Slack messages for GitHub Actions workflows, jobs and steps

A simple and flexible Slack integration with GitHub Actions.

Features

• Advanced users can use a configuration file and Handlebars templates to configure every aspect of the Slack message.

• In addition to "legacy" attachments, rich messages can be created using layout blocks for flexible message visualisation and interactivity.

Configuration

Environment Variables (env)

SLACK_WEBHOOK_URL (required)

Create a Slack Webhook URL using either the Incoming Webhooks App (preferred) or by attaching an incoming webhook to an existing Slack App (beware, channel override not possible when using a Slack App):

env:
  SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}

Input Parameters (with)

status (required)

The status must be defined. It can either be the current job status using:

  with: 
    status: ${{ job.status }}

or a hardcoded custom status such as "starting" or "in progress":

  with: 
    status: in progress

steps (optional)

The individual status of job steps can be included in the Slack message using:

  with: 
    status: ${{ job.status }}
    steps: ${{ toJson(steps) }}

Note: Only steps that have a "step id" will be reported on. See example below.

channel (optional)

To override the channel or to send the Slack message to an individual use:

  with: 
    status: ${{ job.status }}
    channel: '#workflows'

Note: To override the channel the Slack webhook URL must be an Incoming Webhook URL. See https://api.slack.com/faq#incoming_webhooks

message (optional)

To override the slack message use:

  with: 
    status: ${{ job.status }}
    channel: '#workflows'
    message: Deploying {{ env.GITHUB_REF_NAME }} branch

config (optional)

A configuration file can be used to customise the following Slack message fields:

• username
• icon_url
• pretext
• title and title_link
• text
• fallback plain text summary used for dumb clients and notifications
• fields title, value and short/long
• blocks including actions, context, divider, file, header, image, input and section blocks
• message footer
• border colors based job status success, failure, cancelled. valid colors are good (green), warning (yellow), danger (red) or any hex color code eg. #439FE0
• icons for step status success, failure, cancelled, skipped, and a default

Default: .github/slack.yml

  with: 
    status: ${{ job.status }}
    config: .github/config/slack.yml

The following Slack message fields and block layouts support templating using Handlebars.js format:

• pretext
• title
• text and message
• fallback
• fields title and value
• blocks

Supported Template variables

env.*, payload.*, jobName, jobStatus, jobSteps, eventName, workflow, workflowUrl, workflowRunUrl, repositoryName, repositoryUrl, runId, runNumber, sha, shortSha, branch, actor, action, ref, refType, refUrl, diffRef, diffUrl, description, sender

Helper Functions

Apart from the standard helper functions such as #if and #each there are also a few custom ones:

• icon converts a job status into an icon eg. {{icon jobStatus}}

• json dumps the value as a JSON string eg. {{json payload.commits}}

• truncate cuts the string at the limit eg. {{truncate sha 8}}

• default allows a alternative or default value eg. {{default headRef "master"}}

• pluralize outputs different text based on item count eg. {{pluralize requested_reviewers "reviewer" "reviewers"}} (if only singular form is given plural is derived by adding an "s")

• eq, neq, not, and, and or can be used as logical operators eg. {{#if (and (not has_issues) (or has_pages has_wiki))}}yes{{else}}no{{/if}}

• #ifeq and #ifneq test for variable equality or not eg. {{#ifneq event_name "create"}}yes{{else}}no{{/ifneq}}

Example Using Config File

To generate the message format below use the slack.yml configuration file that follows.

Example Configuration File: slack.yml

username: GitHub-CI
icon_url: https://octodex.github.com/images/mona-the-rivetertocat.png

pretext: Triggered via {{eventName}} by {{actor}} {{or action "action"}} {{ref}} `{{diffRef}}`
title: GitHub Actions
title_link: https://support.github.com

text: |
  *<{{workflowRunUrl}}|Workflow _{{workflow}}_ job _{{jobName}}_ triggered by _{{eventName}}_ is _{{jobStatus}}_>* for <{{refUrl}}|`{{ref}}`>
  {{#if description}}<{{diffUrl}}|`{{diffRef}}`> - {{description}}{{/if}}
  {{#if payload.commits}}
  *Commits*
  {{#each payload.commits}}
  <{{this.url}}|`{{truncate this.id 8}}`> - {{this.message}}
  {{/each}}
  {{/if}}

fallback: |-
  [GitHub] {{workflow}} #{{runNumber}} {{jobName}} is {{jobStatus}}

fields:
  - title: Job Steps
    value: "{{#each jobSteps}}{{icon this.outcome}} {{@key}}\n{{/each}}"
    short: false
  - title: Workflow
    value: "<{{workflowUrl}}|{{workflow}}>"
    short: true
  - title: Git Ref
    value: "{{ref}} ({{refType}})"
    short: true
  - title: Run ID
    value: |-
      <{{workflowRunUrl}}|{{runId}}>
    short: true
  - title: Run Number
    value: "{{runNumber}}"
    short: true
  - title: Actor
    value: "{{actor}}"
    short: true
  - title: Job Status
    value: "{{jobStatus}}"
    short: true

footer: >-
  <{{repositoryUrl}}|{{repositoryName}}> {{workflow}} #{{runNumber}}

colors:
  success: '#5DADE2'
  failure: '#884EA0'
  cancelled: '#A569BD'
  default: '#7D3C98'

icons:
  success: ':white_check_mark:'
  failure: ':grimacing:'
  cancelled: ':x:'
  skipped: ':heavy_minus_sign:'
  default: ':interrobang:'

Notes:

• If template expressions occur at the start of a string the string must be double-quoted eg. pretext: "{{eventName}} triggered by {{actor}}"
• Use YAML multiline string formats |, >, |- and >- or double-quotes "\n" to control new lines
• Use ~ (tilde) character to control whitepace when looping see Whitespace control

Conditionals (if)

To ensure the Slack message is sent even if the job fails add the always() function:

if: always()

or use a specific status function to only run when the job status matches. All possible status check functions are:

• success() (default)
• always()
• cancelled()
• failure()

Examples

To send a Slack message when a workflow job has completed add the following as the last step of the job:

- uses: act10ns/slack@v1
  with: 
    status: ${{ job.status }}
  if: always()

To include statuses for each Job Step in the message include the steps input (making sure to use the toJSON function):

- uses: act10ns/slack@v1
  with: 
    status: ${{ job.status }}
    steps: ${{ toJson(steps) }}
  if: always()

Only steps that have a "step id" assigned to them will be reported on:

- name: Build
  id: build
  run: |
    npm install
    npm run build

The default Slack channel for the configured webhook can be overridden using either another channel name #channel or a username @username.

- uses: act10ns/slack@v1
  with: 
    status: ${{ job.status }}
    channel: '#workflows'

or

- uses: act10ns/slack@v1
  with: 
    status: ${{ job.status }}
    channel: '@nick'

Complete example

name: Docker Build and Push

on:
  push:
    branches: [ master, release/* ]

jobs:
  build:
    runs-on: ubuntu-latest
    env:
      REPOSITORY_URL: docker.pkg.github.com
      IMAGE_NAME: ${{ github.repository }}/alerta-cli
      SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
    steps:
      - uses: act10ns/slack@v1
        with:
          status: starting
          channel: '#workflows'
          message: Starting Docker Build and Push...
        if: always()
      - name: Checkout
        uses: actions/checkout@v2
      - name: Variables
        id: vars
        run: echo "::set-output name=SHORT_COMMIT_ID::$(git rev-parse --short HEAD)"
      - name: Build image
        id: docker-build
        run: >-
          docker build
          -t $IMAGE_NAME
          -t $REPOSITORY_URL/$IMAGE_NAME:${{ steps.vars.outputs.SHORT_COMMIT_ID }}
          -t $REPOSITORY_URL/$IMAGE_NAME:latest .
      - name: Docker Login
        env:
          DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
          DOCKER_PASSWORD: ${{ secrets.GITHUB_TOKEN }}
        run: docker login $REPOSITORY_URL --username "$DOCKER_USERNAME" --password "$DOCKER_PASSWORD"
      - name: Publish Image
        id: docker-push
        run: docker push $REPOSITORY_URL/$IMAGE_NAME

      - uses: act10ns/slack@v1
        with:
          status: ${{ job.status }}
          steps: ${{ toJson(steps) }}
          channel: '#workflows'
        if: always()

The above "Docker Build and Push" workflow will appear in Slack as:

Troubleshooting

To enable runner diagnostic logging set the ACTIONS_RUNNER_DEBUG secret to true.

To enable step debug logging set the ACTIONS_STEP_DEBUG secret to true.

See https://docs.github.com/en/free-pro-team@latest/actions/managing-workflow-runs/enabling-debug-logging

References

• GitHub Actions Toolkit https://github.com/actions/toolkit/tree/main/packages/github
• GitHub Actions Starter Workflows https://github.com/actions/starter-workflows
• Slack Incoming Webhooks https://slack.com/apps/A0F7XDUAZ-incoming-webhooks?next_id=0
• Env vars https://docs.github.com/en/free-pro-team@latest/actions/reference/environment-variables
• Webhook Payloads https://docs.github.com/en/free-pro-team@latest/developers/webhooks-and-events/webhook-events-and-payloads#webhook-payload-object-common-properties
• GitHub Actions Cheat Sheet https://github.github.io/actions-cheat-sheet/actions-cheat-sheet.html
• Slack Secondary message attachments https://api.slack.com/reference/messaging/attachments
• Handlebars Language Guide https://handlebarsjs.com/guide/
• YAML multiline string formats https://yaml-multiline.info/
• Migrate your legacy message compositions to blocks https://api.slack.com/messaging/attachments-to-blocks

License

Copyright (c) 2020-2021 Nick Satterly. Available under the MIT License.