Workflow
Background
A workflow consists of an orchestrated and repeatable pattern of activity, enabled by the systematic organization of resources into processes that transform materials, provide services, or process information. It can be depicted as a sequence of operations, the work of a person or group, the work of an organization of staff, or one or more simple or complex mechanisms.[1]
Example
Read an RSS feed, build the article list into a Slack message, and then send it to Slack.
Step 1. Create a Slack Webhook
Please follow this document to create a new Slack WebHook, the URL of the Webhook will be like https://hooks.slack.com/services/T0XXXXXXX/B0YYYYYYYYY/ZZZZZZZZZZZZZZZZZZZZZZZZ.
Step 2. Create a pipeline for the workflow
Save the below YAML to rss-pipeline.yaml, and make sure you have replaced the Slack Webhook URL with yours.
name: rss-pipeline
kind: Pipeline
flow:
---
title: validate the request, a valid request must contain the 'X-Rss-Url' header, and its value must be a URL.
linkTitle: validate the request, a valid request must contain the 'X-Rss-Url' header, and its value must be a URL.
weight: 10
---
- filter: validator
---
title: create the request for the RSS feed.
linkTitle: create the request for the RSS feed.
weight: 10
---
- filter: buildRssRequest
namespace: rss
---
title: read the RSS feed, a 3rd party website is used to covert the feed from XML to JSON.
linkTitle: read the RSS feed, a 3rd party website is used to covert the feed from XML to JSON.
weight: 10
---
- filter: sendRssRequest
namespace: rss
---
title: the RSS feed is gzipped, we need to decompress it.
linkTitle: the RSS feed is gzipped, we need to decompress it.
weight: 10
---
- filter: decompressResponse
namespace: rss
---
title: create the request to Slack (build the Slack message).
linkTitle: create the request to Slack (build the Slack message).
weight: 10
---
- filter: buildSlackRequest
namespace: slack
---
title: send the message to Slack.
linkTitle: send the message to Slack.
weight: 10
---
- filter: sendSlackRequest
namespace: slack
---
title: build the response for the client.
linkTitle: build the response for the client.
weight: 10
---
- filter: buildResponse
filters:
- name: validator
kind: Validator
headers:
"X-Rss-Url":
regexp: ^https?://.+$
- name: buildRssRequest
kind: RequestBuilder
template: |
url: /developers/feed2json/convert?url={{index (index .requests.DEFAULT.Header "X-Rss-Url") 0 | urlquery}}
- name: sendRssRequest
kind: Proxy
pools:
- loadBalance:
policy: roundRobin
servers:
- url: https://www.toptal.com
compression:
minLength: 4096
- name: buildSlackRequest
kind: RequestBuilder
template: |
method: POST
url: /services/T0XXXXXXXXX/B0YYYYYYY/ZZZZZZZZZZZZZZZZZZZZ # This the Slack webhook address, please change it to your own.
body: |
{
"text": "Recent posts - {{.responses.rss.JSONBody.title}}",
"blocks": [{
"type": "section",
"text": {
"type": "plain_text",
"text": "Recent posts - {{.responses.rss.JSONBody.title}}"
}
}, {
"type": "section",
"text": {
"type": "mrkdwn",
"text": "{{range $index, $item := .responses.rss.JSONBody.items}}• <{{$item.url}}|{{$item.title}}>\n{{end}}"
}}]
}
- name: sendSlackRequest
kind: Proxy
pools:
- loadBalance:
policy: roundRobin
servers:
- url: https://hooks.slack.com
compression:
minLength: 4096
- name: decompressResponse
kind: ResponseAdaptor
decompress: gzip
- name: buildResponse
kind: ResponseBuilder
template: |
statusCode: {{.responses.slack.StatusCode}}
body: {{if eq .responses.slack.StatusCode 200}}RSS feed has been sent to Slack successfully.{{else}}Failed to send the RSS feed to Slack{{end}}
Then create the RSS pipeline with the command:
egctl create -f rss-pipeline.yaml
Step 3: Create an HTTPServer to receive client request
Save below YAML to http-server.yaml.
kind: HTTPServer
name: http-server-example
port: 8080
https: false
keepAlive: true
keepAliveTimeout: 75s
maxConnection: 10240
cacheSize: 0
rules:
- paths:
- pathPrefix: /rss
backend: rss-pipeline
Then create the HTTP server with command:
egctl create -f http-server.yaml
Step 4: See the result
Execute the below command and your Slack will receive the article list if everything is correct. You may use another RSS feed, but please note the maximum message size Slack allowed is about 3K, so you will need to limit the number of articles returned by the RSS feed of some sites(e.g. Hack News)
$ curl -v http://127.0.0.1:8080/rss -H X-Rss-Url:https://www.coolshell.cn/rss
* Trying 127.0.0.1:8080...
* TCP_NODELAY set
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
> GET /rss HTTP/1.1
> Host: 127.0.0.1:8080
> User-Agent: curl/7.68.0
> Accept: */*
> X-Rss-Url:https://www.coolshell.cn/rss
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Fri, 17 Jun 2022 08:29:58 GMT
< Content-Length: 45
< Content-Type: text/plain; charset=utf-8
<
* Connection #0 to host 127.0.0.1 left intact
RSS feed has been sent to Slack successfully.