From 57549e2f0f674769f251dc1e163993a6ed6dee11 Mon Sep 17 00:00:00 2001
From: Dirk Steinkopf <dirk@steinkopf.net>
Date: Sat, 26 Jun 2021 08:42:49 +0200
Subject: [PATCH 1/2] make it work for alpine and centos based images, too

---
 docker_push_latest_if_changed.py | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/docker_push_latest_if_changed.py b/docker_push_latest_if_changed.py
index e64da95..0ee3f56 100755
--- a/docker_push_latest_if_changed.py
+++ b/docker_push_latest_if_changed.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.6
+#!/usr/bin/env python3
 import argparse
 import hashlib
 import subprocess
@@ -191,7 +191,19 @@ def _get_commands_hash(image_uri: str) -> str:
 
 
 def _get_packages_hash(image_uri: str) -> str:
-    packages = _run_in_image(image_uri, ('dpkg', '-l'))
+    try:
+        packages = _run_in_image(image_uri, ('dpkg', '-l'))
+    except subprocess.CalledProcessError as oserr:
+        print(f'failed. returncode={oserr.returncode}. stderr:\n{oserr.stderr}')
+        if oserr.returncode == 127:
+            # retry - maybe we have an alpine based image
+            try:
+                packages = _run_in_image(image_uri, ('apk', 'list'))
+            except subprocess.CalledProcessError as oserr:
+                print(f'failed. returncode={oserr.returncode}. stderr:\n{oserr.stderr}')
+                if oserr.returncode == 127:
+                    # retry - maybe we have an centos based image
+                    packages = _run_in_image(image_uri, ('yum', 'list', '--quiet', 'installed'))
     print(f'Packages for {image_uri}:\n{packages}')
     return _get_digest(packages.encode())
 
@@ -207,8 +219,9 @@ def _run_in_image(image_uri: str, command: Tuple[str, ...]) -> str:
         '--rm',
         '--net=none',
         '--user=nobody',
+        '--entrypoint', command[0],
         image_uri,
-        *command,
+        *command[1:],
     )
     return _check_output_and_print(run_command)
 

From bd2c1b0e2f7e3d18df0c298e92789ce35fe30321 Mon Sep 17 00:00:00 2001
From: Dirk Steinkopf <dirk@steinkopf.net>
Date: Sat, 10 Jul 2021 07:19:08 +0200
Subject: [PATCH 2/2] improve error handling for hash creation

---
 docker_push_latest_if_changed.py | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/docker_push_latest_if_changed.py b/docker_push_latest_if_changed.py
index 0ee3f56..f65666b 100755
--- a/docker_push_latest_if_changed.py
+++ b/docker_push_latest_if_changed.py
@@ -2,6 +2,7 @@
 import argparse
 import hashlib
 import subprocess
+import random
 from typing import NamedTuple
 from typing import Optional
 from typing import Sequence
@@ -194,14 +195,20 @@ def _get_packages_hash(image_uri: str) -> str:
     try:
         packages = _run_in_image(image_uri, ('dpkg', '-l'))
     except subprocess.CalledProcessError as oserr:
-        print(f'failed. returncode={oserr.returncode}. stderr:\n{oserr.stderr}')
-        if oserr.returncode == 127:
+        if oserr.returncode != 127:
+            print(f'failed. returncode={oserr.returncode}. stderr:\n{oserr.stderr}')
+        else:
             # retry - maybe we have an alpine based image
             try:
                 packages = _run_in_image(image_uri, ('apk', 'list'))
             except subprocess.CalledProcessError as oserr:
-                print(f'failed. returncode={oserr.returncode}. stderr:\n{oserr.stderr}')
-                if oserr.returncode == 127:
+                if oserr.returncode == 1:
+                    # return code 1 seems ok here
+                    packages = oserr.stdout
+                elif oserr.returncode != 127:
+                    print(f'failed. returncode={oserr.returncode}. stdout:\n{oserr.stdout}\nstderr:\n{oserr.stderr}')
+                    raise
+                else:
                     # retry - maybe we have an centos based image
                     packages = _run_in_image(image_uri, ('yum', 'list', '--quiet', 'installed'))
     print(f'Packages for {image_uri}:\n{packages}')
@@ -219,6 +226,7 @@ def _run_in_image(image_uri: str, command: Tuple[str, ...]) -> str:
         '--rm',
         '--net=none',
         '--user=nobody',
+        '--name', 'tmp_' + str(random.randint(10000, 50000)),
         '--entrypoint', command[0],
         image_uri,
         *command[1:],
@@ -228,7 +236,7 @@ def _run_in_image(image_uri: str, command: Tuple[str, ...]) -> str:
 
 def _check_output_and_print(command: Tuple[str, ...]) -> str:
     print(' '.join(command))
-    output = subprocess.check_output(command, encoding='utf-8')
+    output = subprocess.check_output(command, encoding='utf-8', stderr=subprocess.STDOUT)
     return output