Improved fix for dynamic build and load of shared library support when using pyenv virtualenv (Python)

build.bash

### pyenv hook script to prepare a build env
#
# 0: Intro
# $MYLOC points to your local sideload root (usually ~/.local)
MYLOC=$HOME/.local
#
export PYTHON_CONFIGURE_OPTS="--with-openssl=$MYLOC --enable-shared --enable-optimizations --with-lto"
export PYTHON_CFLAGS="-march=native -mtune=native"
echo ""
echo "This is $(basename $0) hook 'build.bash':"
echo "  Location: $(pyenv root)/pyenv.d/install/build.bash"
echo ""
echo "This add-on performs additional tasks and creates additional"
echo "environment variables to pass to python build process"
echo "when called by the pyenv-build plugin:"
echo ""
echo "    PYTHON_CONFIGURE_OPTS='${PYTHON_CONFIGURE_OPTS}'"
echo "    CONFIGURE_OPTS='${CONFIGURE_OPTS}'"
echo "    PYTHON_CFLAGS='${PYTHON_CFLAGS}'"
echo "    CFLAGS='${CFLAGS}'"
echo ""
#
# Use: with_log "string" cmd...
function with_log () {
 local TTTT=$(mktemp -d)
 local MSG=$1; shift
 "$@" >$TTTT/log 2>$TTTT/log
 echo "$MSG results in $TTTT"
 test -f $TTTT/err && \
  echo -e "ERRORS\nError log in $TTTT/err\n$(tail $TTTT/err)\nDONE: There were ERRORS" || \
  echo "$MSG DONE: No errors, results in $TTTT/log"
 echo ""
 return $?
}
# Use: update_pyenv
function update_pyenv () {
 PYENV=$(pyenv root)
 if [ -d $PYENV/.git ]; then
  echo "Updating pyenv"
  pushd $PYENV
  git show-ref -q --heads mine || git branch mine
  git branch -q --set-upstream-to=origin/master master
  git checkout -q mine
  git merge -q -m "auto merge" origin/master
 fi
 echo ""
}
#
# 1: Make sure pyenv is up to date
with_log "Update pyenv" update_pyenv
#
# 2: Build openssl and side-load it
OPENSSLVER=1.1.1t
echo "Side loading openssl $OPENSSLVER into $MYLOC"
if [ ! -d $MYLOC/bin/openssl ] || ! ( $MYLOC/bin/openssl version | grep $OPENSSLVER ); then
 BUILDDIR=$(mktemp -d)
 pushd $BUILDDIR
 git clone https://github.com/openssl/openssl
 cd openssl
 git checkout -b build OpenSSL_$(echo "$OPENSSLVER" | tr '.' '_')
 with_log "Config" ./config --prefix=$MYLOC --openssldir=$MYLOC/ssl
 echo "Building openssl, please wait...."
 with_log "Build" make
 echo "Installing openssl, please wait...."
 with_log "Install" make install_sw
 popd
 rm -rf $BUILDDIR
fi
echo ""
# 3: Build python, passing some extra options
echo "Building Python, please wait...."

I found problems with using the Python C API together with pyenv virtualenv. The LD_LIBRARY_PATH was not being set correctly
and my C application (which links with Python) would not run.

This gist, named build.bash, should be placed in $(pyenv root)/pyenv.d/install as pyenv install calls another plugin called build that compiles as required.

There are other solutions that involve permanent changes to login environment or obscure pyenv install invocations, but this method is more portable.

TODO: Make this a wrapper for build-<version-regex> | build-default

I was thinking of adding detection of an environment variable or config file with the contents like this:
PYENV_BUILD_SHARED_=Y|N
PYENV_BUILD_SHARED_DEFAULT=Y|N
e.g.
.pyenv/pyenv.cfg

# Use regex compatible fragments that express pyenv version or pyenv virtualenv venv string with spaces ' ' replacing dots '\.'
# (That is to save on parsing and make it easier to read without knowing reged too well, as versions never have spaces in anyway)
# The # character and anything after it are ignored until the end of the line
# A special use of # is on the end of a line where #; Any text is printed at the start and end of the process if it is a script or exe
#
# Each line is read in sequence, with the Y or N being the result of the last regex match
# If Y|y|T|t|1 then the --enable-shared would be included
# If N|n|F|f|0 then the --enable-shared would be excluded
# If there is no match then the system default is used
# So if the the last line is .* then that will override the default
#
[--enabled-shared]
.*        = N        #; Shared libraries are not being built
3 [5-7] = Y
3 8 16= N        # No for 3.8.16
3 9     = Y        # Yes for 3.9.*
2        = N       # No for 2.*.*
myvenv = Y
testv.*  = Y
.*          = N

The same mechanism could be extended to pass any arbitraty configuration to a given pyenv-build build or pyenv virtualenv, through the use of a simple set of additional syntax elements in addition to Y/N, E.g.

• enabling optional modules,
• building extra tools INCLUDE
• setting environment variables SET<x=y>
• run pre or post scripts

e.g.
[--set-env]
3.9.1 = DEBUG=2
3.8 = LD_LIBRARY_PATH=$PYENV/versions/lib/$PY_VERSION

[--enable]
3.8 = zlib

[--sideload]
3.9.5 = git clone https://github.com/mozillazg/pypy #; "Installing PyPy"

[--post-build]
2.7 = scripts/deprecation_warning severity=10