feat: add a fuzzing workflow to github actions

Currently this won't actually run anything, because we haven't written
any fuzz tests, but it sets up the framework for running the built-in Go
fuzzer against any tests that do get added

.github/workflows/ci.yml

@@ -1,3 +1,4 @@
+---
 name: CI
 
 on: [push, pull_request]
@@ -15,6 +16,7 @@ jobs:
 
     env:
       DEBUG: true
+      GOFLAGS: -trimpath
       KAFKA_VERSION: ${{ matrix.kafka-version }}
 
     steps:
@@ -25,9 +27,18 @@ jobs:
       with:
         go-version: ${{ matrix.go-version }}
 
-    - uses: actions/cache@v2
+    - name: Get Go environment
+      id: go-env
+      run: |
+        echo "::set-output name=cache::$(go env GOCACHE)"
+        echo "::set-output name=modcache::$(go env GOMODCACHE)"
+
+    - name: Set up cache
+      uses: actions/cache@v2
       with:
-        path: ~/go/pkg/mod
+        path: |
+          ${{ steps.go-env.outputs.cache }}
+          ${{ steps.go-env.outputs.modcache }}
         key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
         restore-keys: |
           ${{ runner.os }}-go-

.github/workflows/fuzz.yml

@@ -0,0 +1,42 @@
+---
+name: Fuzzing
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Fuzz
+    runs-on: ubuntu-latest
+
+    env:
+      GOFLAGS: -trimpath
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Setup Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.17.x
+
+    - name: Get Go environment
+      id: go-env
+      run: |
+        echo "::set-output name=cache::$(go env GOCACHE)"
+        echo "::set-output name=modcache::$(go env GOMODCACHE)"
+
+    - name: Set up cache
+      uses: actions/cache@v2
+      with:
+        path: |
+          ${{ steps.go-env.outputs.cache }}
+          ${{ steps.go-env.outputs.modcache }}
+        key: fuzz-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          fuzz-go-
+
+    - name: Build Go tip
+      run: go install golang.org/dl/gotip@latest && gotip download
+
+    - name: Run any fuzzing tests
+      run: gotip test -v -run=^Fuzz -test.fuzztime=5m ./...