Merge pull request #1 from amouat/main

Initial version.

Author: amouat

Dockerfile

@@ -0,0 +1,6 @@
+FROM cgr.dev/chainguard/wolfi-base
+
+COPY entrypoint.sh /
+RUN chmod +x entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]

README.md

@@ -1,2 +1,31 @@
 # container-entrypoint
-Simple script for use as entrypoint to a container
+
+Simple script for use as entrypoint to a container.
+
+Attempts to intelligently decide if a command is an argument to an application or calling as system
+command. In other words, it is intended to allow all the following use cases:
+
+```
+$ docker run --rm foo --version
+foo 0.8
+
+$ docker run --rm foo echo boo
+boo
+
+$ docker run -it foo sh
+/ #
+/ # exit
+```
+
+To use the script, set it as the ENTRYPOINT in a Dockerfile or equivalent, making sure it is
+executable. Also set the environment variable `BASE_COMMAND` appropriately. For example:
+
+```
+$ docker run --rm -e BASE_COMMAND="uname" my_image -a
+Linux f3c6b322e73a 5.15.49-linuxkit #1 SMP PREEMPT Tue Sep 13 07:51:32 UTC 2022 aarch64 Linux
+```
+
+We've used `-e` for the purposes of this demo, but the variable should be set in the Dockerfile or
+by editing the script.
+
+This script is based on the [NodeJS entrypoint script](https://github.com/nodejs/docker-node/blob/e75fa5270326ffaff8fee03153f3bf16860084d4/19/bullseye-slim/docker-entrypoint.sh).

entrypoint.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+set -e
+
+# To use this script, set BASE_COMMAND to the name of the base application you want to run e.g.
+# "curl".
+#
+# This script is based on the 
+# Run command with base application if the first argument contains a "-" or is not a system command. 
+# The last part inside the "{}" is a workaround for the following bug in ash/dash:
+# https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=874264
+if [ -z "$BASE_COMMAND" ]; then
+    echo "WARNING: Entryscript in use but \$BASE_COMMAND not configured"
+elif [ "${1#-}" != "${1}" ] || [ -z "$(command -v "${1}")" ] || { [ -f "${1}" ] && ! [ -x "${1}" ]; }; then
+    set -- $BASE_COMMAND "$@"
+fi
+
+exec "$@"

test.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+set -e
+
+docker build -t command_test .
+docker run --rm -e BASE_COMMAND="uname" command_test -a
+docker run --rm -e BASE_COMMAND="ls" command_test
+docker run --rm -e BASE_COMMAND="echo" command_test foo bar
+docker run --rm command_test ls
+
+docker rmi command_test
+
+