From 7f0c59d5c1291c087eccc4fc70014190de6a439f Mon Sep 17 00:00:00 2001
From: Greg MacLellan <github@list.mtechsolutions.ca>
Date: Wed, 5 Oct 2016 04:32:03 -0400
Subject: [PATCH] Add MAX_STAGE and RUN_STAGE variables (#21)

* Add MAX_STAGES variable

If set, only runs up to that stage

* Show "Skipping stageX" message for all skipped stages

* Add RUN_STAGE variable to run a single stage

* Document RUN_STAGE and MAX_STAGE

* Removed SKIP file support for main stage
---
 README.md |  3 ++-
 build.sh  | 43 ++++++++++++++++++++++++++-----------------
 2 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index bf4c65f..dd0cfe9 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,5 @@
 #TODO
 
-1. Simplify running a single stage
 1. Documentation
 
 #Dependencies
@@ -17,6 +16,8 @@ The following environment variables are supported:
 
  * `IMG_NAME`, the name of the distribution to build (required)
  * `APT_PROXY`, proxy/cache URL to be included in the build
+ * `MAX_STAGE`, to only run up to this stage. (default `4`, eg: `MAX_STAGE=2`)
+ * `RUN_STAGE`, to only run a single stage (eg: `RUN_STAGE=1`)
 
 A simple example for building Raspbian:
 
diff --git a/build.sh b/build.sh
index c6abdae..8942314 100755
--- a/build.sh
+++ b/build.sh
@@ -88,24 +88,22 @@ run_stage(){
 	if [ -f ${STAGE_DIR}/EXPORT_IMAGE ]; then
 		EXPORT_DIRS="${EXPORT_DIRS} ${STAGE_DIR}"
 	fi
-	if [ ! -f SKIP ]; then
-		if [ "${CLEAN}" = "1" ]; then
-			if [ -d ${ROOTFS_DIR} ]; then
-				rm -rf ${ROOTFS_DIR}
-			fi
+	if [ "${CLEAN}" = "1" ]; then
+		if [ -d ${ROOTFS_DIR} ]; then
+			rm -rf ${ROOTFS_DIR}
 		fi
-		if [ -x prerun.sh ]; then
-			log "Begin ${STAGE_DIR}/prerun.sh"
-			./prerun.sh
-			log "End ${STAGE_DIR}/prerun.sh"
-		fi
-		for SUB_STAGE_DIR in ${STAGE_DIR}/*; do
-			if [ -d ${SUB_STAGE_DIR} ] &&
-			   [ ! -f ${SUB_STAGE_DIR}/SKIP ]; then
-				run_sub_stage
-			fi
-		done
 	fi
+	if [ -x prerun.sh ]; then
+		log "Begin ${STAGE_DIR}/prerun.sh"
+		./prerun.sh
+		log "End ${STAGE_DIR}/prerun.sh"
+	fi
+	for SUB_STAGE_DIR in ${STAGE_DIR}/*; do
+		if [ -d ${SUB_STAGE_DIR} ] &&
+			[ ! -f ${SUB_STAGE_DIR}/SKIP ]; then
+			run_sub_stage
+		fi
+	done
 	unmount ${WORK_DIR}/${STAGE}
 	PREV_STAGE=${STAGE}
 	PREV_STAGE_DIR=${STAGE_DIR}
@@ -128,6 +126,12 @@ if [ -z "${IMG_NAME}" ]; then
 	exit 1
 fi
 
+if [ -n "${RUN_STAGE}" ]; then
+	echo "Running ONLY stage${RUN_STAGE}"
+elif [ -n "${MAX_STAGE}" ]; then
+	echo "Running stage${MAX_STAGE} build"
+fi
+
 export IMG_DATE=${IMG_DATE:-"$(date -u +%Y-%m-%d)"}
 
 export BASE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -166,7 +170,12 @@ mkdir -p ${WORK_DIR}
 log "Begin ${BASE_DIR}"
 
 for STAGE_DIR in ${BASE_DIR}/stage*; do
-	run_stage
+	STAGE_DIR_NUM=$(echo $STAGE_DIR | grep -o -E "[0-9]+$")
+	if [[ (-z $RUN_STAGE || $STAGE_DIR_NUM -eq $RUN_STAGE) && (-z $MAX_STAGE || $STAGE_DIR_NUM -le $MAX_STAGE) ]]; then
+		run_stage
+	else
+		echo "Skipping ${STAGE_DIR}"
+	fi
 done
 
 CLEAN=1