FEAT: Add static s3 bootstrap file

AWS EMR requires the bootstrap actions to be contained in S3, but this
prevents easy tracking using a VCS.

Create a static file that can be placed in S3, and called with VCS info
to run a dynamic script that is in version control. This means the
version of bootstrap scripts is set in the cloudformation template.

Author: bhosking

cloud/aws-emr/bootstrap/s3-bootstrap.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+set -e -x
+
+# Used to sit in an s3 bucket and will call an arbitrary script, passing in version information
+# This is because AWS EMR requires bootstrap actions to be in a bucket, rather than in a VCS.
+# e.g. /path/to/this_script.sh --path-prefix "https://github.com/<user>/<repo>/raw/<tag>" --bootstrap-file "/path/to/version/controlled/script.sh" -- <script_arguments>
+# Will pass --path-prefix to the called script, so it can reference the relevant version in some VCS.
+
+BOOTSTRAP_LOCAL_FILE="/tmp/bootstrap.sh"
+
+error_out ()
+{
+    >&2 echo "Error: $1"
+    exit 1
+}
+
+options=$(getopt -o '' --longoptions path-prefix:,bootstrap-file: -- "$@")
+eval set -- "$options"
+
+while true; do
+    case "$1" in
+    --path-prefix)
+        shift
+        PATH_PREFIX=$1
+        ;;
+    --bootstrap-file)
+        shift
+        BOOTSTRAP_FILE=$1
+        ;;
+    --)
+        shift
+        break
+        ;;        
+    *)
+        error_out "unrecognised option: $1"
+        ;;
+    esac
+    shift
+done
+
+if [ -z "$PATH_PREFIX" ]; then
+    error_out "missing required option: --path-prefix"
+fi
+if [ -z "$BOOTSTRAP_FILE" ]; then
+    error_out "missing required option: --bootstrap-file"
+fi
+
+curl -L --output "$BOOTSTRAP_LOCAL_FILE" "${PATH_PREFIX}${BOOTSTRAP_FILE}"
+sudo chmod +x "$BOOTSTRAP_LOCAL_FILE"
+"$BOOTSTRAP_LOCAL_FILE" --path-prefix "$PATH_PREFIX" $@