feature: Add a shell script to fetch params

Author: sgillespie

fetch-params.sh

@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+usage () {
+  cat << EOF
+Usage: fetch-params.sh [options] environment
+
+environments:
+ mainnet
+ preprod
+ preview
+ all
+
+Options:
+  -p, --project-id string   Blockfrost API key (overrides BLOCKFROST_PROJECT_ID environment variable)
+  -h, --help                Show this help text
+}
+EOF
+}
+
+# Parse command line arguments
+if ! OPTS=$(getopt -o p:h --long project-id:,help -n "fetch-cardano-cfg.sh" -- "$@"); then
+  exit 1
+fi
+
+eval set -- "${OPTS}"
+
+while true; do
+  case "$1" in
+    -p | --project-id)
+      PROJECT_ID=$2
+      shift 2
+      ;;
+    -h | --help)
+      HELP=
+      shift
+      ;;
+    --)
+      shift
+      break
+      ;;
+    *)
+      echo "Internal error!" >&2
+      exit 1
+      ;;
+  esac
+done
+
+# Validate command line arguments
+if [[ "${HELP+DEFINED}" = true ]]; then
+  usage
+  exit 1
+fi
+
+if [[ "$#" -eq 0 ||  -z "$1" ]]; then
+  echo "Missing required argument environment!" >&2
+  exit 1
+else
+  ENV=$1
+fi
+
+if [[ -z "${PROJECT_ID}" && -n "${BLOCKFROST_PROJECT_ID}" ]]; then
+  PROJECT_ID="${BLOCKFROST_PROJECT_ID}"
+fi
+
+if [[ -z "${PROJECT_ID}" ]]; then
+  cat << EOF >&2
+Missing Blockfrost API key! \
+Use the BLOCKCHAID_PROJECT_ID environment variable or --project-id option to specify it.
+EOF
+
+  exit 2
+fi
+
+# Calculate endpoint
+case "${ENV}" in
+  mainnet)
+    BLOCKFROST_HOST=cardano-mainnet.blockfrost.io
+    ;;
+  preprod)
+    BLOCKFROST_HOST=cardano-preprod.blockfrost.io
+    ;;
+  preview)
+    BLOCKFROST_HOST=cardano-preview.blockfrost.io
+    ;;
+  *)
+    echo "Invalid environment: '${ENV}'" >&2
+esac
+
+tmpfile=$(mktemp --tmpdir "parameters.XXXXXX")
+
+# Do the request
+curl \
+  -H "project_id: ${PROJECT_ID}" \
+  --no-progress-meter \
+  --fail \
+  "https://${BLOCKFROST_HOST}/api/v0/epochs/latest/parameters" \
+  | jq --sort-keys . \
+  > "${tmpfile}"
+
+mkdir -p "${ENV}"
+mv "${tmpfile}" "${ENV}/parameters.json"