internal scripts: use pinned, cached pkgs

Instead of setting up the script PATH via nix-shell, use
`nix shell` with inputs from the nix-bitcoin flake.
Advantages:
- Uses the nixpkgs version from the nix-bitcoin flake instead of
  `<nixpkgs>` from the user env (NIX_PATH), so the script runtime
  env is reproducible.
- The pkg derivations for the runtime env are cached, which greatly
  increases script startup speed.

This commit was generated by running the following script inside the
repo root dir:

def transform(path, src)
  if src =~ /#! *nix-shell +-i +bash +-p +(.*)/
    pkgs = $1
    if src =~ /^.*?(set -e.*?pipefail)\n/
      set_statement = $1
      src.sub!($&, '')
    end
    src.sub!(/\A.*?#! *nix-shell.*?\n/m, '')

    parents = ([ '..' ] * (path.split('/').count - 1)).join('/')

    [
      '#!/usr/bin/env bash',
      *set_statement,
      %(. "${BASH_SOURCE[0]%/*}/#{parents}/helper/run-in-nix-env" "#{pkgs}" "$@"),
      nil,
      src
    ].join("\n")
  end
end

Dir['**/*.sh'].each do |f|
  src = File.read(f)
  if new_src = transform(f, src)
    puts "Changed file #{f}"
    File.write(f, new_src)
  end
end

.cirrus.yml

@@ -39,4 +39,4 @@ task:
 
     - name: shellcheck
       build_script:
-        - nix shell --inputs-from . nixpkgs#{shellcheck,findutils,gnugrep} -c ./test/shellcheck.sh
+        - ./test/shellcheck.sh

helper/run-in-nix-env

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+# Usage:
+# source "path/to/run-in-nix-env" "pkg1 pkg2 ..." "$@"
+#
+# Runs the calling script with pkgs1, pkg2, ... in PATH.
+# The packages are sourced from the nixpkgs input of the nix-bitcoin root flake.
+
+if [[ ${_NIX_BITCOIN_ENV_PKGS:-} != "$1" ]]; then
+    export _NIX_BITCOIN_ENV_PKGS=$1
+    shift
+
+    _shell_pkgs=()
+    for _pkg in $_NIX_BITCOIN_ENV_PKGS; do
+      _shell_pkgs+=("nixpkgs#$_pkg")
+    done
+    # BASH_SOURCE[0] is this file
+    # BASH_SOURCE[-1] is the root src file
+    exec nix shell --inputs-from "${BASH_SOURCE[0]%/*}/.." "${_shell_pkgs[@]}" -c "${BASH_SOURCE[-1]}" "$@"
+fi

pkgs/clightning-plugins/get-sha256.sh

@@ -1,6 +1,6 @@
-#! /usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p git
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "git" "$@"
 
 archive_hash () {
     repo=$1

pkgs/clightning-rest/generate.sh

@@ -1,6 +1,6 @@
-#!/usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p gnupg wget gnused
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "gnupg wget gnused" "$@"
 
 version="0.9.0"
 repo=https://github.com/Ride-The-Lightning/c-lightning-REST

pkgs/joinmarket/get-sha256.sh

@@ -1,6 +1,6 @@
-#! /usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p git gnupg
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "git gnupg" "$@"
 
 TMPDIR="$(mktemp -d -p /tmp)"
 trap 'rm -rf $TMPDIR' EXIT

pkgs/krops/fetch-release.sh

@@ -1,6 +1,6 @@
-#! /usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p git
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "git" "$@"
 
 archive_hash () {
     repo=$1

pkgs/lndinit/get-sha256.sh

@@ -1,6 +1,6 @@
-#! /usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p git gnupg curl jq
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "git gnupg curl jq" "$@"
 
 TMPDIR=$(mktemp -d -p /tmp)
 trap 'rm -rf $TMPDIR' EXIT

pkgs/python-packages/python-bitcointx/get-sha256.sh

@@ -1,6 +1,6 @@
-#! /usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p git gnupg
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../../helper/run-in-nix-env" "git gnupg" "$@"
 
 TMPDIR=$(mktemp -d -p /tmp)
 trap 'rm -rf $TMPDIR' EXIT

pkgs/rtl/generate.sh

@@ -1,6 +1,6 @@
-#!/usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p gnupg wget gnused
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "gnupg wget gnused" "$@"
 
 version="0.13.1"
 repo=https://github.com/Ride-The-Lightning/RTL

pkgs/spark-wallet/generate.sh

@@ -1,6 +1,6 @@
-#!/usr/bin/env nix-shell
+#!/usr/bin/env bash
-#! nix-shell -i bash -p nodePackages.node2nix gnupg wget jq moreutils gnused
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../../helper/run-in-nix-env" "nodePackages.node2nix gnupg wget jq moreutils gnused" "$@"
 
 TMPDIR=$(mktemp -d -p /tmp)
 trap 'rm -rf $TMPDIR' EXIT

test/run-tests.sh

@@ -322,7 +322,7 @@ examples() {
 
 shellcheck() {
     if ! checkFlakeSupport "shellcheck"; then return; fi
-    nix shell --inputs-from "$scriptDir/.." nixpkgs#shellcheck -c "$scriptDir/shellcheck.sh"
+    "$scriptDir/shellcheck.sh"
 }
 
 all() {

test/shellcheck.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 set -euo pipefail
+. "${BASH_SOURCE[0]%/*}/../helper/run-in-nix-env" "shellcheck findutils gnugrep" "$@"
 
 cd "${BASH_SOURCE[0]%/*}/.."
 {