add state file

This allows storing the swarm ID and additionally discovered seeds,
which prevents a formerly genesis node to start a new document.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/config/mod.rs b/src/config/mod.rs
index 73f4432..b4ea0aa 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -107,7 +107,14 @@ pub(crate) const OPTIONS: &[OptionSpec] = &[
         Kind::Flag,
         "BOOL",
         Some("false"),
-        "Start a new swarm, as its genesis node, instead of joining one through seeds. Every start with it starts another new swarm: drop it once the swarm exists, and give the node seeds instead.",
+        "Start a new swarm, as its genesis node, instead of joining one through seeds. Every start with it starts another new swarm: drop it once the swarm exists, and give the node seeds instead. With a --state-file that remembers a swarm, it starts that swarm again instead (empty; nodes of it still running merge with this one).",
+    ),
+    option(
+        "state-file",
+        Kind::Text,
+        "PATH",
+        None,
+        "File where this node remembers its swarm across restarts: the swarm ID and some members to rejoin through (not the document). Written once ready, then rarely. Without it, a restarted node knows only its configured seeds.",
     ),
     option(
         "swarm-key-file",
@@ -222,6 +229,7 @@ pub(crate) struct Settings {
     pub(crate) seeds: Vec<String>,
     #[serde(default)]
     pub(crate) genesis: bool,
+    pub(crate) state_file: Option<PathBuf>,
     pub(crate) swarm_key_file: Option<PathBuf>,
     pub(crate) alias: Option<String>,
     #[serde(default = "default_keepalive_secs")]