Libguestfs - Oct 2019 - [nbdkit PATCH] Check for python3 first

On systems where python is still set to python2 the check will fail even though
it is still completely possible to compile and use nbdkit.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
---
 configure.ac                            |  2 +-
 plugins/python/nbdkit-python-plugin.pod | 13 +++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 5adce7d7bab5..83eefb60ab73 100644
--- a/configure.ac
+++ b/configure.ac
@@ -471,7 +471,7 @@ AC_SUBST([PERL_CFLAGS])
 AC_SUBST([PERL_LDOPTS])
 
 dnl Check for Python 3, for embedding in the python plugin.
-AC_CHECK_PROG([PYTHON],[python],[python],[no])
+AC_PATH_PROGS([PYTHON],[python3 python],[no])
 AC_ARG_ENABLE([python],
     [AS_HELP_STRING([--disable-python], [disable Python embed plugin])],
     [],
diff --git a/plugins/python/nbdkit-python-plugin.pod
b/plugins/python/nbdkit-python-plugin.pod
index 321aeb2c3b53..92a03c3cde6c 100644
--- a/plugins/python/nbdkit-python-plugin.pod
+++ b/plugins/python/nbdkit-python-plugin.pod
@@ -46,14 +46,15 @@ may want to include documentation and globals (eg. for
storing global
 state).  Any other top level statements are run when the script is
 loaded, just like ordinary Python.
 
-=head2 Python 2 and Python 3
+=head2 Python versions
 
-The Python plugin has to be compiled for either Python 2 or Python 3
-when building nbdkit.  You can set the C<PYTHON> environment variable
-to the desired interpreter, otherwise nbdkit will use the interpreter
-called C<python> on the current C<$PATH>.  For example:
+Python 2 end of life is 2020-01-01 and nbdkit >= 1.16 no longer
+supports it.  If you want to use Python 2, you will need to use nbdkit
+version 1.14.  You can set the C<PYTHON> environment variable
+to the desired interpreter, otherwise nbdkit will use interpreter
+called C<python3> or C<python> on the current C<$PATH>.  For
example:
 
- PYTHON=/usr/bin/python3 ./configure
+ PYTHON=/opt/local/bin/python3 ./configure
 
 To find out which version the Python plugin was compiled for, use the
 I<--dump-plugin> option, eg:
-- 
2.23.0

On 10/4/19 3:22 PM, Martin Kletzander wrote:
> On systems where python is still set to python2 the check will fail even
though
> it is still completely possible to compile and use nbdkit.
> 
> Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
> ---
>   configure.ac                            |  2 +-
>   plugins/python/nbdkit-python-plugin.pod | 13 +++++++------
>   2 files changed, 8 insertions(+), 7 deletions(-)
Looks correct to me.
> 
> diff --git a/configure.ac b/configure.ac
> index 5adce7d7bab5..83eefb60ab73 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -471,7 +471,7 @@ AC_SUBST([PERL_CFLAGS])
>   AC_SUBST([PERL_LDOPTS])
>   
>   dnl Check for Python 3, for embedding in the python plugin.
> -AC_CHECK_PROG([PYTHON],[python],[python],[no])
> +AC_PATH_PROGS([PYTHON],[python3 python],[no])
>   AC_ARG_ENABLE([python],
>       [AS_HELP_STRING([--disable-python], [disable Python embed plugin])],
>       [],
> diff --git a/plugins/python/nbdkit-python-plugin.pod
b/plugins/python/nbdkit-python-plugin.pod
> index 321aeb2c3b53..92a03c3cde6c 100644
> --- a/plugins/python/nbdkit-python-plugin.pod
> +++ b/plugins/python/nbdkit-python-plugin.pod
> @@ -46,14 +46,15 @@ may want to include documentation and globals (eg. for
storing global
>   state).  Any other top level statements are run when the script is
>   loaded, just like ordinary Python.
>   
> -=head2 Python 2 and Python 3
> +=head2 Python versions
>   
> -The Python plugin has to be compiled for either Python 2 or Python 3
> -when building nbdkit.  You can set the C<PYTHON> environment
variable
> -to the desired interpreter, otherwise nbdkit will use the interpreter
> -called C<python> on the current C<$PATH>.  For example:
> +Python 2 end of life is 2020-01-01 and nbdkit >= 1.16 no longer
> +supports it.  If you want to use Python 2, you will need to use nbdkit
> +version 1.14.  You can set the C<PYTHON> environment variable
> +to the desired interpreter, otherwise nbdkit will use interpreter
> +called C<python3> or C<python> on the current C<$PATH>. 
For example:
>   
> - PYTHON=/usr/bin/python3 ./configure
> + PYTHON=/opt/local/bin/python3 ./configure
>   
>   To find out which version the Python plugin was compiled for, use the
>   I<--dump-plugin> option, eg:
> 
-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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