contrib/bst-here: Allow users to specify image variant

Now that the `buildstream/buildstream` image has 9 variants, let's make
it easier to choose the desired tag, using a command-line option.

This is otherwise possible by specifying the full image name `image:tag`
using the `-i` option. But, this will make it easier to specify just the
tag using `-j`.

The following two invocations of `bst-here` are now equivalent:

    bst-here -i buildstream/buildstream:dev
    bst-here -j dev

1 files changed, 17 insertions, 3 deletions

diff --git a/contrib/bst-here b/contrib/bst-here
index 51a6252d1..01c2d2c13 100755
--- a/contrib/bst-here
+++ b/contrib/bst-here
@@ -25,16 +25,22 @@
 usage() {
     cat <<EOF
 
-USAGE: $(basename "$0") [-i BST_HERE_IMAGE] [-p] [-t] [-T] [-v VOLUME ...] [-h] [COMMAND [ARG..]]
+USAGE: $(basename "$0") [-i BST_HERE_IMAGE] [-j TAG] [-p] [-t] [-T] [-v VOLUME ...] [-h] [COMMAND [ARG..]]
 
 Run a bst command in a new BuildStream container.
 
 If no command is specified, an interactive shell is launched
 using "/bin/bash -i".
 
+See https://hub.docker.com/r/buildstream/buildstream for details on image
+variants.
+
 OPTIONS:
     -i IMAGE      Specify Docker image to use; can also be specified by setting
                   BST_HERE_IMAGE environment variable.
+                  (default: buildstream/buildstream)
+    -j TAG        Specify the tag of the Docker image to use.
+                  (default: latest)
     -p            Pull the latest buildstream image before running.
     -t            Force pseudo-terminal allocation.
     -T            Disable pseudo-terminal allocation.
@@ -46,7 +52,8 @@ EOF
     exit "$1"
 }
 
-bst_here_image="${BST_HERE_IMAGE:-buildstream/buildstream:latest}"
+bst_here_image="${BST_HERE_IMAGE:-buildstream/buildstream}"
+bst_here_tag=
 
 is_tty=
 update=false
@@ -57,12 +64,15 @@ then
     is_tty=y
 fi
 
-while getopts i:ptTv:h arg
+while getopts i:j:ptTv:h arg
 do
     case $arg in
     i)
         bst_here_image="$OPTARG"
         ;;
+    j)
+        bst_here_tag="$OPTARG"
+        ;;
     p)
         update=true
         ;;
@@ -83,6 +93,10 @@ do
     esac
 done
 
+if [ -n "$bst_here_tag" ]; then
+    bst_here_image="$bst_here_image:$bst_here_tag"
+fi
+
 test "$OPTIND" -gt 1 &&
     shift $(( OPTIND - 1 ))