monitors

Monitor sources for sampler.

This collection of (mostly) shell scripts is primarily intended for use by Blocknet servicenode operators. When used in conjunction with sampler they provide rudimentary monitoring of the XBridge wallets in use by a servicenode and allow for detection of potentially mis-synced wallets.

Each script monitors one particular blockchain and reports the local height and the height at "the explorer". The two values are separated by a slash character, for example 2450806/2450805. If the block height is unavailable at either source then the height at that source is shown as problem.

Any height difference greater than, say, three blocks, is worthy of investigation. Chainz explorers often lag the true block count by one to three blocks, especially for chains with one-minute block times. If sampler/monitors reports a block height difference you could use these unfork scripts to find and potentially correct a forked chain.

Note: explorers are not infallible Oracles and are just as likely to be on the wrong chain, or otherwise out of sync, as any other other node. But they are generally the only well known source of blockheight information, and being external to the local chain, a useful point for comparison.

In addition to the individual monitoring scripts this repo includes a sample configuration file.

In the future there will probably be a more comprehensive monitoring package, perhaps built using Grafana and Prometheus and with automatic generation of configuration information based on the choices made while running awesome builder.

This repo does not include a copy of sampler because the two projects use different licences.

Prerequisites.

curl
jq

Usage.

Either clone the sampler repo or create a new directory and install the appropriate executable from the latest release for your platform in it.
Copy some or all of the height_xxx.sh scripts to the same directory as the sampler executable.
Copy sample.yml to config.yml and customise it for your environment. The sample config is optimised for an 80x56 terminal window. It will operate in a different size window but the results may not be visually appealing. Refer to the sampler documentation for more details.
Run the monitor by

./sampler --config=config.yml

Assumptions.

The monitor scripts were created in a non-containerised, non-EXR environment. Consequently they assume that coin-cli will talk directly to coin. In a containerised, EXR environment the scripts could be modified to send coin-cli commands to the appropriate Docker container, or wrapper scripts could be created to take care of the redirection.

For example, if Bitcoin is running in a container in an environment installed by exrproxy-env then you could replace a call to

bitcoin-cli getblockcount

docker exec exrproxy-env_BTC_1 bitcoin-cli getblockcount

or you could create a bitcoin-cli script with the following contents and place it somewhere in PATH.

#!/bin/bash
docker exec exrproxy-env_BTC_1 bitcoin-cli $*

Caveats.

The samples here include block height monitoring scripts for a number of unsupported (by Blocknet) coins. Specifically, ALQO (XLQ), Crown (CRW) and Merge (MERGE) are not (currently) supported by BlockDX or Blocknet.

Additionally, some of the scripts are servicenode/masternode/systemnode-aware. If the coin is running as one of those node types the script checks if the node is online/started and if not, reports the status instead of the block height.

Remote monitoring.

sampler is capable of monitoring remote machines via ssh. You could have one session monitoring several different servicenodes although you might run out of screen real estate. For example:

This example also includes some Python3 sources:

cpprice.py
yfprice.py

with additional prerequisites given in requirements.txt:

ccxt
yfinance

The config for this example is sample2.yml

Extending monitoring.

sampler is capable of monitoring anything you can generate values for.

Block height scripts are provided for several "popular" chains and can be used as templates for other chains. Many of them rely on the Chainz explorers provided by CryptoID. Any chain supported by them would be trivially easy to add to monitoring. Be aware that some explorers enforce rate-limiting and could block your requests if you exceed their limits.

Some chains do not have freely available public explorers but may have organisations offering paid access. In this case the data will most likely be available with an API key which will have to be added to the curl call. Rate-limiting is less likely to be an issue with paid API access.

An alternative to paying for API access to a third party explorer could be to compare heights between multiple copies of a chain you run on more than one servicenode.

Another possibility is to simply make an blocknet-cli xrGetBlockCount coin count call to the servicenode network for each coin you're interested in, specifying a node count larger than one and hoping the consensus answer is correct. Historically there have been many times when the servicenode consensus for a particular chain was incorrect so I have chosen not to take this approach. Perhaps in the future when the network is larger and the majority of servicenode operators realise the importance of keeping their wallets correctly synced, this will be a more viable alternative.

Yet another possibility is for the monitor to report the local chain height, explorer chain height and servicenode consensus height.

If you do extend the monitoring, either through external scripts or inline code in the sampler config, please consider contributing them to the servicenode operator community through a pull request to this repo.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

walkjivefly/monitors