openvpn.sh: Add easyrsa to wrapper

* Provide a way to invoke easyrsa form the wrapper
* Add ability to set the EasyRSA vars file which manages the default
  settings for the EasyRSA PKI CA.

bin/openvpn.sh

@@ -3,6 +3,13 @@
 # OpenVPN + Docker Wrapper Script
 #
 
+OPENVPN="/etc/openvpn"
+
+# Needed by easyrsa itself
+export EASYRSA="/usr/local/share/easy-rsa/easyrsa3"
+export EASYRSA_PKI="$OPENVPN/pki"
+export EASYRSA_VARS_FILE="$OPENVPN/vars"
+
 set -ex
 
 abort() {
@@ -14,11 +21,46 @@ if [ $# -lt 1 ]; then
     abort "No command specified"
 fi
 
+do_openvpn() {
+    if [ ! -d /dev/net ]; then
+        mkdir -p /dev/net
+    fi
+    if [ ! -c /dev/net/tun ]; then
+        mknod /dev/net/tun c 10 200
+    fi
+
+    cd /etc/easyrsa
+}
+
 # Read arguments from command line
 cmd=$1
 shift
 
 case "$cmd" in
+    # nop for volume creation
+    init)
+        exit 0
+        ;;
+    easyrsa)
+        cd $OPENVPN
+        easyrsa "$@"
+        ;;
+    easyrsa-export-vars)
+        if [ -f "$EASYRSA_VARS_FILE" ]; then
+            cat "$EASYRSA_VARS_FILE"
+        else
+            cat "$EASYRSA/vars.example"
+        fi
+        ;;
+    easyrsa-import-vars)
+        cat > "$EASYRSA_VARS_FILE"
+        ;;
+    bash)
+        $cmd "$@"
+        ;;
+    openvpn)
+        do_openvpn "$@"
+        ;;
     *)
         abort "Unknown cmd \"$cmd\""
         ;;