From 389bfb967cf0a5e5af0c1a215f85e84f295293b3 Mon Sep 17 00:00:00 2001
From: Markus Pesch <markus.pesch@cryptic.systems>
Date: Sun, 12 Sep 2021 19:51:15 +0200
Subject: [PATCH] fix(README): describe environment variables

---
 README.md | 42 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 0e763dd..203e61f 100644
--- a/README.md
+++ b/README.md
@@ -71,12 +71,40 @@ services:
     network_mode: host
 ```
 
-## Build container image manually
+## Environment variables
 
-To build the images manually check out the repository on
-[github](https://github.com/volker-raschek/fetchmail-docker) with git and use
-the make command to build the container image.
+### DATABASE_TYPE
 
-```bash
-make container-image/build
-```
+Currently will be only postgres, mysql and mariadb supported. About the
+environment variable `DATABASE_TYPE` can the backend type defined. The value is
+required.
+
+| database type | value |
+| ------------- | ----- |
+| mysql/mariadb | `my`  |
+| postgres      | `Pg`  |
+
+### DATABASE_USER
+
+The environment variable `DATABASE_USER` is undefined and required. The value
+contains the database user which one fetchmail use to login.
+
+### DATABASE_PASSWORD
+
+The environment variable `DATABASE_PASSWORD` is undefined and required. The value
+contains the password of the database user which one fetchmail use to login.
+
+### DATABASE_HOST
+
+The environment variable `DATABASE_HOST` is undefined and required. The value
+contains the DNS name or IP address of the host, where the database is hosted.
+
+### DATABASE_PORT
+
+The environment variable `DATABASE_PORT` is undefined and required. The value
+contains the port of the host, where the database is listen on.
+
+### DATABASE_NAME
+
+The environment variable `DATABASE_NAME` is undefined and required. The value
+contains the name of the database against which should be logged in.