Using a custom traefik toml file or template

I’m trying with @jhadjar to change the proxy config in /opt/tljh/state/traefik.toml but it is overwritten by traefik.toml.tpl every time the proxy is reloaded, is there any way to set a custom file or template to be used instead?

[yuvipanda]

@GeorgianaElena yeah, an escape hatch sounds great, especially for web proxy config. Maybe something along the lines of https://github.com/jupyterhub/zero-to-jupyterhub-k8s/pull/1636?

[jhadjar]

Can you please explain a bit what’s your use-case and how would modifying traefik.toml.tpl help?

Sure. The issues encountered serving JupyterLab static files on slow, unstable, internet connections lead us to look into two things:

• 1. Compression
• 1. Caching

We failed to enable compression at the jupyterhub_config.py level (Tornado settings), as per https://github.com/tornadoweb/tornado/blob/18d7026853900c56a1879141235c6b6bd51b0a6a/tornado/web.py#L2044

c.JupyterHub.tornado_settings = {
    'headers': {
        'Content-Security-Policy': f"frame-ancestors 'self' {os.getenv('XXX_URL', '*')}",
    },
    'compress_response': True,
    # 'gzip': True,
    # We have also tried the previouly supported parameter 'gzip'
}

This did not work, which lead us to enable compression at the Traefik level:

# traefik.toml

[entryPoints.https]
address = ":8080"
compress = true      # <--------- Add this line

tljh overrides this with the line we feel hard codes the template file and reduces flexibility at https://github.com/jupyterhub/the-littlest-jupyterhub/blob/master/tljh/traefik.py#L90:

    with open(os.path.join(os.path.dirname(__file__), "traefik.toml.tpl")) as f:

Is there a reason this is hard-coded? Given that the function ensure_traefik_config loads a config, is it not sensible to make the config it loads a parameter of the function before touching other parts of the system?

Something like this:

DEFAULT_TOML_TEMPLATE = os.path.join(os.path.dirname(__file__), "traefik.toml.tpl")
TRAEFIK_TOML_TEMPLATE = os.environ.get('TRAEFIK_TOML_TEMPLATE', DEFAULT_TOML_TEMPLATE)

def ensure_traefik_config(state_dir, traefik_toml_template=None):
    ...
    traefik_toml_template = traefik_toml_template or TRAEFIK_TOML_TEMPLATE
    with open(traefik_toml_template) as f:
        template = Template(f.read())
    ...

One way to do that according to @hMED22 is:

# jupyterhub_config.py
c.TraefikTomlProxy.toml_dynamic_config_file = dynamic_conf_file_path

and changing https://github.com/jupyterhub/the-littlest-jupyterhub/blob/87bed7aaf1617960a8137055d2f8d4301a0b72b3/tljh/systemd-units/traefik.service#L21