blockscout/README.md

<p align="center">
  <a href="https://blockscout.com">
    <img width="200" src="https://blockscout.com/eth/mainnet/android-chrome-192x192.png" \>
  </a>
</p>

<h1 align="center">BlockScout</h1>
<p align="center">Blockchain Explorer for inspecting and analyzing EVM Chains.</p>
<div align="center">

[![CircleCI](https://circleci.com/gh/poanetwork/blockscout.svg?style=svg&circle-token=f8823a3d0090407c11f87028c73015a331dbf604)](https://circleci.com/gh/poanetwork/blockscout) [![Coverage Status](https://coveralls.io/repos/github/poanetwork/blockscout/badge.svg?branch=master)](https://coveralls.io/github/poanetwork/blockscout?branch=master) [![Join the chat at https://gitter.im/poanetwork/blockscout](https://badges.gitter.im/poanetwork/blockscout.svg)](https://gitter.im/poanetwork/blockscout?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)

</div>

BlockScout provides a comprehensive, easy-to-use interface for users to view, confirm, and inspect transactions on **all EVM** (Ethereum Virtual Machine) blockchains. This includes the Ethereum main and test networks as well as **Ethereum forks and sidechains**.

Following is an overview of the project and instructions for [getting started](#getting-started).

Visit the [POA BlockScout forum](https://forum.poa.network/c/blockscout) for additional deployment instructions, FAQs, troubleshooting, and other BlockScout related items. You can also post and answer questions here. 

You can also access the dev chatroom on our [Gitter Channel](https://gitter.im/poanetwork/blockscout). 

## About BlockScout

BlockScout is an Elixir application that allows users to search transactions, view accounts and balances, and verify smart contracts on the entire Ethereum network including all forks and sidechains.

Currently available block explorers (i.e. Etherscan and Etherchain) are closed systems which are not independently verifiable.  As Ethereum sidechains continue to proliferate in both private and public settings, transparent tools are needed to analyze and validate transactions.


### Features

- [x] **Open source development**: The code is community driven and available for anyone to use, explore and improve.

- [x] **Real time transaction tracking**: Transactions are updated in real time - no page refresh required. Infinite scrolling is also enabled.

- [x] **Smart contract interaction**: Users can read and verify Solidity smart contracts and access pre-existing contracts to fast-track development. Support for Vyper, LLL, and Web Assembly contracts is in progress.

- [x] **Token support**: ERC20 and ERC721 tokens are supported. Future releases will support additional token types including ERC223 and ERC1155.

- [x] **User customization**: Users can easily deploy on a network and customize the Bootstrap interface.

- [x] **Ethereum sidechain networks**: BlockScout supports the Ethereum mainnet, Ethereum testnets, POA network, and forks like Ethereum Classic, xDAI, additional sidechains, and private EVM networks.

### Supported Projects

| **Hosted Mainnets** | **Hosted Testnets** | **Additional Chains using BlockScout** |
|--------------------------------------------------------|-------------------------------------------------------|----------------------------------------------------|
| [Aerum](https://blockscout.com/aerum/mainnet) | [Goerli Testnet](https://blockscout.com/eth/goerli) | [ARTIS](https://explorer.sigma1.artis.network) |
| [Callisto](https://blockscout.com/callisto/mainnet) | [Kovan Testnet](https://blockscout.com/eth/kovan) | [Ether-1](https://blocks.ether1.wattpool.net/) |
| [Ethereum Classic](https://blockscout.com/etc/mainnet) | [POA Sokol Testnet](https://blockscout.com/poa/sokol) | [Fuse Network](https://explorer.fuse.io/) |
| [Ethereum Mainnet](https://blockscout.com/eth/mainnet) | [Rinkeby Testnet](https://blockscout.com/eth/rinkeby) | [Oasis Labs](https://blockexplorer.oasiscloud.io/) |
| [POA Core Network](https://blockscout.com/poa/core) | [Ropsten Testnet](https://blockscout.com/eth/ropsten) | [Petrichor](https://explorer.petrichor-dev.com/) |
| [RSK](https://blockscout.com/rsk/mainnet) |  | [PIRL](http://pirl.es/) |
| [xDai Chain](https://blockscout.com/poa/dai) |  | [SafeChain](https://explorer.safechain.io) |
|  |  | [SpringChain](https://explorer.springrole.com/) |


### Visual Interface

Interface for the POA network _updated 02/2019_

![BlockScout Example](explorer_example_2_2019.gif)


### Umbrella Project Organization

This repository is an [umbrella project](https://elixir-lang.org/getting-started/mix-otp/dependencies-and-umbrella-projects.html). Each directory under `apps/` is a separate [Mix](https://hexdocs.pm/mix/Mix.html) project and [OTP application](https://hexdocs.pm/elixir/Application.html), but the projects can use each other as a dependency in their `mix.exs`.

Each OTP application has a restricted domain.

| Directory               | OTP Application     | Namespace         | Purpose                                                                                                                                                                                                                                                                                                                                                                         |
|:------------------------|:--------------------|:------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `apps/ethereum_jsonrpc` | `:ethereum_jsonrpc` | `EthereumJSONRPC` | Ethereum JSONRPC client.  It is allowed to know `Explorer`'s param format, but it cannot directly depend on `:explorer`                                                                                                                                                                                                                                                         |
| `apps/explorer`         | `:explorer`         | `Explorer`        | Storage for the indexed chain.  Can read and write to the backing storage.  MUST be able to boot in a read-only mode when run independently from `:indexer`, so cannot depend on `:indexer` as that would start `:indexer` indexing.                                                                                                                                            |
| `apps/block_scout_web`     | `:block_scout_web`     | `BlockScoutWeb`     | Phoenix interface to `:explorer`.  The minimum interface to allow web access should go in `:block_scout_web`.  Any business rules or interface not tied directly to `Phoenix` or `Plug` should go in `:explorer`. MUST be able to boot in a read-only mode when run independently from `:indexer`, so cannot depend on `:indexer` as that would start `:indexer` indexing. |
| `apps/indexer`          | `:indexer`          | `Indexer`         | Uses `:ethereum_jsonrpc` to index chain and batch import data into `:explorer`.  Any process, `Task`, or `GenServer` that automatically reads from the chain and writes to `:explorer` should be in `:indexer`. This restricts automatic writes to `:indexer` and read-only mode can be achieved by not running `:indexer`.                                             |


## Getting Started

### Requirements

| Dependency  | Mac | Linux |
|-------------|-----|-------|
| [Erlang/OTP 21.0.4](https://github.com/erlang/otp) | `brew install erlang` | [Erlang Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L134) |
| [Elixir 1.8.1](https://elixir-lang.org/) | :point_up: | [Elixir Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L138) |
| [Postgres 10.3](https://www.postgresql.org/) | `brew install postgresql` | [Postgres Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L187) |
| [Node.js 10.5.0](https://nodejs.org/en/) | `brew install node` | [Node.js Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L66) |
| [Automake](https://www.gnu.org/software/automake/) | `brew install automake` | [Automake Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L72) |
| [Libtool](https://www.gnu.org/software/libtool/) | `brew install libtool` | [Libtool Install Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L62) |
| [Inotify-tools](https://github.com/rvoicilas/inotify-tools/wiki) | Not Required | Ubuntu - `apt-get install inotify-tools` |
| [GCC Compiler](https://gcc.gnu.org/) | `brew install gcc` | [GCC Compiler Example](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L70) |
| [GMP](https://gmplib.org/) | `brew install gmp` | [Install GMP Devel](https://github.com/poanetwork/blockscout-terraform/blob/33f68e816e36dc2fb055911fa0372531f0e956e7/modules/stack/libexec/init.sh#L74) |

### Build and Run

#### Playbook Deployment

We use [Ansible](https://docs.ansible.com/ansible/latest/index.html) & [Terraform](https://www.terraform.io/intro/getting-started/install.html) to build the correct infrastructure to run BlockScout. See [https://github.com/poanetwork/blockscout-terraform](https://github.com/poanetwork/blockscout-terraform) for details and instructions.

#### Manual Deployment

See [Manual BlockScout Deployment](https://forum.poa.network/t/manual-blockscout-deployment/2458) for instructions.

#### Environment Variables

Our forum contains a [full list of BlockScout environment variables](https://forum.poa.network/t/faq-blockscout-environment-variables/1814).

#### Configuring EVM Chains

* **CSS:** Update the import instruction in `apps/block_scout_web/assets/css/theme/_variables.scss` to select a preset css file. This is reflected in the `production-${chain}` branch for each instance. For example, in the `production-xdai` branch, it is set to `@import "dai-variables"`.

* **ENV:** Update the [environment variables](https://forum.poa.network/t/faq-blockscout-environment-variables/1814) to match the chain specs.

#### Automating Restarts

By default `blockscout` does not restart if it crashes. To enable automated
restarts, set the environment variable `HEART_COMMAND` to whatever command you run to start `blockscout`. Configure the heart beat timeout to change how long it waits before considering the application unresponsive. At that point, it will kill the current blockscout instance and execute the `HEART_COMMAND`. By default a crash dump is not written unless you set `ERL_CRASH_DUMP_SECONDS` to a positive or negative integer. See the [heart](http://erlang.org/doc/man/heart.html) documentation for more information.


#### CircleCI Updates

To monitor build status, configure your local [CCMenu](http://ccmenu.org/) with the following url: [`https://circleci.com/gh/poanetwork/blockscout.cc.xml?circle-token=f8823a3d0090407c11f87028c73015a331dbf604`](https://circleci.com/gh/poanetwork/blockscout.cc.xml?circle-token=f8823a3d0090407c11f87028c73015a331dbf604)


## Testing

### Requirements

  * PhantomJS (for wallaby)

### Running the tests

  1. Build the assets.
  `cd apps/block_scout_web/assets && npm run build; cd -`

  2. Format the Elixir code.
  `mix format`

  3. Run the test suite with coverage for whole umbrella project.  This step can be run with different configuration outlined below.
  `mix coveralls.html --umbrella`

  4. Lint the Elixir code.
  `mix credo --strict`

  5. Run the dialyzer.
  `mix dialyzer --halt-exit-status`

  6. Check the Elixir code for vulnerabilities.
  `cd apps/explorer && mix sobelow --config; cd -`
  `cd apps/block_scout_web && mix sobelow --config; cd -`

  7. Lint the JavaScript code.
  `cd apps/block_scout_web/assets && npm run eslint; cd -`

  8. Test the JavaScript code.
  `cd apps/block_scout_web/assets && npm run test; cd -`

#### Parity

##### Mox

**This is the default setup.  `mix coveralls.html --umbrella` will work on its own, but to be explicit, use the following setup**:

```shell
export ETHEREUM_JSONRPC_CASE=EthereumJSONRPC.Case.Parity.Mox
export ETHEREUM_JSONRPC_WEB_SOCKET_CASE=EthereumJSONRPC.WebSocket.Case.Mox
mix coveralls.html --umbrella --exclude no_parity
```

##### HTTP / WebSocket

```shell
export ETHEREUM_JSONRPC_CASE=EthereumJSONRPC.Case.Parity.HTTPWebSocket
export ETHEREUM_JSONRPC_WEB_SOCKET_CASE=EthereumJSONRPC.WebSocket.Case.Parity
mix coveralls.html --umbrella --exclude no_parity
```

| Protocol  | URL                                |
|:----------|:-----------------------------------|
| HTTP      | `http://localhost:8545`  |
| WebSocket | `ws://localhost:8546`    |

#### Geth

##### Mox

```shell
export ETHEREUM_JSONRPC_CASE=EthereumJSONRPC.Case.Geth.Mox
export ETHEREUM_JSONRPC_WEB_SOCKET_CASE=EthereumJSONRPC.WebSocket.Case.Mox
mix coveralls.html --umbrella --exclude no_geth
```

##### HTTP / WebSocket

```shell
export ETHEREUM_JSONRPC_CASE=EthereumJSONRPC.Case.Geth.HTTPWebSocket
export ETHEREUM_JSONRPC_WEB_SOCKET_CASE=EthereumJSONRPC.WebSocket.Case.Geth
mix coveralls.html --umbrella --exclude no_geth
```

| Protocol  | URL                                               |
|:----------|:--------------------------------------------------|
| HTTP      | `https://mainnet.infura.io/8lTvJTKmHPCHazkneJsY`  |
| WebSocket | `wss://mainnet.infura.io/ws/8lTvJTKmHPCHazkneJsY` |

### API Documentation

To view Modules and API Reference documentation:

1. Generate documentation.
`mix docs`
2. View the generated docs.
`open doc/index.html`

## Front-end

### Javascript

All Javascript files are under [apps/block_scout_web/assets/js](https://github.com/poanetwork/blockscout/tree/master/apps/block_scout_web/assets/js) and the main file is [app.js](https://github.com/poanetwork/blockscout/blob/master/apps/block_scout_web/assets/js/app.js). This file imports all javascript used in the application. If you want to create a new JS file consider creating into [/js/pages](https://github.com/poanetwork/blockscout/tree/master/apps/block_scout_web/assets/js/pages) or [/js/lib](https://github.com/poanetwork/blockscout/tree/master/apps/block_scout_web/assets/js/lib), as follows:

#### js/lib
This folder contains all scripts that can be reused in any page or can be used as a helper to some component.

#### js/pages
This folder contains the scripts that are specific for some page.

#### Redux
This project uses Redux to control the state in some pages. There are pages that have things happening in real-time thanks to the Phoenix channels, e.g. Address page, so the page state changes a lot depending on which events it is listening. The redux is also used to load some contents asynchronous, see [async_listing_load.js](https://github.com/poanetwork/blockscout/blob/master/apps/block_scout_web/assets/js/lib/async_listing_load.js).

To understand how to build new pages that need redux in this project, see the [redux_helpers.js](https://github.com/poanetwork/blockscout/blob/master/apps/block_scout_web/assets/js/lib/redux_helpers.js)

## Internationalization

The app is currently internationalized. It is only localized to U.S. English. To translate new strings.

1. To setup translation file.
`cd apps/block_scout_web; mix gettext.extract --merge; cd -`
2. To edit the new strings, go to `apps/block_scout_web/priv/gettext/en/LC_MESSAGES/default.po`.

## Metrics

BlockScout is setup to export [Prometheus](https://prometheus.io/) metrics at `/metrics`.

### Prometheus

1. Install prometheus: `brew install prometheus`
2. Start the web server `iex -S mix phx.server`
3. Start prometheus: `prometheus --config.file=prometheus.yml`

### Grafana

1. Install grafana: `brew install grafana`
2. Install Pie Chart panel plugin: `grafana-cli plugins install grafana-piechart-panel`
3. Start grafana: `brew services start grafana`
4. Add Prometheus as a Data Source
   1. `open http://localhost:3000/datasources`
   2. Click "+ Add data source"
   3. Put "Prometheus" for "Name"
   4. Change "Type" to "Prometheus"
   5. Set "URL" to "http://localhost:9090"
   6. Set "Scrape Interval" to "10s"
5. Add the dashboards from https://github.com/deadtrickster/beam-dashboards:
   For each `*.json` file in the repo.
   1. `open http://localhost:3000/dashboard/import`
   2. Copy the contents of the JSON file in the "Or paste JSON" entry
   3. Click "Load"
6. View the dashboards.  (You will need to click-around and use BlockScout for the web-related metrics to show up.)

## Tracing

Blockscout supports tracing via
[Spandex](http://git@github.com:spandex-project/spandex.git). Each application
has its own tracer, that is configured internally to that application. In order
to enable it, visit each application's `config/<env>.ex` and update its tracer
configuration to change `disabled?: true` to `disabled?: false`. Do this for
each application you'd like included in your trace data.

Currently, only [Datadog](https://www.datadoghq.com/) is supported as a
tracing backend, but more will be added soon.

### DataDog

If you would like to use DataDog, after enabling `Spandex`, set
`"DATADOG_HOST"` and `"DATADOG_PORT"` environment variables to the
host/port that your Datadog agent is running on. For more information on
Datadog and the Datadog agent, see their
[documentation](https://docs.datadoghq.com/).

### Other

If you want to use a different  backend, remove the
`SpandexDatadog.ApiServer` `Supervisor.child_spec` from
`Explorer.Application` and follow any instructions provided in `Spandex`
for setting up that backend.

## Memory Usage

The work queues for building the index of all blocks, balances (coin and token), and internal transactions can grow quite large.   By default, the soft-limit is 1 GiB, which can be changed in `apps/indexer/config/config.exs`:

```
config :indexer, memory_limit: 1 <<< 30
```

Memory usage is checked once per minute.  If the soft-limit is reached, the shrinkable work queues will shed half their load.  The shed load will be restored from the database, the same as when a restart of the server occurs, so rebuilding the work queue will be slower, but use less memory.

If all queues are at their minimum size, then no more memory can be reclaimed and an error will be logged.

## Acknowledgements

We would like to thank the [EthPrize foundation](http://ethprize.io/) for their funding support.

## Contributing

See [CONTRIBUTING.md](CONTRIBUTING.md) for contribution and pull request protocol. We expect contributors to follow our [code of conduct](CODE_OF_CONDUCT.md) when submitting code or comments.


## License

[![License: GPL v3.0](https://img.shields.io/badge/License-GPL%20v3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0)

This project is licensed under the GNU General Public License v3.0. See the [LICENSE](LICENSE) file for details.