CI/Makefile: decouple test for linkcheck to allow it to fail

.gitlab-ci.yml

@@ -172,6 +172,15 @@ test:documentation:
     - sudo ln -s /usr/bin/sphinx-build-3 /usr/bin/sphinx-build
     - make doc-html
 
+test:linkcheck:
+  <<: *test_definition
+  script:
+    - sudo apk add --no-cache py3-sphinx py3-sphinx_rtd_theme
+    - sudo pip3 uninstall 'idna' --yes ## Fix up dependencies in alpine:3.8
+    - sudo pip3 install 'idna<2.7'
+    - sudo ln -s /usr/bin/sphinx-build-3 /usr/bin/sphinx-build
+    - make doc-linkcheck
+  allow_failure: true
 
 
 ############################################################

Makefile

@@ -56,7 +56,10 @@ doc-html: all
 	@mkdir -p $$(pwd)/docs/_build/api/odoc
 	@rm -rf $$(pwd)/docs/_build/api/odoc/*
 	@cp -r $$(pwd)/_build/default/_doc/* $$(pwd)/docs/_build/api/odoc/
-	@${MAKE} -C docs
+	@${MAKE} -C docs html
+
+doc-linkcheck:
+	@${MAKE} -C docs linkcheck
 
 build-test:
 	@dune build @buildtest