Create README.md

Added readme

README.md

@@ -0,0 +1,64 @@
+# docker-letsencrypt-cron
+Create and automatically renew website certificates using letsencrypt CA.
+
+This image will renew your certificates every 2 months, and place the lastest ones in the /certs folder on the host.
+
+# Setup
+
+In docker-compose.yml, change the environment variables:
+- set the DOMAINS environment variable to a space separated list of domains for which you want to generate certificates.
+- set the EMAIL environment variable for your account on the ACME server, and where you will receive updates from letsencrypt.
+
+If you want to use the certificates with nginx or apache, uncomment the relevant lines in scripts/run_letsencrypt.sh.
+
+# ACME Validation challenge
+
+To authenticate the certificates, the you need to pass the ACME validation challenge. This requires requests made to on port 80 to example.com/.well-known/ to be forwarded to this image.
+
+## Haproxy example
+
+If you use a haproxy reverse proxy, you can add the following to your configuration file in order to pass the ACME challenge.
+
+``` haproxy
+frontend http
+  bind *:80
+  acl letsencrypt_check path_beg /.well-known
+
+  use_backend letsencrypt if letsencrypt_check
+
+backend letsencrypt
+  server letsencrypt letsencrypt:80 maxconn 32
+```
+
+## Nginx example
+
+If you use nginx as a reverse proxy, you can add the following to your configuration file in order to pass the ACME challenge.
+
+``` nginx
+upstream letsencrypt_upstream{
+  server letsencrypt:80;
+}
+
+server {
+  listen              80;
+  location '/.well-known/acme-challenge' {
+    default_type "text/plain";
+    proxy_pass http://letsencrypt_upstream;
+  }
+}
+
+```
+
+# Usage
+
+```shell
+docker-compose up -d
+```
+
+The first time you start it up, you may want to run the certificate generation script immediately:
+
+```shell
+docker exec letsencrypt sh -c "/run_letsencrypt.sh"
+```
+
+At 3AM, on the 1st of every even month, a cron job will start the script, renewing your certificates.