Send a Message via a Mattermost Incoming Webhook — send_webhook

Posts a message to Mattermost using an incoming webhook URL. Incoming webhooks are simpler than bot-token authentication — no auth object is needed. The webhook URL itself acts as the credential.

Usage

send_webhook_message(
  webhook_url,
  text = NULL,
  channel = NULL,
  username = NULL,
  icon_url = NULL,
  icon_emoji = NULL,
  attachments = NULL,
  props = NULL,
  priority = NULL
)

Arguments

webhook_url: The full incoming webhook URL (e.g. "https://mattermost.example.com/hooks/xxx-generatedkey-xxx"). Treat this as a secret.
text: Markdown-formatted message text. Required unless attachments is provided.
channel: Optional. Override the channel the message posts in. Use the channel's short name (e.g. "town-square"), not the display name. Use "@username" to send a direct message.
username: Optional. Override the username the message posts as. Requires the server setting Enable integrations to override usernames to be enabled.
icon_url: Optional. Override the profile picture with an image URL. Requires the server setting Enable integrations to override profile picture icons to be enabled.
icon_emoji: Optional. Override the profile picture with an emoji (e.g. ":robot:"). Takes precedence over icon_url.
attachments: Optional. A list of message attachment objects for richer formatting. Required if text is not provided.
props: Optional. A named list of extra properties for the post. Supports the card key for additional Markdown shown in the right-hand side panel.
priority: Optional. A list specifying message priority (e.g. list(priority = "important")).

Value

The httr2 response object, returned invisibly. A successful request returns HTTP 200 with body "ok".

Details

Incoming webhooks must be enabled on the Mattermost server (System Console > Integrations > Integration Management). The webhook URL is created via Product menu > Integrations > Incoming Webhook in Mattermost.

The request is retried up to 3 times on transient failures.

Examples

if (FALSE) { # \dontrun{
# Simple text message
send_webhook_message(
  webhook_url = "https://mattermost.example.com/hooks/xxx-generatedkey-xxx",
  text = "Hello from R!"
)

# Override channel and username
send_webhook_message(
  webhook_url = "https://mattermost.example.com/hooks/xxx-generatedkey-xxx",
  text = "Build passed :white_check_mark:",
  channel = "ci-notifications",
  username = "CI Bot",
  icon_emoji = ":robot:"
)

# Rich attachment without text
send_webhook_message(
  webhook_url = "https://mattermost.example.com/hooks/xxx-generatedkey-xxx",
  attachments = list(
    list(
      title = "Trade Alert",
      text = "AAPL filled at $185.50",
      color = "#00FF00"
    )
  )
)

# Direct message via webhook
send_webhook_message(
  webhook_url = "https://mattermost.example.com/hooks/xxx-generatedkey-xxx",
  text = "Private notification for you.",
  channel = "@jsmith"
)
} # }