Gitlab - use gitlab-runner on multiple hosts to update the same project with a simple gitlab-ci.yml file

Question

I am running gitlab and gitlab-runners to update projects on linux hosts and they all update the same project. However the gitlab-ci.yml configuration is lacking at best for what I need.

For example I have around 500 hosts that will run a script when the project gets pushed to re-configure the machines per the script from contents in the project. Note: this is the same project on every host.

To get this to work I have to modify a tag like host1 and host2 per host and then create a huge file with 500 hosts.

The gitlab-ci.yml is as follows for the working method:

stages:
  - build

host1_build:
  stage: build
  tags:
    - host1
  script:
    - sudo bash /project/update.sh

host2_build:
  stage: build
  tags:
    - host2
  script:
    - sudo bash /project/update.sh

I would like to be able to have one tag like update on each host and a single build in the gitlab-ci.yml file; however when configured like this it only runs on a single host.

update_build:
  stage: build
  tags:
    - update
  script:
    - sudo bash /project/update.sh

I have done some other things with no success except the first working option shown which is time-consuming to manage and hoped someone knew of some other option here to update the same project on many hosts at once.