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README.md

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+# GOMBAK (GO-Mikrotik-BAcKup)
+
+A program used for creating MirkoTik routers backups.    
+There are different modes of backup:   
+* `single` - backup of a single router
+* `multi` - backup of multiple routers
+* `l2tp` - discover routers ip addresses using remote ip of the L2TP tunnels
+
+## Prerequisites
+* Mikrotik router with enabled SSH access
+* For `l2tp` discovery, the "concentrator" router/s must have Mikrotik API port available
+
+## Usage
+Download appropriate binary for your OS from the releases page.     
+Run the program in desired mode.
+
+### Single
+Single router backup can be run in a single line:    
+`gombak --single.host "<router_ip>" --single.user "<username>" --single.pass "<password>" --backup-dir "<backup_directory>" `    
+This is the default mode. 
+
+### Environment variables
+Environment variables can be used instead of `cli` flags.    
+The prefix is `GOMBAK_` and the rest is the flag name.    
+For example, to use environment variable instead of `--single.pass` flag, set `GOMBAK_SINGLE_PASS=<pass>`.   
+For `--single.user`, set `GOMBAK_SINGLE_USER=<user>` and so on...
+
+### Multi router backup
+For multiple router backups, a yaml config file is more appropriate.
+Here is a sample of this config file, named `config.yaml`:
+```yaml config.yaml
+mode: multi
+backup-dir: "<backup_dir>"
+multi-router:
+  - host: "<router_1_ip>"
+    ssh-port: "<router_1_ssh_port>"
+    username: "<router_1_username>"
+    password: "<router_1_password>"
+  - host: "<router_2_ip>"
+    ssh-port: "<router_2_ssh_port>"
+    username: "<router_2_username>"
+    password: "<router_2_password>"
+  - host: "<router_3_ip>"
+    ssh-port: "<router_3_ssh_port>"
+    username: "<router_3_username>"
+    password: "<router_3_password>"
+  # add as many router you like
+```
+Use the config file with `gombak -c config.yaml`
+
+## Discovery
+
+When there are a lot of routers that needs backing up, some kind of discovery mechanism must exist. 
+
+### L2TP
+For now only `l2tp` discovery mechanism is supported. A user should provide an API access to the router, which 
+all other routers connected to it via `L2TP` tunnel. This is basically a scenario where there is one or more "concentrator" 
+routers, which are being used to manage all others.   
+The "concentrator" router/s must have their API open, as we need to fetch the information about remote `l2tp` tunnel addresses.
+
+The config file example is as following:
+```yaml
+
+mode: l2tp
+backup-dir: "<backup_folder>"
+discovery:
+  hosts:
+    - "<concentrator_1_router_ip>"
+    - "<concentrator_2_router_ip>"
+  username: "<router_username>"
+  password: "<router_password>"
+```
+
+This mode presumes that the username/password combination will be the same across all the routers. 
+It is usually done via RADIUS server or similar solution.
+
+Use the config file with `gombak -c config.yaml`
+
+## Flags
+Check which flags are available with `gombak -h`
+```
+-b, --backup-dir string        mikrotik backup export directory (default "mt-backup")
+-c, --config string            configuration yaml file
+    --log.file string          write logs to the specified file
+    --log.json                 output logs in json format
+    --log.level string         define log level (default "info")
+-m, --mode string              mode of operation (default "single")
+-r, --retention-days int       days of retention (default 5)
+    --single.host string       the ip address of the router
+    --single.pass string       the password for the username
+    --single.ssh-port string   the ssh port of the router (default "22")
+    --single.user string       the username for the router
+```
+
+## TODO
+* Email report
+* CLI command to set up a system service
+* More discovery modes