Add sidecar for evm

utils/Dockerfile

@@ -20,6 +20,7 @@ RUN     PIP_INST="pip --no-cache install"					\
   && $PIP_INST base58 pynacl					\
   && $PIP_INST mnemonic pytezos requests				\
   && $PIP_INST pyblake2 pysodium flask \
+  && $PIP_INST web3 \
   && apk del .build-deps \
   && $APK_ADD jq netcat-openbsd curl binutils \
   && $APK_ADD lz4
@@ -29,6 +30,7 @@ COPY config-generator.sh /
 COPY entrypoint.sh /
 COPY logger.sh /
 COPY sidecar.py /
+COPY sidecar-evm.py /
 COPY snapshot-downloader.sh /
 COPY wait-for-dns.sh /
 ENTRYPOINT ["/entrypoint.sh"]

utils/entrypoint.sh

@@ -7,6 +7,7 @@ case "$CMD" in
 	config-generator)	exec /config-generator.sh	"$@"	;;
 	logger)			exec /logger.sh			"$@"	;;
 	sidecar)		exec /sidecar.py		"$@"	;;
+	sidecar-evm)		exec /sidecar-evm.py		"$@"	;;
 	snapshot-downloader)	exec /snapshot-downloader.sh	"$@"	;;
 	wait-for-dns)		exec /wait-for-dns.sh		"$@"	;;
 esac

utils/sidecar-evm.py

@@ -0,0 +1,43 @@
+#! /usr/bin/env python
+from flask import Flask
+from web3 import Web3
+import requests
+import time
+import logging
+
+log = logging.getLogger("werkzeug")
+log.setLevel(logging.ERROR)
+
+application = Flask(__name__)
+web3 = Web3(Web3.HTTPProvider('http://localhost:8545'))
+
+AGE_LIMIT_IN_SECS = 600
+# https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/
+# Default readiness probe timeoutSeconds is 1s, timeout sync request before that and return a
+# connect timeout error if necessary
+
+@application.route("/health")
+def health():
+    if not web3.is_connected():
+        err = ("Error: Failed to connect evm node. ", 500)
+        application.logger.error(err)
+        return err
+
+    latest_block = web3.eth.get_block('latest')
+
+    latest_block_timestamp = latest_block['timestamp']
+    current_timestamp = int(time.time())
+    time_diff = current_timestamp - latest_block_timestamp
+    if time_diff > AGE_LIMIT_IN_SECS:
+        err = (
+            "Error: Chain head is %s secs old, older than %s"
+            % (time_diff, AGE_LIMIT_IN_SECS),
+            500,
+        )
+        application.logger.error(err)
+        return err
+    return "evm rpc is healthy"
+
+
+if __name__ == "__main__":
+    application.run(host="0.0.0.0", port=32767, debug=False)