Document how to setup a gitlabrunner connected to repo for CI testing.

docs/developer/testing-repo1-CI.md

+# Testing repo1 CI against a dedicated runner
+
+This page will describe how to deploy bigbang with a GitLab Runner that is connected to repo1. Source documentation for GitLab Runner is available at https://docs.gitlab.com/runner/.
+
+## Why
+
+* You need to test GitLab Runner configuration against repo1
+* You need to test integrating CI pipelines to infrastructure or other bigbang services.
+
+## How
+
+### Request access
+
+You will need either of these:
+
+* Admin access to a repo on repo1
+* Or access to create personal repos under your account on repo1
+
+Contact the Big Bang Government Team Lead to request access.
+
+### Create gitlab runner and token
+
+1. Go to *Settings -> CI/CD* on the repo you want to test against.
+1. Expand the *Runners* section and click *New project runner*
+1. Select *Run untagged jobs* and *Lock to current projects* and click *Create runner*
+1. On the next page Copy the *runner authentication token* for later
+
+### Deploy a k8s cluster and install flux
+
+by default the easiest way to test is to spin up a cluster using the k3d-dev.sh script.
+you can follow the directions <https://repo1.dso.mil/big-bang/bigbang/-/blob/master/docs/developer/aws-k3d-script.md>
+
+### Deploy Big Bang
+
+1. Create an overrides file with the following content, along with any additional [configuration settings](https://docs.gitlab.com/runner/executors/kubernetes/#configuration-settings) you need to test
+
+```yaml
+# enable grafana alloy to push traces to
+addons:
+  alloy:
+    enabled: true
+
+# enable gitlabrunners for ci-tracing
+  gitlabRunner:
+    enabled: true
+    values:
+      # set the url to repo1
+      gitlabUrl: https://repo1.dso.mil
+      runners:
+        # use custom config and remove cloneUrl paramaters
+        config: |
+          [[runners]]
+            [runners.kubernetes]
+              pull_policy = "always"
+              namespace = "{{.Release.Namespace}}"
+              image = "{{ printf "%s/%s:%s" .Values.runners.job.registry .Values.runners.job.repository .Values.runners.job.tag }}"
+              helper_image = "{{ printf "%s/%s:%s" .Values.runners.helper.registry .Values.runners.helper.repository .Values.runners.helper.tag }}"
+              image_pull_secrets = ["private-registry"]
+            [runners.kubernetes.pod_security_context]
+              run_as_non_root = true
+              run_as_user = 1001
+            [runners.kubernetes.helper_container_security_context]
+              run_as_non_root = true
+              run_as_user = 1001
+            [runners.kubernetes.pod_labels]
+              "job_id" = "${CI_JOB_ID}"
+              "job_name" = "${CI_JOB_NAME}"
+              "pipeline_id" = "${CI_PIPELINE_ID}"
+              "app" = "gitlab-runner"
+```
+
+1. Deploy BigBang with the above override file
+
+```bash
+helm upgrade -i bigbang ./chart -n bigbang --create-namespace -f ./docs/assets/configs/example/policy-overrides-k3d.yaml -f ../overrides/registry-values.yaml -f ./chart/ingress-certs.yaml -f ../overrides/gitlabrunner-test.yaml
+```
+
+1. Create a secret with the token for the runner
+Replace *runnertoken* with the token that was created for the runner.
+
+```bash
+kubectl -n gitlab-runner create secret generic gitlab-gitlab-runner-secret --from-literal=runner-registration-token=runnertoken --from-literal=runner-token=runnertoken
+```
+
+1. Validate that the runner is connected to repo1. Goto the repo on repo1 then *Settings->CI/CD*, expand the *Runners* section the runner should be marked as green.
+1. Now create a CI workflow for the repo and let it run, it should choose the gitlab runner on your k3d cluster.