Add script to provide dev shell

dev/dev_shell.sh

+#!/bin/bash
+set -e
+
+SCRIPT_DIR="$(dirname "$(readlink -f "$0")")"
+PROJ_DIR="$(dirname "$SCRIPT_DIR")"
+
+docker run -it --rm --entrypoint /bin/sh -e GANDI_API_KEY -v "$PROJ_DIR:/tmp/work" certbot/certbot:v0.22.0 '/tmp/work/dev/tools/initfile.sh'

dev/readme.txt

+Set env var GANDI_API_KEY to your GANDI LiveDNS API key and run ./dev_shell.sh to get a shell with certbot ready to run with the plugin installed.

dev/tools/initfile.sh

+pip install -e /tmp/work/plugin
+printf 'certbot_plugin_gandi:dns_api_key=%s\n' $GANDI_API_KEY > /tmp/config.ini && chmod 400 /tmp/config.ini 
+echo 'Example: certbot certonly --test-cert -a certbot-plugin-gandi:dns --certbot-plugin-gandi:dns-credentials /tmp/config.ini -d domain.com'
+exec /bin/sh