Slack Post GitHub Action

GitHub Action that posts a message to a Slack channel

Inputs

token

Optional The Slack auth token. This is only required if environment variable SLACK_BOT_TOKEN is not set.

channel

Required The channel name to post to (example: #general)

thread_ts

Optional The timestamp ID of the parent message to reply to (e.g., the ts output from a previous Slack message call)

text

Required The message text to post. See Slack's documentation on formatting.

Notes:

• quotes, backticks, $(...) and $VAR in the text are posted literally, never executed or expanded
• backslash escapes are interpreted the way bash's $'...' quoting does (e.g. \n becomes a newline and \' becomes '), so write \\ for a literal backslash. In a double-quoted YAML string, YAML removes one layer of escaping first, so double each backslash again (example: text: "C:\\\\temp, won\\'t" posts C:\temp, won't, the same as C:\\temp, won\'t in a | block scalar)
• environment variables will only be expanded if referenced using the env GitHub Action context ${{ env.MY_VAR }} format (example: text: "This is the value of MY_VAR: ${{ env.MY_VAR }}")

unfurl_links

Optional Whether links in the message should be unfurled (default: true)

Requirements

The runner's bash must be version 4.4 or newer (GitHub-hosted runners are).

Outputs

ts

The timestamp ID of the message (can be used to make subsequent Slack messages a threaded reply)

error

The Slack API error code (e.g. channel_not_found, or ratelimited on an HTTP 429) when Slack rejected the message. The step fails in that case, so read this from a step with continue-on-error: true.

Example usage

- name: Post Slack message
  uses: ynab/slack-post-message-action@v1.6
  with:
    token: ${{ secrets.SLACK_API_TOKEN }}
    channel: "#general"
    text: ":tada: This is a test from the ${{ env.GITHUB_ACTION }} workflow! <https://github.com/ynab/slack-post-message-action|Action Documentation>"