stx tool: Add the env variable CENGN_STRATEGY

Add the environment variable CENGN_STRATEGY for supporting CENGN.
Set the default value to 'cengn_first', and we also can set the value
to the other three value 'cengn', 'upstream' or 'upstream_first'.

Story: 2008862
Task: 44361

Signed-off-by: Zhixiong Chi <zhixiong.chi@windriver.com>
Change-Id: I0326da798e808dce1b6fefd49e54f54ca41e8bcd

stx.conf.sample

@@ -24,6 +24,7 @@ mode = local
 [repomgr]
 type = aptly
 cengnurl = http://mirror.starlingx.cengn.ca:80/mirror
+cengnstrategy = cengn_first
 sourceslist =
 deblist =
 dsclist =

stx/lib/stx/stx_control.py

@@ -84,6 +84,7 @@ class HandleControlTask:
         buildbranch = self.stxconfig.getConfig('project', 'buildbranch')
         manifest = self.stxconfig.getConfig('project', 'manifest')
         cengnurl = self.stxconfig.getConfig('repomgr', 'cengnurl')
+        cengnstrategy = self.stxconfig.getConfig('repomgr', 'cengnstrategy')
         sourceslist = self.stxconfig.getConfig('repomgr', 'sourceslist')
         deblist = self.stxconfig.getConfig('repomgr', 'deblist')
         dsclist = self.stxconfig.getConfig('repomgr', 'dsclist')
@@ -158,6 +159,7 @@ stx-pkgbuilder/configmap/')
                 line = line.replace("@MANIFEST@", manifest)
                 line = line.replace("@HOSTUSERNAME@", hostusername)
                 line = line.replace("@CENGNURL@", cengnurl)
+                line = line.replace("@CENGNSTRATEGY@", cengnstrategy)
                 line = line.replace("@OSTREE_OSNAME@", ostree_osname)
                 line = line.replace("@MAX_CPUS@", max_cpus)
                 if sourceslist:

stx/stx-build-tools-chart/stx-builder/configmap/localrc.sample

@@ -38,6 +38,9 @@ export HOSTUSERNAME=@HOSTUSERNAME@
 
 export CENGNURL=@CENGNURL@
 
+# CENGN_STRATEGY value: [ cengn|cengn_first|upstream|upstream_first ]
+export CENGN_STRATEGY=@CENGNSTRATEGY@
+
 if [[ x"@fetch@" == x"true" ]];then
     export SOURCESLIST=/usr/local/bin/stx/@SOURCESLIST@
     export DEBLIST=/usr/local/bin/stx/@DEBLIST@