[CIFuzz] Documentation (#3368)

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docs/getting-started/continuous_integration.md

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+---
+layout: default
+title: Continuous Integration
+parent: Getting started
+nav_order: 5
+permalink: /getting-started/continuous-integration/
+---
+
+# Continuous Integration
+
+OSS-Fuzz offers **CIFuzz**, which will run your fuzz targets each time a pull request
+is submitted, for projects hosted on GitHub. This allows you to detect and
+fix bugs before they make it into your codebase
+
+## How it works
+
+CIFuzz works by checking out a repository at the head of a pull request. The
+project's fuzz targets are built and run for
+a definite amount of time (default is 10 minutes). If a bug is found, the
+stack trace as well as the test case are made abailable for download.
+ If a crash is not found the test passes with a green check.
+
+## Requirements
+
+1. Your project must be integrated in OSS-Fuzz.
+1. Your project is hosted on GitHub.
+
+## Integrating into your repository
+
+You can integrate CIFuzz into your project using the following steps:
+1. Create a `.github` directory in the root of your project.
+1. Create a `workflows` directory inside of your `.github` directory.
+1. Copy the example [`main.yml`](https://github.com/google/oss-fuzz/blob/master/infra/cifuzz/example_main.yml)
+file over from the OSS-Fuzz repository to the `workflows` directory.
+1. Change the `project-name` value in `main.yml` from `example` to the name of your OSS-Fuzz project. It is **very important** that you use your OSS-Fuzz project name which is case sensitive. This name
+is the name of your project's subdirectory in the [`projects`](https://github.com/google/oss-fuzz/tree/master/projects) directory of OSS-Fuzz.
+
+Your directory structure should look like the following:
+```
+project
+|___ .github
+|    |____ workflows
+|          |____ main.yml
+|___ other-files
+```
+
+main.yml for an example project:
+
+```yaml
+name: CIFuzz
+on: [pull_request]
+jobs:
+ Fuzzing:
+   runs-on: ubuntu-latest
+   steps:
+   - name: Build Fuzzers
+     uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+     with:
+       project-name: 'example'
+       dry-run: false
+   - name: Run Fuzzers
+     uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+     with:
+       fuzz-time: 600
+       dry-run: false
+   - name: Upload Crash
+     uses: actions/upload-artifact@v1
+     if: failure()
+     with:
+       name: artifacts
+       path: ./out/artifacts
+```
+
+
+
+### Optional configuration
+
+`fuzz-time`: Determines how long CIFuzz spends fuzzing your project in seconds.
+The default is 600 seconds. The GitHub Actions max run time is 21600 seconds (6 hours).
+
+`dry-run`: Determines if CIFuzz surfaces errors. The default value is `false`. When set to `true`,
+CIFuzz will never report a failure even if it finds a crash in your project.
+This requires the user to manually check the logs for detected bugs. If dry run mode is desired,
+make sure to set the dry-run parameters in both the `Build Fuzzers` and `Run Fuzzers` action step.
+
+## Understanding results
+
+The results of CIFuzz can be found in two different places.
+
+* Run fuzzers log:
+    1. This log can be accessed in the `actions` tab of a CIFuzz integrated repo.
+    1. Click on the `CIFuzz` button in the workflow selector on the left hand side.
+    1. Click on the event triggered by your desired pull request.
+    1. Click the `Fuzzing` workflow.
+    1. Select the `Run Fuzzer` drop down. It should show the timestamps and results
+    from each of the fuzz targets.
+
+![Finding fuzzer output](../images/run_fuzzers.png)
+
+
+*  Artifacts:
+    1. When a crash is found by CIFuzz the Upload Artifact event is triggered.
+    1. This will cause a pop up in the right hand corner, allowing
+    you to download a zip file called `artifacts`.
+    1. `artifacts` contains two files:
+        * `test_case` - a test case that can be used to reproduce the crash.
+        * `bug_summary` - the stack trace and summary of the crash.
+
+![Finding uploaded artifacts](../images/artifacts.png)
+
+
+## Feedback/Questions/Issues
+
+Create an issue in [OSS-Fuzz](https://github.com/google/oss-fuzz/issues/new) if you have questions of any other feedback on CIFuzz.