Configure

Every operator-tunable setting on a DAPPS node has three configuration surfaces:

1. A persisted default in the SQLite database, seeded on first start.
2. An environment variable, of the form DAPPS_SCREAMING_SNAKE_NAME, which overrides the persisted default at first start and updates the persisted row.
3. The dashboard's /Config form (or POST /Config REST API), which writes a new value to the persisted row at any time.

For runtime-changeable knobs (probing on/off, fragment threshold, airtime budget, etc.), the dashboard is the right surface - changes pick up without a restart. For startup-only knobs (callsign, packet-node host/port, MQTT port, dashboard URL), the env var is the right surface - they're read once at boot.

Deployment-managed mode (DAPPS_ENV_MANAGED=true): when a supervising deployment (a packet.net node host, say) sets DAPPS_ENV_MANAGED=true, every set DAPPS_* env var becomes deployment-managed config instead - re-applied over the persisted row at every start, with the matching dashboard fields badged "managed by environment" and rendered read-only. DAPPS_ENV_MANAGED itself is a mode switch read each start, never stored. Leave it unset for the standalone installs documented here: with it unset (or false) env vars keep the first-start-only semantics above and the dashboard stays in charge.

Show the current persisted config

dapps --show-config

Walks the persisted systemoptions table and prints DAPPS_SCREAMING_SNAKE=value pairs for every set knob, without booting the host. Useful when the daemon won't start and you need to see what state it'd boot into.

The knobs

Identity (startup-only)

Name	Env var	Default	What it does
Callsign	DAPPS_CALLSIGN	N0CALL	Your callsign with SSID, e.g. M0LTE-1. Refuses to start on the placeholder.
Node host	DAPPS_NODE_HOST	localhost	TCP host of your packet node (BPQ, XRouter, etc.).
Node bearer	DAPPS_NODE_BEARER	agw	Which host protocol DAPPS speaks to the packet node: agw (BPQ, Direwolf, AGWPE, ...) or rhpv2 (XRouter, future RHPv2-capable BPQ). See Connect a node.
AGW port	DAPPS_AGW_PORT	8000	TCP port the packet node's AGW interface listens on. Used when Node bearer = agw.
RHPv2 port	DAPPS_RHP_PORT	9000	TCP port the packet node's RHPv2 listener is on. Used when Node bearer = rhpv2.
RHPv2 user	DAPPS_RHP_USER	empty	Username for RHPv2 authentication. Leave empty if your packet node accepts unauthenticated RHPv2.
RHPv2 password	DAPPS_RHP_PASS	empty	Password matching the RHPv2 user.
Default bearer port	DAPPS_DEFAULT_BEARER_PORT	0	Bearer port (0-indexed) for outbound sessions when a neighbour has no per-row override. For AGW this is the AGW port byte; for RHPv2 DAPPS adds 1 internally to derive XRouter's 1-indexed PORT=N name.

App-interface ports

Name	Env var	Default	What it does
MQTT broker port	DAPPS_MQTT_PORT	1883	Port the embedded MQTT broker binds.
UDP listener port	DAPPS_UDP_LISTEN_PORT	0	UDP datagram bearer listen port. 0 disables.

The dashboard / REST / MCP endpoint port is configured via ASPNETCORE_URLS (a .NET convention), e.g. ASPNETCORE_URLS=http://127.0.0.1:5000.

Authentication

Name	Env var	Default	What it does
Auth required	DAPPS_AUTH_REQUIRED	false	When true, MQTT / REST app-interface clients must present a per-app token.

The admin password (for the dashboard cookie) is set on /Setup first-run flow, not via env var.

Discovery & routing

Name	Env var	Default	What it does
Routing algorithm	DAPPS_ROUTING_ALGORITHM	passive-flood	passive-flood (AODV-style, learns from observed forwards) or meshcore (DSR-style source routing). Restart required.
Probing enabled	DAPPS_PROBING_ENABLED	false	Periodically open a connected-mode session to known peers to confirm reachability.
Probe interval (hours)	DAPPS_PROBE_INTERVAL_HOURS	24	Sweep cadence when probing is on.
Probe strategy	DAPPS_PROBE_STRATEGY	FixedInterval	One of FixedInterval, Overnight, WhenQuiet. See Tune.
Overnight start hour	DAPPS_PROBE_OVERNIGHT_START_HOUR	2	Local-time hour the Overnight strategy's window opens.
Overnight end hour	DAPPS_PROBE_OVERNIGHT_END_HOUR	6	Local-time hour the Overnight strategy's window closes. Wraps midnight if end < start.
Quiet window (s)	DAPPS_PROBE_QUIET_WINDOW_SECONDS	300	Seconds of forwarder-quiet required for WhenQuiet to fire.
Auto-discover via NODECALL	DAPPS_AUTO_DISCOVER_VIA_NODE_CALL	false	When true, AGW DAPPS beacons auto-seed node-prompt-probe candidates for the source's base callsign.
Node-prompt application command	DAPPS_NODE_PROMPT_APPLICATION_COMMAND	DAPPS	The application name typed at the BPQ node prompt to enter the DAPPS slot. Override if your APPLICATION line uses a different name.
Discovery airtime budget (s/hr)	DAPPS_DISCOVERY_AIRTIME_BUDGET_SECONDS_PER_HOUR	0	Trailing-hour cap on discovery transmissions (beacons + solicits + probes). 0 disables the cap.

Polling

Name	Env var	Default	What it does
Scheduled poll enabled	DAPPS_SCHEDULED_POLL_ENABLED	false	Periodic reverse-poll of every known forward target.
Poll interval (hours)	DAPPS_POLL_INTERVAL_HOURS	6	Sweep cadence when scheduled polling is on.
Opportunistic poll enabled	DAPPS_OPPORTUNISTIC_POLL_ENABLED	true	Drains a peer's queued mail at the end of every push session.

Multi-part messages

Name	Env var	Default	What it does
Fragment threshold (bytes)	DAPPS_FRAGMENT_THRESHOLD_BYTES	4096	Payloads strictly larger than this get split into N fragments at submit. 0 disables.
Fragment reassembly timeout (s)	DAPPS_FRAGMENT_REASSEMBLY_TIMEOUT_SECONDS	604800 (7 d)	Drop incomplete reassembly buffers older than this.

Route gossip

Name	Env var	Default	What it does
Route gossip staleness (hours)	DAPPS_ROUTE_GOSSIP_STALENESS_HOURS	6	Minimum hours between consecutive routes pulls from the same neighbour. The piggyback gate skips gossip if the previous pull is younger than this. 0 disables route gossip entirely.

Updates

Name	Env var	Default	What it does
Update check enabled	DAPPS_UPDATE_CHECK_ENABLED	true	Periodically poll GitHub Releases. Powers the dashboard banner.

Heartbeat

Name	Env var	Default	What it does
Heartbeat enabled	DAPPS_HEARTBEAT_ENABLED	true	Publishes an operational snapshot to MQTT topic dapps/metrics/heartbeat.
Heartbeat interval (s)	DAPPS_HEARTBEAT_INTERVAL_SECONDS	60	Cadence; minimum 10 s.

Versioning

The session-protocol version is the suffix on the prompt - DAPPSv1> today; DAPPSv2> for any future incompatible cut. The policy:

• Forward-compatible additions stay on the current version. New optional ihave headers and new commands ride the existing prompt; receivers ignore unknown headers and respond ? to unrecognised commands.
• Bump the prompt on any incompatible wire change. A clean version cut beats sticking a patch on v1 and hoping every implementation interprets it the same way.
• Newer implementations should speak older versions for one-way compatibility.
• The UDP / MeshCore datagram bearer codec versions independently - different format, different schedule. (MeshCore also versions its shared compression dictionary on the wire, so a dictionary change can't silently corrupt a mixed-version fleet.)

Pre-shipping caveat: while DAPPS has no non-author operators on the air, breaking changes to either format are still fair game without a version bump. The cost of compatibility tape that nobody benefits from is real. The policy fully kicks in when the first independent operator picks DAPPS up.

Where the config lives on disk

Everything is in the SQLite database at /var/lib/dapps/dapps.db (Linux/systemd) or data/dapps.db (run-from-anywhere). The file is the only state worth backing up.