webhookd

A very simple webhook server to launch shell scripts.

Installation

Run the following command:

$ go get -v github.com/ncarlier/webhookd/webhookd

Or download the binary regarding your architecture:

$ sudo curl -s https://raw.githubusercontent.com/ncarlier/webhookd/master/install.sh | bash

Or use Docker:

$ docker run -d --name=webhookd \
  --env-file .env \
  -v ${PWD}/scripts:/var/opt/webhookd/scripts \
  -p 8080:8080 \
  ncarlier/webhookd

Check the provided environment file .env for configuration details.

Note that this image extends docker:dind Docker image. Therefore you are able to interact with a Docker daemon with yours shell scripts.

Configuration

You can configure the daemon by:

Setting environment variables:

Variable	Default	Description
APP_LISTEN_ADDR	:8080	HTTP service address
APP_NB_WORKERS	2	The number of workers to start
APP_HOOK_TIMEOUT	10	Hook maximum delay before timeout (in second)
APP_SCRIPTS_DIR	./scripts	Scripts directory
APP_SCRIPTS_GIT_URL	none	GIT repository that contains scripts (Note: this is only used by the Docker image or by using the Docker entrypoint script)
APP_SCRIPTS_GIT_KEY	none	GIT SSH private key used to clone the repository (Note: this is only used by the Docker image or by using the Docker entrypoint script)
APP_WORKING_DIR	/tmp (OS temp dir)	Working directory (to store execution logs)
APP_NOTIFIER	none	Post script notification (http or smtp)
APP_NOTIFIER_FROM	none	Sender of the notification
APP_NOTIFIER_TO	none	Recipient of the notification
APP_HTTP_NOTIFIER_URL	none	URL of the HTTP notifier
APP_SMTP_NOTIFIER_HOST	none	Hostname of the SMTP relay
APP_DEBUG	false	Output debug logs

Using command parameters:

Parameter	Default	Description
-l <address> or --listen <address>	:8080	HTTP service address
-d or --debug	false	Output debug logs
--nb-workers <workers>	2	The number of workers to start
--scripts <dir>	./scripts	Scripts directory
--timeout <timeout>	10	Hook maximum delay before timeout (in second)

Usage

Directory structure

Webhooks are simple scripts dispatched into a directory structure.

By default inside the ./scripts directory. You can override the default using the APP_SCRIPTS_DIR environment variable.

Example:

/scripts
|--> /github
  |--> /build.sh
  |--> /deploy.sh
|--> /ping.sh
|--> ...

Webhook URL

The directory structure define the webhook URL. The Webhook can only be call with HTTP POST verb. If the script exists, the HTTP response will be a text/event-stream content type (Server-sent events).

Example:

The script: ./scripts/foo/bar.sh

#!/bin/bash

echo "foo foo foo"
echo "bar bar bar"

$ curl -XPOST http://localhost/foo/bar
data: Hook work request "foo/bar" queued...

data: Running foo/bar script...

data: foo foo foo

data: bar bar bar

data: done

Webhook parameters

You have several way to provide parameters to your webhook script:

• URL query parameters and HTTP headers are converted into environment variables. Variable names follows "snakecase" naming convention. Therefore the name can be altered.

  ex: CONTENT-TYPE will become content_type.

• Body content (text/plain or application/json) is transmit to the script as parameter.

Example:

The script:

#!/bin/bash

echo "Query parameter: foo=$foo"
echo "Header parameter: user-agent=$user_agent"
echo "Script parameters: $1"

The result:

$ curl --data @test.json http://localhost/echo?foo=bar
data: Hook work request "echo" queued...

data: Running echo script...

data: Query parameter: foo=bar

data: Header parameter: user-agent=curl/7.52.1

data: Script parameter: {"foo": "bar"}

data: done

Webhook timeout configuration

By default a webhook has a timeout of 10 seconds. This timeout is globally configurable by setting the environment variable: APP_HOOK_TIMEOUT (in seconds).

You can override this global behavior per request by setting the HTTP header: X-Hook-Timeout (in seconds).

Example:

$ curl -XPOST -H "X-Hook-Timeout: 5" http://localhost/echo?foo=bar

Post hook notifications

The script's output is collected and stored into a log file (configured by the APP_WORKING_DIR environment variable).

Once the script executed, you can send the result and this log file to a notification channel. Currently only two channels are supported: Email and HTTP.

HTTP notification

HTTP notification configuration:

• APP_NOTIFIER=http
• APP_NOTIFIER_FROM=webhookd noreply@nunux.org
• APP_NOTIFIER_TO=hostmaster@nunux.org
• APP_HTTP_NOTIFIER_URL=http://requestb.in/v9b229v9

Note that the HTTP notification is compatible with Mailgun API.

Email notification

SMTP notification configuration:

• APP_NOTIFIER=smtp
• APP_SMTP_NOTIFIER_HOST=localhost:25

The log file will be sent as an GZIP attachment.

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