CI: add link-checking GH action, stop failing Netlify build on link-check issues (#2504)

.github/workflows/check-links.yml

@@ -0,0 +1,18 @@
+name: Check links and refcache # cSpell:ignore refcache
+
+on:
+  pull_request:
+
+jobs:
+  check-formatting:
+    name: Check links and refcache
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - run: npm install
+      - run: npm run build
+      - run: npm run _check:links
+
+      - name: Fail on uncommitted refcache changes
+        run: npm run diff:fail

netlify.toml

@@ -1,9 +1,9 @@
 [build]
 publish = "public"
-command = "npm run s build:preview diff:fail"
+command = "npm run s build:preview diff:check"
 
 [context.production]
-command = "npm run s build:production diff:fail"
+command = "npm run s build:production diff:check"
 
 [[redirects]]
 from = "https://docs.opentelemetry.io/*"

package.json

@@ -11,6 +11,7 @@
     "_check:formatting": "npx prettier --check .",
     "_check:links": "HTMLTEST_ARGS='--log-level 1' npm run __check:links",
     "_check:links:internal": "npm run __check:links",
+    "_check:links--warn": "npm run _check:links || (echo; echo 'WARNING: see link-checker output for issues.'; echo)",
     "_get:no": "echo SKIPPING get operation",
     "_get:submodule:non-lang": "npm run _get:submodule -- content-modules/opentelemetry-specification themes/docsy",
     "_get:submodule": "set -x && git submodule update --init ${DEPTH:- --depth 1}",
@@ -33,8 +34,8 @@
     "diff:fail": "git diff --name-only --exit-code || (echo; echo 'ERROR: the files above have changed. Locally rerun `npm run test` and commit changes'; echo; git diff | head -100; exit 1)",
     "get:submodule": "npm run _get:${GET:-submodule}",
     "make:public": "make public ls-public",
-    "postbuild:preview": "npm run _check:links",
-    "postbuild:production": "npm run _check:links",
+    "postbuild:preview": "npm run _check:links--warn",
+    "postbuild:production": "npm run _check:links--warn",
     "prebuild:preview": "run-s _prebuild",
     "prebuild:production": "run-s _prebuild check:formatting",
     "prebuild": "npm run _prebuild",