counterweight
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jar-lid-archive's CI needs `docker build` and `docker compose`, and job
containers had no Docker at all: config.yml carried the stock
`container.docker_host: "-"`, which is precisely "find a daemon for the
runner and do not let jobs near it".
A docker:dind sidecar now runs on forgejo-runner-box, published on
127.0.0.1 only, and jobs build against that instead of the host daemon.
Following Forgejo's own admin docs, which make the point that this is
THREE settings and not one:
forgejo-dind.service a privileged docker:dind on the host daemon
container.docker_host tcp://127.0.0.1:2376 - where the runner
CREATES job containers
runner.envs.DOCKER_HOST + tcp://forgejo-dind.docker.internal:2375 -
container.options how a job, from INSIDE dind, reaches it
The third is the one that is easy to miss and fails identically to
having done nothing: for a tcp:// docker_host the runner mounts nothing
into the job container, so the job still finds no daemon. The two
addresses differ because they are used from different places - the
runner is a process on the host; a job container is inside dind, where
127.0.0.1 is itself. `host-gateway` is expanded by the daemon creating
the container, which is dind, so it lands on dind's own bridge gateway.
Verified on the box, along the exact path a job takes - a container on a
user-defined network, with the same --add-host and DOCKER_HOST the
runner will set: the name resolves to 172.20.0.1, `docker version`
returns the dind server, and `docker build` succeeds. The host daemon
runs forgejo-dind and nothing else.
config.yml had to become a template to do any of this. It was previously
`generate-config` run once on first deploy and never touched again, so
the repo had no say in its contents. Every value was transcribed from
the live file and diffed against it key by key: with dind disabled, 30
of 30 identical. Two deliberate differences - runner.envs drops
A_TEST_ENV_NAME_1/2, upstream's placeholders, which were being injected
into every job here; and the upstream comment blob is gone. Because the
file is managed now it also gets a restart handler, the absence of which
has bitten this repo before.
Things deliberately chosen rather than defaulted into:
- the flag lives in the playbook, not the role defaults, so the role's
default stays the configuration this host has always run and turning
it off is one line. Disabling it also tears the units down rather than
just skipping them.
- dind is a hard Requires= of forgejo-runner, and its unit stays in
"activating" until the daemon answers. A dead dind is then one red
unit instead of a green runner failing every job it claims.
- the healthcheck and monitored_services learned about dind for the same
reason: runner up + dind down is the interesting failure and it was
previously invisible.
- /var/lib/docker is a named volume, or every image is re-pulled on each
container recreation; a weekly prune keeps that from growing forever.
- dind's network pool is pinned to 172.20.0.0/14. Docker's stock pool
reaches into 192.168.x, and act_runner creates a network per job, so a
job could eventually allocate this LAN's subnet and lose the route to
every box on it.
Note this runner is SHARED - arbret, arbret-biz, arbretdos and
arbret-ops build here too, far more often, and docker_host is per-runner
not per-repo. Their workflows are unchanged but their next run pulls
images into a cold cache. Job images still need a docker client of their
own: node:{20,22}-bookworm ship none.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
51 lines
2.3 KiB
YAML
51 lines
2.3 KiB
YAML
---
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# config.yml is a TEMPLATE now, not a one-shot `generate-config`.
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#
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# Before this, the file was generated on first deploy and never touched again,
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# so the repo had no say in anything inside it - including container.docker_host,
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# which is the setting that decides whether jobs can use Docker at all. The
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# alternative was patching keys in place with a regex, which in a YAML file
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# with repeated key names under different parents is the kind of thing that
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# works until it silently does not.
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#
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# owner/group/mode are runner:runner 0644, read off the live box, matching what
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# `generate-config` plus the old chown produced. Nothing secret is in here; the
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# registration token lives in .runner.
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- name: Write the forgejo-runner configuration
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ansible.builtin.template:
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src: config.yml.j2
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dest: "{{ forgejo_runner_config_path }}"
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owner: "{{ forgejo_runner_user }}"
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group: "{{ forgejo_runner_user }}"
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mode: '0644'
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# A malformed config is a runner that will not start. Catch it here, while
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# the old file is still in place, rather than after it has been replaced.
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validate: "python3 -c \"import yaml,sys; yaml.safe_load(open(sys.argv[1]))\" %s"
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notify: Restart forgejo-runner
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# ── Register runner ────────────────────────────────────────────────────────
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# Registration is separate from configuration and happens once. The labels are
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# frozen into .runner at this point; changing forgejo_runner_labels later does
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# not move them, which is why the label set is left exactly as it was.
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- name: Check if runner is already registered
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stat:
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path: "{{ forgejo_runner_dir }}/.runner"
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register: runner_stat
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- name: Register runner with Forgejo instance
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command: >
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{{ forgejo_runner_bin_path }} register --no-interactive
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--instance {{ forgejo_instance_url }}
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--token {{ forgejo_runner_registration_token }}
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--name forgejo-runner-box
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--labels "{{ forgejo_runner_labels }}"
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args:
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chdir: "{{ forgejo_runner_dir }}"
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when: not runner_stat.stat.exists
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- name: Set runner registration file ownership
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file:
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path: "{{ forgejo_runner_dir }}/.runner"
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owner: "{{ forgejo_runner_user }}"
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group: "{{ forgejo_runner_user }}"
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when: not runner_stat.stat.exists
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