From 1b521ac4e385505b7987034f9ece9041d9ebb97c Mon Sep 17 00:00:00 2001
From: Jonathon Reinhart <Jonathon.Reinhart@gmail.com>
Date: Wed, 5 Sep 2018 23:37:01 -0400
Subject: [PATCH] scuba: Don't run the entrypoint for each line in a multi-line
 script

**This is a breaking change.**

The previous logic was generally incorrect. For a multi-line script,
Scuba would prepend each line with the entrypoint. This sort of makes
sense, except the script is run within *one*  `docker run` invocation.
Many image entrypoints are wrappers which set up things in the
container, and then execute the user command which is passed as
arguments to the entrypoint (e.g. `exec "@"`). Thus, it isn't right to
execute the entrypoint multiple times in the same container.

This changes the behavior of Scuba to instead invoke the entrypoint,
passing it the path of the scuba-generated script to be executed. In
this way, the entrypoint is only run once.

N.B. This means that Scuba no longer works with images which wrap a
single command (e.g. an "application" image which sets some CLI
application as the entrypoint). If this use case is needed in the
future, an additional YAML option (e.g. `entrypoint_each_line`) could be
added to restore the old behavior.

Fixes #114
---
 scuba/__main__.py  | 10 ++++------
 tests/test_main.py | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/scuba/__main__.py b/scuba/__main__.py
index 3bcdd5b7..bd65dcad 100644
--- a/scuba/__main__.py
+++ b/scuba/__main__.py
@@ -291,20 +291,18 @@ def __setup_native_run(self):
             verbose_msg('{} Cmd: "{}"'.format(context.image, default_cmd))
             context.script = [shell_quote_cmd(default_cmd)]
 
-        # Make scubainit the entrypoint, and manually insert an existing
-        # entrypoint before each user command
-        entrypoint = get_image_entrypoint(context.image) or []
+        # Make scubainit the real entrypoint, and use the defined entrypoint as
+        # the docker command (if it exists)
+        self.docker_cmd = get_image_entrypoint(context.image) or []
         self.add_option('--entrypoint={}'.format(scubainit_cpath))
 
         # The user command is executed via a generated shell script
         with self.open_scubadir_file('command.sh', 'wt') as f:
-            self.docker_cmd = ['/bin/sh', f.container_path]
+            self.docker_cmd += ['/bin/sh', f.container_path]
             writeln(f, '#!/bin/sh')
             writeln(f, '# Auto-generated from scuba')
             writeln(f, 'set -e')
             for cmd in context.script:
-                if entrypoint:
-                    cmd = shell_quote_cmd(entrypoint) + ' ' + cmd
                 writeln(f, cmd)
 
         self.context = context
diff --git a/tests/test_main.py b/tests/test_main.py
index caa9b11e..141508e3 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -368,6 +368,22 @@ def test_image_entrypoint(self):
         assert_str_equalish('success', out)
 
 
+    def test_image_entrypoint_multiline(self):
+        '''Verify entrypoints are handled correctly with multi-line scripts'''
+        with open('.scuba.yml', 'w') as f:
+            f.write('''
+                image: scuba/entrypoint-test
+                aliases:
+                  testalias:
+                    script:
+                      - cat entrypoint_works.txt
+                      - echo $ENTRYPOINT_WORKS
+                ''')
+
+        out, _ = self.run_scuba(['testalias'])
+        assert_str_equalish('\n'.join(['success']*2), out)
+
+
     def test_image_override(self):
         '''Verify --image works'''