Add disable option (#52)

The `disable` option lets you temporarily disable Slack notifications
(for testing pipeline configurations or errors) without editing the whole
pipeline to remove or comment out the put steps and the resource itself.

README.md

@@ -26,6 +26,7 @@ To setup an [Incoming Webhook](https://api.slack.com/incoming-webhooks) go to ht
 -   `insecure`: *Optional.* Connect to Slack insecurely - i.e. skip SSL validation. Defaults to false if not provided.
 - `proxy`: *Optional.* Connect to Slack using an HTTP(S) proxy. In the form: `http://my.proxy:3128`
 - `proxy_https_tunnel`: *Optional.* Set to `true` to use an HTTP proxy as an HTTPS tunnel.
+- `disable`: *Optional.* Set to `true` to skip all messaging. Convenient for temporarily disabling notifications without editing your pipelines.
 -   `ca_certs`: *Optional.* An array of objects with the following format:
 
   ```yaml

out

@@ -14,6 +14,15 @@ payload=$(mktemp /tmp/resource-in.XXXXXX)
 
 cat > "${payload}" <&0
 
+timestamp="$(jq -n "{version:{timestamp:\"$(date +%s)\"}}")"
+
+disable="$(jq -r '.source.disable' < "${payload}")"
+if [[ "$disable" == "true" ]]
+then
+    echo "$timestamp" >&3
+    exit 0
+fi
+
 webhook_url="$(jq -r '.source.url' < "${payload}")"
 allow_insecure="$(jq -r '.source.insecure // "false"' < "${payload}")"
 raw_ca_certs=$(jq -r '.source.ca_certs // []' < $payload)
@@ -187,5 +196,4 @@ EOF
 
 fi
 
-timestamp="$(jq -n "{version:{timestamp:\"$(date +%s)\"}}")"
 echo "$timestamp $metadata $debug_info " | jq -s add  >&3