Add attachments to the blockkit

[jldmota]

json example

"attachments": [
{
"blocks": [
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "Alternative hotel options"
}
},
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "<https://example.com|Bates Motel> ⭐⭐"
},
"accessory": {
"type": "button",
"text": {
"type": "plain_text",
"text": "View",
"emoji": true
},
"value": "view_alternate_1"
}
},
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "<https://example.com|The Great Northern Hotel> ⭐⭐⭐⭐"
},
"accessory": {
"type": "button",
"text": {
"type": "plain_text",
"text": "View",
"emoji": true
},
"value": "view_alternate_2"
}
}
]
}
]
}

[BenKuhar]

Would be nice to have this to wrap blocks in a message with the attachments color bar applied.

[pykenny]

Unfortunately Slack officials has labeled attachments as legacy feature, and discourage use of attachments for messaging. (they lied a bit in the statement, because a long message can still be truncated by Slack client in message thread, even when using "pure" block elements only in message content, however.)

[imryche]

Closing this since attachments are a legacy feature.