Add custom labels in build request with conda and spack packges

src/main/groovy/io/seqera/wave/service/builder/ContainerBuildServiceImpl.groovy

@@ -165,6 +165,44 @@ class ContainerBuildServiceImpl implements ContainerBuildService {
         }
     }
 
+    //this method adds labels in singularity container
+    protected static String addLabels(String containerFile, final BuildRequest req){
+        final labels = req.containerConfig?.labels
+        if(labels) {
+            if (req.formatSingularity()) {
+                return containerFile + getSingularityLabels(labels)
+            }
+            if (req.formatDocker()){
+                return containerFile + getDockerLabels(labels)
+            }
+        }
+        return containerFile
+    }
+
+    protected static String getSingularityLabels(Map<String, String> labels){
+        StringBuilder labelsBuilder = new StringBuilder()
+        labelsBuilder.append("\n%labels\n")
+        labels.each() { key, value ->
+            labelsBuilder.append(key)
+            labelsBuilder.append(" ")
+            labelsBuilder.append(value)
+            labelsBuilder.append("\n")
+        }
+        return labelsBuilder.toString()
+    }
+
+    protected static String getDockerLabels(Map<String, String> labels){
+        StringBuilder labelsBuilder = new StringBuilder()
+        labelsBuilder.append("\nLABEL ")
+        labels.each() { key, value ->
+            labelsBuilder.append(key)
+            labelsBuilder.append("=")
+            labelsBuilder.append(value)
+            labelsBuilder.append(" ")
+        }
+        return labelsBuilder.toString()
+    }
+
     protected BuildResult launch(BuildRequest req) {
         // launch an external process to build the container
         BuildResult resp=null
@@ -177,7 +215,7 @@ class ContainerBuildServiceImpl implements ContainerBuildService {
             catch (FileAlreadyExistsException e) { /* ignore it */ }
             // save the dockerfile
             final containerFile = req.workDir.resolve('Containerfile')
-            Files.write(containerFile, containerFile0(req, context, spackConfig).bytes, CREATE, WRITE, TRUNCATE_EXISTING)
+            Files.write(containerFile, addLabels(containerFile0(req, context, spackConfig), req).bytes, CREATE, WRITE, TRUNCATE_EXISTING)
             // save build context
             if( req.buildContext ) {
                 saveBuildContext(req.buildContext, context, req.identity)

src/test/groovy/io/seqera/wave/service/builder/ContainerBuildServiceTest.groovy

@@ -393,7 +393,6 @@ class ContainerBuildServiceTest extends Specification {
         and:
         def layer = new Packer().layer(source)
         def context = BuildContext.of(layer)
-        and:
 
         when:
         service.saveBuildContext(context, target, Mock(PlatformId))
@@ -445,4 +444,59 @@ class ContainerBuildServiceTest extends Specification {
         server?.stop(0)
     }
 
+    def 'should resolve singularity file with labels' () {
+        given:
+        def folder = Files.createTempDirectory('test')
+        def builder = new ContainerBuildServiceImpl()
+        and:
+        def context = Path.of('/some/context/dir')
+        def singularityFile = "Bootstrap: docker \n from alpine"
+        def REQ = new BuildRequest(singularityFile, folder, 'box:latest', null, null, BuildFormat.SINGULARITY, Mock(PlatformId),null, null,  ContainerPlatform.of('amd64'), null, null, null, "", null)
+        and:
+        def labels = [
+                "arch": "arm64",
+                "packageName": "salmon",
+                "version": "1.0.0"
+        ]
+        REQ.withLabels(labels)
+
+        when:
+        def result = builder.addLabels(builder.containerFile0(REQ, context, null), REQ)
+
+        then:
+        result.contains('%labels\n'+
+                'arch arm64\n' +
+                'packageName salmon\n' +
+                'version 1.0.0')
+
+        cleanup:
+        folder?.deleteDir()
+    }
+
+    def 'should resolve docker file with labels' () {
+        given:
+        def folder = Files.createTempDirectory('test')
+        def builder = new ContainerBuildServiceImpl()
+        and:
+        def context = Path.of('/some/context/dir')
+        def dockerFile = "from alpine"
+        def REQ = new BuildRequest(dockerFile, folder, 'box:latest', null, null, BuildFormat.DOCKER, Mock(PlatformId),null, null,  ContainerPlatform.of('amd64'), null, null, null, "", null)
+        and:
+        def labels = [
+                "arch": "arm64",
+                "packageName": "salmon",
+                "version": "1.0.0"
+        ]
+        REQ.withLabels(labels)
+
+        when:
+        def result = builder.addLabels(builder.containerFile0(REQ, context, null), REQ)
+
+        then:
+        result.contains('LABEL arch=arm64 packageName=salmon version=1.0.0')
+
+        cleanup:
+        folder?.deleteDir()
+    }
+
 }