  To reproduce eScience, several challenges need to be solved: scientific
workflows need to be automated; the involved software versions need to be
provided in an unambiguous way; input data needs to be easily accessible;
High-Performance Computing (HPC) clusters are often involved and to achieve
bit-to-bit reproducibility, it might be even necessary to execute the code on a
particular cluster to avoid differences caused by different HPC platforms (and
unless this is a scientist's local cluster, it needs to be accessed across
(administrative) borders). Preferably, to allow even inexperienced users to
(re-)produce results, all should be user-friendly. While some easy-to-use
web-based scientific portals support already to access HPC resources, this
typically only refers to computing and data resources that are local. By the
example of two community-specific portals in the fields of biodiversity and
climate research, we present a solution for accessing remote HPC (and cloud)
compute and data resources from scientific portals across borders, involving
rigorous container-based packaging of the software version and setup
automation, thus enhancing reproducibility.
