fetch from url

apps/explorer/lib/explorer/chain_spec/genesis_data.ex

@@ -8,6 +8,7 @@ defmodule Explorer.ChainSpec.GenesisData do
   require Logger
 
   alias Explorer.ChainSpec.Parity.Importer
+  alias HTTPoison.Response
 
   @interval :timer.minutes(2)
 
@@ -56,15 +57,52 @@ defmodule Explorer.ChainSpec.GenesisData do
 
   # sobelow_skip ["Traversal"]
   def fetch_genesis_data do
-    if Application.get_env(:explorer, __MODULE__)[:chain_spec_path] do
+    path = Application.get_env(:explorer, __MODULE__)[:chain_spec_path]
+
+    if path do
       Task.Supervisor.async_nolink(Explorer.GenesisDataTaskSupervisor, fn ->
-        chain_spec = Application.get_env(:explorer, __MODULE__)[:chain_spec_path] |> File.read!() |> Jason.decode!()
+        case fetch_spec(path) do
+          {:ok, chain_spec} ->
             Importer.import_emission_rewards(chain_spec)
-
             {:ok, _} = Importer.import_genesis_coin_balances(chain_spec)
+
+          {:error, reason} ->
+            Logger.warn(fn -> "Failed to fetch genesis data. #{inspect(reason)}" end)
+        end
       end)
     else
       Logger.warn(fn -> "Failed to fetch genesis data. Chain spec path is not set." end)
     end
   end
+
+  defp fetch_spec(path) do
+    if valid_url?(path) do
+      fetch_from_url(path)
+    else
+      fetch_from_file(path)
+    end
+  end
+
+  defp fetch_from_file(path) do
+    with {:ok, data} <- File.read(path),
+         {:ok, json} <- Jason.decode(data) do
+      {:ok, json}
+    end
+  end
+
+  defp fetch_from_url(url) do
+    case HTTPoison.get(url) do
+      {:ok, %Response{body: body, status_code: 200}} ->
+        {:ok, Jason.decode!(body)}
+
+      reason ->
+        {:error, reason}
+    end
+  end
+
+  defp valid_url?(string) do
+    uri = URI.parse(string)
+
+    uri.scheme != nil && uri.host =~ "."
+  end
 end

docs/env-variables.md

@@ -53,7 +53,7 @@ $ export NETWORK=POA
 | `ADDRESS_WITH_BALANCES` <br /> `_UPDATE_INTERVAL`|  | Interval in seconds to restart the task, which calculates addresses with balances. | 30 * 60 |  v1.3.9+ |
 | `LINK_TO_OTHER_EXPLORERS` | | true/false. If true, links to other explorers are added in the footer  | (empty)  |  v1.3.0+ |
 | `COINMARKETCAP_PAGES` | | the number of pages on coinmarketcap to list in order to find token's price  | 10 |  v1.3.10+ |
-| `CHAIN_SPEC_PATH` | | Chain specification path to import block emission reward ranges and genesis account balances from | (empty) | master |
+| `CHAIN_SPEC_PATH` | | Chain specification path (absolute file system path or url) to import block emission reward ranges and genesis account balances from | (empty) | master |
 | `SUPPORTED_CHAINS` | | Array of supported chains that displays in the footer and in the chains dropdown. This var was introduced in this PR [#1900](https://github.com/poanetwork/blockscout/pull/1900) and looks like an array of JSON objects.  | (empty) |  v2.0.0+ |
 | `BLOCK_COUNT_CACHE_PERIOD ` | | time to live of cache in seconds. This var was introduced in [#1876](https://github.com/poanetwork/blockscout/pull/1876)  | 600 |  v2.0.0+ |
 | `ALLOWED_EVM_VERSIONS ` | | the comma-separated list of allowed EVM versions for contracts verification. This var was introduced in [#1964](https://github.com/poanetwork/blockscout/pull/1964)  | "homestead, tangerineWhistle, spuriousDragon, byzantium, constantinople, petersburg" |  v2.0.0+ |