release: Fix GC conditional check

Refactor load_gc function to streamline file path handling
and improve error handling, while updating the GC job trigger
to check gc_policy_data for better clarity and robustness.

Author: gursewak1997

jobs/release.Jenkinsfile

@@ -4,6 +4,7 @@ node {
     pipeutils = load("utils.groovy")
     pipecfg = pipeutils.load_pipecfg()
     libcloud = load("libcloud.groovy")
+    gc_policy_data = pipeutils.load_gc()
 }
 
 def brew_principal = pipecfg.brew?.principal
@@ -343,7 +344,7 @@ lock(resource: "release-${params.STREAM}", extra: locks) {
             }
         }
         // Trigger the GC job only if `gc-policy.yaml` exists, which currently applies only to FCOS.
-        if (pipeutils.load_gc()) {
+        if (gc_policy_data) {
             stage('Fork Garbage Collection') {
                 build job: 'garbage-collection', wait: false, parameters: [
                     string(name: 'STREAM', value: params.STREAM),

utils.groovy

@@ -98,12 +98,13 @@ def load_gc() {
     def jenkinscfg = load_jenkins_config()
     def url = jenkinscfg['pipecfg-url']
     def gc_policy_data
+    def filePath = (url == 'in-tree') ? 'gc-policy.yaml' : 'pipecfg/gc-policy.yaml'
 
-    if (url == 'in-tree') {
-        gc_policy_data = readYaml(file: "gc-policy.yaml")
+    if (fileExists(filePath)) {
+        gc_policy_data = readYaml(file: filePath)
     } else {
-        // assume the user called `load_pipecfg()` in this workdir; if not, let error out
-        gc_policy_data = readYaml(file: "pipecfg/gc-policy.yaml")
+        echo "GC policy file '${filePath}' not found. Skipping load."
+        return null
     }
 
     return gc_policy_data