Use GITHUB_TOKEN to authenticate downloads in CI (#2415)

* Allow Trixi.download to read the GH_TOKEN from the environment

* expose GH_TOKEN in CI

* fixup! expose GH_TOKEN in CI

* Apply suggestions from code review

Co-authored-by: Hendrik Ranocha <[email protected]>

* Update src/auxiliary/auxiliary.jl

---------

Co-authored-by: Michael Schlottke-Lakemper <[email protected]>
Co-authored-by: Hendrik Ranocha <[email protected]>

Author: 3 people

.github/workflows/ci.yml

@@ -119,6 +119,7 @@ jobs:
         env:
           PYTHON: ''
           TRIXI_TEST: ${{ matrix.trixi_test }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # for authenticated downloads without strict rate limits
       - uses: julia-actions/julia-processcoverage@v1
         if: ${{ !cancelled() }}
         with:

src/auxiliary/auxiliary.jl

@@ -311,12 +311,24 @@ Download a file from given `src_url` to given `file_path` if
 `file_path`.
 This is a small wrapper of `Downloads.download(src_url, file_path)`
 that avoids race conditions when multiple MPI ranks are used.
+Furthermore, when run as part of a GitHub Action, it uses
+token-authenticated downloads to avoid GitHub's rate limiting
+for unauthenticated HTTP request. To use this feature, provide
+the environment variable `GITHUB_TOKEN`.
 """
 function download(src_url, file_path)
     # Note that `mpi_isroot()` is also `true` if running
     # in serial (without MPI).
     if mpi_isroot()
-        isfile(file_path) || Downloads.download(src_url, file_path)
+        if !isfile(file_path)
+            headers = Pair{String, String}[]
+            # Pass the GITHUB_TOKEN through to prevent rate-limiting
+            token = get(ENV, "GITHUB_TOKEN", nothing)
+            if token !== nothing
+                push!(headers, "authorization" => "Bearer $token")
+            end
+            Downloads.download(src_url, file_path; headers)
+        end
     end
 
     if mpi_isparallel()