SUPPORTED_CHAINS ENV var

[vbaranov]

Closes #1899

Motivation

We have no ability to manage supported chains list without redeploying the application

Changelog

Enhancements

A new ENV var SUPPORTED_CHAINS has been added. It represents a minified array of JSON objects

[
    {
      "title": "POA Core",
      "url": "https://blockscout.com/poa/core"
    },
    {
      "title": "POA Sokol",
      "url": "https://blockscout.com/poa/sokol",
      "test_net?": true
    },
    {
      "title": "xDai Chain",
      "url": "https://blockscout.com/poa/dai"
    },
    {
      "title": "Ethereum Mainnet",
      "url": "https://blockscout.com/eth/mainnet"
    },
    {
      "title": "Kovan Testnet",
      "url": "https://blockscout.com/eth/kovan",
      "test_net?": true
    },
    {
      "title": "Ropsten Testnet",
      "url": "https://blockscout.com/eth/ropsten",
      "test_net?": true
    },
    {
      "title": "Goerli Testnet",
      "url": "https://blockscout.com/eth/goerli",
      "test_net?": true
    },
    {
      "title": "Rinkeby Testnet",
      "url": "https://blockscout.com/eth/rinkeby",
      "test_net?": true
    },
    {
      "title": "Ethereum Classic",
      "url": "https://blockscout.com/etc/mainnet",
      "other?": true
    },
    {
      "title": "Aerum Mainnet",
      "url": "https://blockscout.com/aerum/mainnet",
      "other?": true
    },
    {
      "title": "Callisto Mainnet",
      "url": "https://blockscout.com/callisto/mainnet",
      "other?": true
    },
    {
      "title": "RSK Mainnet",
      "url": "https://blockscout.com/rsk/mainnet",
      "other?": true
    },
    {
      "title": "LUKSO L14 testnet",
      "url": "https://blockscout.com/lukso/l14",
      "test_net?": true,
      "hide_in_dropdown?": true
    }
  ]

and the minified version:

export SUPPORTED_CHAINS='[ { "title": "POA Core", "url": "https://blockscout.com/poa/core" }, { "title": "POA Sokol", "url": "https://blockscout.com/poa/sokol", "test_net?": true }, { "title": "xDai Chain", "url": "https://blockscout.com/poa/dai" }, { "title": "Ethereum Mainnet", "url": "https://blockscout.com/eth/mainnet" }, { "title": "Kovan Testnet", "url": "https://blockscout.com/eth/kovan", "test_net?": true }, { "title": "Ropsten Testnet", "url": "https://blockscout.com/eth/ropsten", "test_net?": true }, { "title": "Goerli Testnet", "url": "https://blockscout.com/eth/goerli", "test_net?": true }, { "title": "Rinkeby Testnet", "url": "https://blockscout.com/eth/rinkeby", "test_net?": true }, { "title": "Ethereum Classic", "url": "https://blockscout.com/etc/mainnet", "other?": true }, { "title": "Aerum Mainnet", "url": "https://blockscout.com/aerum/mainnet", "other?": true }, { "title": "Callisto Mainnet", "url": "https://blockscout.com/callisto/mainnet", "other?": true }, { "title": "RSK Mainnet", "url": "https://blockscout.com/rsk/mainnet", "other?": true }, { "title": "LUKSO L14 testnet", "url": "https://blockscout.com/lukso/l14", "test_net?": true, "hide_in_dropdown?": true } ]'

• fallback const @default_other_networks has been added to be able to run without ENV var
• hide_in_dropdown has been added to the chain JSON object to support hiding of chain in the dropdown list whereas keeping it in the footer

The list of ENV vars updated https://forum.poa.network/t/faq-environment-variables/1814

Checklist for your PR

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so if necessary

[goodsoft]

This kinda complicates local development, doesn't it?
I think that some kind of default list should be present in the code, so that it is possible to run the app server with only actually local configuration (i.e. node/db credentials)

[coveralls]

Pull Request Test Coverage Report for Build 2be3a366-52b7-4da6-b426-e1329df72978

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.08%) to 81.716%

---

Files with Coverage Reduction	New Missed Lines	%
apps/indexer/lib/indexer/fetcher/token.ex	1	78.57%
apps/indexer/lib/indexer/fetcher/token_balance.ex	2	87.1%
apps/indexer/lib/indexer/block/fetcher.ex	3	86.57%

Totals
Change from base Build 611097b2-d5ee-4ff8-9a33-d20b5a47b491:	-0.08%
Covered Lines:	4639
Relevant Lines:	5677

---

💛 - Coveralls

[zachdaniel]

Yeah, I think just adding a

|> Kernel.||(@default_other_networks) would be good for those that don't want to customize this list.

[zachdaniel]

Small piece of feedback, but otherwise 👍

[vbaranov]

@zachdaniel @goodsoft tnx for comments. I added the fallback to @default_other_networks const for those who don't need to set this env var.
In addition, hide_in_dropdown? attribute has been added to chain's object to be able to manage visibility in chains dropdown

[vbaranov]

Missing tests were added