build(train): Train's server and BRouter deployable beside the instance (ADR 0030, D46)

deploy/compose.train.yaml adds Train's server at train.halkyon.eu, a
member of Learn's register, with its database halkyon_train in the
instance's PostgreSQL, and BRouter beside it alone (v1.7.10, checked by
SHA-256, no log), its segments of the operator's region kept current
monthly. Nothing changes until deploy/.env names the compose file:
redeploy.sh and backup.sh take Train in only then, and the operator's
steps are in sidecars/README.md. restic now forgets snapshots grouped by
host alone, so adding Train's dump leaves no group behind for good.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

deploy/brouter/Dockerfile

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+# BRouter for Train's routes (ADR 0030, D11, D44, D46): its release, checked against
+# GitHub's SHA-256 of it, on Eclipse Temurin's Java 17 as BRouter's own image, with
+# its profiles and Train's running profile. Built from the repository root:
+#
+#   docker build -f deploy/brouter/Dockerfile .
+#
+# The same image refreshes the segments (segments.sh), so it carries curl.
+FROM eclipse-temurin:17-jre-noble
+
+# BRouter v1.7.10, released 17 Jul 2026.
+ADD --checksum=sha256:023fec3ba997758e8cd7ab9e1bae52e962af3f00b57683e3de86b84ffad01532 \
+  https://github.com/abrensch/brouter/releases/download/v1.7.10/brouter-1.7.10.zip /tmp/brouter.zip
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends unzip curl ca-certificates \
+ && rm -rf /var/lib/apt/lists/* \
+ && unzip -q /tmp/brouter.zip -d /tmp \
+ && mkdir -p /app \
+ && mv /tmp/brouter-1.7.10/brouter-1.7.10-all.jar /app/brouter.jar \
+ && mv /tmp/brouter-1.7.10/profiles2 /profiles2 \
+ && rm -rf /tmp/brouter.zip /tmp/brouter-1.7.10
+COPY apps/train/brouter/halkyon-run.brf /profiles2/halkyon-run.brf
+COPY --chmod=755 deploy/brouter/segments.sh /app/segments.sh
+
+WORKDIR /app
+EXPOSE 17777
+
+# Segments in /segments4 (a volume), profiles in the image, no custom profiles; four
+# routes at a time, each stopped after a minute. -Xmx as BRouter's script raised: the
+# memory a route takes grows with its length, and Europe's long routes need more than
+# its 128 MB.
+CMD ["java", "-Xmx384M", "-Xms128M", "-Xmn16M", "-DmaxRunningTime=60", "-DuseRFCMimeType=false", "-DusePOSTRequests=false", \
+  "-cp", "/app/brouter.jar", "btools.server.RouteServer", "/segments4", "/profiles2", "/tmp", "17777", "4", "0.0.0.0"]

deploy/brouter/segments.sh

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+#!/bin/sh
+# Keeps BRouter's segments of the operator's region current (ADR 0030, D11, D44):
+# every 5°×5° segment of BRouter's project whose south-west corner lies in
+# BROUTER_REGION (`west,south,east,north` in whole degrees, multiples of 5; Europe's
+# `-25,35,40,70` by default), downloaded where the project has a newer one than the
+# volume holds, then again every BROUTER_REFRESH_DAYS days (30). Each is written beside
+# its old self and moved over it, so BRouter never reads half a file. Segments of
+# the sea, which the project doesn't have, are skipped.
+set -eu
+
+base=https://brouter.de/brouter/segments4
+region=${BROUTER_REGION:--25,35,40,70}
+days=${BROUTER_REFRESH_DAYS:-30}
+cd /segments4
+
+IFS=, read -r west south east north <<END
+$region
+END
+
+name() {
+  lon=$1 lat=$2
+  if [ "$lon" -lt 0 ]; then ew="W$((-lon))"; else ew="E$lon"; fi
+  if [ "$lat" -lt 0 ]; then ns="S$((-lat))"; else ns="N$lat"; fi
+  echo "${ew}_${ns}.rd5"
+}
+
+refresh() {
+  listing=$(curl -fsS "$base/") || { echo "The segments' listing didn't come." >&2; return 0; }
+  fetched=0 kept=0
+  lon=$west
+  while [ "$lon" -le "$east" ]; do
+    lat=$south
+    while [ "$lat" -le "$north" ]; do
+      file=$(name "$lon" "$lat")
+      if echo "$listing" | grep -q "href=\"$file\""; then
+        # Only where the project's is newer than ours (If-Modified-Since): a
+        # current one comes back empty.
+        if [ -e "$file" ]; then set -- -z "$file"; else set --; fi
+        if curl -fsS -R --retry 3 "$@" -o "$file.part" "$base/$file" &&
+          [ -s "$file.part" ]; then
+          mv "$file.part" "$file"
+          fetched=$((fetched + 1))
+        else
+          rm -f "$file.part"
+          kept=$((kept + 1))
+        fi
+      fi
+      lat=$((lat + 5))
+    done
+    lon=$((lon + 5))
+  done
+  echo "Segments: $fetched fetched, $kept current, $(du -sh . | cut -f1) in all."
+}
+
+while :; do
+  refresh
+  sleep $((days * 86400))
+done