--generate-dir option to publish heroku, refs #1905

datasette/publish/heroku.py

@@ -3,7 +3,9 @@ from datasette import hookimpl
 import click
 import json
 import os
+import pathlib
 import shlex
+import shutil
 from subprocess import call, check_output
 import tempfile
 
@@ -28,6 +30,11 @@ def publish_subcommand(publish):
         "--tar",
         help="--tar option to pass to Heroku, e.g. --tar=/usr/local/bin/gtar",
     )
+    @click.option(
+        "--generate-dir",
+        type=click.Path(dir_okay=True, file_okay=False),
+        help="Output generated application files and stop without deploying",
+    )
     def heroku(
         files,
         metadata,
@@ -49,6 +56,7 @@ def publish_subcommand(publish):
         about_url,
         name,
         tar,
+        generate_dir,
     ):
         "Publish databases to Datasette running on Heroku"
         fail_if_publish_binary_not_installed(
@@ -105,6 +113,16 @@ def publish_subcommand(publish):
             secret,
             extra_metadata,
         ):
+            if generate_dir:
+                # Recursively copy files from current working directory to it
+                if pathlib.Path(generate_dir).exists():
+                    raise click.ClickException("Directory already exists")
+                shutil.copytree(".", generate_dir)
+                click.echo(
+                    f"Generated files written to {generate_dir}, stopping without deploying",
+                    err=True,
+                )
+                return
             app_name = None
             if name:
                 # Check to see if this app already exists

docs/cli-reference.rst

@@ -501,6 +501,8 @@ See :ref:`publish_heroku`.
       -n, --name TEXT                 Application name to use when deploying
       --tar TEXT                      --tar option to pass to Heroku, e.g.
                                       --tar=/usr/local/bin/gtar
+      --generate-dir DIRECTORY        Output generated application files and stop
+                                      without deploying
       --help                          Show this message and exit.
 
 

docs/publish.rst

@@ -73,6 +73,10 @@ This will output some details about the new deployment, including a URL like thi
 
 You can specify a custom app name by passing ``-n my-app-name`` to the publish command. This will also allow you to overwrite an existing app.
 
+Rather than deploying directly you can use the ``--generate-dir`` option to output the files that would be deployed to a directory::
+
+    datasette publish heroku mydatabase.db --generate-dir=/tmp/deploy-this-to-heroku
+
 See :ref:`cli_help_publish_heroku___help` for the full list of options for this command.
 
 .. _publish_vercel:

tests/test_publish_heroku.py

@@ -2,6 +2,7 @@ from click.testing import CliRunner
 from datasette import cli
 from unittest import mock
 import os
+import pathlib
 import pytest
 
 
@@ -128,3 +129,48 @@ def test_publish_heroku_plugin_secrets(
             mock.call(["heroku", "builds:create", "-a", "f", "--include-vcs-ignore"]),
         ]
     )
+
+
+@pytest.mark.serial
+@mock.patch("shutil.which")
+def test_publish_heroku_generate_dir(mock_which, tmp_path_factory):
+    mock_which.return_value = True
+    runner = CliRunner()
+    os.chdir(tmp_path_factory.mktemp("runner"))
+    with open("test.db", "w") as fp:
+        fp.write("data")
+    output = str(tmp_path_factory.mktemp("generate_dir") / "output")
+    result = runner.invoke(
+        cli.cli,
+        [
+            "publish",
+            "heroku",
+            "test.db",
+            "--generate-dir",
+            output,
+        ],
+    )
+    assert result.exit_code == 0
+    path = pathlib.Path(output)
+    assert path.exists()
+    file_names = {str(r.relative_to(path)) for r in path.glob("*")}
+    assert file_names == {
+        "requirements.txt",
+        "bin",
+        "runtime.txt",
+        "Procfile",
+        "test.db",
+    }
+    for name, expected in (
+        ("requirements.txt", "datasette"),
+        ("runtime.txt", "python-3.8.10"),
+        (
+            "Procfile",
+            (
+                "web: datasette serve --host 0.0.0.0 -i test.db "
+                "--cors --port $PORT --inspect-file inspect-data.json"
+            ),
+        ),
+    ):
+        with open(path / name) as fp:
+            assert fp.read().strip() == expected