SlackThreads

Provides a simple way to update a running Slack thread with text and attachments (files, images, etc).

Requirements

1. OAuth token

This package needs a Slack OAuth token associated to a Slack app with the permissions chat:write and files:write (only needed for uploading files/images). You can make an app at https://api.slack.com/apps. Then install it to a workplace and add the permissions, and get an "Bot User OAuth Token". Set this as the environmental variable SLACK_TOKEN. You can do this in a running Julia session via

ENV["SLACK_TOKEN"] = let buffer = Base.getpass("Slack token")
    str = read(buffer, String)
    Base.shred!(buffer)
    str
end;

and pasting it in. You will need to do this every session, or set the variable elsewhere (e.g. in a shell startup script, CI secret, Kubernetes secret, etc.)

2. Channel ID

One also needs to specify a Slack channel to create threads in. You will likely need to invite your bot app into that channel (an easy way is to ping them and then click invite to channel). Once you have a channel for which your bot app has access, get the channel ID (a value like C1H9RESGL which you can find at the bottom of the "About" section of a channel). You can pass this to the SlackThread constructor or set an environmental variable SLACK_CHANNEL.

Usage

The main object of interest is a SlackThread, constructed by thread = SlackThread() (one may pass a channel and the default is ENV["SLACK_CHANNEL"]).

The first time a message is sent with a particular SlackThread, a new thread is started in the channel. Subsequent messages will be posted to that thread.

The thread can be called as a function to send a message. Additionally, file paths or pairs of the form name_with_extension => object may be passed to add attachments to the message. See the docstring for more details.

julia> using SlackThreads, CairoMakie

julia> thread = SlackThread();

julia> thread("New thread!");

julia> thread("Update", "plot1.png" => scatter(rand(10), rand(10)),
                        "plot2.png" => lines(rand(10)));

One may use thread = DummyThread() to instead store messages without sending them to Slack. See the docstring for more details.

Exceptions

SlackThreads does not throw any exceptions when:

• constructing a SlackThread
• sending a message to Slack by calling thread::SlackThread object

Instead, @error and @warn logs are used. This is so that SlackThreads can easily be incorporated into long-running computations without the risk of introducing runtime errors.

SlackThreads can also be used to log exceptions to a thread, via slack_log_exception. For example,

slack_log_exception(thread) do
    sqrt(-1)
end

This will rethrow the exception, after logging it (and the stacktrace) to the Slack thread. Any errors encountered while logging the message (e.g. due to network issues or authentication problems) will be caught and emitted as @error logs.

Similar packages

Slack.jl provides a partial wrapper of the Slack API. SlackThreads.jl instead focuses on providing an easy way to update a Slack thread and avoiding runtime errors.