txoo: healthcheck based on latest block

- fail if latest attestation is more than a block behind
Signed-off-by: Lakshya Singh <lakshay.singh1108@gmail.com>

txood/Dockerfile

@@ -30,14 +30,22 @@ RUN apk update && \
       build-base \
       bind-tools \
       libev-dev \
-      curl-dev
+      curl-dev \
+      curl \
+      jq
 
 COPY --from=builder /usr/local/bin/txood /usr/bin/txood
 
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 
+COPY healthcheck.sh /healthcheck.sh
+RUN chmod +x /healthcheck.sh
+
 VOLUME ["${TXOO_DATA}"]
 
+HEALTHCHECK --interval=5s --timeout=10s --start-period=5s \
+    CMD ["/bin/sh", "-c", "/healthcheck.sh"]
+
 ENTRYPOINT ["/entrypoint.sh"]
 CMD ["txood"]

txood/healthcheck.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+set -ex
+
+# Get the latest file with extension .sa from /root/.txoo/$BITCOIN_NETWORK/public directory and get the block number from the file name
+TXOO_LOCATION=/root/.txoo/$BITCOIN_NETWORK/public
+latest_block=$(ls -r1t $TXOO_LOCATION | grep '.sa' | head -n1 | cut -d'-' -f1)
+
+# Check if no file was found
+if [ -z "$latest_block" ]; then
+  echo "No file found" >&2
+  exit 1
+fi
+
+# Convert latest_block to a number
+latest_block=$(expr $latest_block + 0)
+
+# Get the block count from bitcoind
+bitcoind_block_count=$(curl --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getblockcount", "params": [] }' -H 'content-type: text/plain;' $BITCOIND_RPC_URL | jq .result)
+
+blocks_behind=$((bitcoind_block_count - latest_block))
+
+# Check if the latest attestation is more than 1 block behind
+if [[ $blocks_behind -gt 1 ]]; then
+  echo "The latest attestation is more than 1 block behind" >&2
+  exit 1
+fi