add linting (#378)

* add linting

* remove bad filepath.Join

* appease linter

* update linter version

* add lint script

scripts/lint.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o pipefail
+set -e
+
+if ! [[ "$0" =~ scripts/lint.sh ]]; then
+  echo "must be run from repository root"
+  exit 255
+fi
+
+if [ "$#" -eq 0 ]; then
+  # by default, check all source code
+  # to test only "node" package do:
+  # ./scripts/lint.sh ./node/...
+  TARGET="./..."
+else
+  TARGET="${1}"
+fi
+
+TESTS=${TESTS:-"golangci_lint"}
+
+function test_golangci_lint {
+  go install -v github.com/golangci/golangci-lint/cmd/golangci-lint@v1.49.0
+  golangci-lint run --config .golangci.yml
+}
+
+# find_go_files [package]
+# all go files except generated ones
+function find_go_files {
+  local target="${1}"
+  go fmt -n "${target}"  | grep -Eo "([^ ]*)$" | grep -vE "(\\.pb\\.go|\\.pb\\.gw.go)"
+}
+
+function run {
+  local test="${1}"
+  shift 1
+  echo "START: '${test}' at $(date)"
+  if "test_${test}" "$@" ; then
+    echo "SUCCESS: '${test}' completed at $(date)"
+  else
+    echo "FAIL: '${test}' failed at $(date)"
+    exit 255
+  fi
+}
+
+echo "Running '$TESTS' at: $(date)"
+for test in $TESTS; do
+  run "${test}" "${TARGET}"
+done
+
+echo "ALL SUCCESS!"