Flatten the curve!

Dockerfile

@@ -1,12 +1,10 @@
-FROM alpine:3.10
+FROM alpine:3.12
 
-RUN apk add --no-cache curl jq bash
+RUN apk add --no-cache curl jq
 
-RUN mkdir /lnd/
-RUN mkdir /secrets/
-RUN mkdir /statuses/
+RUN mkdir /lnd/ /secrets/ /statuses/
 
-COPY switch.sh /bin/switch
-RUN chmod +x /bin/switch
+COPY switch.sh /usr/local/bin/switch
+RUN chmod +x   /usr/local/bin/switch
 
-ENTRYPOINT ["switch"]
+ENTRYPOINT ["/usr/local/bin/switch"]

switch.sh

@@ -1,4 +1,4 @@
-#!/bin/bash -e
+#!/bin/sh -e
 
 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
@@ -15,59 +15,81 @@
 
 # Output: /statuses/node-status-bitcoind-ready  (when ready, where a service can pick it up)
 # Then
-PASSWORD=`cat /secrets/rpcpass.txt`
+PASSWORD="$(cat /secrets/rpcpass.txt)"
 
 # If JSONRPCURL doesn't exist then set it
-if [ -z $JSONRPCURL ]; then
-    JSONRPCURL="http://10.254.2.2:8332"
+if [ -z "$JSONRPCURL" ]; then
+    JSONRPCURL='http://10.254.2.2:8332'
 fi
 
+PREV_MATCH=
+
+switch_on_sync_done() {
+	# Node not pruned so lets do the switching
+	echo 'Checking if synced...'
+	if [ -f /statuses/node-status-bitcoind-ready ]; then
+		echo 'LND is already switched to bitcoind!'
+		return 1
+	fi
+
+	if ! grep -q 'bitcoin.node=neutrino' /lnd/lnd.conf; then
+		echo 'Neutrino mode has been disabled'
+		echo 'Switchback is not supported in this version'
+		return 1
+	fi
+
+	echo 'If set to neutrino then lets check bitcoind'
+
+	if ! INFO="$(curl --silent --user "lncm:$PASSWORD" --data-binary '{"jsonrpc": "1.0", "id":"switchme", "method": "getblockchaininfo", "params": [] }' $JSONRPCURL)"; then
+		echo "Error: 'getblockchaininfo' request to bitcoind failed"
+		return
+	fi
+
+	if err="$(jq -ner "${INFO:-{}} | .error")"; then
+		echo 'Error: from bitcoind'
+		echo "${err:-Unknown error}"
+		return
+	fi
+
+	INFO="$(jq -ne "$INFO | .result")"
+
+	# Check if pruned
+	if jq -ne "$INFO | .pruned == true"; then
+		echo 'No need to switch from neutrino in pruned mode'
+		return 1
+	fi
+	echo 'Not pruned'
+
+	if jq -ne "$INFO | .headers - .blocks > 10"; then
+		echo "Node isn't full synced yet"
+		PREV_MATCH=
+		return
+	fi
+
+	if [ -z "$PREV_MATCH" ]; then
+		PREV_MATCH="$(jq -ne "$INFO | .headers")"
+		echo 'Sync seems complete!  Will switch on next check.'
+		return
+	fi
+
+	# Skip switch, if headers number didn't change since last check
+	#	(possible network issue).
+	if jq -ne "$INFO | .headers == $PREV_MATCH"; then
+		echo 'Skipping switch for now: headers seem stale'
+		return
+	fi
+
+	echo 'Bitcoind has been switched across to neutrino'
+	touch /statuses/node-status-bitcoind-ready
+	sed -Ei 's|(bitcoin.node)=neutrino|\1=bitcoind|g' /lnd/lnd.conf
+}
+
 while true; do
-  IS_NEUTRINO=`grep -c 'bitcoin.node=neutrino' /lnd/lnd.conf`
-  if [ $IS_NEUTRINO -eq 1 ]; then
-    echo "If set to neutrino then lets check bitcoind"
-
-    INFO=`curl --user lncm:$PASSWORD --data-binary '{"jsonrpc": "1.0", "id":"switchme", "method": "getblockchaininfo", "params": [] }' $JSONRPCURL 2>/dev/null`
-    # check for errors
-    ERROR=`echo $INFO | jq .error`
-    if [ ! -z $ERROR ]; then
-      # if no errors
-      # Check prune mode
-      PRUNE_MODE=`echo $INFO | jq .result.pruned`
-      # check headers
-      HEADERS=`echo $INFO | jq .result.headers`
-      # check blocks
-      BLOCKS=`echo $INFO | jq .result.blocks`
-
-      if [ $PRUNE_MODE != "true" ]; then
-        echo "Not pruned"
-        # Node pruned so lets do the switching
-        echo "Checking if synced...."
-        if [ ! -f /statuses/node-status-bitcoind-ready ]; then
-          if [ $HEADERS -eq $BLOCKS ]; then
-              echo "Bitcoind has been switched across to neutrino"
-              touch /statuses/node-status-bitcoind-ready
-              sed -i 's/bitcoin.node\=neutrino/bitcoin.node\=bitcoind/g; ' /lnd/lnd.conf
-          else
-              echo "Node isn't full synched yet"
-          fi
-        else
-            echo "LND is already switched to bitcoind!"
-        fi
-      else
-        echo "No need to switch from neutrino in pruned mode"
-      fi
-    else
-      # if bitcoind error
-      echo "Error from bitcoind"
-      echo $ERROR
-    fi
-  else
-    echo "Neutrino mode has been disabled"
-    echo "Switchback is not supported in this version"
-
-    #TODO: Lets maybe try to switch back
-  fi
-  # Run every every 1 hour
-  sleep 3600
+	if ! switch_on_sync_done; then
+		echo 'Checking not necessary. Exiting.'
+		break
+	fi
+
+	# Run every every 1 hour
+	sleep 3600
 done