might work now

rootfs/etc/service/postgres/run

@@ -2,7 +2,28 @@
 
 echo "postgres starting..."
 
-mkdir -p /state/db
-chown mastodon:mastodon /state/db
-exec chpst -u mastodon:mastodon /usr/lib/postgresql/bin/postmaster \
-   -D /state/db 2>&1
+chown mastodon:mastodon /var/run/postgresql
+chown -R mastodon:mastodon /etc/postgresql
+
+echo "local all all peer" > /etc/postgresql/10/main/pg_hba.conf
+echo "local all mastodon peer" >> /etc/postgresql/10/main/pg_hba.conf
+echo "local all root peer" >> /etc/postgresql/10/main/pg_hba.conf
+echo "host all all 127.0.0.0/8 trust" >> /etc/postgresql/10/main/pg_hba.conf
+
+if [[ ! -d /state/db ]]; then
+    mkdir -p /state/db/data
+    rsync -a /var/lib/postgresql/10/main/ /state/db/data/
+    cp -a /etc/postgresql/10/main/* /state/db/
+    grep -v '^data_directory' /state/db/postgresql.conf |
+        grep -v "^ssl" |
+        grep -v "^stats_temp_directory" > /state/db/postgresql.new
+    echo "data_directory = '/state/db/data'" >> /state/db/postgresql.new
+    echo "stats_temp_directory = '/tmp'" >> /state/db/postgresql.new
+    mv /state/db/postgresql.new /state/db/postgresql.conf
+    chown -R mastodon:mastodon /state/db
+    chmod go-rwx /state/db/data
+fi
+
+exec \
+    chpst -u mastodon:mastodon \
+    /usr/lib/postgresql/10/bin/postmaster -D /state/db 2>&1