Post a Slack message

Sends a message to a Slack channel with an optional file attachment.

For prerequisites, see Slack chat actions.

Post a message

The action identifier is slack.chat.postMessage.

Sends a message to a Slack channel, with an optional file attachment.

The following table describes all available input fields for this action.

Input	Type	Description	Example
token	Secret	Required. The Slack bot token to use. This should be passed as a secret syntax. Refer to Add Slack configuration for instructions on setting up a token.	`${{ :secrets:slackToken }}`
channel	String	Required. The name of the channel, or a channelID, to send the message. See Slack API for more information.	`my-slack-channel`
text	String	Required. The message to be posted to Slack in the specified `channel`.	`Hello World!`
threadTs	String	Optional. Timestamp belonging to parent message, used to create a message reply in a thread.	`<digits>.<digits>`
attachment	Map	Optional. Allows attaching a file with a message onto the specified `channel`.
attachment.filename	String	Required when using `attachment`. Specify the filename for the uploaded file in Slack.	`file.txt`
attachment.content	String	Required when using `attachment`. The content of the file to upload as UTF8.	`Hello\nWorld!`
selectors	List	Optional. The selectors to get only the specified parameters as output.	`[{\"name\": \"threadTs\", \"expression\": \".threadTs\"}, {\"name\": \"channelID\", \"expression\": \".channelID\"}]`

The following table describes all output fields returned by this action.

Output	Type	Description
threadTs	String	Timestamp of the message thread. May be used in future `postMessage` calls to post a reply in a thread. Example: `<digits>.<digits>`.
channelID	String	ID of the channel where the message is posted.
success	Boolean	`true` on success, `false` on failure.
errorMessage	String	Failure reason as message. `null` on success.

Example 1: Send a Slack message

Workflow example
`name: SendMessage steps: - name: send_slack_message type: action action: slack.chat.postMessage version: 1 inputs: token: ${{ :secrets:dn_staging_slack_token }} channel: ${{ .workflowInputs.channel }} text: ${{ .workflowInputs.text }} selectors: - name: threadTs expression: ".threadTs" - name: channelID expression: ".channelID"` Inputs: { "inputs": [ { "key": "channel", "value": "test-channel-workflow" }, { "key": "text", "value": "This is my message with bold text and `code backticks`" } ] } Expected output: `[ { "threadTs": "1718897637.400609", "channelID": "C063JK1RHN1", "success": true } ]`

Workflow example

name: SendMessage

steps:
  - name: send_slack_message
    type: action
    action: slack.chat.postMessage
    version: 1
    inputs:
      token: ${{ :secrets:dn_staging_slack_token }}
      channel: ${{ .workflowInputs.channel }}
      text: ${{ .workflowInputs.text }}
      selectors:
        - name: threadTs
          expression: ".threadTs"
        - name: channelID
          expression: ".channelID"

Inputs:

{
  "inputs": [
    {
      "key": "channel",
      "value": "test-channel-workflow"
    },
    {
      "key": "text",
      "value": "This is my message *with bold text* and `code backticks`"
    }
  ]
}

Expected output:

[
  {
    "threadTs": "1718897637.400609",
    "channelID": "C063JK1RHN1",
    "success": true
  }
]

Example 2: Attach a file

Workflow example
`name: SendFileMessage steps: - name: postCsv type: action action: slack.chat.postMessage version: 1 inputs: token: ${{ :secrets:dn_staging_slack_token }} channel: test-channel-workflow text: "Please find the attached file:" attachment: filename: 'file.txt' content: "Hello\nWorld!"` Expected output: `[ { "threadTs": "1718897637.400609", "channelID": "C063JK1RHN1", "success": true } ]`

Workflow example

name: SendFileMessage

steps:
  - name: postCsv
    type: action
    action: slack.chat.postMessage
    version: 1
    inputs:
      token: ${{ :secrets:dn_staging_slack_token }}
      channel: test-channel-workflow
      text: "Please find the attached file:"
      attachment:
        filename: 'file.txt'
        content: "Hello\nWorld!"

Expected output:

[
  {
    "threadTs": "1718897637.400609",
    "channelID": "C063JK1RHN1",
    "success": true
  }
]

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Post a message