In Phase 2, recreate a venv and reinstall Python packages only if necessary.

* Teach the build script how to do special vars. Factor up file reading.
* Use a static string for the PyPI JSON location, as it will soon be overrideable via an env var for testing.

letsencrypt_auto/build.py

@@ -2,7 +2,8 @@
 """Stitch together the letsencrypt-auto script.
 
 Implement a simple templating language in which {{ some/file }} turns into the
-contents of the file at ./pieces/some/file.
+contents of the file at ./pieces/some/file except for certain tokens which have
+other, special definitions.
 
 """
 from os.path import dirname, join
@@ -10,18 +11,37 @@ import re
 from sys import argv
 
 
+def le_version(build_script_dir):
+    """Return the version number stamped in letsencrypt/__init__.py."""
+    return re.search('''^__version__ = ['"](.+)['"].*''',
+                     file_contents(join(dirname(build_script_dir),
+                                        'letsencrypt',
+                                        '__init__.py')),
+                     re.M).group(1)
+
+
+def file_contents(path):
+    with open(path) as file:
+        return file.read()
+
+
 def main():
     dir = dirname(argv[0])
 
-    def replacer(match):
-        rel_path = match.group(1)
-        with open(join(dir, 'pieces', rel_path)) as replacement:
-            return replacement.read()
+    special_replacements = {
+        'LE_AUTO_VERSION': le_version(dir)
+    }
 
-    with open(join(dir, 'letsencrypt-auto.template')) as template:
-        result = re.sub(r'{{\s*([A-Za-z0-9_./-]+)\s*}}',
-                        replacer,
-                        template.read())
+    def replacer(match):
+        token = match.group(1)
+        if token in special_replacements:
+            return special_replacements[token]
+        else:
+            return file_contents(join(dir, 'pieces', token))
+
+    result = re.sub(r'{{\s*([A-Za-z0-9_./-]+)\s*}}',
+                    replacer,
+                    file_contents(join(dir, 'letsencrypt-auto.template')))
     with open(join(dir, 'letsencrypt-auto'), 'w') as out:
         out.write(result)
 

letsencrypt_auto/letsencrypt-auto.template

@@ -160,43 +160,49 @@ elif [ "$1" = "--no-self-upgrade" ]; then
   # Phase 2: Create venv, install LE, and run.
 
   shift 1  # the --no-self-upgrade arg
-  echo "Creating virtual environment..."
-  # TODO: Embed LE version here, and compare it against letsencrypt --version.
-  # If it matches, there's no need to recreate the venv.
-  rm -rf "$VENV_PATH"
-  DeterminePythonVersion
-  if [ "$VERBOSE" = 1 ]; then
-    virtualenv --no-site-packages --python $LE_PYTHON $VENV_PATH
+  if [ -f $VENV_BIN/letsencrypt ]; then
+    INSTALLED_VERSION=$($VENV_BIN/letsencrypt --version 2>&1 | cut -d " " -f 2)
   else
-    virtualenv --no-site-packages --python $LE_PYTHON $VENV_PATH > /dev/null
+    INSTALLED_VERSION="0.0.0"
   fi
+  if [ "{{ LE_AUTO_VERSION }}" = $INSTALLED_VERSION ]; then
+    echo "Reusing old virtual environment."
+  else
+    echo "Creating virtual environment..."
+    rm -rf "$VENV_PATH"
+    DeterminePythonVersion
+    if [ "$VERBOSE" = 1 ]; then
+      virtualenv --no-site-packages --python $LE_PYTHON $VENV_PATH
+    else
+      virtualenv --no-site-packages --python $LE_PYTHON $VENV_PATH > /dev/null
+    fi
 
-  # Install Python dependencies with peep, then run letsencrypt.
-  echo "Installing Python package dependencies..."
-  TEMP_DIR=`mktemp -d 2>/dev/null || mktemp -d -t 'le'`  # Linux || OS X
-  # ---------------------------------------------------------------------------
-  cat << "UNLIKELY_EOF" > $TEMP_DIR/letsencrypt-auto-requirements.txt
+    # Install Python dependencies with peep, then run letsencrypt.
+    echo "Installing Python package dependencies..."
+    TEMP_DIR=`mktemp -d 2>/dev/null || mktemp -d -t 'le'`  # Linux || OS X
+    # ---------------------------------------------------------------------------
+    cat << "UNLIKELY_EOF" > $TEMP_DIR/letsencrypt-auto-requirements.txt
 {{ letsencrypt-auto-requirements.txt }}
 UNLIKELY_EOF
-  # ---------------------------------------------------------------------------
-  cat << "UNLIKELY_EOF" > $TEMP_DIR/peep.py
+    # ---------------------------------------------------------------------------
+    cat << "UNLIKELY_EOF" > $TEMP_DIR/peep.py
 {{ peep.py }}
 UNLIKELY_EOF
-  # ---------------------------------------------------------------------------
-  set +e
-  PEEP_OUT=`$VENV_BIN/python $TEMP_DIR/peep.py install -r $TEMP_DIR/letsencrypt-auto-requirements.txt`
-  PEEP_STATUS=$?
-  set -e
-  rm -rf $TEMP_DIR
-  if [ "$PEEP_STATUS" = 0 ]; then
-    echo "Running letsencrypt..."
-    echo "  " $SUDO $VENV_BIN/letsencrypt "$@"
-    $SUDO $VENV_BIN/letsencrypt "$@"
-  else
-    # Report error:
-    echo $PEEP_OUT
-    exit 1
+    # ---------------------------------------------------------------------------
+    set +e
+    PEEP_OUT=`$VENV_BIN/python $TEMP_DIR/peep.py install -r $TEMP_DIR/letsencrypt-auto-requirements.txt`
+    PEEP_STATUS=$?
+    set -e
+    rm -rf $TEMP_DIR
+    if [ "$PEEP_STATUS" != 0 ]; then
+      # Report error:
+      echo $PEEP_OUT
+      exit 1
+    fi
   fi
+  echo "Running letsencrypt..."
+  echo "  " $SUDO $VENV_BIN/letsencrypt "$@"
+  $SUDO $VENV_BIN/letsencrypt "$@"
 else
   # Phase 1: Upgrade letsencrypt-auto if neceesary, then self-invoke.
 
@@ -215,9 +221,7 @@ else
     # dependencies (curl, etc.), for better flow control, and for the option of
     # future Windows compatibility.
     #
-    # This Python script prints a path to a temp dir containing a new copy of
-    # letsencrypt-auto or returns non-zero. There is no $ interpolation due to
-    # quotes on heredoc delimiters.
+    # There is no $ interpolation due to quotes on heredoc delimiters.
     set +e
     # -------------------------------------------------------------------------
     TEMP_DIR=`$LE_PYTHON - << "UNLIKELY_EOF"

letsencrypt_auto/pieces/download_upgrade.py

@@ -1,3 +1,8 @@
+"""Print a path to a temp dir containing a new copy of letsencrypt-auto.
+
+On failure, return non-zero.
+
+"""
 from distutils.version import LooseVersion
 from json import loads
 from os import devnull
@@ -67,7 +72,7 @@ class TempDir(object):
 def latest_stable_version(get, package):
     """Apply a fairly safe heuristic to determine the latest stable release of
     a PyPI package."""
-    metadata = loads(get('https://pypi.python.org/pypi/%s/json' % package))
+    metadata = loads(get('https://pypi.python.org/pypi/letsencrypt/json'))
     # metadata['info']['version'] actually returns the latest of any kind of
     # release release, contrary to https://wiki.python.org/moin/PyPIJSON.
     return str(max(LooseVersion(r) for r
@@ -108,7 +113,7 @@ def main():
     get = HttpsGetter().get
     temp = TempDir()
     try:
-        stable_tag = 'v' + latest_stable_version(get, 'letsencrypt')
+        stable_tag = 'v' + latest_stable_version(get)
         print dirname(verified_new_le_auto(get, stable_tag, temp))
     except ExpectedError as exc:
         print exc.args[0], exc.args[1]