SCM" jobs;
-                        // it also covers "inline" pipeline scripts
-                        // but throws a hudson.AbortException since
-                        // there is no SCM attached.
-                        WorkflowRun wfRun = (WorkflowRun) run;
-                        SCM scm0 = wfRun.getSCMs().get(0);
+                    runVersion = run.getEnvironment(listener).get("BRANCH_NAME", null);
+                } catch (Exception x) {
+                    // no-op, keep null
+                }
+
+                if (runVersion == null) {
+                    // Probably not in a multibranch pipeline workflow
+                    // type of job?
+                    // Ask for SCM source of the pipeline (if any),
+                    // as the most authoritative source of the branch
+                    // name we want:
+                    try {
+                        SCM scm0 = null;
+
+                        if (runParent instanceof WorkflowJob) {
+                            // This covers both "Multibranch Pipeline"
+                            // and "Pipeline script from SCM" jobs;
+                            // it also covers "inline" pipeline scripts
+                            // but should return an empty Collection of
+                            // SCMs since there is no SCM attached to
+                            // the "static source".
+                            // TODO: If there are "pre-loaded libraries"
+                            // in a Jenkins deployment, can they interfere?
+                            FlowDefinition fd = ((WorkflowJob)runParent).getDefinition();
+                            if (fd != null) {
+                                for (SCM scmN : fd.getSCMs()) {
+                                    if ("hudson.plugins.git.GitSCM".equals(scm0.getClass().getName())) {
+                                        // The best we can do here is accept
+                                        // the first seen SCM (with branch
+                                        // support which we know how to query).
+                                        scm0 = scmN;
+                                        break;
+                                    }
+                                }
+                            }
+                        }
+
+/*
+                        // NOTE: the list of SCMs used by the run does not
+                        // seem trustworthy: if an "inline" pipeline script
+                        // (not from SCM) is used, there is no "relevant"
+                        // branch name to request; however the list of SCMs
+                        // would be populated as @Library lines are processed
+                        // and some SCM sources get checked out.
+                        if (scm0 == null && run instanceof WorkflowRun) {
+                            // This covers both "Multibranch Pipeline"
+                            // and "Pipeline script from SCM" jobs;
+                            // it also covers "inline" pipeline scripts
+                            // but throws a hudson.AbortException since
+                            // there is no SCM attached.
+                            WorkflowRun wfRun = (WorkflowRun) run;
+                            scm0 = wfRun.getSCMs().get(0);
+                        }
+*/
+
                         if (scm0 != null) {
                             // Avoid importing GitSCM and so requiring that
                             // it is always installed even if not used by
@@ -255,24 +303,14 @@ public LibraryCachingConfiguration getCachingConfiguration() {
                             } // else SVN, Gerritt or some other SCM -
                               // add handling when needed and known how
                               // or rely on BRANCH_NAME (if set) below...
-                        }
 
-                        // Still alive? Chop off leading '*/'
-                        // (if any) from single-branch MBP and
-                        // plain "Pipeline" job definitions.
-                        if (runVersion != null) {
-                            runVersion = runVersion.replaceFirst("^\\*/", "");
+                            // Still alive? Chop off leading '*/'
+                            // (if any) from single-branch MBP and
+                            // plain "Pipeline" job definitions.
+                            if (runVersion != null) {
+                                runVersion = runVersion.replaceFirst("^\\*/", "");
+                            }
                         }
-                    }
-                } catch (Exception x) {
-                    // no-op, keep null
-                }
-
-                if (runVersion == null) {
-                    // Probably not in a multibranch pipeline workflow
-                    // type of job? Is envvar BRANCH_NAME defined?
-                    try {
-                        runVersion = run.getEnvironment(listener).get("BRANCH_NAME", null);
                     } catch (Exception x) {
                         // no-op, keep null
                     }