Extend migrator to support upgrading between versioned data directories

balena-entrypoint.sh

@@ -2,21 +2,7 @@
 
 set -e
 
-# creates a backup archive of the dir $1...
-backup_data () {
-    gosu postgres tar --exclude backup.tar.gz -zcf /tmp/backup.tar.gz -C "$1" .
-    mv /tmp/backup.tar.gz "${1}/backup.tar.gz"
-}
-
-# copies all the data from $1 to $2...
-restore_volume () {
-    echo "=== Restoring data volume structure"
-    find "$1" -maxdepth 1 \
-        ! -path "$1" \
-        | xargs mv -t "$2"
-}
-
-# install the old version of Postgres, required when doing an upgrade...
+# install the old version of Postgres, required when doing an upgrade
 install_old_version () {
     if [ ! -d "/usr/lib/postgresql/$1/bin" ]; then
         sed -i 's/$/ '"$1"'/' /etc/apt/sources.list.d/pgdg.list
@@ -28,62 +14,84 @@ install_old_version () {
     fi
 }
 
-# creates a dir at $1 which is valid for Postgres data to live in...
-create_postgres_data_dir () {
-    echo "=== Creating data dir $1"
+# creates a dir at $1 which is valid for Postgres data to live in
+create_postgres_dir () {
+    echo "=== Creating postgres directory $1"
     mkdir -p "$1"
     chmod 700 "$1"
     chown -R postgres:postgres "$1"
 }
 
-# echo a message and die...
+# echo a message and die
 die_with_message () {
     echo "[FATAL] $1"
     exit 2
 }
 
-# check that this is running from within a valid Postgres container environment...
+# check that this is running from within a valid Postgres container environment
 [ ! -z "$PG_MAJOR" ] || die_with_message "Not a compatible Postgres runtime environment"
 
-# set our target version...
+# set our target version
 TARGET_VERSION="$PG_MAJOR"
+PGDATANEW="${PGDATA}/${TARGET_VERSION}"
+
+WORKDIR=/usr/lib/postgresql/upgrade
+
+# check there's no previously interrupted upgrade, it would be dangerous to continue
+[ ! -d "${WORKDIR}" ] || die_with_message "Found possibly interrupted upgrade in ${WORKDIR}; not continuing"
+
+migrate_pgdata_root_if_needed () {
+    # perform a one-time migration from storing data under $PGDATA root,
+    # to storing it under $PGDATA/$PG_VERSION
+    if [ -f "${PGDATA}/PG_VERSION" ]; then
+        local version="$(cat "${PGDATA}/PG_VERSION")"
+        if [ ! -d "${PGDATA}/${version}" ]; then
+            create_postgres_dir "${PGDATA}/${version}"
+            echo "=== Moving existing data to directory "${PGDATA}/${version}""
+            find "$PGDATA" -maxdepth 1 \
+                ! -path "$PGDATA" \
+                ! -path "${PGDATA}/${version}*" \
+                | xargs mv -t "${PGDATA}/${version}"
+        fi
+    fi
+}
 
-# ensure we have a versioned data directory...
-[ -d "${PGDATA}/${TARGET_VERSION}" ] || create_postgres_data_dir "${PGDATA}/${TARGET_VERSION}"
+find_source_version () {
+    # find our source version by looking for a PG_VERSION file
+    # in every directory under $PGDATA
+    for src in $(find "$PGDATA" -maxdepth 2 -type f -name 'PG_VERSION' | sort -rn); do
+        local version="$(cat "$src")"
+        if [ "$version" -ne "$TARGET_VERSION" ]; then
+            SOURCE_VERSION="$version"
+            PGDATAOLD="$(dirname "$src")" # drop 'PG_VERSION' from path
+            break
+        fi
+    done
+}
 
-# check for Postgres data in the root of the $PGDATA directory...
-if [ -f "${PGDATA}/PG_VERSION" ]; then
-    SOURCE_VERSION="$(cat ${PGDATA}/PG_VERSION)"
-
-    # does the data need upgrading...
-    if [ "$SOURCE_VERSION" -ne "$TARGET_VERSION" ]; then
+perform_upgrade_if_needed () {
+    # does the data need upgrading?
+    if [ -n "${SOURCE_VERSION}" ]; then
         echo "=== Upgrading data from v${SOURCE_VERSION} to v${TARGET_VERSION}"
 
-        # define our directories...
-        PGDATAOLD="${PGDATA}/${SOURCE_VERSION}"
-        PGDATANEW="${PGDATA}/${TARGET_VERSION}"
+        create_postgres_dir "${WORKDIR}"
+
         PGBINOLD="/usr/lib/postgresql/$SOURCE_VERSION/bin"
         PGBINNEW="/usr/lib/postgresql/$TARGET_VERSION/bin"
-        
+
         echo "=== Installing tools for Postgres v${SOURCE_VERSION}"
         install_old_version "$SOURCE_VERSION"
 
-        echo "=== Moving extisting data to ${PGDATAOLD}"
-        create_postgres_data_dir "${PGDATAOLD}"
-        find "$PGDATA" -maxdepth 1 \
-            ! -path "$PGDATA" \
-            ! -path "$PGDATAOLD*" \
-            | xargs mv -t "${PGDATAOLD}"
-
-        trap "restore_volume ${PGDATAOLD} ${PGDATA}" ERR
-
-        echo "=== Initialising new data directory ${PGDATANEW}"
-        rm -rf "${PGDATANEW}"
-        create_postgres_data_dir "${PGDATANEW}"
-        gosu postgres initdb -D "$PGDATANEW" -U "$POSTGRES_USER" $POSTGRES_INITDB_ARGS
-
-        echo "=== Beginning pg_upgrade"
-        cd /tmp
+        echo "=== Initializing new data directory ${PGDATANEW}"
+        create_postgres_dir "${PGDATANEW}"
+        gosu postgres initdb \
+            -D "$PGDATANEW" \
+            -U "$POSTGRES_USER" \
+            $POSTGRES_INITDB_ARGS
+
+        echo "=== Running pg_upgrade"
+        pushd "${WORKDIR}" >/dev/null
+
         gosu postgres pg_upgrade \
             -U "$POSTGRES_USER" \
             --old-datadir="$PGDATAOLD" \
@@ -98,21 +106,64 @@ if [ -f "${PGDATA}/PG_VERSION" ]; then
             --new-datadir="$PGDATANEW" \
             --old-bindir="$PGBINOLD" \
             --new-bindir="$PGBINNEW"
-    
+
         echo "=== Restoring configuration files"
         cp "${PGDATAOLD}/pg_hba.conf" "${PGDATANEW}/pg_hba.conf"
         cp "${PGDATAOLD}/pg_ident.conf" "${PGDATANEW}/pg_ident.conf"
-    else
-        echo "=== Moving extisting data to directory "${PGDATA}/${TARGET_VERSION}""
-        find "$PGDATA" -maxdepth 1 \
-            ! -path "$PGDATA" \
-            | xargs mv -t "${PGDATA}/${TARGET_VERSION}"
+
+        popd >/dev/null
+
+        echo "=== Data upgraded successfully"
     fi
-fi
+}
+
+complete_upgrade_if_needed () {
+    if [ -d "${WORKDIR}" ]; then
+        echo "=== Performing post-upgrade steps"
+        pushd "${WORKDIR}" >/dev/null
+
+        echo "=== Starting temp server"
+        gosu postgres bash -c '. /usr/local/bin/docker-entrypoint.sh; docker_temp_server_start'
+
+        if [ -f "${WORKDIR}/update_extensions.sql" ]; then
+            echo "=== Updating extensions"
+            gosu postgres psql \
+                -U "$POSTGRES_USER" \
+                -f "${WORKDIR}/update_extensions.sql"
+        fi
+        if [ -f "${WORKDIR}/analyze_new_cluster.sh" ]; then
+            echo "=== Analyzing new cluster"
+            gosu postgres "${WORKDIR}/analyze_new_cluster.sh"
+        fi
+        if [ -f "${WORKDIR}/delete_old_cluster.sh" ]; then
+            echo "=== Deleting old cluster"
+            gosu postgres "${WORKDIR}/delete_old_cluster.sh"
+        else
+            rm -rf "${PGDATAOLD}"
+        fi
+
+        echo "=== Stopping temp server"
+        gosu postgres bash -c '. /usr/local/bin/docker-entrypoint.sh; docker_temp_server_stop'
+
+        popd >/dev/null
+        rm -rf "${WORKDIR}"
+
+        echo "=== Data upgrade complete"
+    fi
+}
+
+migrate_pgdata_root_if_needed
+find_source_version
+perform_upgrade_if_needed
+
+# ensure we have a versioned data directory
+[ -d "${PGDATANEW}" ] || create_postgres_dir "${PGDATANEW}"
+
+# set our runtime data directory to the target version
+export PGDATA="${PGDATANEW}"
 
-# set our runtime data directory to the versioned one...
-export PGDATA="${PGDATA}/${TARGET_VERSION}"
+complete_upgrade_if_needed
 
-# run the existing Postgres entrypoint script...
+# run the existing Postgres entrypoint script
 . /usr/local/bin/docker-entrypoint.sh
 _main "$@"