Update from upstream github repo

- pipenv is locked to older stable version
- ENV for micropipenv
- no python-virtualenv package
- updated documentation

s2i/bin/assemble

@@ -14,22 +14,30 @@ function virtualenv_bin() {
     python3.8 -m venv $1
 }
 
-# Install pipenv to the separate virtualenv to isolate it
+# Install pipenv or micropipenv to the separate virtualenv to isolate it
 # from system Python packages and packages in the main
 # virtualenv. Executable is simlinked into ~/.local/bin
 # to be accessible. This approach is inspired by pipsi
 # (pip script installer).
-function install_pipenv() {
-  echo "---> Installing pipenv packaging tool ..."
-  VENV_DIR=$HOME/.local/venvs/pipenv
+function install_tool() {
+  echo "---> Installing $1 packaging tool ..."
+  VENV_DIR=$HOME/.local/venvs/$1
   virtualenv_bin "$VENV_DIR"
-  $VENV_DIR/bin/pip --isolated install -U pipenv
+  $VENV_DIR/bin/pip --isolated install -U $1$2  # Combines package name with [extras] if [extras] is defined as $2
   mkdir -p $HOME/.local/bin
-  ln -s $VENV_DIR/bin/pipenv $HOME/.local/bin/pipenv
+  ln -s $VENV_DIR/bin/$1 $HOME/.local/bin/$1
 }
 
 set -e
 
+# First of all, check that we don't have disallowed combination of ENVs
+if [[ ! -z "$ENABLE_PIPENV" && ! -z "$ENABLE_MICROPIPENV" ]]; then
+  echo "ERROR: Pipenv and micropipenv cannot be enabled at the same time!"
+  # podman/buildah does not relay this exit code but it will be fixed hopefuly
+  # https://github.com/containers/buildah/issues/2305
+  exit 3
+fi
+
 shopt -s dotglob
 echo "---> Installing application source ..."
 mv /tmp/src/* "$HOME"
@@ -50,7 +58,7 @@ if [[ ! -z "$UPGRADE_PIP_TO_LATEST" ]]; then
 fi
 
 if [[ ! -z "$ENABLE_PIPENV" ]]; then
-  install_pipenv
+  install_tool "pipenv" "==2018.11.26"
   echo "---> Installing dependencies via pipenv ..."
   if [[ -f Pipfile ]]; then
     pipenv install --deploy
@@ -58,6 +66,11 @@ if [[ ! -z "$ENABLE_PIPENV" ]]; then
     pipenv install -r requirements.txt
   fi
   # pipenv check
+elif [[ ! -z "$ENABLE_MICROPIPENV" ]]; then
+  install_tool "micropipenv" "[toml]"
+  echo "---> Installing dependencies via micropipenv ..."
+  # micropipenv detects Pipfile.lock and requirements.txt in this order
+  micropipenv install --deploy
 elif [[ -f requirements.txt ]]; then
   echo "---> Installing dependencies ..."
   pip install -r requirements.txt