Self-hosting fxTeX Server

Running it

One image, listening on port 80, with nothing to persist. A converter with no cache and no database has no state to lose, so a replica can be stopped at any moment and scaling is simply a matter of adding replicas.

docker login
docker run -d -p 8080:80 -e FXTEX_SITE=https://equations.example.com willzyba/fxtexserver:version
curl "http://localhost:8080/svg.image?x%5E2"Copy

On Docker Swarm, the registry credential has to travel with the deploy — that is what --with-registry-auth does; without it no node can pull the image and the tasks never start:

docker stack deploy --with-registry-auth --compose-file docker-fxtex.yml fxtexCopy

version: "3.9"

services:
    fxtex:
        image: willzyba/fxtexserver:version
        deploy:
            mode: replicated
            replicas: 4
            placement:
                max_replicas_per_node: 2
            update_config:
                parallelism: 2
                delay: 10s
            restart_policy:
                condition: any
                delay: 5s
                max_attempts: 5
                window: 120s
        volumes:
            - /etc/fxtex:/etc/fxtex:ro         # the domain and key lists, if you use them
        environment:
            - FXTEX_SITE=https://equations.example.com
            - FXTEX_DOMAINS_FILE=/etc/fxtex/domains
            - FXTEX_API_KEYS_FILE=/etc/fxtex/keys
        ports:
            - 8080:80
        healthcheck:
            test: wget -qO - http://127.0.0.1/health || exit 1
            interval: 30s
            timeout: 5s
            retries: 3
            start_period: 15sCopy

Each replica serves one request at a time and conversion takes a fraction of a millisecond, so throughput comes from the number of replicas. max_replicas_per_node keeps one node's failure from taking the whole service with it. Updating is the same deploy with a new tag; Swarm rolls the replicas two at a time and the service stays up throughout.

/health answers OK on its first line, followed by counters: requests by type, errors, and whether access control is on.

Who may use it

With no domains and no keys configured, the service is open to anyone who can reach it — the usual arrangement inside a private network. Configure either and it enforces them, with the same rules as the hosted service: a request is accepted if its Referer is a listed domain or it carries a listed key. See Access and keys.

Both lists are plain text, one entry per line, # for comments:

# /etc/fxtex/domains - the domain, then its allowance
example.com       enterprise      # example.com and every subdomain, unlimited
*.partner.org     100 1000        # subdomains of partner.org (not partner.org itself):
                                  # 100 a second, bursts of 1000

# /etc/fxtex/keys - the key, a label the logs use in its place, then its allowance
sk_internal_8f2a  reporting-service  enterpriseCopy

The allowance is either a tier name — demo, essential, pro or enterprise, the last meaning no limit — or a rate and a burst given as numbers. An entry with neither gets demo, the lightest, so on a private deployment you will usually want enterprise.

The files are watched: an edit takes effect within about five seconds, with no restart and no dropped request. If a file cannot be read, the list already loaded stays in force. Under Swarm the files must be present, and identical, on every node that can run a replica.

Configuration

Everything else — logs included — goes to standard error, which in a container is the log, collected and rotated by whatever collects the rest of yours.

Pointing the editor and plugins at it

Anything that renders through fxTeX Server can be pointed at your own. For the plugins, set their render URL option — renderUrl, eqneditor_render_url and so on — to your FXTEX_SITE. For fxTeX's right-click menu, use fxTeX.configureContextMenu({ server: 'https://equations.example.com/' }).

More

API — the URL interface your deployment answers.

Access and keys — how domains and keys are matched.

Contact us — about an Enterprise licence.