struct(entrypoint): skeleton entrypoint script

- basic operation flow with placeholder functions
- implement server and shell launch
- allow commands to pass to shell
- update Dockerfile to load entrypoint only
- update Dockerfile to set permissions for certs directory

build/entrypoint.sh

@@ -0,0 +1,89 @@
+#!/bin/sh
+
+#
+# entrypoint script for livereload-tls-npm container
+#
+
+# functions
+certificateGenerateNew() {
+    printf "\nGenerating new self-signed certificate:\n"
+    printf "Exporting new certificate:\n"
+    exit 0
+}
+
+certificateShow() {
+    printf "\nCurrently loaded certificate:\n"
+    exit 0
+}
+
+certificateExport() {
+    printf "\nExporting currently loaded certificate:\n"
+    exit 0
+}
+
+# default variable values
+doCertExport=0
+doCertNew=0
+doCertShow=0
+doServer=0
+doShell=0
+
+# process action parameter
+case "$1" in
+listen | server | run | start)
+    doServer=1
+    ;;
+shell) ;;
+
+new-cert)
+    doCertNew=1
+    ;;
+show-cert)
+    doCertShow=1
+    ;;
+export-cert)
+    doCertExport=1
+    ;;
+*)
+    # invalid or unknown option
+    printf "\nUnknown action requested: %s\n" "$1"
+    printf "Valid actions: [listen | server | run | start] | shell | new-cert | show-cert | export-cert"
+    exit 1
+    ;;
+esac
+
+# action: run server
+if [ "$doServer" -eq 1 ]; then
+    exec "node livereload.js"
+    exit "$?"
+fi
+
+# action: drop to shell
+if [ "$doShell" -eq 1 ]; then
+    exec /bin/sh "$@"
+    exit "$?"
+fi
+
+# action: generate new self-signed certificate
+if [ "$doCertNew" -eq 1 ]; then certificateGenerateNew; fi
+
+# action: show loaded certificate
+if [ "$doCertShow" -eq 1 ]; then certificateShow; fi
+
+# action: export loaded certificate
+if [ "$doCertExport" -eq 1 ]; then certificateExport; fi
+
+# failsafe exit - terminate with code 99: this code should never be executed!
+exit 99
+
+# exit codes:
+# 0:   normal exit, no errors
+# 1:   invalid or invalid parameter passed to script
+# 50:  certificate errors
+# 51:    unable to read certificate/chain
+# 52:    unable to read private key
+# 55:    unable to generate new certificate
+# 56:    unable to export certificate, likely write error
+# 99:  code error
+
+#EOF