DevOopsSbtExtraPlugin - Always Show the Welcome Message (sbt 2)

Why?

On sbt 2, the welcome message set through onLoadMessage (for example the sbt-welcome banner that DevOopsStarterPlugin configures with the logo and the list of useful tasks) often does not appear when you start sbt. It shows up once, then seems to disappear for every later run.

That is not a bug in the banner. sbt 2's sbt launcher is a thin client (sbtn). When an sbt server is already running for the build, the client simply attaches to it instead of loading the project again:

sbt shutdown
sbt            # cold start: the project is loaded, the welcome message is printed
exit
sbt            # attaches to the running server: no load, so no welcome message

onLoadMessage is only printed while the project is being loaded, so on a warm attach it is never printed at all. sbt's own welcome to sbt ... line disappears in exactly the same situations, for exactly the same reason.

DevOopsSbtExtraPlugin can re-emit the welcome message when a client attaches to an already running server, so it appears on every interactive start.

note

This is an sbt 2 only feature. On sbt 1 the setting exists but does nothing, because sbt 1 has no thin client and therefore always loads the project and always prints the message.

How to Use

Set devOopsAlwaysShowOnLoadMessage to true at the Global scope in build.sbt to opt in.

Global / devOopsAlwaysShowOnLoadMessage := true

Whatever onLoadMessage the build has configured is what gets shown, so the banner looks exactly the same as it does on a cold start. It is printed once per interactive start and is never printed twice: on a cold start or after a reload, sbt has already printed it itself, and the plugin suppresses the duplicate.

Setting

Setting	Type	Default	Description
devOopsAlwaysShowOnLoadMessage	Boolean	false	sbt 2 only. Show onLoadMessage on every interactive start, including a warm thin-client attach.

The default is false, so sbt 2's stock behaviour is unchanged unless you opt in.

Limitations

• Interactive mode only. Batch invocations such as sbt -batch compile or sbt compile that run a command and exit do not render a shell prompt, so no message is shown. The message is a greeting for an interactive session.
• sbt's own welcome to sbt ... line is not restored. That line is produced inside sbt itself and is out of scope here; only the onLoadMessage banner is re-emitted.
• This feature relies on sbt 2 internals that carry no compatibility guarantee. Everything is written so that a future sbt change degrades to "the banner is not shown" rather than breaking the build.

Alternative Without This Setting

If you would rather not enable the setting, running sbt in the foreground instead of through the thin client also loads the project every time, so the welcome message always appears:

sbt --server

The trade-off is that you lose the fast startup that the warm server gives you.