Readme

docs/usage/bash_plugin.md

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+This provides a brief tutorial for creating a Drone webhook plugin, using simple shell scripting, to make an http requests during the build pipeline. The below example demonstrates how we might configure a webhook plugin in the Yaml file:
+
+```yaml
+pipeline:
+  webhook:
+    image: foo/webhook
+    url: http://foo.com
+    method: post
+    body: |
+      hello world
+```
+
+Create a simple shell script that invokes curl using the Yaml configuration parameters, which are passed to the script as environment variables in uppercase and prefixed with `PLUGIN_`.
+
+```bash
+#!/bin/sh
+
+curl \
+  -X ${PLUGIN_METHOD} \
+  -d ${PLUGIN_BODY} \
+  ${PLUGIN_URL}
+
+```
+Create a Dockerfile that adds your shell script to the image, and configures the image to execute your shell script as the main entrypoint.
+
+```dockerfile
+FROM alpine
+ADD script.sh /bin/
+RUN chmod +x /bin/script.sh
+RUN apk -Uuv add curl ca-certificates
+ENTRYPOINT /bin/script.sh
+```
+
+Build and publish your plugin to the Docker registry. Once published your plugin can be shared with the broader Drone community.
+
+```nohighlight
+docker build -t foo/webhook .
+docker push foo/webhook
+```
+
+Execute your plugin locally from the command line to verify it is working:
+
+```nohighlight
+docker run --rm \
+  -e PLUGIN_METHOD=post \
+  -e PLUGIN_URL=http://foo.com \
+  -e PLUGIN_BODY="hello world" \
+  foo/webhook
+```