doc: added comments and guides

Signed-off-by: Glenn Vriesman <[email protected]>

README.md

@@ -1,3 +1,70 @@
-### F2B-Exporter
+# F2B-Exporter
 
-This is a simple Fail2Ban prometheus exporter
+[![GoDoc](https://godoc.org/github.com/glvr182/f2b-exporter?status.svg)](https://godoc.org/github.com/glvr182/f2b-exporter)
+[![GitHub tag](https://img.shields.io/github/tag/glvr182/f2b-exporter.svg)]()
+![Docker Image Size (latest by date)](https://img.shields.io/docker/image-size/glvr182/f2b-exporter)
+![Docker Image Version (latest by date)](https://img.shields.io/docker/v/glvr182/f2b-exporter)
+
+This is a simple Fail2Ban prometheus exporter
+
+## Installation
+
+### From source
+You can clone this repository from git `https://github.com/glvr182/f2b-exporter.git`.  
+Then all you have to do is run `go build` and you're done!
+
+### Docker
+Using the following command you can run this program with docker.  
+NOTE: When running the docker image you might want to mount the certificates since some remotes use TLS.
+```
+docker run \
+-d \
+--name f2b-exporter \
+-v /var/lib/fail2ban/fail2ban.sqlite3:/var/lib/fail2ban/fail2ban.sqlite3 \
+-v /etc/ssl/certs:/etc/ssl/certs \
+glvr182/f2b-exporter
+```
+Depending on your deployment you might want to expose the configured port (default 8080) like this:
+```
+docker run \
+-d \
+-p 8080:8080 \
+--name f2b-exporter \
+-v /var/lib/fail2ban/fail2ban.sqlite3:/var/lib/fail2ban/fail2ban.sqlite3 \
+-v /etc/ssl/certs:/etc/ssl/certs \
+glvr182/f2b-exporter
+```
+
+## Configuration
+The exporter has a few settings that you can tweak using the cli or using env variables:
+| cli        | env          | default                            |
+|------------|--------------|------------------------------------|
+| --port     | F2B_PORT     | 8080                               |
+| --database | F2B_DATABASE | /var/lib/fail2ban/fail2ban.sqlite3 |
+| --remote   | F2B_REMOTE   | freeGeoIP                          |
+
+To add the exporter to prometheus a simple config like this would do the trick:  
+NOTE: this is from prometheus, NOT for this exporter.
+```
+global:
+  scrape_interval:     15s
+  evaluation_interval: 15s
+
+scrape_configs:
+  - job_name: 'f2b-exporter'
+    scrape_interval: 5s
+    static_configs:
+    - targets: ['localhost:8080']
+```
+Or using docker and a dedicated network:
+```
+global:
+  scrape_interval:     15s
+  evaluation_interval: 15s
+
+scrape_configs:
+  - job_name: 'f2b-exporter'
+    scrape_interval: 5s
+    static_configs:
+    - targets: ['f2b-exporter:8080']
+```

main.go

@@ -70,6 +70,7 @@ func main() {
 	}
 }
 
+// update refreshes the prometheus metrics
 func update() error {
 	db, err := sqlittle.Open(viper.GetString("database"))
 	if err != nil {
@@ -95,6 +96,7 @@ func update() error {
 	return nil
 }
 
+// jailed is a helper function which fetches all the prisoners in the given database
 func jailed(db *sqlittle.DB, provider provider.Provider) ([]prisoner, error) {
 	var (
 		prisoners []prisoner