Jenkinsfile: Add metadata to detect partial builds

Keep track of skipped artifacts, failed builds and if the build has been
killed half way so we can find out if a build is suitable for
releasing/longer term preservation (for instance, for being saved as a
weekly entry).

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

Jenkinsfile

@@ -474,7 +474,11 @@ def buildImages(architecture, type, boards, debosarguments = "", image = true, s
 
                 // Mark the whole pipeline as failed in case of failure at any stage
                 if (buildStatus.containsValue(false)) {
-                      currentBuild.result = 'FAILURE'
+                  currentBuild.result = 'FAILURE'
+                  // mark builds where some artifacts have failed to build
+                  dir ("${env.PIPELINE_VERSION}/meta/") {
+                    writeFile (file: "failed-${architecture}-${type}", text: '')
+                  }
                 }
 
                 // Upload artifacts
@@ -551,3 +555,35 @@ buildCandidates.each { name, arch ->
 parallel first_pass
 parallel second_pass
 
+node() {
+  stage("upload meta") {
+    skipped = architectures - buildCandidates
+    complete = !skipped && currentBuild.resultIsBetterOrEqualTo('SUCCESS')
+
+    skippednames = []
+    for (architecture in skipped) {
+      for (type in architecture.value.types) {
+        skippednames << "skipped-${architecture.key}-${type.key}"
+      }
+    }
+
+    dir ("${env.PIPELINE_VERSION}/meta/") {
+      writeFile (file: "build-version", text: env.PIPELINE_VERSION)
+      writeFile (file: "build-url", text: env.BUILD_URL)
+
+      // report which entries have been skipped
+      for (String skippedname : skippednames) {
+        writeFile (file: skippedname, text: '')
+      }
+
+      // mark builds that have not been killed half way
+      writeFile (file: "finished", text: '')
+      // mark successful builds with no skipped artifacts, they're the best candidates for longer term storage
+      if (complete) {
+        writeFile (file: "complete", text: '')
+      }
+    }
+
+    uploadDirectory (env.PIPELINE_VERSION, "daily/${release}")
+  }
+}