view contrib/dockerlib.sh @ 27142:060f83d219b9

extensions: refuse to load extensions if minimum hg version not met

As the author of several 3rd party extensions, I frequently see bug
reports from users attempting to run my extension with an old version
of Mercurial that I no longer support in my extension. Oftentimes, the
extension will import just fine. But as soon as we run extsetup(),
reposetup(), or get into the guts of a wrapped function, we encounter
an exception and abort. Today, Mercurial will print a message about
extensions that don't have a "testedwith" declaring explicit
compatibility with the current version.

The existing mechanism is a good start. But it isn't as robust as I
would like. Specifically, Mercurial assumes compatibility by default.
This means extension authors must perform compatibility checking in
their extsetup() or we wait and see if we encounter an abort at
runtime. And, compatibility checking can involve a lot of code and
lots of error checking. It's a lot of effort for extension authors.

Oftentimes, extension authors know which versions of Mercurial there
extension works on and more importantly where it is broken.

This patch introduces a magic "minimumhgversion" attribute in
extensions. When found, the extension loading mechanism will compare
the declared version against the current Mercurial version. If the
extension explicitly states we require a newer Mercurial version, a
warning is printed and the extension isn't loaded beyond importing
the Python module. This causes a graceful failure while alerting
the user of the compatibility issue.

I would be receptive to the idea of making the failure more fatal.
However, care would need to be taken to not criple every hg command.
e.g. the user may use `hg config` to fix the hgrc and if we aborted
trying to run that, the user would effectively be locked out of `hg`!

A potential future improvement to this functionality would be to catch
ImportError for the extension/module and parse the source code for
"minimumhgversion = 'XXX'" and do similar checking. This way we could
give more information about why the extension failed to load.

#!/bin/sh -eu

# This function exists to set up the DOCKER variable and verify that
# it's the binary we expect. It also verifies that the docker service
# is running on the system and we can talk to it.
function checkdocker() {
  if which docker.io >> /dev/null 2>&1 ; then
    DOCKER=docker.io
  elif which docker >> /dev/null 2>&1 ; then
    DOCKER=docker
  else
    echo "Error: docker must be installed"
    exit 1
  fi

  $DOCKER -h 2> /dev/null | grep -q Jansens && { echo "Error: $DOCKER is the Docking System Tray - install docker.io instead"; exit 1; }
  $DOCKER version | grep -q "^Client version:" || { echo "Error: unexpected output from \"$DOCKER version\""; exit 1; }
  $DOCKER version | grep -q "^Server version:" || { echo "Error: could not get docker server version - check it is running and your permissions"; exit 1; }
}

# Construct a container and leave its name in $CONTAINER for future use.
function initcontainer() {
  [ "$1" ] || { echo "Error: platform name must be specified"; exit 1; }

  DFILE="$ROOTDIR/contrib/docker/$1"
  [ -f "$DFILE" ] || { echo "Error: docker file $DFILE not found"; exit 1; }

  CONTAINER="hg-dockerrpm-$1"
  DBUILDUSER=build
  (
    cat $DFILE
    if [ $(uname) = "Darwin" ] ; then
        # The builder is using boot2docker on OS X, so we're going to
        # *guess* the uid of the user inside the VM that is actually
        # running docker. This is *very likely* to fail at some point.
        echo RUN useradd $DBUILDUSER -u 1000
    else
        echo RUN groupadd $DBUILDUSER -g `id -g` --non-unique
        echo RUN useradd $DBUILDUSER -u `id -u` -g $DBUILDUSER --non-unique
    fi
  ) | $DOCKER build --tag $CONTAINER -
}