Build pipeline

This document describes the requirements and recommendations for setting up a continuous build pipeline for a project using ClusterFuzz.

Why do you need a build pipeline?

Fuzzing is a software testing technique which works out best if done continuously. As your target projects evolve, ClusterFuzz needs to be able to fuzz the most recent versions of them. Having a continuously running build pipeline allows ClusterFuzz to identify revisions when a regression was introduced as well as detect bug fixes and the corresponding revisions.

Setting up a builder

ClusterFuzz does not provide any build infrastructure, as build systems can be very different across projects. If you have existing CI infrastructure, very likely it can be used for providing builds to ClusterFuzz.


As described in the Setting up fuzzing docs, your builds need to be instrumented with a sanitizer. See the individual links for each sanitizer here for instructions on how to use them.

Providing the builds to ClusterFuzz

  • The builds should be packed into zip or tar archives and uploaded to a GCS bucket. Uploading can be done via gsutil tool or by using signed URLs.
  • The archive name should be of any-name-([0-9]+).zip format, where ([0-9]+) stands for a revision number such as SVN commit position, a timestamp, or another build number which increases with every build. Other than zip, we support tar extensions as well.
  • When setting up a fuzzing job, specify RELEASE_BUILD_BUCKET_PATH env variable to point to the builds location, e.g. gs://bucket-name/subdirectory/any-name-([0-9]+).zip.

Providing revisions for the build dependencies

ClusterFuzz is able to detect regression and fixed revision ranges not only for your target project, but for its dependencies as well. The only requirement is to provide a .srcmap.json file alongside the build archive. The filename should be the same as the build archive name, but with .srcmap.json suffix instead of .zip/.tar* (i.e. any-name-([0-9]+).srcmap.json).

When setting up a fuzzing job, specify REVISION_VARS_URL env variable to point to srcmap files location, e.g. gs://bucket-name/subdirectory/any-name-([0-9]+).srcmap.json.

These srcmap files have the following format:

  "/path/to/library": {
    "type": "type_of_version_control_system",
    "url": "repository_url",
    "rev": "revision_identifier",
  // any number of the projects enumerated in this format

An example of .srcmap.json for a libpng build:

  "/src/libpng": {
    "type": "git",
    "url": "",
    "rev": "eddf9023206dc40974c26f589ee2ad63a4227a1e"
  "/src/zlib": {
    "type": "git",
    "url": "",
    "rev": "cacf7f1d4e3d44d871b605da3b647f07d718623f"
  "/src/libfuzzer": {
    "type": "svn",
    "url": "",
    "rev": "350185"

Other artifacts and runtime dependencies

If your target program requires any additional runtime dependencies or artifacts such as seed corpus or a dictionary for libFuzzer or AFL, all these files should be placed in the same directory as the target executable and be included in the build archive.

Build pipeline solutions

Most of the Continuous Integration systems can be used for providing builds to ClusterFuzz. Examples include Google Cloud Build, Jenkins, and others.