Use Github workflow cache for Go CI builds (#2499)

We cache downloaded Go modules and the Go build cache. The cache is
OS-specific. See
https://github.com/mvdan/github-actions-golang#how-do-i-set-up-caching-between-builds

Signed-off-by: Antonin Bas <abas@vmware.com>

.github/workflows/go.yml

@@ -9,6 +9,9 @@ on:
     - main
     - release-*
 
+env:
+  go-cache-name: go
+
 jobs:
   test-unit:
     name: Unit test
@@ -17,18 +20,28 @@ jobs:
         os: [ubuntu-latest, windows-2019]
     runs-on: ${{ matrix.os }}
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
+    - uses: actions/cache@v2
+      with:
+        # In order:
+        # * Module download cache
+        # * Build cache (Linux)
+        # * Build cache (Mac)
+        path: |
+          ~/go/pkg/mod
+          ~/.cache/go-build
+          ~/Library/Caches/go-build
+          %LocalAppData%\go-build
+        key: ${{ runner.os }}-${{ env.go-cache-name }}-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-${{ env.go-cache-name }}-
     - name: Run unit tests
       run: make test-unit
-
     - name: Codecov
       uses: codecov/codecov-action@v1
       with:
@@ -37,26 +50,35 @@ jobs:
         flags: unit-tests
         name: codecov-unit-test
 
-
   golangci-lint:
     name: Golangci-lint
     strategy:
       matrix:
         platform: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.platform }}
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
+    - uses: actions/cache@v2
+      with:
+        # In order:
+        # * Module download cache
+        # * Build cache (Linux)
+        # * Build cache (Mac)
+        path: |
+          ~/go/pkg/mod
+          ~/.cache/go-build
+          ~/Library/Caches/go-build
+          %LocalAppData%\go-build
+        key: ${{ runner.os }}-${{ env.go-cache-name }}-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-${{ env.go-cache-name }}-
     - name: Run golangci-lint
       run: make golangci
-
     - name: Run golangci-lint for netpol
       working-directory: hack/netpol
       run: make golangci
@@ -65,89 +87,98 @@ jobs:
     name: Build Antrea and antctl binaries
     runs-on: [ubuntu-latest]
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
+    - uses: actions/cache@v2
+      with:
+        # In order:
+        # * Module download cache
+        # * Build cache (Linux)
+        # * Build cache (Mac)
+        path: |
+          ~/go/pkg/mod
+          ~/.cache/go-build
+          ~/Library/Caches/go-build
+          %LocalAppData%\go-build
+        key: ${{ runner.os }}-${{ env.go-cache-name }}-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-${{ env.go-cache-name }}-
     - name: Build Antrea binaries for amd64
       run: GOARCH=amd64 make bin
-
     - name: Build Antrea binaries for arm64
       run: GOARCH=arm64 make bin
-
     - name: Build Antrea binaries for arm
       run: GOARCH=arm make bin
-
     - name: Build antctl binaries
       run: make antctl
 
   windows-bin:
     name: Build Antrea Windows binaries
     runs-on: [ubuntu-latest]
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
+    - uses: actions/cache@v2
+      with:
+        # In order:
+        # * Module download cache
+        # * Build cache (Linux)
+        # * Build cache (Mac)
+        path: |
+          ~/go/pkg/mod
+          ~/.cache/go-build
+          ~/Library/Caches/go-build
+          %LocalAppData%\go-build
+        key: ${{ runner.os }}-${{ env.go-cache-name }}-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-${{ env.go-cache-name }}-
     - name: Build Antrea windows binaries
       run: make windows-bin
 
   tidy-codegen-manifest:
     name: Check tidy, code generation and manifest
     runs-on: [ubuntu-latest]
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
     # tidy check need to be run before code generation which will regenerate codes.
     - name: Check tidy
       run: make test-tidy
-
     - name: Check code generation
       run: ./ci/check-codegen.sh
-
     - name: Check manifest
       run: ./ci/check-manifest.sh
 
   verify:
     name: Verify docs and spelling
     runs-on: [ubuntu-latest]
     steps:
-
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
         go-version: 1.15
-
     - name: Check-out code
       uses: actions/checkout@v2
-
     - name: Run verify scripts
       run: make verify
-
     - name: Checking for broken Markdown links
       uses: antoninbas/github-action-markdown-link-check@1.0.9-pre
       with:
         folder-path: './docs'
         file-path: './README.md, ./CHANGELOG.md, ./CONTRIBUTING.md, ./GOVERNANCE.md, ./MAINTAINERS.md, ./ROADMAP.md, ./SECURITY.md'
         config-file: 'hack/.md_links_config.json'
-
     - name: Markdownlint
       run: |
         sudo npm install -g markdownlint-cli