Research spike Arch-Z (docker-compose)

[efritz]

Implements a portion of RFC 696: Reduced isolation deployments for executor.

Explore how to write a docker-compose.override.yaml file with our current executor distribution so that we can loosely bundle privileged executors on compose deployments. Findings should be added to product documentation (on installing/configuring executors).

[efritz]

Current work in progress:

version: '2.4'
services:
  executor:
    container_name: executor
    image: 'index.docker.io/sourcegraph/executor:insiders@sha256:4909f85ba9b2446cf7c901dc735f265493b50e90acaf4cc0d36bac11d8c0d1b4'
    cpus: 1
    mem_limit: '4g'
    user: root
    privileged: true
    environment:
      # sync with `executors.frontendURL` in site config
      - EXECUTOR_FRONTEND_URL=http://sourcegraph-frontend-0:3080
      # sync with `executors.accessToken` in site config
      - EXECUTOR_FRONTEND_PASSWORD=hunter2hunter2hunter2
      # Choose what work to process
      - EXECUTOR_QUEUE_NAME=codeintel
      # Documenting defaults
      - EXECUTOR_MAXIMUM_RUNTIME_PER_JOB=30m
      - EXECUTOR_MAXIMUM_NUM_JOBS=2
      - EXECUTOR_NUM_TOTAL_JOBS=200
      - EXECUTOR_MAX_ACTIVE_TIME=2h
      # Run as root
      - UID=1000
      - GID=1000
      # Note: path must be equivalent to mounted executor-scratch (see volumes)
      - TMPDIR=/tmp/sourcegraph/executor-scratch
    volumes:
      # Note: paths must be equivalent on host and in docker
      - '/tmp/sourcegraph/executor-scratch:/tmp/sourcegraph/executor-scratch'
      - '/var/run/docker.sock:/var/run/docker.sock'
    networks:
      - sourcegraph
    restart: always

[efritz]

Related: #36830

[efritz]

A working solution can be found in this branch/PR.