jarl/docs/development.md

# Developing Jarl

## Layout

```
cmd/jarld/            daemon: serve, init, import, adopt, check, render, resync, backup, user
cmd/jarl/             CLI
internal/
  model/              configuration objects (State: views, ACLs, keys, zones, records, options) and changesets
  dnsname/            DNS name handling: FQDNs, relative names, check-names rules, reverse zones
  rr/                 record data parsing/canonicalization (miekg/dns), TXT quoting, the record type catalog
  namedconf/          named.conf lexer, parser and printer; address match lists
  catalog/            every BIND 9.20 statement: grammar (from named.conf(5)) + ARM descriptions, embedded
  validate/           whole-configuration validation and security lints
  render/             State → named.conf, keys.conf and zone files, with a source map for error messages
  bind/               named-checkconf, named-checkzone and rndc wrappers
  engine/             changesets: expand requests into ops, replay, validate, render, check, deploy, reload, verify, revert;
                      import and adopt
  importer/           reads an existing named.conf tree and its zone files
  store/              SQLite (modernc.org/sqlite, no cgo): state, changesets, users, tokens, sessions, audit
  auth/               argon2id passwords, tokens, sessions, grants and roles
  server/             HTTP API, authentication, the web UI
  stats/              query statistics: statistics-channel poller, response-log tailer, collector, separate SQLite store
  web/static/         the web UI: plain ES modules, no build step, embedded with go:embed
  api/, client/       JSON types and the Go client shared by server and CLI
  acme/               ACME DNS-01 challenge records, shared by jarl acme and the httpreq endpoint
  config/             jarld's YAML configuration
deploy/               systemd unit, sysusers.d and tmpfiles.d files
deploy/debian/        the Debian package's control template and postinst/prerm/postrm
contrib/acme.sh/      acme.sh DNS API hook
contrib/lego/         program for lego's exec DNS provider
scripts/e2e.sh        end-to-end test against a real named
scripts/mkdeb.sh      builds the Debian package (make deb)
scripts/logo.py       traces artwork/logo.png into the web UI's logo (logo.svg, logo.js)
scripts/banner.py     builds the README's banner from the web UI's logo and wordmark
artwork/              the logo's master image and the README's banner
```

The main flow is in `internal/engine/engine.go` (`applyOps`):
expand → replay → validate → render → check → install → reload → verify →
record. [concepts.md](concepts.md) describes it from the outside.

## Building and testing

```sh
make            # bin/jarld, bin/jarl (CGO_ENABLED=0, version from ./VERSION),
                # and bin/completion/{jarl,jarld} (bash completion)
make test       # go vet, gofmt check, go test ./...
make e2e        # scripts/e2e.sh
make deb        # dist/jarl_<version>_<arch>.deb (DEB_ARCH=arm64 etc. cross-builds)
```

### The Debian package

`make deb` runs `scripts/mkdeb.sh`: it builds the binaries for
`DEB_ARCH`, installs them with `make install-files` into a staging tree
with Debian's paths (`PREFIX=/usr`, the unit in `/usr/lib/systemd/system`),
adds `deploy/debian/{postinst,prerm,postrm}` and a `control` file filled in
from `deploy/debian/control.in`, and packs it with `dpkg-deb
--root-owner-group`, so no root is needed. The version comes from
`./VERSION` (a `-` becomes `~`, so `0.2.0-rc1` sorts before `0.2.0`;
override with `DEB_VERSION`), and the maintainer from your git name and
email (override with `DEB_MAINTAINER`). The package ships no files in
`/etc`: postinst writes `/etc/jarl/jarl.yaml` once, so upgrades never touch
it.

To try the package without installing it on your machine:

```sh
docker run --rm -it -v "$PWD/dist:/pkg:ro" debian:trixie \
  sh -c 'apt-get update && apt-get install -y /pkg/jarl_*_amd64.deb && bash'
```

### Shell completion

The completion scripts are generated by cobra (`jarl completion bash`).
`cmd/jarl/complete.go` adds value completion: it reads each command's usage
line (`add ZONE NAME TYPE DATA...`) and completes the placeholders it knows
(`ZONE`, `VIEW`, `ACL`, `USER`, TSIG `KEY`, `TYPE`, server and group
names), so a new command whose usage line uses these names gets completion
without extra code. Try it without a shell:
`jarl __complete record add ''`.

### Tests against real BIND

The render, engine and adopt tests run the real `named-checkconf`,
`named-checkzone`, `named`, `rndc` and `dig` when they can find them, and
skip otherwise. They are found through `JARL_BIND_ROOT` (an extracted
package tree) or on the system. To get them without root or AppArmor in the
way, extract the packages:

```sh
mkdir -p ~/bind-root/debs && cd ~/bind-root/debs
apt-get download bind9 bind9-utils bind9-libs bind9-dnsutils \
    liblmdb0 libmaxminddb0 liburcu8t64 libuv1t64 libjemalloc2 libjson-c5 libnghttp2-14
for f in *.deb; do dpkg -x "$f" ~/bind-root; done
cd -
JARL_BIND_ROOT=~/bind-root make test
JARL_BIND_ROOT=~/bind-root make e2e
```

The tests start named unprivileged on random high ports in temporary
directories. On Debian/Ubuntu, AppArmor confines the installed
`/usr/sbin/named` to BIND's own directories, so the tests that *start*
named (engine integration tests, `make e2e`) need the extracted copy. The
checker tests work with the installed `bind9-utils` too.

`scripts/e2e.sh` builds a legacy BIND setup, starts named, runs
`jarld init`, `import`, `adopt` and `serve`, then drives every CLI command
(records, batches, changesets, views, ACLs, TSIG, options, users, tokens,
ACME hooks, audit) and checks the answers with `dig`. `KEEP=1` leaves named
and jarld running afterwards. The output says where; set `JARL_CLI_CONFIG`
to that directory's `cli.yaml` to keep using the CLI against it.

### The web UI

The UI is plain JavaScript modules under `internal/web/static/`, with no
framework and no build step. The logo's master is `artwork/logo.png` (blue
`#1d5287` and white on a transparent background). `scripts/logo.py` traces it
with potrace (needs `potrace` and ImageMagick) into `assets/logo.svg` (the
favicon) and `assets/logo.js` (the same paths); change the PNG and rerun the
script rather than editing those files. The header and
login page draw the logo inline from `logo.js` (`logo()` in `brand.js`), so
it appears with the page instead of popping in after a separate download.
Static files are served with `Cache-Control: no-cache` and a content ETag,
so a reload revalidates them with cheap 304 answers. The
"JARL" wordmark is drawn as SVG paths by `wordmark()` in `assets/brand.js`
(over a rule on the login page, the letters alone in the header), so the UI
needs no web font and the wordmark takes the theme's text and accent colors.
The README's banner, `artwork/banner.svg`, is the login page's logo and
wordmark, generated by `scripts/banner.py` from `logo.js` and `brand.js`
(`logo.py` runs it; run it yourself after editing the wordmark).
All DOM is built with the `h()` helper in
`ui.js`, which never uses `innerHTML`, so record data and comments can't
inject markup. The Content-Security-Policy only allows the app's own
scripts and styles. To work on it, run jarld and reload the browser: the
files are embedded at build time, so rebuild jarld after changes.

## Conventions

* **Every user-visible change goes into `CHANGELOG.md`** (under
  "Unreleased"), and the docs in `docs/` are updated in the same change.
* Errors that reach users say what is wrong and how to fix it, naming the
  object.
* New validation rules get a stable `code`, a test in
  `internal/validate/validate_test.go`, and a row in
  [validation.md](validation.md).
* New API operations go through the engine (`internal/engine/expand.go`,
  `ops.go`) so they get permissions, validation, history and revert for
  free, and are documented in [api.md](api.md).
* `gofmt` and `go vet` clean (`make vet`).

## Releasing

1. Move the "Unreleased" section of `CHANGELOG.md` under the new version
   and date.
2. Put the version in `VERSION`.
3. `make test && JARL_BIND_ROOT=... make e2e && make dist`.