# Finding the longest attestation slot gap

## :fast\_forward: Quick steps guide

{% hint style="info" %}
The following steps align with our [mainnet guide](https://nodebridge-africa.gitbook.io/nodebridge-africa/readme/ethereum-staking-guide/ethereum-staking-guide/setting-up-a-validator-on-eth2-mainnet). You may need to adjust file names and directory locations where appropriate. The core concepts remain the same.
{% endhint %}

### :dagger: Why do I want to calculate the longest attestation slot gap?

* Your validators are assigned duties to attest and propose blocks.
* Understanding the schedule of your validator's duties better, you can find the best time to plan consensus/execution client updates, system reboots or outages.
* Since the Altair Hard Fork, checking sync committee membership is a must before performing any maintenance. This will give you up to [\~27 hours of advanced notice](https://github.com/ethereum/consensus-specs/pull/2453) in case your validators have been selected for sync committee duties.

### :robot: Pre-requisites

* python3
* validator index number(s) -- Lookup on [https://beaconcha.in/](https://beaconcha.in) or [https://beaconscan.com/](https://beaconscan.com)
* Works with **Lighthouse / Teku / Prysm** currently

{% hint style="success" %}
:sparkles: Kudos to **pietjepuk2** on Discord for authoring this process.
{% endhint %}

### :construction: How to Run the Validator Duties script

1\. Install python3

```
sudo apt update && sudo apt-get install python3
```

2\. Download [pietjepuk2](https://gist.github.com/pietjepuk2)'s `get_validator_duties.py` python script.

{% tabs %}
{% tab title="Lighthouse | Teku" %}

```bash
cd $HOME
wget https://gist.githubusercontent.com/pietjepuk2/eb021db978ad20bfd94dce485be63150/raw/cc874b3035f97495416353f203d70477b31ab05d/get_validator_duties.py
```

{% endtab %}

{% tab title="Prysm" %}

```bash
cd $HOME
# modified by mohamedmansour for prysm
wget https://gist.githubusercontent.com/mohamedmansour/9a82071802ffd58bef7ab5db530f23fd/raw/d48a3f0948cf2ae8cf571b42d50f80d66841118f/get_validator_duties.py
```

{% endtab %}
{% endtabs %}

3\. Enter your validator index numbers as parameters to the python script.

```bash
python3 get_validator_duties.py <validator index number(s)>
# Example
# python3 get_validator_duties.py 1000 1001 1002 1003
```

Sample Output showing the longest gap in seconds, # of slots and time range.

> Longest gap (first):
>
> 120.0 seconds (10 slots), from 13:37:35 until 13:39:35

{% hint style="info" %}
:question:**Troubleshooting:**

* The python script calls the `http API` on port 5052.
* Ensure the `http API` is enabled for your consensus layer client.
  * teku: `--rest-api-enabled=true`
* Teku by default uses port 5051, rather than 5052. Search and replace the port number before using.
  {% endhint %}

{% hint style="warning" %}
:fire: **Script Usage Caveats**:

* This version does not include block proposals, although the odds of having one scheduled are really low of course.
* Block proposal duties are only known for the current epoch, whereas attestation duties are known for the current and next one.
  {% endhint %}

{% hint style="success" %}
Nice work. Now you now the best gap to avoid missing any validator duties.
{% endhint %}

## :robot: Start staking by building a validator <a href="#start-staking-by-building-a-validator" id="start-staking-by-building-a-validator"></a>

### Visit here for our Mainnet guide

{% hint style="success" %}
Congrats on completing the guide. ✨
{% endhint %}

## :jigsaw: Reference Material

{% embed url="<https://gist.githubusercontent.com/pietjepuk2/eb021db978ad20bfd94dce485be63150/raw/cc874b3035f97495416353f203d70477b31ab05d/get_validator_duties.py>" %}

<https://gist.github.com/mohamedmansour/9a82071802ffd58bef7ab5db530f23fd>