feat: Support Environment Variables for Hook Commands (#27)

Adds ability to configure environment variables to be set when invoking hook commands.
Variables are configured via hook "args" using the following argument pattern:

    --hook:env:NAME=VALUE

feat: Add support for "--hook:error-on-output" in my-cmd-* hooks.
* Can exist anywhere in the arg list before a '--' argument
* re: Support for plain '--error-on-output' at first element
  * Still works (currently)
  * Is now deprecated and will be removed in a future version

chore: Use "/usr/bin/env" to  invoke commands
* No-longer invokes the commands directly
* Makes it trivial to pass environment variables to commands
* Should not cause issues as /usr/bin/env was already vital

chore:  Add "shellcheck source" declarations on dynamically sourced files
* Only files that were already modified for this PR were addressed

Breaking Change: For compatibility with file-based hooks, Repo-based hooks
no-longer ignore '--', or proceeding arguments, in the argument list.
However, to further match file-based logic, the first '--' will be consumed,
treating anything after it as OPTIONS to be passed to the hook command.

Author: TekWizely

README.md

@@ -1,6 +1,6 @@
 # Pre-Commit-GoLang [![MIT license](https://img.shields.io/badge/License-MIT-green.svg)](https://github.com/tekwizely/pre-commit-golang/blob/master/LICENSE)
 
-A set of git pre-commit hooks for Golang with support for multi-module monorepos, the ability to pass arguments to all hooks, and the ability to invoke custom go tools.
+A set of git pre-commit hooks for Golang with support for multi-module monorepos, the ability to pass arguments and environment variables to all hooks, and the ability to invoke custom go tools.
 
 Requires the [Pre-Commit.com](https://pre-commit.com) Hook Management Framework.
 
@@ -26,6 +26,11 @@ You can copy/paste the following snippet into your `.pre-commit-config.yaml` fil
     #       that Pre-Commit passes into the hook.
     #       For repo-based hooks, '--' is not needed.
     #
+    # NOTE: You can pass environment variables to hooks using args with the 
+    #       following format:
+    #
+    #           --hook:env:NAME=VALUE
+    #
     # Consider adding aliases to longer-named hooks for easier CLI usage.
     # ==========================================================================
 -   repo: https://github.com/tekwizely/pre-commit-golang
@@ -117,8 +122,10 @@ You can copy/paste the following snippet into your `.pre-commit-config.yaml` fil
     # Invoking Custom Go Tools
     # - Configured *entirely* through the `args` attribute, ie:
     #   args: [ go, test, ./... ]
+    # - Use arg `--hook:error-on-output` to indicate that any output from the tool
+    #   should be treated as an error.
     # - Use the `name` attribute to provide better messaging when the hook runs
-    # - Use the `alias` attribute to be able invoke your hook via `pre-commit run`
+    # - Use the `alias` attribute to be able to invoke your hook via `pre-commit run`
     #
     -   id: my-cmd
     -   id: my-cmd-mod
@@ -205,6 +212,21 @@ See each hook's description below for some popular options that you might want t
 
 Additionally, you can view each tool's individual home page or help settings to learn about all the available options.
 
+#### Passing Environment Variables To Hooks
+You can pass environment variables to hooks to customize tool behavior.
+
+**NOTE:** The Pre-Commit framework does not directly support the ability to pass environment variables to hooks.
+
+This feature is enabled via support for a specially-formatted argument:
+
+* `--hook:env:NAME=VALUE`
+
+The hook script will detect this argument and set the variable `NAME` to the value `VALUE` before invoking the configured tool.
+
+You can pass multiple  `--hook:env:` arguments.
+
+The arguments can appear anywhere in the `args:` list.
+
 #### Always Run
 By default, hooks ONLY run when matching file types (usually `*.go`) are staged.
 
@@ -214,10 +236,10 @@ When configured to `"always_run"`, a hook is executed as if EVERY matching file
 
 pre-commit supports the ability to assign both an `alias` and a `name` to a configured hook:
 
-| config | description
-|--------|------------
-| alias  | (optional) allows the hook to be referenced using an additional id when using `pre-commit run <hookid>`
-| name   | (optional) override the name of the hook - shown during hook execution
+| config | description                                                                                             |
+|--------|---------------------------------------------------------------------------------------------------------|
+| alias  | (optional) allows the hook to be referenced using an additional id when using `pre-commit run <hookid>` |
+| name   | (optional) override the name of the hook - shown during hook execution                                  |
 
 These are beneficial for a couple of reasons:
 
@@ -735,7 +757,7 @@ The alias will enable you to invoke the hook manually from the command-line when
 
 Some tools, like `gofmt`, `goimports`, and `goreturns`, don't generate error codes, but instead expect the presence of any output to indicate warning/error conditions.
 
-The my-cmd hooks accept an `--error-on-output` argument to indicate this behavior.
+The my-cmd hooks accept a `--hook:error-on-output` argument to indicate this behavior.
 
 Here's an example of what it would look like to use the my-cmd hooks to invoke `gofmt` if it wasn't already included:
 
@@ -748,10 +770,10 @@ _.pre-commit-config.yaml_
         -   id: my-cmd
             name: go-fmt
             alias: go-fmt
-            args: [ --error-on-output, gofmt, -l, -d ]
+            args: [ gofmt, -l, -d, --hook:error-on-output]
 ```
 
-**NOTE:** When used, the `--error-on-output` option **must** be the first argument.
+**NOTE:** The plain `--error-on-output` option is now deprecated, but still supported, as long as it's the **very first** entry in the `args:` list.
 
 ----------
 ## License

lib/cmd-files.bash

@@ -1,18 +1,19 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_file_hook_cmd "$@"
 
 error_code=0
 for file in "${FILES[@]}"; do
 	if [ "${error_on_output:-}" -eq 1 ]; then
-		output=$("${cmd[@]}" "${OPTIONS[@]}" "${file}" 2>&1)
+		output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" "${file}" 2>&1)
 		if [ -n "${output}" ]; then
 			printf "%s\n" "${output}"
 			error_code=1
 		fi
-	elif ! "${cmd[@]}" "${OPTIONS[@]}" "${file}"; then
+	elif ! /usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" "${file}"; then
 		error_code=1
 	fi
 done

lib/cmd-mod.bash

@@ -1,5 +1,6 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_file_hook_cmd "$@"
@@ -14,12 +15,12 @@ error_code=0
 for sub in $(find_module_roots "${FILES[@]}" | sort -u); do
 	pushd "${sub}" > /dev/null || exit 1
 	if [ "${error_on_output:-}" -eq 1 ]; then
-		output=$("${cmd[@]}" "${OPTIONS[@]}" 2>&1)
+		output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" 2>&1)
 		if [ -n "${output}" ]; then
 			printf "%s\n" "${output}"
 			error_code=1
 		fi
-	elif ! "${cmd[@]}" "${OPTIONS[@]}"; then
+	elif ! /usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}"; then
 		error_code=1
 	fi
 	popd > /dev/null || exit 1

lib/cmd-pkg.bash

@@ -1,5 +1,6 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_file_hook_cmd "$@"
@@ -8,12 +9,12 @@ export GO111MODULE=off
 error_code=0
 for sub in $(printf "%q\n" "${FILES[@]}" | xargs -n1 dirname | sort -u); do
 	if [ "${error_on_output:-}" -eq 1 ]; then
-		output=$("${cmd[@]}" "${OPTIONS[@]}" "./${sub}" 2>&1)
+		output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" "./${sub}" 2>&1)
 		if [ -n "${output}" ]; then
 			printf "%s\n" "${output}"
 			error_code=1
 		fi
-	elif ! "${cmd[@]}" "${OPTIONS[@]}" "./${sub}"; then
+	elif ! /usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" "./${sub}"; then
 		error_code=1
 	fi
 done

lib/cmd-repo-mod.bash

@@ -1,5 +1,6 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_repo_hook_cmd "$@"
@@ -14,12 +15,12 @@ error_code=0
 for sub in $(find . -name go.mod -not -path '*/vendor/*' -exec dirname "{}" ';' | sort -u); do
 	pushd "${sub}" > /dev/null || exit 1
 	if [ "${error_on_output:-}" -eq 1 ]; then
-		output=$("${cmd[@]}" "${OPTIONS[@]}" 2>&1)
+		output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" 2>&1)
 		if [ -n "${output}" ]; then
 			printf "%s\n" "${output}"
 			error_code=1
 		fi
-	elif ! "${cmd[@]}" "${OPTIONS[@]}"; then
+	elif ! /usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}"; then
 		error_code=1
 	fi
 	popd > /dev/null || exit 1

lib/cmd-repo-pkg.bash

@@ -1,5 +1,6 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_repo_hook_cmd "$@"
@@ -9,11 +10,11 @@ if [ "${use_dot_dot_dot:-}" -eq 1 ]; then
 fi
 export GO111MODULE=off
 if [ "${error_on_output:-}" -eq 1 ]; then
-	output=$("${cmd[@]}" "${OPTIONS[@]}" 2>&1)
+	output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" 2>&1)
 	if [ -n "${output}" ]; then
 		printf "%s\n" "${output}"
 		exit 1
 	fi
 else
-	"${cmd[@]}" "${OPTIONS[@]}"
+	/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}"
 fi

lib/cmd-repo.bash

@@ -1,5 +1,6 @@
 # shellcheck shell=bash
 
+# shellcheck source=./common.bash
 . "$(dirname "${0}")/lib/common.bash"
 
 prepare_repo_hook_cmd "$@"
@@ -10,11 +11,11 @@ if [[ ${#target[@]} -gt 0 ]]; then
 	OPTIONS+=("${target[@]}")
 fi
 if [ "${error_on_output:-}" -eq 1 ]; then
-	output=$("${cmd[@]}" "${OPTIONS[@]}" 2>&1)
+	output=$(/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}" 2>&1)
 	if [ -n "${output}" ]; then
 		printf "%s\n" "${output}"
 		exit 1
 	fi
 else
-	"${cmd[@]}" "${OPTIONS[@]}"
+	/usr/bin/env "${ENV_VARS[@]}" "${cmd[@]}" "${OPTIONS[@]}"
 fi

lib/common.bash

@@ -5,7 +5,7 @@
 : "${ignore_file_pattern_array:=}"
 
 ##
-# prepare_repo_hook_cmd
+# prepare_file_hook_cmd
 #
 function prepare_file_hook_cmd {
 	verify_hook_cmd
@@ -38,10 +38,46 @@ function verify_hook_cmd {
 ##
 # parse_file_hook_args
 # Creates global vars:
-#   OPTIONS: List of options to passed to comand
-#   FILES  : List of files to process, filtered against ignore_file_pattern_array
+#   ENV_VARS: List of variables to assign+export before invoking command
+#   OPTIONS : List of options to pass to command
+#   FILES   : List of files to process, filtered against ignore_file_pattern_array
+#
+# NOTE: We consume the first (optional) '--' we encounter.
+#       If you want to pass '--' to the command, you'll need to use 2 of them
+#       in hook args, i.e. "args: [..., '--', '--']"
 #
 function parse_file_hook_args {
+	# Look for '--hook:*' options up to the first (optional) '--'
+	# Anything else (including '--' and after) gets saved and passed to next step
+	# Positional order of saved arguments is preserved
+	#
+	local ENV_REGEX='^[a-zA-Z_][a-zA-Z0-9_]*=.*$'
+	ENV_VARS=()
+	local __ARGS=()
+	while [ $# -gt 0 ] && [ "$1" != "--" ]; do
+		case "$1" in
+			--hook:env:*)
+				local env_var="${1#--hook:env:}"
+				if [[ "${env_var}" =~ ${ENV_REGEX} ]]; then
+					ENV_VARS+=("${env_var}")
+				else
+					printf "ERROR: Invalid hook:env variable: '%s'\n" "${env_var}" >&2
+					exit 1
+				fi
+				shift
+				;;
+			--hook:*)
+				printf "ERROR: Unknown hook option: '%s'\n" "${1}" >&2
+				exit 1
+				;;
+			*) # preserve positional arguments
+				__ARGS+=("$1")
+				shift
+				;;
+		esac
+	done
+	set -- "${__ARGS[@]}" "${@}"
+	unset __ARGS
 	OPTIONS=()
 	# If arg doesn't pass [ -f ] check, then it is assumed to be an option
 	#
@@ -60,6 +96,7 @@ function parse_file_hook_args {
 	done
 
 	# If '--' next, then files = options
+	# NOTE: We consume the '--' here
 	#
 	if [ "$1" == "--" ]; then
 		shift
@@ -90,14 +127,52 @@ function parse_file_hook_args {
 
 ##
 # parse_repo_hook_args
-# Build options list, ignoring '--', and anything after
+# Creates global vars:
+#   ENV_VARS: List of variables to assign+export before invoking command
+#   OPTIONS : List of options to pass to command
+#
+# NOTE: For consistency with file hooks,
+#       we consume the first (optional) '--' we encounter.
+#       If you want to pass '--' to the command, you'll need to use 2 of them
+#       in hook args, i.e. "args: [..., '--', '--']"
 #
 function parse_repo_hook_args {
+	# Look for '--hook:*' options up to the first (optional) '--'
+	# Consumes the first '--', treating anything after as OPTIONS
+	# Positional order of OPTIONS is preserved
+	#
+	local ENV_REGEX='^[a-zA-Z_][a-zA-Z0-9_]*=.*$'
+	ENV_VARS=()
 	OPTIONS=()
-	while [ $# -gt 0 ] && [ "$1" != "--" ]; do
-		OPTIONS+=("$1")
-		shift
+	while [ $# -gt 0 ]; do
+		case "$1" in
+			--hook:env:*)
+				local env_var="${1#--hook:env:}"
+				if [[ "${env_var}" =~ ${ENV_REGEX} ]]; then
+					ENV_VARS+=("${env_var}")
+				else
+					printf "ERROR: Invalid hook:env variable: '%s'\n" "${env_var}" >&2
+					exit 1
+				fi
+				shift
+				;;
+			--hook:*)
+				printf "ERROR: Unknown hook option: '%s'\n" "${1}" >&2
+				exit 1
+				;;
+			--) # consume '--' and stop loop
+				shift
+				break
+				;;
+			*) # preserve positional arguments
+				OPTIONS+=("$1")
+				shift
+				;;
+		esac
 	done
+	# Any remaining items also considered OPTIONS
+	#
+	OPTIONS+=("$@")
 }
 
 ##

lib/prepare-my-cmd.bash

@@ -1,16 +1,36 @@
 # shellcheck shell=bash
 use_dot_dot_dot=0
-while (($#)); do
+# Check for error-on-output
+# '--error-on-output' can *only* appear at the FRONT
+# !! NOTE: This is DEPRECATED and will be removed in a future version !!
+#
+if [[ "${1:-}" == "--error-on-output" ]]; then
+	error_on_output=1
+	shift
+fi
+# '--hook:error-on-output' can appear anywhere before (the optional) '--'
+# Anything else (including '--' and after) gets saved and passed to next step
+# Positional order of saved arguments is preserved
+#
+_ARGS=()
+while [ $# -gt 0 ] && [ "$1" != "--" ]; do
 	case "$1" in
-		--error-on-output)
+		--hook:error-on-output)
 			error_on_output=1
+			# We continue (vs break) in order to consume multiple occurrences
+			# of the arg. VERY unlikely but let's be safe.
+			#
 			shift
 			;;
-		*)
-			break
+		*) # preserve positional arguments
+			__ARGS+=("$1")
+			shift
 			;;
 	esac
 done
+set -- "${__ARGS[@]}" "${@}"
+unset __ARGS
+
 cmd=()
 if [ -n "${1:-}" ]; then
 	cmd+=("${1}")