From 9b55169251624be7feffe834e1a7e7820a1d4f5c Mon Sep 17 00:00:00 2001
From: Azamat M <25627421+mazamats@users.noreply.github.com>
Date: Fri, 26 Oct 2018 05:51:08 -0600
Subject: [PATCH] Add readiness check for docker container (#9804)

* Update Dockerfile

Since parity is built for "mission critical use", I thought other operators may see the need for this.

Adding the `curl` and `jq` commands allows for an extremely simple health check to be usable in container orchestrators.

For example. Here is a health check for a parity docker container running in Kubernetes.

This can be setup as a readiness Probe that would prevent clustered nodes that aren't ready from serving traffic.

```bash
#!/bin/bash

ETH_SYNCING=$(curl -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}' http://localhost:8545 -H 'Content-Type: application/json')
RESULT=$(echo "$ETH_SYNCING | jq -r .result)

if [ "$RESULT" == "false" ]; then
  echo "Parity is ready to start accepting traffic"
  exit 0
else
  echo "Parity is still syncing the blockchain"
  exit 1
fi
```

* add sync check script
---
 scripts/docker/hub/Dockerfile    |  4 +++-
 scripts/docker/hub/check_sync.sh | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100755 scripts/docker/hub/check_sync.sh

diff --git a/scripts/docker/hub/Dockerfile b/scripts/docker/hub/Dockerfile
index 53fa092ef9e..35d1b05705e 100644
--- a/scripts/docker/hub/Dockerfile
+++ b/scripts/docker/hub/Dockerfile
@@ -5,7 +5,7 @@ ARG TARGET
 ENV TARGET ${TARGET}
 
 # install tools and dependencies
-RUN apt update && apt install -y --no-install-recommends openssl libudev-dev file
+RUN apt update && apt install -y --no-install-recommends openssl libudev-dev file curl jq
 
 # show backtraces
 ENV RUST_BACKTRACE 1
@@ -31,6 +31,8 @@ COPY artifacts/x86_64-unknown-linux-gnu/$TARGET ./bin/$TARGET
 RUN echo "#!/bin/bash \n ${TARGET} \$@" > ./entrypoint.sh
 RUN chmod +x ./entrypoint.sh
 
+ADD check_sync.sh /check_sync.sh
+
 # setup ENTRYPOINT
 EXPOSE 5001 8080 8082 8083 8545 8546 8180 30303/tcp 30303/udp
 ENTRYPOINT ["./entrypoint.sh"]
diff --git a/scripts/docker/hub/check_sync.sh b/scripts/docker/hub/check_sync.sh
new file mode 100755
index 00000000000..4640a05386a
--- /dev/null
+++ b/scripts/docker/hub/check_sync.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+# checks if parity has a fully synced blockchain
+
+ETH_SYNCING=$(curl -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}' http://localhost:8545 -H 'Content-Type: application/json')
+RESULT=$(echo "$ETH_SYNCING" | jq -r .result)
+
+if [ "$RESULT" == "false" ]; then
+  echo "Parity is ready to start accepting traffic"
+  exit 0
+else
+  echo "Parity is still syncing the blockchain"
+  exit 1
+fi