CI: return docs jobs (#8307)

* CI: return docs jobs allowing them to fail

* CI: refrain from Dwarnings for now

* CI: pass RUSTFLAGS directly; no need removing what wasn't there

substrate/.gitlab-ci.yml

@@ -468,6 +468,30 @@ build-macos-subkey:
   tags:
     - osx
 
+build-rust-doc:
+  stage:                           build
+  <<:                              *docker-env
+  <<:                              *test-refs
+  needs:
+    - job:                         test-linux-stable
+      artifacts:                   false
+  variables:
+    <<:                            *default-vars
+    SKIP_WASM_BUILD:               1
+  artifacts:
+    name:                          "${CI_JOB_NAME}_${CI_COMMIT_REF_NAME}-doc"
+    when:                          on_success
+    expire_in:                     7 days
+    paths:
+    - ./crate-docs/
+  script:
+    - RUSTDOCFLAGS="--html-in-header $(pwd)/.maintain/rustdoc-header.html"
+        time cargo +nightly doc --no-deps --workspace --all-features --verbose
+    - mv ./target/doc ./crate-docs
+    - echo "<meta http-equiv=refresh content=0;url=sc_service/index.html>" > ./crate-docs/index.html
+    - sccache -s
+  allow_failure:                   true
+
 #### stage:                        publish
 
 .build-push-docker-image:          &build-push-docker-image
@@ -550,6 +574,32 @@ publish-s3-release:
     - aws s3 ls s3://${BUCKET}/${PREFIX}/latest/
         --recursive --human-readable --summarize
 
+publish-s3-doc:
+  stage:                           publish
+  image:                           paritytech/awscli:latest
+  allow_failure:                   true
+  needs:
+    - job:                         build-rust-doc
+      artifacts:                   true
+    - job:                         build-linux-substrate
+      artifacts:                   false
+  <<:                              *publish-refs
+  <<:                              *kubernetes-build
+  variables:
+    GIT_STRATEGY:                  none
+    BUCKET:                        "releases.parity.io"
+    PREFIX:                        "substrate-rustdoc"
+  script:
+    - test -r ./crate-docs/index.html || (
+        echo "./crate-docs/index.html not present, build:rust:doc:release job not complete";
+        exit 1
+      )
+    - aws s3 sync --delete --size-only --only-show-errors
+        ./crate-docs/ s3://${BUCKET}/${PREFIX}/
+  after_script:
+    - aws s3 ls s3://${BUCKET}/${PREFIX}/
+        --human-readable --summarize
+
 publish-draft-release:
   stage:                           publish
   image:                           paritytech/tools:latest