feat: Do not change permissions on existing data directory

snap/hooks/install

@@ -1,28 +1,45 @@
-#!/bin/bash
+#!/usr/bin/env bash
+# Installation hook for charmed-mongodb snap
 
 set -eux
 
+export CONF="${SNAP_DATA}"/etc/mongod
+export PBM_CONF="${SNAP_DATA}"/etc/pbm
+export DATA="${SNAP_COMMON}"/var/lib/mongodb
+export LOGS="${SNAP_COMMON}"/var/log/mongodb
+export MONGO_CONFIG_FILE="${CONF}"/mongod.conf
+
 # Create the necessary parent directories 
-mkdir -p "${SNAP_DATA}/etc/pbm/"
-mkdir -p "${SNAP_DATA}/etc/mongod/"
-mkdir -p "${SNAP_COMMON}/var/lib/mongodb/"
-mkdir -p "${SNAP_COMMON}/var/log/mongodb/"
+mkdir -p $DATA
+mkdir -p $LOGS
+mkdir -p $PBM_CONF
+mkdir -p $CONF
+
+# If we just created the directory, we set up permissions
+if [ stat -c '%u' "$DATA" == 0 ]; then
+    chmod -R 770 "${SNAP_COMMON}"
+    chmod 750 "${DATA}"
+fi
+
+# If we just created the directory, we set up permissions
+if [ stat -c '%u' "$LOGS" == 0 ]; then
+    chmod -R 770 "${SNAP_COMMON}"
+    chmod g+s "$LOGS"/*
+fi
+
+chown -R 584788:root "${SNAP_COMMON}"/*
 
 # Copy over the mongod.conf and create needed directories/files
-MONGO_CONFIG_FILE="${SNAP_DATA}/etc/mongod/mongod.conf"
 echo "configuration file does not exist."
 echo "copying default config to ${MONGO_CONFIG_FILE}"
 cp -r ${SNAP}/etc/mongod.conf ${MONGO_CONFIG_FILE}
 
 
 # mongod.conf default values are not consistent with the snap directory system.
 sed -i "s/fork: true/fork: false/g" $MONGO_CONFIG_FILE
-sed -i "s:/var/log/mongodb:$SNAP_COMMON/var/log/mongodb:g" $MONGO_CONFIG_FILE
-sed -i "s:/var/lib/mongodb:$SNAP_COMMON/var/lib/mongodb:g" $MONGO_CONFIG_FILE
+sed -i "s:/var/log/mongodb:$LOGS:g" $MONGO_CONFIG_FILE
+sed -i "s:/var/lib/mongodb:$DATA:g" $MONGO_CONFIG_FILE
 sed -i "s:/var/run:/tmp:g" $MONGO_CONFIG_FILE
 
 # Change ownership of snap directories to allow snap_daemon to read/write
-chmod g+s "${SNAP_COMMON}/var/log/"*
 chown -R 584788:root "${SNAP_DATA}"/*
-chown -R 584788:root "${SNAP_COMMON}"/*
-chgrp root "${SNAP_COMMON}/var/log/"*

snap/local/drop_priv.sh

@@ -4,13 +4,14 @@
 export PBM_MONGODB_URI="$(snapctl get pbm-uri)"
 
 if [[ $(id -u) == "0" ]]; then
-
-exec "${SNAP}"/usr/bin/setpriv \
+    exec bash -c "cd ${SNAP} && \
+        ${SNAP}/usr/bin/setpriv \
         --clear-groups \
         --reuid snap_daemon \
-        --regid snap_daemon -- \
-        "$SNAP/usr/bin/$@"
+        --regid snap_daemon \
+        -- \
+        ${SNAP}/usr/bin/$*"
 else
-
-exec "$SNAP/usr/bin/$@"
+    exec bash -c "cd ${SNAP} && \
+        ${SNAP}/usr/bin/$*"
 fi