Hello everyone,

I have decided to do little steem updates for the various bits of dev work I do.

I just completed work on the first version of a BitShares witness monitoring script with telegram integration.

You can find it here:  https://github.com/clockworkgr/bitshares-witness-monitor

First of all, I would like to acknowledge @roelandp 's work (https://github.com/roelandp/Bitshares-Witness-Monitor) for the inspiration.

My monitoring script only checks witness health in its current iteration but price-feed health and seed node might be added in future versions.

I've decided to allow almost full control of the monitoring parameters through access controlled telegram commands so  in theory you'd almost never have to restart the monitoring script. You can pause it, update backup keys, resume, change API node used as well as update all of the monitoring parameters.

For example, if you want very "tight" monitoring, you can set the checking interval to 3 seconds (essentially per block), the missed block threshold to 1 missed block before switching and a very large reset time window. Thus ensuring that your signing key is updated to that of your backup witness as soon as a single block is missed.

A "looser" monitoring strategy would be to look for more than 3 missed blocks in quite rapid succession before switching. So missed block threshold at 3, a reset window of 5 minutes (so every 5 minutes the missed block counter gets reset) and checking every 30 secs or so.

You can also force a switch to the backup witness on demand in case you need to undertake some work on one of your witness servers etc.

If any witnesses try it out please take some time to provide feedback, feature requests  or bugs you come across by leaving an issue on GitHub.

The following (essentially the repo README file) explains the features better:

To use, clone the repo (or download the zip).

```
git clone https://github.com/clockworkgr/bitshares-witness-monitor
cd bitshares-witness-monitor
npm install
```

Open config-sample.json in your favourite text editor and edit with your own settings:

```
{
    "witness_id": "1.6.XXX",
    "api_node": "wss://<your_preferred_api_node>",
    "private_key": "5kTSOMEPRIVATEKEY111111111111",
    "missed_block_threshold": 3,
    "checking_interval": 10,
    "backup_key": "BTSXXXXXXXXXXXXXXXXXX",
    "reset_period": 300
    "debug_level": 3,
    "telegram_token": "<telegram_access_token>",
    "telegram_password": "<chosen_access_password>",
    "retries_threshold": 3
}
``` 
  
and then save as config.json

`private_key`  
The active key of your normal witness-owning account used to sign the witness_update operation.

`missed_block_threshold`  
How many blocks must be missed within a `reset_period` sec window before the script switches your signing key. Recommend to set at 2 or higher since 1 will possibly trigger updates on maintenance intervals (see: https://github.com/bitshares/bitshares-core/issues/504)

`checking_interval`  
How often should the script check for new missed blocks in seconds.

`backup_key`  
The public signing key of your backup witness to be used when switching.

`reset_period`  
The time after which the missed blocks counter is reset for the session in seconds.

`debug_level`  
Logging level. Can be:  
0: Minimum - Explicit logging & Errors  
1: Info - 0 + Basic logging  
2: Verbose - 1 + Verbose logging  
3: Transient - 2 + Transient messages  
but not currently used.

`telegram_token`  
The telegram access token for your notifications bot. You can get one here: https://telegram.me/BotFather

`telegram_password`  
Your chosen access password through telegram.

`retries_threshold`  
Number of failed connections to API node before the bot notifies you on telegram.

## Running

Simply use:

`node index.js`

inside a screen (or similar) session.

For peace of mind I recommend you also install the forever tool:

`sudo npm install forever -g`

and run as:

`forever index.js`

instead. 

*NOTE:* In case forever restarts the process, it will start with the DEFAULT config.json you have provided and not with the session-only changes you might have made using the telegram commands below.

## Telegram commands

Open a chat to your bot and use the following:

`/pass <your_configured_telegram_pass>`

This is required to authenticate. Otherwise none of the following commands will work.

`/changepass <new_password>` 

This will update your telegram access password and will require you to authenticate again using `/pass`

`/stats`

This will return the current configuration and statistics of the monitoring session.

`/switch`

This will IMMEDIATELY update your signing key to the currently configured backup key.

`/new_key <BTS_public_signing_key>`

This will set a new backup key in place of the configured one.

`/new_node wss://<api_node_url>`

This will set a new API node to connect to.

`/threshold X`

This will set the missed block threshold before updating signing key to X blocks.

`/interval Y`

This will set the checking interval to every Y seconds.

`/window Z`

This will set the time until missed blocks counter is reset to Z seconds.

`/retries N` 

This will set the threshold for failed API node connection attempts to N times before notifying you in telegram.

`/reset`

This will reset the missed blocks counter in the current time-window.

`/pause`

This will pause monitoring.

`/resume`

This will resume monitoring.