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diff --git a/README.md b/README.md new file mode 100644 index 0000000..dcf6ed9 --- /dev/null +++ b/README.md @@ -0,0 +1,67 @@ +D53 +=== + +[](https://drone.deuxfleurs.fr/lx/D53) + +D53 is a dynamic DNS updater that sources information from Consul to route services to the correct place + +### Tag syntax + +D53 reads tags affected to services in Consul. Tags can be formatted as follows: + +- `d53-a <domain> <subdomain>`, will set the node running this service as an IPv4 target in an A record for `<subdomain>.<domain>` +- `d53-aaaa <domain> <subdomain>`, same but as an IPv6 target in a AAAA record +- `d53-cname <domain> <subdomain>`, same but as an alias using a CNAME record + +Example Nomad service configurations: + +```hcl +# The following can be used in the Tricot service definition +# to redirect the current deuxfleurs.fr and <site_name>.site.deuxfleurs.fr +# to this node through A and AAAA records + tags = [ + "(diplonat (tcp_port 80))" + "d53-a deuxfleurs.fr ${meta.site}.site", + "d53-a deuxfleurs.fr global.site", + "d53-aaaa deuxfleurs.fr ${meta.site}.site", + "d53-aaaa deuxfleurs.fr global.site", + ] +``` + +```hcl +# The following can be used in the Guichet service definition +# to configure a Tricot reverse proxy entry, and to redirect using +# a CNAME the guichet.deuxfleurs.fr to the correct target, +# which is usually defined in the form of <site_name>.site.deuxfleurs.fr + tags = [ + "tricot guichet.deuxfleurs.fr", + "d53-cname deuxfleurs.fr guichet", + ] +``` + +### Finding targets + +The IPv4, IPv6 and CNAME targets to set in the record are extracted from the metadata values affected to each node in the Consul configuration. +In particular, the following values are used: + +- `public_ipv4`: a public IPv4 through which the current node is possibly reachable (see DiploNAT to automatically open ports in a NAT) +- `public_ipv6`: a public IPv6 through which the current node is reachable +- `cname_target`: a CNAME target that resolves to a domain name whose A and/or AAAA entries point to this node (possibly among others) + +Here is the relevant Nix configuration snippet that sets up these metadata values: + +```nix + let node_meta = { + "site" = cfg.site_name; + "public_ipv6" = cfg.ipv6; + } // + (if cfg.public_ipv4 != null + then { "public_ipv4" = cfg.public_ipv4; } + else {}) // + (if cfg.cname_target != null + then { "cname_target" = cfg.cname_target; } + else {}); + + ### ... later ... + services.consul.extraConfig.node_meta = node_meta; +``` |