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BlockScout

Overview

This guide goes into details on how to compile and deploy BlockScout instance to work with Polygon-Edge. BlockScout has its own documentation, but this guide focuses on simple but detailed step-by-step instructions on how to setup BlockScout instance.

Environment

  • Operating System: Ubuntu Server 20.04 LTS download link with sudo permissions
  • Server Hardware: 8CPU / 16GB RAM / 50GB HDD (LVM)
  • Database Server: Dedicated server with 2 CPU / 4GB RAM / 100GB SSD / PostgreSQL 13.4

DB Server

The requirement for following this guide is to have a database server ready, database and db user configured. This guide will not go into details on how to deploy and configure PostgreSQL server. There are plenty of guides on now to do this, for example DigitalOcean Guide

DISCLAIMER

This guide is meant only to help you to get BlockScout up and running on a single instance which is not ideal production setup.
For production, you'll probably want to introduce reverse proxy, load balancer, scalability options, etc. into the architecture.

BlockScout Deployment Procedure

Part 1 - install dependencies

Before we start we need to make sure we have all the binaries installed that the blockscout is dependent on.

Update & upgrade system

sudo apt -y update && sudo apt -y upgrade

Add erlang repos

# go to your home dir
cd ~
# download deb
wget https://packages.erlang-solutions.com/erlang-solutions_2.0_all.deb
# download key
wget https://packages.erlang-solutions.com/ubuntu/erlang_solutions.asc
# install repo
sudo dpkg -i erlang-solutions_2.0_all.deb
# install key
sudo apt-key add erlang_solutions.asc
# remove deb
rm erlang-solutions_2.0_all.deb
# remove key
rm erlang_solutions.asc

Add NodeJS repo

sudo curl -sL https://deb.nodesource.com/setup_16.x | sudo -E bash -

Install Rust

sudo curl https://sh.rustup.rs -sSf | sh -s -- -y

Install required version of Erlang

sudo apt -y install esl-erlang=1:24.*

Install required version of Elixir

The version of Elixir must be 1.13. If we try and install this version from the official repo, the erlang will update to Erlang/OTP 25 and we do not want that.
Because of this, we need to install the specific precompiled elixir version from GitHub releases page.

cd ~
mkdir /usr/local/elixir
wget https://github.com/elixir-lang/elixir/releases/download/v1.13.4/Precompiled.zip
sudo unzip -d /usr/local/elixir/ Precompiled.zip
rm Precompiled.zip

Now we need to properly set up exlixir system binaries.

sudo ln -s /usr/local/elixir/bin/elixir /usr/local/bin/elixir
sudo ln -s /usr/local/elixir/bin/mix /usr/local/bin/mix
sudo ln -s /usr/local/elixir/bin/iex /usr/local/bin/iex
sudo ln -s /usr/local/elixir/bin/elixirc /usr/local/bin/elixirc

Check if elixir and erlang are properly installed by running elixir -v. This should be the output:

Erlang/OTP 24 [erts-12.3.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]

Elixir 1.13.4 (compiled with Erlang/OTP 22)
danger

Erlang/OTP must be version 24 and Elixir must be version 1.13.*.
If that is not the case, you will run into issues with compiling BlockScout and/or running it.

info

Check out the official BlockScout requirements page

Install NodeJS

sudo apt -y install nodejs

Install Cargo

sudo apt -y install cargo

Install other dependencies

sudo apt -y install automake libtool inotify-tools gcc libgmp-dev make g++ git

Optionally install postgresql client to check your db connection

sudo apt install -y postgresql-client

Part 2 - set environment variables

We need to set the environment variables, before we begin with BlockScout compilation. In this guide we'll set only the basic minimum to get it working. Full list of variables that can be set you can find here

Set database connection as environment variable

# postgresql connection example:  DATABASE_URL=postgresql://blockscout:[email protected]:5432/blockscout
export DATABASE_URL=postgresql://<db_user>:<db_pass>@<db_host>:<db_port>/<db_name> # db_name does not have to be existing database

# we set these env vars to test the db connection with psql
export PGPASSWORD=Passw0Rd
export PGUSER=blockscout
export PGHOST=db.instance.local
export PGDATABASE=postgres # on AWS RDS postgres database is always created

Now test your DB connection with provided parameters. Since you've provided PG env vars, you should be able to connect to the database only by running:

psql

If the database is configured correctly, you should see a psql prompt:

psql (12.9 (Ubuntu 12.9-0ubuntu0.20.04.1))
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

blockscout=>

Otherwise, you might see an error like this:

psql: error: FATAL:  password authentication failed for user "blockscout"
FATAL: password authentication failed for user "blockscout"

If this is the case these docs might help you.

DB Connection

Make sure you've sorted out all db connection issues before proceeding to the next part. You'll need to provide superuser privileges to blockscout user.

[email protected]:~$ createuser --interactive
Enter name of role to add: blockscout
Shall the new role be a superuser? (y/n) y

Part 3 - clone and compile BlockScout

Now we finally get to start the BlockScout installation.

Clone BlockScout repo

cd ~
git clone https://github.com/Trapesys/blockscout

Generate secret key base to protect production build

cd blockscout
mix deps.get
mix local.rebar --force
mix phx.gen.secret

At the very last line, you should see a long string of random characters.
This should be set as your SECRET_KEY_BASE environment variable, before the next step.
For example:

export SECRET_KEY_BASE="912X3UlQ9p9yFEBD0JU+g27v43HLAYl38nQzJGvnQsir2pMlcGYtSeRY0sSdLkV/"

Set production mode

export MIX_ENV=prod

Compile

Cd into clone directory and start compiling

cd blockcout
mix local.hex --force
mix do deps.get, local.rebar --force, deps.compile, compile
info

If you have deployed previously, remove static assets from the previous build mix phx.digest.clean.

Migrate databases

info

This part will fail if you didn't set up your DB connection properly, you didn't provide, or you've defined wrong parameters at DATABASE_URL environment variable. The database user needs to have superuser privileges.

mix do ecto.create, ecto.migrate

If you need to drop the database first, run

mix do ecto.drop, ecto.create, ecto.migrate

Install npm dependencies and compile frontend assets

You need to change directory to the folder which contains frontend assets.

cd apps/block_scout_web/assets
sudo npm install
sudo node_modules/webpack/bin/webpack.js --mode production
Be patient

Compilation of these assets can take a few minutes, and it will display no output. It can look like the process is stuck, but just be patient. When compile process is finished, it should output something like: webpack 5.69.1 compiled with 3 warnings in 104942 ms

Build static assets

For this step you need to return to the root of your BlockScout clone folder.

cd ~/blockscout
sudo mix phx.digest

Generate self-signed certificates

info

You can skip this step if you won't use https.

cd apps/block_scout_web
mix phx.gen.cert blockscout blockscout.local

Part 4 - create and run BlockScout service

In this part we need to set up a system service as we want BlockScout to run in the background and persist after system reboot.

Create service file

sudo touch /etc/systemd/system/explorer.service

Edit service file

Use your favorite linux text editor to edit this file and configure the service.

sudo vi /etc/systemd/system/explorer.service

The contents of the explorer.service file should look like this:

[Unit]
Description=BlockScout Server
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=root
StandardOutput=syslog
StandardError=syslog
WorkingDirectory=/usr/local/blockscout
ExecStart=/usr/local/bin/mix phx.server
EnvironmentFile=/usr/local/blockscout/env_vars.env

[Install]
WantedBy=multi-user.target

Enable starting service on system boot

sudo systemctl daemon-reload
sudo systemctl enable explorer.service

Move your BlockScout clone folder to system-wide location

BlockScout service needs to have access to the folder you've cloned from BlockScout repo and compiled all the assets.

sudo mv ~/blockscout /usr/local

Create env vars file which will be used by BlockScout service

sudo touch /usr/local/blockscout/env_vars.env
# use your favorite text editor
sudo vi /usr/local/blockscout/env_vars.env

# env_vars.env file should hold these values ( adjusted for your environment )
ETHEREUM_JSONRPC_HTTP_URL="localhost:8545" # json-rpc API of the chain
ETHEREUM_JSONRPC_TRACE_URL="localhost:8545" # same as json-rpc API
DATABASE_URL='postgresql://blockscout:[email protected]:5432/blockscout' # database connection from Step 2
SECRET_KEY_BASE="912X3UlQ9p9yFEBD0JU+g27v43HLAYl38nQzJGvnQsir2pMlcGYtSeRY0sSdLkV/" # secret key base
ETHEREUM_JSONRPC_WS_URL="ws://localhost:8545/ws" # websocket API of the chain
CHAIN_ID=93201 # chain id
HEART_COMMAND="systemctl restart explorer" # command used by blockscout to restart it self in case of failure
SUBNETWORK="Supertestnet PoA" # this will be in html title
LOGO="/images/polygon_edge_logo.svg" # logo location
LOGO_FOOTER="/images/polygon_edge_logo.svg" # footer logo location
COIN="EDGE" # coin
COIN_NAME="EDGE Coin" # name of the coin
INDEXER_DISABLE_BLOCK_REWARD_FETCHER="true" # disable block reward indexer as Polygon Edge doesn't support tracing
INDEXER_DISABLE_PENDING_TRANSACTIONS_FETCHER="true" # disable pending transactions indexer as Polygon Edge doesn't support tracing
INDEXER_DISABLE_INTERNAL_TRANSACTIONS_FETCHER="true" # disable internal transactions indexer as Polygon Edge doesn't support tracing
MIX_ENV="prod" # run in production mode
BLOCKSCOUT_PROTOCOL="http" # protocol to run blockscout web service on
PORT=4000 # port to run blockscout service on
DISABLE_EXCHANGE_RATES="true" # disable fetching of exchange rates
POOL_SIZE=200 # the number of database connections
POOL_SIZE_API=300 # the number of read-only database connections
ECTO_USE_SSL="false" # if protocol is set to http this should be false
HEART_BEAT_TIMEOUT=60 # run HEARTH_COMMAND if heartbeat missing for this amount of seconds
INDEXER_MEMORY_LIMIT="10Gb" # soft memory limit for indexer - depending on the size of the chain and the amount of RAM the server has
FETCH_REWARDS_WAY="manual" # disable trace_block query
INDEXER_EMPTY_BLOCKS_SANITIZER_BATCH_SIZE=1000 # sanitize empty block in this batch size
info

Use SECRET_KEY_BASE you've generated in Part 3.

Save the file and exit.

Finally, start BlockScout service

sudo systemctl start explorer.service

Part 5 - test out the functionality of your BlockScout instance

Now all that's left to do is to check if BlockScout service is running. Check service status with:

sudo systemctl status explorer.service

To check service output:

sudo journalctl -u explorer.service -f

You can check if there are some new listening ports:

# if netstat is not installed
sudo apt install net-tools
sudo netstat -tulpn

You should get a list of listening ports and on the list there should be something like this:

tcp        0      0 0.0.0.0:5432            0.0.0.0:*               LISTEN      28142/postgres
tcp 0 0 0.0.0.0:4000 0.0.0.0:* LISTEN 42148/beam.smp

BlockScout web service runs the port and protocol defined in env file. In this example it runs on 4000(http).
If everything is ok, you should be able to access the BlockScout web portal with http://<host_ip>:4000.

Considerations

For best performance, it is advisable to have a dedicated/local polygon-edge full archive non-validator node that will be used exclusively for BlockScout queries.
The json-rpc API of this node, doesn't need to be exposed publicly, as BlockScout runs all queries from the backend.

Final thoughts

We've just deployed a single BlockScout instance, which works fine, but for production you should consider placing this instance behind a reverse proxy like Nginx. You should also think about database and instance scalability, depending on your use case.

You should definitely check out the official BlockScout documentation as there a lot of customisation options.