# HG changeset patch
# User wenzelm
# Date 1663428471 -7200
# Node ID 74d6567c2274aaa158ec3c109e2a12a9fa4251d7
# Parent  8089593a364a3af828b2b513ad9f5056a0cbd22a
clarified Docker base image;

diff -r 8089593a364a -r 74d6567c2274 src/Doc/System/Misc.thy
--- a/src/Doc/System/Misc.thy	Sat Sep 17 16:50:39 2022 +0200
+++ b/src/Doc/System/Misc.thy	Sat Sep 17 17:27:51 2022 +0200
@@ -38,7 +38,7 @@
 \<open>Usage: isabelle build_docker [OPTIONS] APP_ARCHIVE
 
   Options are:
-    -B NAME      base image (default "ubuntu")
+    -B NAME      base image (default "ubuntu:22.04")
     -E           set Isabelle/bin/isabelle as entrypoint
     -P NAME      additional Ubuntu package collection ("X11", "latex")
     -W DIR       working directory that is accessible to docker,
@@ -70,10 +70,10 @@
 
   \<^medskip>
   Option \<^verbatim>\<open>-B\<close> specifies the Docker image taken as starting point for the
-  Isabelle installation: it needs to be a suitable version of Ubuntu Linux.
-  The default \<^verbatim>\<open>ubuntu\<close> refers to the latest LTS version provided by Canonical
-  as the official Ubuntu vendor\<^footnote>\<open>\<^url>\<open>https://hub.docker.com/_/ubuntu\<close>\<close>. For
-  Isabelle2022 this is normally Ubuntu 22.04 LTS.
+  Isabelle installation: it needs to be a suitable version of Ubuntu Linux,
+  see also \<^url>\<open>https://hub.docker.com/_/ubuntu\<close>. The default for Isabelle2022
+  is \<^verbatim>\<open>ubuntu:22.04\<close>, but other versions often work as well, after some
+  experimentation with packages.
 
   Option \<^verbatim>\<open>-p\<close> includes additional Ubuntu packages, using the terminology
   of \<^verbatim>\<open>apt-get install\<close> within the underlying Linux distribution.
diff -r 8089593a364a -r 74d6567c2274 src/Pure/Tools/build_docker.scala
--- a/src/Pure/Tools/build_docker.scala	Sat Sep 17 16:50:39 2022 +0200
+++ b/src/Pure/Tools/build_docker.scala	Sat Sep 17 17:27:51 2022 +0200
@@ -8,7 +8,7 @@
 
 
 object Build_Docker {
-  private val default_base = "ubuntu"
+  private val default_base = "ubuntu:22.04"
   private val default_work_dir = Path.current
   private lazy val default_logic = Isabelle_System.getenv("ISABELLE_LOGIC")