Add a script to switch mySociety deployments to using shared files

This is required by our switch to timestamped-based deploys.  There
are certain files and directories (e.g. cache, the Xapian databases,
generated graphs) that should be shared between deployments,
rather than recreating them when creating the next deployment in
a new directory.

This script should be run as a one-off before switching an
instance to using timestamped deploys, to ensure that the existing
data is stored in the shared subdirectory of the vhost directory,
so that any future deployment can simply create symlinks into the
shared directory.

1 files changed, 71 insertions, 0 deletions

diff --git a/script/mysociety-switch-to-shared b/script/mysociety-switch-to-shared
new file mode 100755
index 000000000..f82e77706
--- /dev/null
+++ b/script/mysociety-switch-to-shared
@@ -0,0 +1,71 @@
+#!/bin/bash
+
+# This script is a one-off script to move the shared files on a
+# mySociety instance of Alaveteli out of the repository and into the
+# vhost's shared directory.  This is specific to mySociety's servers -
+# the list of files and directories which are moved would be unlikely
+# to be correct in another environment.
+#
+# This should be run *before* the first time the site is deployed with
+# the timestamped_deploy option.
+
+set -e
+
+# (Using `pwd -P` here instead of readlink -f so that it works on Mac
+# OS as well, just in case that's required for testing on a laptop.)
+RAILS_ROOT="$(cd "$(dirname "$BASH_SOURCE")/.." && pwd -P)"
+VHOST_DIR="$(cd "$RAILS_ROOT/.." && pwd -P)"
+SHARED_DIR="$VHOST_DIR/shared"
+
+cd "$RAILS_ROOT"
+
+mkdir -p "$SHARED_DIR"
+
+for F in \
+    cache \
+    public/foi-live-creation.png \
+    public/foi-user-use.png \
+    config/aliases \
+    lib/acts_as_xapian/xapiandbs \
+    vendor/bundle
+do
+    SYMLINK_LOCATION="$F"
+    INTENDED_DESTINATION="$SHARED_DIR/$F"
+    echo "Switching to $SYMLINK_LOCATION -> $INTENDED_DESTINATION"
+    # If anything exists where the symlink should be:
+    if [ -e "$SYMLINK_LOCATION" ]
+    then
+        # First, if it's a symlink, check whether it's correct:
+        if [ -L "$SYMLINK_LOCATION" ]
+        then
+            SYMLINK_DESTINATION="$(readlink "$SYMLINK_LOCATION")"
+            if [ "$SYMLINK_DESTINATION" = "$INTENDED_DESTINATION" ]
+            then
+                echo "  already correct!"
+            else
+                echo "  ERROR: already symlinked to $INTENDED_DESTINATION"
+            fi
+        else
+            # So the file or directory is there, and it's not a
+            # symlink.  Check first that that destination doesn't
+            # exist (in which case a move would either fail or
+            # overwrite what's there):
+            if [ -e "$INTENDED_DESTINATION" ]
+            then
+                echo "   ERROR: would move, but something already existed at $INTENDED_DESTINATION"
+            else
+                # Otherwise (bar race condition) everything's fine,
+                # and we should be able to move the file or directory
+                # and create a symlink to its new location:
+                mkdir -p "$(dirname "$INTENDED_DESTINATION")"
+                mv "$SYMLINK_LOCATION" "$INTENDED_DESTINATION"
+                ln -snf "$INTENDED_DESTINATION" "$SYMLINK_LOCATION"
+            fi
+        fi
+    else
+        # This may not be anything to worry about, e.g. if the
+        # public/foi-user-use.png graph has never been generated:
+        echo "  ERROR: nothing existed at $SYMLINK_LOCATION"
+    fi
+
+done