Polkascan Explorer provides a generalized block explorer for Substrate-based blockchains.
It combines data retrieved directly from the Substrate node RPC with data retrieved from a third-party indexer API.
At the moment the following third-party data are supported:
- Polkascan API
- Subsquid
Run init.sh to initialize repository; this will basically setup git submodules and copy necessary scripts.
Run polkascan on L1 Testnet:
docker compose -f docker-compose.L1.yml -p polkascan-l1 up --build
Run polkascan on L2 Testnet:
docker compose -f docker-compose.L2.yml -p polkascan-l2 up --build
Run the Explorer UI:
docker compose -f docker-compose.yml -p polkascan up --build
- Polkascan UI: http://127.0.0.1:8080/
API playground: http://127.0.0.1:8000/graphql/.
Websocket: ws://127.0.0.1:8000/graphql-ws.
MySQL database exposed at mysql://root:root@localhost:33060.
API playground: http://127.0.0.1:8001/graphql/.
Websocket: ws://127.0.0.1:8001/graphql-ws.
MySQL database exposed at mysql://root:root@localhost:33061.
The explorer application consist of several components:
The harvester retrieves data from the connected Substrate node and stores it into a MySQL (by default) database.
With the processing of each block, it can also be desirable to retrieve and decode certain storage records. By default,
for every block the System.Events are stored as this is a fundamental element to determine which calls are executed.
When other storage records are needed, for example a balance snapshot of all accounts every 10000 blocks, additional cron items can be added:
cd harvester
./harvester-cli.sh storage-cron add
> Block interval (e.g. 10 = every 10th block): 10000
> Pallet: System
> Storage function: Account
> Added cron System.Account every 10000 blocksCheck the current storage cron items:
Id Block interval Pallet Storage name
---- ---------------- -------- --------------
1 1 System Events
2 10000 System Account
Then run the harvester:
./harvester-cli.sh run When storage cron items retrieve records as part of the block harvest process, storage tasks can be added to retrieve records for any given blocks that are already processed.
Also, this feature can be used standalone, so it basically acts as a storage harvester.
Example: Store total issuance for blocks 1-1000:
cd harvester
./harvester-cli.sh storage-tasks add
> Pallet: Balances
> Storage function: TotalIssuance
> Blocks (e.g. '100,104' or '100-200'): 1-1000
> Added task Balances.TotalIssuance for blocks 1-1000 Then run only the 'cron' job of the harvester:
./harvester-cli.sh run --job cron List progress of tasks:
./harvester-cli.sh storage-tasks list
> Id Pallet Storage name Blocks Complete
> ---- -------- -------------- ------------------------------------- ----------
> 1 System Account {'block_ids': [1, 2]} True
> 2 Balances TotalIssuance {'block_end': 1000, 'block_start': 1} TrueThe explorer API transforms the data via an ETL process into an explorer-specific format. It exposes a GraphQL endpoint and enables subscription-based communication to the UI.
Explorer UI is a client-sided Angular based application that utilizes PolkADAPT and its Adapters to obtain data from multiple data sources, like the Explorer API and the Substrate node. Its design is based on flat Material component design, styled in Polkascan branding.
- Substrate runtimes that implements metadata prior to
MetadataV14decode in a different format as expected by the explorer, so not all functionality is available. This can have effect on early blocks as well, a workaround is to setBLOCK_STARTenv setting for the harvester, to a block number withMetadataV14. - Errors during building
explorer-uiDocker container on M1 architecture. This could happen when the chromium binary is not available for arm64, there is a workaround available - Currently, the
explorer-apiapplication supports Python version >3.6 and <3.10