add clusterfuzzlite PR fuzzing. (#2784)

Signed-off-by: Sepehrdad Sh <26747519+sepehrdaddev@users.noreply.github.com>

.clusterfuzzlite/Dockerfile

@@ -0,0 +1,6 @@
+FROM gcr.io/oss-fuzz-base/base-builder-go
+
+COPY . $SRC/skipper
+COPY ./.clusterfuzzlite/build.sh $SRC/
+
+WORKDIR $SRC/skipper

.clusterfuzzlite/build.sh

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+#!/bin/bash -eu
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+for target in $(find $SRC/skipper/fuzz/fuzz_targets -name 'Fuzz*.go'); do
+        target_basename=$(basename -s .go $target)
+
+        compile_go_fuzzer github.com/zalando/skipper/fuzz/fuzz_targets $target_basename $target_basename gofuzz
+done
+
+mv $SRC/skipper/fuzz/dictionaries/*.dict $OUT/

.clusterfuzzlite/project.yaml

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+language: go
+fuzzing_engines:
+  - libfuzzer
+sanitizers:
+  - address

.github/workflows/cflite_pr.yaml

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+name: ClusterFuzzLite PR fuzzing
+on:
+  pull_request:
+    paths:
+      - '**'
+permissions: read-all
+jobs:
+  PR:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: ${{ github.workflow }}-${{ matrix.sanitizer }}-${{ github.ref }}
+      cancel-in-progress: true
+    strategy:
+      fail-fast: false
+      matrix:
+        sanitizer:
+        - address
+    steps:
+    - name: Build Fuzzers (${{ matrix.sanitizer }})
+      id: build
+      uses: google/clusterfuzzlite/actions/build_fuzzers@v1
+      with:
+        language: go
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        sanitizer: ${{ matrix.sanitizer }}
+    - name: Run Fuzzers (${{ matrix.sanitizer }})
+      id: run
+      uses: google/clusterfuzzlite/actions/run_fuzzers@v1
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        fuzz-seconds: 300
+        mode: 'code-change'
+        sanitizer: ${{ matrix.sanitizer }}
+        output-sarif: true