Update a test

Co-Authored-By: Brad Warren <bmw@users.noreply.github.com>

letsencrypt-auto-source/Dockerfile.centos6

@@ -27,11 +27,17 @@ RUN mkdir -p /home/lea/certbot
 COPY ./tests/certs/ca/my-root-ca.crt.pem /usr/local/share/ca-certificates/
 RUN update-ca-trust
 
-# Copy code:
+# Copy current letsencrypt-auto:
 COPY . /home/lea/certbot/letsencrypt-auto-source
 
+# Fetch previous letsencrypt-auto that was installing python 3.4
+RUN curl https://raw.githubusercontent.com/certbot/certbot/v0.38.0/letsencrypt-auto-source/letsencrypt-auto \
+    -o /home/lea/certbot/letsencrypt-auto-source/letsencrypt-auto_py_34 \
+ && chmod +x /home/lea/certbot/letsencrypt-auto-source/letsencrypt-auto_py_34
+
+RUN chmod +x /home/lea/certbot/letsencrypt-auto-source/tests/centos6_tests.sh
+
 USER lea
 WORKDIR /home/lea
 
-RUN sudo chmod +x certbot/letsencrypt-auto-source/tests/centos6_tests.sh
-CMD sudo certbot/letsencrypt-auto-source/tests/centos6_tests.sh
+CMD ["sudo", "certbot/letsencrypt-auto-source/tests/centos6_tests.sh"]

letsencrypt-auto-source/letsencrypt-auto

@@ -256,20 +256,28 @@ DeprecationBootstrap() {
   fi
 }
 
-MIN_PYTHON_VERSION="2.7"
-MIN_PYVER=$(echo "$MIN_PYTHON_VERSION" | sed 's/\.//')
+MIN_PYTHON_2_VERSION="2.7"
+MIN_PYVER2=$(echo "$MIN_PYTHON_2_VERSION" | sed 's/\.//')
+MIN_PYTHON_3_VERSION="3.5"
+MIN_PYVER3=$(echo "$MIN_PYTHON_3_VERSION" | sed 's/\.//')
 # Sets LE_PYTHON to Python version string and PYVER to the first two
-# digits of the python version
+# digits of the python version.
+# MIN_PYVER and MIN_PYTHON_VERSION are also sets by this function, and their
+# values depend on if we try to use Python 3 or Python 2.
 DeterminePythonVersion() {
   # Arguments: "NOCRASH" if we shouldn't crash if we don't find a good python
   #
   # If no Python is found, PYVER is set to 0.
   if [ "$USE_PYTHON_3" = 1 ]; then
+    MIN_PYVER=$MIN_PYVER3
+    MIN_PYTHON_VERSION=$MIN_PYTHON_3_VERSION
     for LE_PYTHON in "$LE_PYTHON" python3; do
       # Break (while keeping the LE_PYTHON value) if found.
       $EXISTS "$LE_PYTHON" > /dev/null && break
     done
   else
+    MIN_PYVER=$MIN_PYVER2
+    MIN_PYTHON_VERSION=$MIN_PYTHON_2_VERSION
     for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
       # Break (while keeping the LE_PYTHON value) if found.
       $EXISTS "$LE_PYTHON" > /dev/null && break
@@ -285,7 +293,7 @@ DeterminePythonVersion() {
     fi
   fi
 
-  PYVER=`"$LE_PYTHON" -V 2>&1 | cut -d" " -f 2 | cut -d. -f1,2 | sed 's/\.//'`
+  PYVER=$("$LE_PYTHON" -V 2>&1 | cut -d" " -f 2 | cut -d. -f1,2 | sed 's/\.//')
   if [ "$PYVER" -lt "$MIN_PYVER" ]; then
     if [ "$1" != "NOCRASH" ]; then
       error "You have an ancient version of Python entombed in your operating system..."
@@ -368,7 +376,6 @@ BootstrapDebCommon() {
 
 # Sets TOOL to the name of the package manager
 # Sets appropriate values for YES_FLAG and QUIET_FLAG based on $ASSUME_YES and $QUIET_FLAG.
-# Enables EPEL if applicable and possible.
 InitializeRPMCommonBase() {
   if type dnf 2>/dev/null
   then
@@ -388,26 +395,6 @@ InitializeRPMCommonBase() {
   if [ "$QUIET" = 1 ]; then
     QUIET_FLAG='--quiet'
   fi
-
-  if ! $TOOL list *virtualenv >/dev/null 2>&1; then
-    echo "To use Certbot, packages from the EPEL repository need to be installed."
-    if ! $TOOL list epel-release >/dev/null 2>&1; then
-      error "Enable the EPEL repository and try running Certbot again."
-      exit 1
-    fi
-    if [ "$ASSUME_YES" = 1 ]; then
-      /bin/echo -n "Enabling the EPEL repository in 3 seconds..."
-      sleep 1s
-      /bin/echo -ne "\e[0K\rEnabling the EPEL repository in 2 seconds..."
-      sleep 1s
-      /bin/echo -e "\e[0K\rEnabling the EPEL repository in 1 second..."
-      sleep 1s
-    fi
-    if ! $TOOL install $YES_FLAG $QUIET_FLAG epel-release; then
-      error "Could not enable EPEL. Aborting bootstrap!"
-      exit 1
-    fi
-  fi
 }
 
 BootstrapRpmCommonBase() {
@@ -488,13 +475,69 @@ BootstrapRpmCommon() {
   BootstrapRpmCommonBase "$python_pkgs"
 }
 
+# If new packages are installed by BootstrapRpmPython3 below, this version
+# number must be increased.
+BOOTSTRAP_RPM_PYTHON3_LEGACY_VERSION=1
+
+EnablePython36SCL() {
+  set +e
+  # Do nothing if Python 3.6 is already available
+  "$EXISTS" python3.6 > /dev/null 2> /dev/null && set -e && return
+  # Do nothing if SCL Python 3.6 is not installed
+  ! scl --list 2>/dev/null | grep -q rh-python36 && set -e && return
+  # Enable SCL rh-python36
+  . scl_source enable rh-python36 && set -e
+}
+
+BootstrapRpmPython3Legacy() {
+  # Tested with:
+  #   - CentOS 6
+
+  InitializeRPMCommonBase
+
+  if ! "${TOOL}" list rh-python36 >/dev/null 2>&1; then
+    echo "To use Certbot on this operating system, packages from the SCL repository need to be installed."
+    if ! "${TOOL}" list centos-release-scl >/dev/null 2>&1; then
+      error "Enable the SCL repository and try running Certbot again."
+      exit 1
+    fi
+    if [ "${ASSUME_YES}" = 1 ]; then
+      /bin/echo -n "Enabling the SCL repository in 3 seconds... (Press Ctrl-C to cancel)"
+      sleep 1s
+      /bin/echo -ne "\e[0K\rEnabling the SCL repository in 2 seconds... (Press Ctrl-C to cancel)"
+      sleep 1s
+      /bin/echo -e "\e[0K\rEnabling the SCL repository in 1 second... (Press Ctrl-C to cancel)"
+      sleep 1s
+    fi
+    if ! "${TOOL}" install "${YES_FLAG}" "${QUIET_FLAG}" centos-release-scl; then
+      error "Could not enable SCL. Aborting bootstrap!"
+      exit 1
+    fi
+  fi
+
+  # CentOS 6 must use rh-python36 from SCL
+  if "${TOOL}" list rh-python36 >/dev/null 2>&1; then
+    python_pkgs="rh-python36-python
+      rh-python36-python-virtualenv
+      rh-python36-python-devel
+    "
+  else
+    error "No supported Python package available to install. Aborting bootstrap!"
+    exit 1
+  fi
+
+  BootstrapRpmCommonBase "${python_pkgs}"
+
+  # Enable SCL rh-python36 after bootstrapping.
+  EnablePython36SCL
+}
+
 # If new packages are installed by BootstrapRpmPython3 below, this version
 # number must be increased.
 BOOTSTRAP_RPM_PYTHON3_VERSION=1
 
 BootstrapRpmPython3() {
   # Tested with:
-  #   - CentOS 6
   #   - Fedora 29
 
   InitializeRPMCommonBase
@@ -505,12 +548,6 @@ BootstrapRpmPython3() {
       python3-virtualenv
       python3-devel
     "
-  # EPEL uses python34
-  elif $TOOL list python34 >/dev/null 2>&1; then
-    python_pkgs="python34
-      python34-devel
-      python34-tools
-    "
   else
     error "No supported Python package available to install. Aborting bootstrap!"
     exit 1
@@ -769,29 +806,43 @@ elif [ -f /etc/redhat-release ]; then
      RPM_DIST_VERSION=0
   fi
 
-  # Starting to Fedora 29, python2 is on a deprecation path. Let's move to python3 then.
-  # RHEL 8 also uses python3 by default.
-  if [ "$RPM_DIST_NAME" = "fedora" -a "$RPM_DIST_VERSION" -ge 29 -o "$PYVER" -eq 26 ]; then
-    RPM_USE_PYTHON_3=1
-  elif [ "$RPM_DIST_NAME" = "rhel" -a "$RPM_DIST_VERSION" -ge 8 ]; then
-    RPM_USE_PYTHON_3=1
-  else
-    RPM_USE_PYTHON_3=0
-  fi
-
-  if [ "$RPM_USE_PYTHON_3" = 1 ]; then
+  # Handle legacy RPM distributions
+  if [ "$PYVER" -eq 26 ]; then
     Bootstrap() {
-      BootstrapMessage "RedHat-based OSes that will use Python3"
-      BootstrapRpmPython3
+      BootstrapMessage "Legacy Red Hat-based OSes that will use Python3"
+      BootstrapRpmPython3Legacy
     }
     USE_PYTHON_3=1
-    BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+    BOOTSTRAP_VERSION="BootstrapRpmPython3Legacy $BOOTSTRAP_RPM_PYTHON3_LEGACY_VERSION"
+
+    # Try now to enable SCL rh-python36 for systems already bootstrapped
+    # NB: EnablePython36SCL has been defined along with BootstrapRpmPython3Legacy in certbot-auto
+    EnablePython36SCL
   else
-    Bootstrap() {
-      BootstrapMessage "RedHat-based OSes"
-      BootstrapRpmCommon
-    }
-    BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+    # Starting to Fedora 29, python2 is on a deprecation path. Let's move to python3 then.
+    # RHEL 8 also uses python3 by default.
+    if [ "$RPM_DIST_NAME" = "fedora" -a "$RPM_DIST_VERSION" -ge 29 ]; then
+      RPM_USE_PYTHON_3=1
+    elif [ "$RPM_DIST_NAME" = "rhel" -a "$RPM_DIST_VERSION" -ge 8 ]; then
+      RPM_USE_PYTHON_3=1
+    else
+      RPM_USE_PYTHON_3=0
+    fi
+
+    if [ "$RPM_USE_PYTHON_3" = 1 ]; then
+      Bootstrap() {
+        BootstrapMessage "Red Hat-based OSes that will use Python3"
+        BootstrapRpmPython3
+      }
+      USE_PYTHON_3=1
+      BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+    else
+      Bootstrap() {
+        BootstrapMessage "Red Hat-based OSes"
+        BootstrapRpmCommon
+      }
+      BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+    fi
   fi
 
   LE_PYTHON="$prev_le_python"

letsencrypt-auto-source/letsencrypt-auto.template

@@ -256,20 +256,28 @@ DeprecationBootstrap() {
   fi
 }
 
-MIN_PYTHON_VERSION="2.7"
-MIN_PYVER=$(echo "$MIN_PYTHON_VERSION" | sed 's/\.//')
+MIN_PYTHON_2_VERSION="2.7"
+MIN_PYVER2=$(echo "$MIN_PYTHON_2_VERSION" | sed 's/\.//')
+MIN_PYTHON_3_VERSION="3.5"
+MIN_PYVER3=$(echo "$MIN_PYTHON_3_VERSION" | sed 's/\.//')
 # Sets LE_PYTHON to Python version string and PYVER to the first two
-# digits of the python version
+# digits of the python version.
+# MIN_PYVER and MIN_PYTHON_VERSION are also sets by this function, and their
+# values depend on if we try to use Python 3 or Python 2.
 DeterminePythonVersion() {
   # Arguments: "NOCRASH" if we shouldn't crash if we don't find a good python
   #
   # If no Python is found, PYVER is set to 0.
   if [ "$USE_PYTHON_3" = 1 ]; then
+    MIN_PYVER=$MIN_PYVER3
+    MIN_PYTHON_VERSION=$MIN_PYTHON_3_VERSION
     for LE_PYTHON in "$LE_PYTHON" python3; do
       # Break (while keeping the LE_PYTHON value) if found.
       $EXISTS "$LE_PYTHON" > /dev/null && break
     done
   else
+    MIN_PYVER=$MIN_PYVER2
+    MIN_PYTHON_VERSION=$MIN_PYTHON_2_VERSION
     for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
       # Break (while keeping the LE_PYTHON value) if found.
       $EXISTS "$LE_PYTHON" > /dev/null && break
@@ -285,7 +293,7 @@ DeterminePythonVersion() {
     fi
   fi
 
-  PYVER=`"$LE_PYTHON" -V 2>&1 | cut -d" " -f 2 | cut -d. -f1,2 | sed 's/\.//'`
+  PYVER=$("$LE_PYTHON" -V 2>&1 | cut -d" " -f 2 | cut -d. -f1,2 | sed 's/\.//')
   if [ "$PYVER" -lt "$MIN_PYVER" ]; then
     if [ "$1" != "NOCRASH" ]; then
       error "You have an ancient version of Python entombed in your operating system..."
@@ -298,6 +306,7 @@ DeterminePythonVersion() {
 {{ bootstrappers/deb_common.sh }}
 {{ bootstrappers/rpm_common_base.sh }}
 {{ bootstrappers/rpm_common.sh }}
+{{ bootstrappers/rpm_python3_legacy.sh }}
 {{ bootstrappers/rpm_python3.sh }}
 {{ bootstrappers/suse_common.sh }}
 {{ bootstrappers/arch_common.sh }}
@@ -344,29 +353,43 @@ elif [ -f /etc/redhat-release ]; then
      RPM_DIST_VERSION=0
   fi
 
-  # Starting to Fedora 29, python2 is on a deprecation path. Let's move to python3 then.
-  # RHEL 8 also uses python3 by default.
-  if [ "$RPM_DIST_NAME" = "fedora" -a "$RPM_DIST_VERSION" -ge 29 -o "$PYVER" -eq 26 ]; then
-    RPM_USE_PYTHON_3=1
-  elif [ "$RPM_DIST_NAME" = "rhel" -a "$RPM_DIST_VERSION" -ge 8 ]; then
-    RPM_USE_PYTHON_3=1
-  else
-    RPM_USE_PYTHON_3=0
-  fi
-
-  if [ "$RPM_USE_PYTHON_3" = 1 ]; then
+  # Handle legacy RPM distributions
+  if [ "$PYVER" -eq 26 ]; then
     Bootstrap() {
-      BootstrapMessage "RedHat-based OSes that will use Python3"
-      BootstrapRpmPython3
+      BootstrapMessage "Legacy Red Hat-based OSes that will use Python3"
+      BootstrapRpmPython3Legacy
     }
     USE_PYTHON_3=1
-    BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+    BOOTSTRAP_VERSION="BootstrapRpmPython3Legacy $BOOTSTRAP_RPM_PYTHON3_LEGACY_VERSION"
+
+    # Try now to enable SCL rh-python36 for systems already bootstrapped
+    # NB: EnablePython36SCL has been defined along with BootstrapRpmPython3Legacy in certbot-auto
+    EnablePython36SCL
   else
-    Bootstrap() {
-      BootstrapMessage "RedHat-based OSes"
-      BootstrapRpmCommon
-    }
-    BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+    # Starting to Fedora 29, python2 is on a deprecation path. Let's move to python3 then.
+    # RHEL 8 also uses python3 by default.
+    if [ "$RPM_DIST_NAME" = "fedora" -a "$RPM_DIST_VERSION" -ge 29 ]; then
+      RPM_USE_PYTHON_3=1
+    elif [ "$RPM_DIST_NAME" = "rhel" -a "$RPM_DIST_VERSION" -ge 8 ]; then
+      RPM_USE_PYTHON_3=1
+    else
+      RPM_USE_PYTHON_3=0
+    fi
+
+    if [ "$RPM_USE_PYTHON_3" = 1 ]; then
+      Bootstrap() {
+        BootstrapMessage "Red Hat-based OSes that will use Python3"
+        BootstrapRpmPython3
+      }
+      USE_PYTHON_3=1
+      BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+    else
+      Bootstrap() {
+        BootstrapMessage "Red Hat-based OSes"
+        BootstrapRpmCommon
+      }
+      BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+    fi
   fi
 
   LE_PYTHON="$prev_le_python"

letsencrypt-auto-source/pieces/bootstrappers/rpm_common_base.sh

@@ -3,7 +3,6 @@
 
 # Sets TOOL to the name of the package manager
 # Sets appropriate values for YES_FLAG and QUIET_FLAG based on $ASSUME_YES and $QUIET_FLAG.
-# Enables EPEL if applicable and possible.
 InitializeRPMCommonBase() {
   if type dnf 2>/dev/null
   then
@@ -23,26 +22,6 @@ InitializeRPMCommonBase() {
   if [ "$QUIET" = 1 ]; then
     QUIET_FLAG='--quiet'
   fi
-
-  if ! $TOOL list *virtualenv >/dev/null 2>&1; then
-    echo "To use Certbot, packages from the EPEL repository need to be installed."
-    if ! $TOOL list epel-release >/dev/null 2>&1; then
-      error "Enable the EPEL repository and try running Certbot again."
-      exit 1
-    fi
-    if [ "$ASSUME_YES" = 1 ]; then
-      /bin/echo -n "Enabling the EPEL repository in 3 seconds..."
-      sleep 1s
-      /bin/echo -ne "\e[0K\rEnabling the EPEL repository in 2 seconds..."
-      sleep 1s
-      /bin/echo -e "\e[0K\rEnabling the EPEL repository in 1 second..."
-      sleep 1s
-    fi
-    if ! $TOOL install $YES_FLAG $QUIET_FLAG epel-release; then
-      error "Could not enable EPEL. Aborting bootstrap!"
-      exit 1
-    fi
-  fi
 }
 
 BootstrapRpmCommonBase() {

letsencrypt-auto-source/pieces/bootstrappers/rpm_python3.sh

@@ -4,7 +4,6 @@ BOOTSTRAP_RPM_PYTHON3_VERSION=1
 
 BootstrapRpmPython3() {
   # Tested with:
-  #   - CentOS 6
   #   - Fedora 29
 
   InitializeRPMCommonBase
@@ -15,12 +14,6 @@ BootstrapRpmPython3() {
       python3-virtualenv
       python3-devel
     "
-  # EPEL uses python34
-  elif $TOOL list python34 >/dev/null 2>&1; then
-    python_pkgs="python34
-      python34-devel
-      python34-tools
-    "
   else
     error "No supported Python package available to install. Aborting bootstrap!"
     exit 1

letsencrypt-auto-source/pieces/bootstrappers/rpm_python3_legacy.sh

@@ -0,0 +1,56 @@
+# If new packages are installed by BootstrapRpmPython3 below, this version
+# number must be increased.
+BOOTSTRAP_RPM_PYTHON3_LEGACY_VERSION=1
+
+EnablePython36SCL() {
+  set +e
+  # Do nothing if Python 3.6 is already available
+  "$EXISTS" python3.6 > /dev/null 2> /dev/null && set -e && return
+  # Do nothing if SCL Python 3.6 is not installed
+  ! scl --list 2>/dev/null | grep -q rh-python36 && set -e && return
+  # Enable SCL rh-python36
+  . scl_source enable rh-python36 && set -e
+}
+
+BootstrapRpmPython3Legacy() {
+  # Tested with:
+  #   - CentOS 6
+
+  InitializeRPMCommonBase
+
+  if ! "${TOOL}" list rh-python36 >/dev/null 2>&1; then
+    echo "To use Certbot on this operating system, packages from the SCL repository need to be installed."
+    if ! "${TOOL}" list centos-release-scl >/dev/null 2>&1; then
+      error "Enable the SCL repository and try running Certbot again."
+      exit 1
+    fi
+    if [ "${ASSUME_YES}" = 1 ]; then
+      /bin/echo -n "Enabling the SCL repository in 3 seconds... (Press Ctrl-C to cancel)"
+      sleep 1s
+      /bin/echo -ne "\e[0K\rEnabling the SCL repository in 2 seconds... (Press Ctrl-C to cancel)"
+      sleep 1s
+      /bin/echo -e "\e[0K\rEnabling the SCL repository in 1 second... (Press Ctrl-C to cancel)"
+      sleep 1s
+    fi
+    if ! "${TOOL}" install "${YES_FLAG}" "${QUIET_FLAG}" centos-release-scl; then
+      error "Could not enable SCL. Aborting bootstrap!"
+      exit 1
+    fi
+  fi
+
+  # CentOS 6 must use rh-python36 from SCL
+  if "${TOOL}" list rh-python36 >/dev/null 2>&1; then
+    python_pkgs="rh-python36-python
+      rh-python36-python-virtualenv
+      rh-python36-python-devel
+    "
+  else
+    error "No supported Python package available to install. Aborting bootstrap!"
+    exit 1
+  fi
+
+  BootstrapRpmCommonBase "${python_pkgs}"
+
+  # Enable SCL rh-python36 after bootstrapping.
+  EnablePython36SCL
+}

letsencrypt-auto-source/tests/centos6_tests.sh

@@ -1,81 +1,145 @@
 #!/bin/bash
 # Start by making sure your system is up-to-date:
-yum update -y > /dev/null
-yum install -y centos-release-scl > /dev/null
-yum install -y python27 > /dev/null 2> /dev/null
+yum update -y >/dev/null
+yum install -y centos-release-scl >/dev/null
+yum install -y python27 >/dev/null 2>/dev/null
 
+LE_AUTO_PY_34="certbot/letsencrypt-auto-source/letsencrypt-auto_py_34"
 LE_AUTO="certbot/letsencrypt-auto-source/letsencrypt-auto"
 
+# Last version of certbot-auto that was bootstraping Python 3.4 for CentOS 6 users
+INITIAL_CERTBOT_VERSION_PY34="certbot 0.38.0"
+
 # we're going to modify env variables, so do this in a subshell
 (
-source /opt/rh/python27/enable
+  . scl_source enable python27
 
-# ensure python 3 isn't installed
-python3 --version 2> /dev/null
-RESULT=$?
-if [ $RESULT -eq 0 ]; then
-  error "Python3 is already installed."
-  exit 1
-fi
+  # ensure python 3 isn't installed
+  python3 --version >/dev/null 2>/dev/null
+  RESULT=$?
+  if [ $RESULT -eq 0 ]; then
+    echo "ERROR: Python3 is already installed."
+    exit 1
+  fi
 
-# ensure python2.7 is available
-python2.7 --version 2> /dev/null
-RESULT=$?
-if [ $RESULT -ne 0 ]; then
-  error "Python3 is not available."
-  exit 1
-fi
+  # ensure python2.7 is available
+  python2.7 --version >/dev/null 2>/dev/null
+  RESULT=$?
+  if [ $RESULT -ne 0 ]; then
+    echo "ERROR: Python2.7 is not available."
+    exit 1
+  fi
 
-# bootstrap, but don't install python 3.
-"$LE_AUTO" --no-self-upgrade -n > /dev/null 2> /dev/null
+  # bootstrap, but don't install python 3.
+  "$LE_AUTO" --no-self-upgrade -n >/dev/null 2>/dev/null
 
-# ensure python 3 isn't installed
-python3 --version 2> /dev/null
-RESULT=$?
-if [ $RESULT -eq 0 ]; then
-  error "letsencrypt-auto installed Python3 even though Python2.7 is present."
-  exit 1
-fi
+  # ensure python 3 isn't installed
+  python3 --version >/dev/null 2>/dev/null
+  RESULT=$?
+  if [ $RESULT -eq 0 ]; then
+    echo "ERROR: letsencrypt-auto installed Python3 even though Python2.7 is present."
+    exit 1
+  fi
 
-echo ""
-echo "PASSED: Did not upgrade to Python3 when Python2.7 is present."
+  echo "PASSED: Did not upgrade to Python3 when Python2.7 is present."
 )
 
 # ensure python2.7 isn't available
-python2.7 --version 2> /dev/null
+python2.7 --version >/dev/null 2>/dev/null
 RESULT=$?
 if [ $RESULT -eq 0 ]; then
-  error "Python2.7 is still available."
+  error "ERROR: Python2.7 is still available."
   exit 1
 fi
 
 # Skip self upgrade due to Python 3 not being available.
 if ! "$LE_AUTO" 2>&1 | grep -q "WARNING: couldn't find Python"; then
-  echo "Python upgrade failure warning not printed!"
+  echo "ERROR: Python upgrade failure warning not printed!"
   exit 1
 fi
 
-# bootstrap, this time installing python3
-"$LE_AUTO" --no-self-upgrade -n > /dev/null 2> /dev/null
+# bootstrap from the old letsencrypt-auto, this time installing python3.4
+"$LE_AUTO_PY_34" --no-self-upgrade -n >/dev/null 2>/dev/null
 
-# ensure python 3 is installed
-python3 --version > /dev/null
+# ensure python 3.4 is installed
+python3.4 --version >/dev/null 2>/dev/null
 RESULT=$?
 if [ $RESULT -ne 0 ]; then
-  error "letsencrypt-auto failed to install Python3 when only Python2.6 is present."
+  echo "ERROR: letsencrypt-auto failed to install Python3.4 using letsencrypt-auto < 0.37.0 when only Python2.6 is present."
   exit 1
 fi
 
-echo "PASSED: Successfully upgraded to Python3 when only Python2.6 is present."
-echo ""
+echo "PASSED: Successfully upgraded to Python3.4 using letsencrypt-auto < 0.37.0 when only Python2.6 is present."
 
-export VENV_PATH=$(mktemp -d)
-"$LE_AUTO" -n --no-bootstrap --no-self-upgrade --version >/dev/null 2>&1
-if [ "$($VENV_PATH/bin/python -V 2>&1 | cut -d" " -f2 | cut -d. -f1)" != 3 ]; then
-  echo "Python 3 wasn't used with --no-bootstrap!"
+# As "certbot-auto" (so without implicit --non-interactive flag set), check that the script
+# refuses to install SCL Python 3.6 when run in a non interactive shell (simulated here
+# using | tee /dev/null) if --non-interactive flag is not provided.
+cp "$LE_AUTO" /tmp/certbot-auto
+# NB: Readline has an issue on all Python versions for CentOS 6, making `certbot --version`
+# output an unprintable ASCII character on a new line at the end.
+# So we take the second last line of the output.
+version=$(/tmp/certbot-auto --version 2>/dev/null | tee /dev/null | tail -2 | head -1)
+
+if ! echo "$version" | grep -q certbot; then
+  echo "Invalid certbot version: ${version}"
   exit 1
 fi
-unset VENV_PATH
+
+if [ "$version" != "$INITIAL_CERTBOT_VERSION_PY34" ]; then
+  echo "ERROR: certbot-auto upgraded certbot in a non-interactive shell with --non-interactive flag not set."
+  exit 1
+fi
+
+echo "PASSED: certbot-auto did not upgrade certbot in a non-interactive shell with --non-interactive flag not set."
+
+if [ -f /opt/rh/rh-python36/enable ]; then
+  echo "ERROR: certbot-auto installed Python3.6 in a non-interactive shell with --non-interactive flag not set."
+  exit 1
+fi
+
+echo "PASSED: certbot-auto did not install Python3.6 in a non-interactive shell with --non-interactive flag not set."
+
+# now bootstrap from current letsencrypt-auto, that will install python3.6 from SCL
+"$LE_AUTO" --no-self-upgrade -n >/dev/null 2>/dev/null
+
+# Following test is exectued in a subshell, to not leak any environment variable
+(
+  # enable SCL rh-python36
+  . scl_source enable rh-python36
+
+  # ensure python 3.6 is installed
+  python3.6 --version >/dev/null 2>/dev/null
+  RESULT=$?
+  if [ $RESULT -ne 0 ]; then
+    echo "ERROR: letsencrypt-auto failed to install Python3.6 using current letsencrypt-auto when only Python2.6/Python3.4 are present."
+    exit 1
+  fi
+
+  echo "PASSED: Successfully upgraded to Python3.6 using current letsencrypt-auto when only Python2.6/Python3.4 are present."
+)
+
+# Following test is exectued in a subshell, to not leak any environment variable
+(
+  export VENV_PATH=$(mktemp -d)
+  "$LE_AUTO" -n --no-bootstrap --no-self-upgrade --version >/dev/null 2>&1
+  if [ "$($VENV_PATH/bin/python -V 2>&1 | cut -d" " -f2 | cut -d. -f1-2)" != "3.6" ]; then
+    echo "ERROR: Python 3.6 wasn't used with --no-bootstrap!"
+    exit 1
+  fi
+)
+
+# Following test is exectued in a subshell, to not leak any environment variable
+(
+  # enable SCL rh-python36
+  . scl_source enable rh-python36
+
+  # ensure everything works fine with certbot-auto bootstrap when python 3.6 is already enabled
+  export VENV_PATH=$(mktemp -d)
+  if ! "$LE_AUTO" --no-self-upgrade -n --version >/dev/null 2>/dev/null; then
+    echo "ERROR: Certbot-auto broke when Python 3.6 SCL is already enabled."
+    exit 1
+  fi
+)
 
 # test using python3
 pytest -v -s certbot/letsencrypt-auto-source/tests

tests/letstest/scripts/test_leauto_upgrades.sh

@@ -117,6 +117,8 @@ if ! diff letsencrypt-auto letsencrypt-auto-source/letsencrypt-auto ; then
 fi
 
 if [ "$RUN_RHEL6_TESTS" = 1 ]; then
+    # Add the SCL python release to PATH in order to resolve python3 command
+    PATH="/opt/rh/rh-python36/root/usr/bin:$PATH"
     if ! command -v python3; then
         echo "Python3 wasn't properly installed"
         exit 1

tests/letstest/scripts/test_sdists.sh

@@ -1,8 +1,21 @@
 #!/bin/sh -xe
 
 cd letsencrypt
+
+# If we're on a RHEL 6 based system, we can be confident Python is already
+# installed because the package manager is written in Python.
+if command -v python && [ $(python -V 2>&1 | cut -d" " -f 2 | cut -d. -f1,2 | sed 's/\.//') -eq 26 ]; then
+    # RHEL/CentOS 6 will need a special treatment, so we need to detect that environment
+    RUN_RHEL6_TESTS=1
+fi
+
 letsencrypt-auto-source/letsencrypt-auto --install-only -n --debug
 
+if [ "$RUN_RHEL6_TESTS" = 1 ]; then
+  # Enable the SCL Python 3.6 installed by letsencrypt-auto bootstrap
+  PATH="/opt/rh/rh-python36/root/usr/bin:$PATH"
+fi
+
 PLUGINS="certbot-apache certbot-nginx"
 PYTHON_MAJOR_VERSION=$(/opt/eff.org/certbot/venv/bin/python --version 2>&1 | cut -d" " -f 2 | cut -d. -f1)
 TEMP_DIR=$(mktemp -d)