Add --tar option to "datasette publish heroku"

[betatim]

This issue is about how best to pass additional options to tools used for publishing datasettes. A concrete example is wanting to pass the --tar flag to the heroku CLI tool. I think there are at least two options for doing this: documentation for each publishing tool to explain how to set flags via env variables (if possible) or building a mechanism that lets users pass additional flags through datasette.

When using datasette publish heroku binder-launches.db --extra-options="--config facet_time_limit_ms:35000 --config sql_time_limit_ms:35000" --name=binderlytics --install=datasette-vega to publish https://binderlytics.herokuapp.com/ the following error happens:

 ›   Warning: heroku update available from 7.42.1 to 7.43.0.
 ›   Warning: heroku update available from 7.42.1 to 7.43.0.
 ›   Warning: heroku update available from 7.42.1 to 7.43.0.
Setting WEB_CONCURRENCY and restarting ⬢ binderlytics... done, v13
WEB_CONCURRENCY: 1
 ›   Warning: heroku update available from 7.42.1 to 7.43.0.
 ▸    Couldn't detect GNU tar. Builds could fail due to decompression errors
 ▸    See https://devcenter.heroku.com/articles/platform-api-deploying-slugs#create-slug-archive
 ▸    Please install it, or specify the '--tar' option
 ▸    Falling back to node's built-in compressor
buffer.js:358
    throw new ERR_INVALID_OPT_VALUE.RangeError('size', size);
    ^

RangeError [ERR_INVALID_OPT_VALUE]: The value "3303763968" is invalid for option "size"
    at Function.alloc (buffer.js:367:3)
    at new Buffer (buffer.js:281:19)
    at Readable.<anonymous> (/Users/thead/.local/share/heroku/node_modules/archiver-utils/index.js:39:15)
    at Readable.emit (events.js:322:22)
    at endReadableNT (/Users/thead/.local/share/heroku/node_modules/readable-stream/lib/_stream_readable.js:1010:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21) {
  code: 'ERR_INVALID_OPT_VALUE'
}

After installing GNU tar with brew install gnu-tar and modifying datasette/publish/heroku.py to include the --tar=/path/to/gnu-tar publishing works.

I think the problem occurs once your heroku slug reaches a certain size. At least when I add only a few 100 entries to the datasette then the error does not occcur.

datasette version 0.49.1
OSX 10.14.6 (18G103)

[simonw]

I don't think a standard "pass these extra arguments to the publish tool" mechanism will work because there's no guarantee that a publisher uses a CLI tool - or if it does, it might make several calls to different CLI tools. The Cloud Run one runs a couple of commands, as illustrated by this test:

datasette/tests/test_publish_cloudrun.py

Lines 63 to 73 in a648bb8

	mock_call.assert_has_calls(
	[
	mock.call("gcloud builds submit --tag {}".format(tag), shell=True),
	mock.call(
	"gcloud run deploy --allow-unauthenticated --platform=managed --image {} input-service".format(
	tag
	),
	shell=True,
	),
	]
	)

Adding a --tar option for datasette publish heroku is a good fix for this though.

[simonw]

I'm working on this now. Just ran this test and it worked (no longer showed my the warning message).

datasette publish heroku fixtures.db -n datasette-issue-999 --branch=main --tar=/usr/local/bin/gtar

But... I wonder if it should automatically do this if it detects that gtar is available?

[simonw]

For the moment I'm going to ship this as the --tar= option. Can consider detecting gtar in the future.