Polkascan Open-Source

Polkascan Open-Source Application

Quick deployment (Use hosted Polkascan API endpoints)

Step 1: Clone repository:

git clone https://github.com/polkascan/polkascan-os.git

Step 2: Change directory:

cd polkascan-os

Step 3: Check available releases:

git tag

Step 4: Checkout latest releases:

git checkout v0.x.x

Step 5: Make sure to also clone submodules within the cloned directory:

git submodule update --init --recursive

Step 6: Then build the other docker containers

docker-compose -p kusama -f docker-compose.kusama-quick.yml up --build

Use public Substrate RPC endpoints

Step 1: Clone repository:

git clone https://github.com/polkascan/polkascan-os.git

Step 2: Change directory:

cd polkascan-os

Step 3: Check available releases:

git tag

Step 4: Checkout latest releases:

git checkout v0.x.x

Step 5: Make sure to also clone submodules within the cloned directory:

git submodule update --init --recursive

Step 6: During the first run let MySQL initialize (wait for about a minute)

docker-compose -p kusama -f docker-compose.kusama-public.yml up -d mysql

Step 7: Then build the other docker containers

docker-compose -p kusama -f docker-compose.kusama-public.yml up --build

Full deployment

The following steps will run a full Polkascan-stack that harvests blocks from a new local network.

Step 1: Clone repository:

git clone https://github.com/polkascan/polkascan-os.git

Step 2: Change directory:

cd polkascan-os

Step 3: Check available releases:

git tag

Step 4: Checkout latest releases:

git checkout v0.x.x

Step 5: Make sure to also clone submodules within the cloned directory:

git submodule update --init --recursive

Step 6: During the first run let MySQL initialize (wait for about a minute)

docker-compose -p kusama -f docker-compose.kusama-full.yml up -d mysql

Step 7: Then build the other docker containers

docker-compose -p kusama -f docker-compose.kusama-full.yml up --build

Links to applications

• Polkascan Explorer GUI: http://127.0.0.1:8080
• Monitor harvester progress: http://127.0.0.1:8080/kusama/harvester/admin
• Harvester Task Monitor: http://127.0.0.1:5555
• Polkadot JS Apps: http://127.0.0.1:8081

Other networks

• Polkadot: Use docker-compose.polkadot-quick.yml, docker-compose.polkadot-public.yml and docker-compose.polkadot-full.yml
• Substrate Node Template (https://github.com/substrate-developer-hub/substrate-node-template): Use docker-compose.substrate-node-template.yml

Add custom types for Substrate Node Template

• Modify harvester/app/type_registry/substrate-node-template.json to match the introduced types of the custom chain
• Truncate runtime and runtime_* tables on database
• Start harvester
• Check http://127.0.0.1:8080/node-template/runtime-type if all type are now correctly supported
• Monitor http://127.0.0.1:8080/node-template/harvester/admin if blocks are being processed and try to restart by pressing "Process blocks in harvester queue" if process is interupted.

Cleanup Docker

Use the following commands with caution to cleanup your Docker environment.

Prune images

docker system prune

Prune images (force)

docker system prune -a

Prune volumes

docker volume prune

API specification

The Polkascan API implements the https://jsonapi.org/ specification. An overview of available endpoints can be found here: https://github.com/polkascan/polkascan-pre-explorer-api/blob/master/app/main.py#L60

Troubleshooting

When certain block are not being processed or no blocks at all then most likely there is a missing or invalid type definition in the type registry.

Some steps to check:

• The Substrate node should be started in archive mode (--pruning archive)
• Be sure to regularly update, also the Git submodules: git submodule update --init --recursive for latest version of py-scale-codec
• Check which blocks are not being processed and try to restart manually at: http://127.0.0.1:8080/<NETWORK_NAME>/harvester/admin
• Check Celery queue for more details about failing blocks: http://127.0.0.1:5555/tasks?state=FAILURE
• Check and match types in ./harvester/app/type_registry/custom_types.json with added types in Substrate

You can also dive into Python to pinpoint which types are failing to decode:

import json
from scalecodec.type_registry import load_type_registry_file
from substrateinterface import SubstrateInterface

substrate = SubstrateInterface(
    url='ws://127.0.0.1:9944',
    type_registry_preset='substrate-node-template',
    type_registry=load_type_registry_file('harvester/app/type_registry/custom_types.json'),
)

block_hash = substrate.get_block_hash(block_id=3899710)

extrinsics = substrate.get_block_extrinsics(block_hash=block_hash)

print('Extrinsincs:', json.dumps([e.value for e in extrinsics], indent=4))

events = substrate.get_events(block_hash)

print("Events:", json.dumps([e.value for e in events], indent=4))