buildContainerImage: Allow passing arguments

The `registry`, `project`, `name`, and `tag` values can now be passed as
keyword arguments to the `buildContainerImage` function.  This will
allow jobs to override the default values if necessary.

vars/buildContainerImage.groovy

@@ -1,21 +1,33 @@
 // vim: set sw=4 sts=4 ts=4 et :
 
-def call() {
+def call(args) {
     properties([
         pipelineTriggers([cron('H H H * *')])
     ])
 
-    def registry ='git.pyrocufflink.net'
-    def project = 'containerimages'
-    def name = env.JOB_NAME.
-        split('/')[1].
-        toLowerCase().
-        replaceAll('[^a-zA-z0-9._-]', '-').
-        replaceAll('^[.-]', '_')
-    def tag = env.BRANCH_NAME.
-        toLowerCase().
-        replaceAll('[^a-zA-z0-9._-]', '-').
-        replaceAll('^[.-]', '_')
+    def registry = args.registry
+    def project = args.project
+    def name = args.name
+    def tag = args.tag
+    if (registry == null) {
+        registry = 'git.pyrocufflink.net'
+    }
+    if (project == null) {
+        project = 'containerimages'
+    }
+    if (name == null) {
+        name = env.JOB_NAME.
+            split('/')[1].
+            toLowerCase().
+            replaceAll('[^a-zA-z0-9._-]', '-').
+            replaceAll('^[.-]', '_')
+    }
+    if (tag == null) {
+        tag = env.BRANCH_NAME.
+            toLowerCase().
+            replaceAll('[^a-zA-z0-9._-]', '-').
+            replaceAll('^[.-]', '_')
+    }
     def repo = "${registry}/${project}/${name}"
     def full_name = "${repo}:${tag}"