Merge branch '2-allow-read' into 'master'

Resolve #2 "Allow read"

See merge request ix.ai/mariadb-backup!10

Author: tlex

README.md

@@ -15,20 +15,22 @@ To backup a [MySQL](https://hub.docker.com/_/mysql/) or [MariaDB](https://hub.do
 
 ## Environment variables
 
-| **Variable**  | **Default** | **Mandatory** | **Description**                                      |
-|:--------------|:-----------:|:-------------:|:-----------------------------------------------------|
-| `DB_HOST`     | -           | *yes*         | The host to connect to                               |
-| `DB_PASS`     | -           | *yes*         | The password for the SQL server                      |
-| `DB_NAME`     | -           | *no*          | If specified, only this database will be backed up   |
-| `DB_PORT`     | `3306`      | *no*          | The port of the SQL server                           |
-| `DB_USER`     | `root`      | *no*          | The user to connect to the SQL server                |
-| `MODE`        | `BACKUP`    | *no*          | One of `BACKUP` or `RESTORE`                         |
-| `BASE_DIR`    | `/backup`   | *no*          | Path of the base directory (aka working directory)   |
-| `RESTORE_DIR` | -           | *no*          | Name of a backup directory to restore                |
-| `BACKUP_UID`  | `666`       | *no*          | UID of the backup                                    |
-| `BACKUP_GID`  | `666`       | *no*          | GID of the backup                                    |
-| `UMASK`       | `0022`      | *no*          | Umask which should be used to write the backup files |
-| `OPTIONS`     | `-c` / `-o` | *no*          | Options passed to `mydumper` / `myloader`            |
+| **Variable**  | **FILE Support** | **Default** | **Mandatory** | **Description**                                      |
+|:--------------|:----------------:|:-----------:|:-------------:|:-----------------------------------------------------|
+| `DB_HOST`     | `DB_HOST__FILE`  | -           | *yes*         | The host to connect to                               |
+| `DB_PASS`     | `DB_PASS__FILE`  | -           | *yes*         | The password for the SQL server                      |
+| `DB_NAME`     | `DB_NAME__FILE`  | -           | *no*          | If specified, only this database will be backed up   |
+| `DB_PORT`     | N/A              | `3306`      | *no*          | The port of the SQL server                           |
+| `DB_USER`     | `DB_USER__FILE`  | `root`      | *no*          | The user to connect to the SQL server                |
+| `MODE`        | N/A              | `BACKUP`    | *no*          | One of `BACKUP` or `RESTORE`                         |
+| `BASE_DIR`    | N/A              | `/backup`   | *no*          | Path of the base directory (aka working directory)   |
+| `RESTORE_DIR` | N/A              | -           | *no*          | Name of a backup directory to restore                |
+| `BACKUP_UID`  | N/A              | `666`       | *no*          | UID of the backup                                    |
+| `BACKUP_GID`  | N/A              | `666`       | *no*          | GID of the backup                                    |
+| `UMASK`       | N/A              | `0022`      | *no*          | Umask which should be used to write the backup files |
+| `OPTIONS`     | N/A              | `-c` / `-o` | *no*          | Options passed to `mydumper` / `myloader`            |
+
+The following environment variables support setting via `*__FILE`, where
 
 Please note the backup will be written to `/backup` by default, so you might want to mount that directory from your host.
 

mariadb-backup.sh

@@ -6,6 +6,37 @@ set -e
 # Based on the mode, different default options will be set.
 #
 
+file_env() {
+   local var="$1"
+   local fileVar="${var}__FILE"
+   local def="${2:-}"
+
+   if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
+      echo >&2 "error: both $var and $fileVar are set (but are exclusive)"
+      exit 1
+   fi
+   local val="$def"
+   if [ "${!var:-}" ]; then
+      val="${!var}"
+   elif [ "${!fileVar:-}" ]; then
+      val="$(< "${!fileVar}")"
+   fi
+   export "$var"="$val"
+   unset "$fileVar"
+}
+
+if [[ "${DB_USER}" == "root" ]]; then
+    #
+    # If this is set to the default, then unset it in case we are going to get it from a secret
+    #
+    unset DB_USER
+fi
+
+file_env "DB_PASS"
+file_env "DB_USER"
+file_env "DB_HOST"
+file_env "DB_NAME"
+
 MODE=${MODE:-BACKUP}
 TARBALL=${TARBALL:-}
 DB_PORT=${DB_PORT:-3306}
@@ -43,7 +74,7 @@ echo "  UID:                ${BACKUP_UID:=666}"
 echo "  GID:                ${BACKUP_GID:=666}"
 echo "  Umask:              ${UMASK:=0022}"
 echo
-echo "  Base directory: i   ${BASE_DIR:=/backup}"
+echo "  Base directory:     ${BASE_DIR:=/backup}"
 [[ "${MODE^^}" == "RESTORE" ]] && \
 echo "  Restore directory:  ${RESTORE_DIR}"
 echo