reckon_db_discovery (reckon_db v5.1.0)

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Cluster discovery for reckon-db

Handles node discovery via UDP multicast (LAN) or Kubernetes DNS. Ported from LibCluster's gossip strategy.

Protocol (v2, since 5.1.0): 1. Broadcast {gossip_v2, NodeBin, Timestamp, Hmac} every BROADCAST_INTERVAL, where Hmac = HMAC-SHA256 over the node name and timestamp keyed with the cluster secret. The secret itself never goes on the wire (v1 broadcast it in cleartext). 2. On receive: safe-decode, constant-time HMAC check, freshness window, THEN net_kernel:connect_node/1. The node name travels as a binary and is only atomized after authentication, so unauthenticated LAN datagrams can neither grow the atom table nor trigger term decoding of attacker-shaped structures. 3. On node up: trigger Khepri cluster join via StoreCoordinator

Discovery requires an explicitly configured cluster secret: the RECKON_DB_CLUSTER_SECRET env var, or the cluster_secret application environment key. Without one, cluster-mode discovery stays passive: no broadcasts, inbound gossip ignored. v1 shipped a hardcoded default secret, which made every unconfigured deployment trust any LAN host.

Summary

Types

index_decl/0
integrity_config/0
integrity_key_source/0
store_config/0

Functions

get_discovered_nodes(StoreId)

Get list of discovered nodes

handle_call(Request, From, State)
handle_cast(Msg, State)
handle_info(Info, State)
init(Store_config)
start_link(Store_config)
terminate(Reason, State)
trigger_discovery(StoreId)

Trigger immediate discovery broadcast

Types

index_decl/0

-type index_decl() :: tags | event_type | {meta, Key :: binary()}.

integrity_config/0

-type integrity_config() :: disabled | #{enabled := true, key_source := integrity_key_source()}.

integrity_key_source/0

-type integrity_key_source() :: {env_var, EnvName :: binary()} | {sealed_file, Path :: file:filename()}.

store_config/0

-type store_config() ::
          #store_config{store_id :: atom(),
                        data_dir :: string(),
                        mode :: single | cluster,
                        timeout :: pos_integer(),
                        writer_pool_size :: pos_integer(),
                        reader_pool_size :: pos_integer(),
                        gateway_pool_size :: pos_integer(),
                        options :: map(),
                        integrity :: integrity_config(),
                        indexes :: [index_decl()]}.

Functions

get_discovered_nodes(StoreId)

-spec get_discovered_nodes(atom()) -> [node()].

Get list of discovered nodes

handle_call(Request, From, State)

handle_cast(Msg, State)

handle_info(Info, State)

init(Store_config)

start_link(Store_config)

-spec start_link(store_config()) -> {ok, pid()} | {error, term()}.

terminate(Reason, State)

trigger_discovery(StoreId)

-spec trigger_discovery(atom()) -> ok.

Trigger immediate discovery broadcast