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Revision df716c98d203ab64cdf05f9c17fdae565b7daa1c authored by Eelco Dolstra on 23 June 2012, 04:28:35 UTC, committed by Eelco Dolstra on 23 June 2012, 04:28:35 UTC
In chroot builds, use a private network namespace
On Linux it's possible to run a process in its own network namespace,
meaning that it gets its own set of network interfaces, disjunct from
the rest of the system.  We use this to completely remove network
access to chroot builds, except that they get a private loopback
interface.  This means that:

- Builders cannot connect to the outside network or to other processes
  on the same machine, except processes within the same build.

- Vice versa, other processes cannot connect to processes in a chroot
  build, and open ports/connections do not show up in "netstat".

- If two concurrent builders try to listen on the same port (e.g. as
  part of a test), they no longer conflict with each other.

This was inspired by the "PrivateNetwork" flag in systemd.
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nix-profile.sh.in 
export NIX_USER_PROFILE_DIR=@localstatedir@/nix/profiles/per-user/$USER
export NIX_PROFILES="@localstatedir@/nix/profiles/default $HOME/.nix-profile"

# Set up the per-user profile.
mkdir -m 0755 -p $NIX_USER_PROFILE_DIR
if test "$(stat --printf '%u' $NIX_USER_PROFILE_DIR)" != "$(id -u)"; then
    echo "WARNING: bad ownership on $NIX_USER_PROFILE_DIR" >&2
fi

if ! test -L $HOME/.nix-profile; then
    echo "creating $HOME/.nix-profile" >&2
    if test "$USER" != root; then
        @coreutils@/ln -s $NIX_USER_PROFILE_DIR/profile $HOME/.nix-profile
    else
        # Root installs in the system-wide profile by default.
        @coreutils@/ln -s /nix/var/nix/profiles/default $HOME/.nix-profile
    fi
fi

export PATH="$HOME/.nix-profile/bin:$PATH"

# Subscribe the root user to the NixOS channel by default.
if [ "$USER" = root -a ! -e $HOME/.nix-channels ]; then
    echo "http://nixos.org/releases/nixos/channels/nixos-unstable nixos" > $HOME/.nix-channels
fi

# Create the per-user garbage collector roots directory.
NIX_USER_GCROOTS_DIR=@localstatedir@/nix/gcroots/per-user/$USER
mkdir -m 0755 -p $NIX_USER_GCROOTS_DIR
if test "$(stat --printf '%u' $NIX_USER_GCROOTS_DIR)" != "$(id -u)"; then
    echo "WARNING: bad ownership on $NIX_USER_GCROOTS_DIR" >&2
fi

# Set up a default Nix expression from which to install stuff.
if [ ! -e $HOME/.nix-defexpr -o -L $HOME/.nix-defexpr ]; then
    echo "creating $HOME/.nix-defexpr" >&2
    rm -f $HOME/.nix-defexpr
    mkdir $HOME/.nix-defexpr
    if [ "$USER" != root ]; then
        @coreutils@/ln -s @localstatedir@/nix/profiles/per-user/root/channels $HOME/.nix-defexpr/channels_root
    fi
fi

# Set up secure multi-user builds: non-root users build through the
# Nix daemon.
if test "$USER" != root; then
    export NIX_REMOTE=daemon
else
    unset NIX_REMOTE
fi