checker-alias

CNAME / DNAME / ALIAS chain checker for happyDomain.

Walks the alias chain of a name, validates hop count, TTLs, target resolvability, apex coexistence (RFC 1912 §2.4, RFC 1034 §3.6.2, RFC 2181 §10.1), DNAME substitutions, and DNSSEC signing of the CNAME RRset.

Usage

Standalone HTTP server

# Build and run
make
./checker-alias -listen :8080

The server exposes:

GET /health — health check
POST /collect — collect alias observations (happyDomain external checker protocol)

Docker

make docker
docker run -p 8080:8080 happydomain/checker-alias

happyDomain plugin

make plugin
# produces checker-alias.so, loadable by happyDomain as a Go plugin

The plugin exposes a NewCheckerPlugin symbol returning the checker definition and observation provider, which happyDomain registers in its global registries at load time.

Versioning

The binary, plugin, and Docker image embed a version string overridable at build time:

make CHECKER_VERSION=1.2.3
make plugin CHECKER_VERSION=1.2.3
make docker CHECKER_VERSION=1.2.3

happyDomain remote endpoint

Set the endpoint admin option for the alias checker to the URL of the running checker-alias server (e.g., http://checker-alias:8080). happyDomain will delegate observation collection to this endpoint.

Options

Id	Type	Default	Description
`maxChainLength`	uint	`8`	Above this number of hops the chain is reported as critical.
`minTargetTTL`	uint	`60`	Hops with a TTL below this threshold are flagged as a warning.
`requireResolvableTarget`	bool	`true`	When enabled, a final target with no A/AAAA is critical (otherwise warning).
`allowApexCNAME`	bool	`false`	When enabled, a CNAME at apex is only a warning (RFC 1912 forbids it).
`recognizeApexFlattening`	bool	`true`	Recognize provider-side ALIAS/ANAME flattening as informational.

Finding codes emitted by the checker include: alias_no_apex, alias_loop, alias_chain_too_long, alias_query_failed, alias_rcode, alias_low_ttl, alias_cname_at_apex, alias_apex_flattening, alias_coexisting_rrset, alias_cname_not_signed, alias_target_unresolvable, alias_multiple_records.

License

Licensed under the MIT License (see LICENSE).

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