Add document on running a seed node as a daemon in a GNU/Linux server

doc/seed-node-daemon.md

@@ -0,0 +1,85 @@
+# Running a seed node as a daemon
+
+This document presents some steps to be able to run a Bitsquare seed node as
+an unattended daemon in a GNU/Linux server with a traditional System V init.
+
+## Before you start
+
+We assume that you have already configured a Bitsquare seed node to run in a
+computer.  You will need to upload the seed node code and configuration to the
+server:
+
+  - The code is contained in the ``SeedNode.jar`` file which is usually left
+    under ``seednode/target`` after building Bitsquare.
+  - The seed node configuration is the ``Bitsquare_seed_node_HOST_PORT``
+    directory under ``~/.local/share`` (Unix), ``%APPDATA%`` (Windows) or
+    ``~/Library/Application Support`` (Mac OS X).
+
+## Dedicated user
+
+In order to avoid security risks, it is highly recommended that you create a
+dedicated user in the server to run the seed node daemon, and that you forbid
+other users to access its files, for instance:
+
+    # adduser bsqsn
+    # chmod go-rwx ~bsqsn
+
+Place the jar file where the ``bsqsn`` user can read it and tag it with
+Bitsquare's version number (to allow running several instances of mutually
+incompatible versions), e.g. ``~bsqsn/SeedNode-VERSION.jar``.  Copy the
+configuration directory to the ``~bsqsb/.local/share``  directory.
+
+## Testing the seed node
+
+You need to check that the seed node can actually run in your system.  For
+instance, if you are using version 0.4.2 and your seed node's Tor address is
+``1a2b3c4d5e6f7g8h.onion:8000``, try to run this as the ``bsqsn`` user:
+
+    $ java -jar ~bsqsn/SeedNode-0.4.2.jar 1a2b3c4d5e6f7g8h.onion:8000 0 50
+
+Please check error messages if it fails to run.  Do note that you will need
+OpenJDK and OpenJFX in the server.  In Debian-like systems you may install the
+needed dependencies with:
+
+    # apt-get --no-install-recommends install openjfx
+
+After the node runs successfully, interrupt it with Control-C.
+
+## Init script
+
+To allow the daemon to start automatically on system boot, use the attached
+[init script](bitsquare-sn.init.sh).  First edit it and change its
+configuration variables to your needs, especially ``SN_ADDRESS``, ``SN_JAR``
+and ``SN_USER``.  In the previous example, the values would be:
+
+    SN_ADDRESS=1a2b3c4d5e6f7g8h.onion:8000
+    SN_JAR=~bsqsn/SeedNode-0.4.2.jar
+    SN_USER=bsqsn
+
+Put the customized script under ``/etc/init.d`` using a name without
+extensions (e.g. ``bitsquare-sn``), make it executable, add it to the boot
+sequence and finally start it:
+
+    # cp /path/to/bitsquare-sn.init.sh /etc/init.d/bitsquare-sn
+    # chmod a+rx /etc/init.d/bitsquare-sn
+    # update-rc.d bitsquare-sn defaults
+    # service bitsquare-sn start
+
+Executing ``service bitsquare-sn status`` should report that the process is
+running.
+
+## Cron script
+
+The attached [Cron script](bitsquare-sn.cron.sh) can be used to check the seed
+node daemon periodically and restart it if it is using too much memory (RSS at
+the time, may change to VSS later).
+
+To enable this check, edit the script and change the ``MAX_RSS_MiB`` to
+whatever limit (in MiB), copy it to ``/etc/cron.hourly`` and make it
+executable:
+
+    # cp /path/to/bitsquare-sn.cron.sh /etc/cron.hourly/bitsquare-sn
+    # chmod a+rx /etc/cron.hourly/bitsquare-sn
+
+The check will be run every hour.  For more sophisticated checks, use a proper
+monitor like [Monit](https://mmonit.com/monit/).