Introduce rusty-cachier (#11462)

* Introduce `rusty-cachier`

* Return LF at the end of file

* Use `entrypoint` to `unshare(1)` into a new mount namespace

* Use `rusty-cachier`-provided absolute path for `CARGO_TARGET_DIR` everywhere

* Debug single `build-rustdoc` job

* CI: debug

* CI: debug

* CI: debug

* `unshare(1)` is no longer needed

* CI: remove debug

* Revert "Debug single `build-rustdoc` job"

* Formatiing

* Update scripts/ci/gitlab/pipeline/build.yml

Co-authored-by: Denis Pisarev <denis.pisarev@parity.io>

substrate/.gitlab-ci.yml

@@ -47,6 +47,8 @@ variables:                         &default-vars
   DOCKER_OS:                       "debian:stretch"
   ARCH:                            "x86_64"
   CI_IMAGE:                        "paritytech/ci-linux:production"
+  RUSTY_CACHIER_SINGLE_BRANCH:     master
+  RUSTY_CACHIER_DONT_OPERATE_ON_MAIN_BRANCH: "true"
 
 default:
   retry:
@@ -86,10 +88,22 @@ default:
     - rustup +nightly show
     - cargo +nightly --version
 
+.rusty-cachier:
+  before_script:
+    - curl -s https://gitlab-ci-token:${CI_JOB_TOKEN}@gitlab.parity.io/parity/infrastructure/ci_cd/rusty-cachier/client/-/raw/release/util/install.sh | bash
+    - rusty-cachier environment check --gracefully
+    - $(rusty-cachier environment inject)
+    - rusty-cachier project mtime
+  after_script:
+    - rusty-cachier snapshot destroy
+
 .docker-env:
   image:                           "${CI_IMAGE}"
   before_script:
     - !reference [.rust-info-script, script]
+    - !reference [.rusty-cachier, before_script]
+  after_script:
+    - !reference [.rusty-cachier, after_script]
   tags:
     - linux-docker