try

container/lib.yaml

@@ -8,6 +8,7 @@
         else
           DOCKER_AUTH=$(echo -n "${DOCKER_USERNAME}:${DOCKER_PASSWORD}" | base64 -w0)
           echo "{\"auths\":{\"https://index.docker.io/v1/\":{\"auth\":\"$DOCKER_AUTH\"}}}" > /kaniko/.docker/config.json
+          cat /kaniko/.docker/config.json
         fi
     - |
         if [[ -z "${CI_COMMIT_TAG}" ]]; then