README: move nomad-girlab-runner documentation to github wiki

README.md

@@ -185,156 +185,12 @@ context to or from the local host using stdout and stdin forwarded by
 An implementation of custom Gitlab executor driver that runs Gitlab CI/CD jobs
 using Nomad.
 
-Allows running _not_ the `gitlab-runner` itself in Nomad. Rather, the
-`gitlab-runner` is running on (any) one host. That `gitlab-runner` will the
-schedule Nomad job to execute. These jobs will execute the CI/CD from Gitlab.
-
-The `nomad-gitlab-runner` script runs a background Nomad job for the
-whole duration of Gitlab CI/CD task. There are 3 modes available that you
-can specify in configuration file: `raw_exec`, `exec` and `docker` mode.
-
-In `raw_exec` and `exec` modes, the Nomad job has one task. It is
-not supported to specify services in `gitlab-ci.yml`. On each stage of
-`gitlab-runner` executor is executed with `nomad alloc exec` inside the task
-spawned in Nomad with a provided entrypoint script. This script adjusts
-niceness levels, adjusts OOM killer, sets `taskset -s` and switches user
-with `runuser -u` and runs bash shell if available with falling back to
-sh shell.
-
-In `docker` mode, the Nomad job has multiple tasks, similar to
-`gitlab-runner` docker executor spawning multiple images. One task
-is used to clone the repository and manage artifacts, exactly like in
-https://docs.gitlab.com/runner/executors/docker.html#docker-executor-workflow
-in gitlab-runner docker executor. The other task is the main task of the
-job. It does not run the job image entrypoint. All commands are executed
-with `nomad alloc exec` with the custom entrypoint wrapper. In this case
-the wrapper does not use `taskset` nor `runuser`, as these parameters are
-set with docker configuration.
-
-Specifying services in `.gitlab-ci.yml` in `docker` mode
-is supported.  Each service is a separate task in the group
-in the Nomad job. The Nomad job runs the task group in
-bridge mode docker networking, so that all tasks share the
-same network stack. One additional "waiter" task is created that
-runs `prestart` to wait for the services to respond. This is meant to mimic 
-the default `gitlab-runner` docker executor behavior described in
-https://docs.gitlab.com/runner/executors/docker.html#how-gitlab-runner-performs-the-services-health-check .
-
-In order for services to work, it is hard coded that the
-waiter helper image starts with `/var/run/docker.sock` mounted
-inside to connect to docker. Additionally, Nomad has to support
-'bridge' docker network driver for Nomad to start the job. See
-https://developer.hashicorp.com/nomad/docs/networking#bridge-networking .
-
-Below is an example `/etc/gitlab-runner/config.toml` configuration file
-to work with `nomad-gitlab-runner`. Just execute it on each stage and pass
-the argument with the stage name.
-
-    # /etc/gitlab-runner/runner.toml
-    [[runners]]
-      id = 27898742
-      executor = "custom"
-      [runners.custom]
-        config_exec = "nomad-gitlab-runner"
-        config_args = ["config"]
-        prepare_exec = "nomad-gitlab-runner"
-        prepare_args = ["prepare"]
-        run_exec = "nomad-gitlab-runner"
-        run_args = ["run"]
-        cleanup_exec = "nomad-gitlab-runner"
-        cleanup_args = ["cleanup"]
-
-`nomad-gitlab-runner` uses configuration stores in `/etc/gitlab-runner/nomad-gitlab-runner.yml` file.
-Execute `nomad-gitlab-runner showconfig` to print current program
-configuration. The example shortest sensible needed configuration file is presented below.
-
-    # /etc/gitlab-runner/nomad-gitlab-runner.yml
-    ---
-    default:
-      NOMAD_TOKEN: "1234567"
-      CPU: 2048
-      MemoryMB: 2048
-      docker:
-        services_privileged: true
-
-    27898742:
-      mode: docker
-
-This is another longer example of configuration file with some comments:
-
-    # /etc/gitlab-runner/nomad-gitlab-runner.yml
-    ---
-    default:
-      # You can use NOMAD_* variables here.
-      NOMAD_TOKEN: "12345"
-      NOMAD_NAMESPACE: gitlabrunner
-    27898742
-      mode: docker
-      CPU: 2048
-      MemoryMB: 2048
-      MemoryMBMax: 2048
-      docker:
-        # Default docker image.
-        image: "alpine:latest"
-        # Set to true to be able to run dind service.
-        services_privileged: true
-      override:
-        task_config:
-          cpuset_cpus: "2-8"
-
-The configuration file has a default section that applies to all
-configurations. Then, each key is the runner ID as specified in `config.toml`
-of `gitlab-runner` configuration. Each key has a separate configuration.
-
-The Nomad job by default makes available the standard Nomad directories. The
-`alloc` directory is shared between all the tasks, including "waiter" task,
-cloning task and services specified in `.gitlab-ci.yml`.
-
-To use `docker:dind` you can use the standard configuration if you use
-`auto_fix_docker_dind` configuration option. `auto_fix_docker_dind` is by
-default true and if `DOCKER_TLS_CERTDIR` is specified in the variables, then
-`nomad-gitlab-runner` mounts allocation at `/certs` and sets other needed
-`DOCKER_*` variables by itself.
-
-    # .gitlab-ci.yml
-    ---
-    docker_dind_auto:
-      image: docker:24.0.5
-      services:
-        - docker:24.0.5-dind
-      variables:
-        # When the configuration option auto_fix_docker_dind is set to true, then:
-        DOCKER_TLS_CERTDIR: "/certs"
-      script:
-        - docker info
-        - docker run -ti --rm alpine echo hello world
-
-If `auto_fix_docker_dind` is false, you need to set `DOCKER_*` variables
-yourself just like for Kubernetes executor. Use `/alloc` directory to share
-the certificates between client and server.
-
-    # .gitlab-ci.yml
-    ---
-    docker_dind_alloc:
-      variables:
-        DOCKER_CERT_PATH: "/alloc/client"
-        DOCKER_HOST: tcp://docker:2376
-        DOCKER_TLS_CERTDIR: "/alloc"
-        DOCKER_TLS_VERIFY: 1
-      script:
-        - docker info
-        - docker run -ti --rm alpine echo hello world
-
-`nomad-gitlab-runner` requires to be able to `nomad alloc exec` in Nomad
-policy. I recommend `gitlabrunner` namespace name. The policy might look
-like the following:
-
-    namespace "gitlabrunner" {
-        # For creating jobs.
-        policy = "write"
-        # To alloc 'raw_exec' to execute anything.
-        capabilities = ["alloc-node-exec"]
-    }
+This program does _not_ run the `gitlab-runner` itself in Nomad. Rather, the
+`gitlab-runner` is running on (any) one host. That `gitlab-runner` will then
+schedule Nomad jobs to execute using the script as an executor. These jobs will
+execute the CI/CD from Gitlab inside Nomad cluster.
+
+More on it can be read on [github wiki](https://github.com/Kamilcuk/nomad-tools/wiki/nomad%E2%80%90gitlab%E2%80%90runner).
 
 ## nomad-dockers