[build] docker: add entrypoint script

First of all, this script moves the duniter configuration file 'conf.json'
into the '/etc/duniter' volume, so that one could delete the '/var/lib/duniter'
volume without losing the configuration.

A symbolic link is set up into /var/lib/duniter/duniter_default to point to
the new path:
 /var/lib/duniter/duniter_default/conf.json -> /etc/duniter/conf.json

Then, this script enables the folowing environment variables:

* DUNITER_MANUAL_CONFIG (boolean, default = false)

  When set to 'true' (or 'yes', or '1'), the script waits until the file
  '/etc/duniter/conf.json.orig' is present before starting the duniter
  service. Here is the workflow when enabled:
  1. wait for '/etc/duniter/conf.json.orig'
  2. if this file was changed since the previous startup:
    2.1. Save 'conf.json' to 'conf.json.old'
    2.2. Replace 'conf.json' with 'conf.json.orig'
    2.3. Save the new file's checksum to compare with at next startup
  3. continue the startup sequence

  When set to false, the startup sequence continues.

  Requires 'jq' to sort the files before comparing them.

* DUNITER_AUTO_SYNC (boolean, default = false)
  Requires 'DUNITER_SYNC_HOST'.

  When set to 'true' (or 'yes', or '1') and the folder
  '/var/lib/duniter/duniter_default/data' doesn't exist, a 'duniter sync'
  command will be issued before starting the service.

  When set to false, the service is started directly.

* DUNITER_SYNC_HOST (hostname, default = "")

  This is the 'host:port' parameter to use with 'duniter sync' when
  'DUNITER_AUTO_SYNC' is enabled.

  The synchronization won't be launched when the variable is not defined
  or empty.

release/docker/Dockerfile

@@ -36,6 +36,9 @@ RUN PATH=${HOME}/.cargo/bin:${PATH} \
 
 FROM node:10-alpine
 
+# install jq
+RUN apk add jq
+
 # create group and user duniter
 RUN addgroup -S -g 1111 duniter && \
 	adduser -SD -h /duniter -G duniter -u 1111 duniter
@@ -49,6 +52,9 @@ RUN cp /duniter/duniter/docker.sh /usr/bin/duniter && \
    chmod +x /usr/bin/duniter && \
    chown duniter:duniter /usr/bin/duniter
 
+# copy entrypoint
+COPY release/docker/docker-entrypoint.sh /
+
 # create volumes
 VOLUME /var/lib/duniter
 VOLUME /etc/duniter
@@ -60,5 +66,5 @@ EXPOSE 9220 10901 20901
 USER duniter
 WORKDIR /duniter
 
-ENTRYPOINT ["/usr/bin/duniter"]
+ENTRYPOINT ["/docker-entrypoint.sh"]
 CMD []

release/docker/docker-entrypoint.sh

+#!/bin/sh
+
+home=/var/lib/duniter
+config=/etc/duniter
+home_default=$home/duniter_default
+
+function boolean () {
+  echo "$1" | sed -E 's/^(true|yes|1)$/true/i'
+}
+
+manual_config="$(boolean "${DUNITER_MANUAL_CONFIG:-false}")"
+auto_sync="$(boolean "${DUNITER_AUTO_SYNC:-false}")"
+
+# Use path /etc/duniter/conf.json
+if ! [ -f "$config/conf.json" ] && [ -f "$home_default/conf.json" ]; then
+  mv "$home_default/conf.json" "$conf/conf.json"
+fi
+mkdir -p "$home/duniter_default"
+ln -fs "$config/conf.json" "$home_default/conf.json"
+
+# Manual config when enabled
+if [ "$manual_config" = true ]; then
+  # Do not start until a configuration file was initialized
+  while ! [ -f "$config/conf.json.orig" ]; do
+    echo "Waiting for initial configuration file... Please copy your configuration file to '$config/conf.json.orig'"
+    sleep 10
+  done
+  echo "Configuration file found. Continuing..."
+  # Use new conf.json.orig when changed
+  md5_file="$config/conf.json.orig.md5"
+  if ! md5sum -c "$md5_file"; then
+    if [ -f "$config/conf.json" ]; then
+      echo "Backing up old configuration file to '$config/conf.json.old'..."
+      mv $config/conf.json $config/conf.json.old
+    fi
+    echo "Installing new configuration file..."
+    cp "$config/conf.json.orig" "$config/conf.json"
+    md5sum "$config/conf.json.orig" >"$md5_file"
+  fi
+  # Log differences between initial, old and current conf file
+  jq --sort-keys -r . "$config/conf.json.orig" >"$config/conf.json.orig.sorted"
+  jq --sort-keys -r . "$config/conf.json" >"$config/conf.json.sorted"
+  if [ -f "$config/conf.json.old" ]; then
+    jq --sort-keys -r . "$config/conf.json.old" >"$config/conf.json.old.sorted"
+    if ! diff -q "$config/conf.json.old.sorted" "$config/conf.json.orig.sorted"; then
+      diff -u "$config/conf.json.old.sorted" "$config/conf.json.orig.sorted"
+    fi
+  fi
+  if ! diff -q "$config/conf.json.orig.sorted" "$config/conf.json.sorted"; then
+    diff -u "$config/conf.json.orig.sorted" "$config/conf.json.sorted"
+  fi
+fi
+
+# Auto start synchronization when enabled and starting from scratch
+if [ "$auto_sync" = true ]; then
+  if ! [ -d "$home_default/data" ]; then
+    echo "No 'data' folder. "
+    if [ -z "$DUNITER_SYNC_HOST" ]; then
+      echo "DUNITER_SYNC_HOST undefined. Can't start synchronization!"
+    else
+      echo "Starting synchronization..."
+      /usr/bin/duniter sync --home "$home" "$DUNITER_SYNC_HOST"
+    fi
+  fi
+fi
+
+# Start duniter
+echo Starting duniter with:
+echo /usr/bin/duniter "$@"
+/usr/bin/duniter "$@"