Allow setting up wifi from config

Add WPA_ESSID, WPA_PASSWORD and WPA_COUNTRY options to config.

README.md

@@ -81,6 +81,10 @@ The following environment variables are supported:
 
    Password for the first user
 
+ * `WPA_ESSID`, `WPA_PASSWORD` and `WPA_COUNTRY` (Default: unset)
+
+   If these are set, they are use to configure `wpa_supplicant.conf`, so that the raspberry pi can automatically connect to a wifi network on first boot.
+
 A simple example for building Raspbian:
 
 ```bash

build.sh

@@ -143,6 +143,9 @@ export LOG_FILE="${WORK_DIR}/build.log"
 
 export FIRST_USER_NAME=${FIRST_USER_NAME:-pi}
 export FIRST_USER_PASS=${FIRST_USER_PASS:-raspberry}
+export WPA_ESSID
+export WPA_PASSWORD
+export WPA_COUNTRY
 
 export BASE_DIR
 

stage2/02-net-tweaks/01-run.sh

@@ -16,3 +16,14 @@ chown root:root /boot/dhcpcd.conf
 ln -s /boot/dhcpcd.conf /etc/dhcpcd.conf
 EOF
 
+if [ -v WPA_COUNTRY ]
+then
+	echo "country=${WPA_COUNTRY}" >> "${ROOTFS_DIR}/etc/wpa_supplicant/wpa_supplicant.conf"
+fi
+
+if [ -v WPA_ESSID -a -v WPA_PASSWORD ]
+then
+on_chroot <<EOF
+wpa_passphrase ${WPA_ESSID} ${WPA_PASSWORD} >> "/etc/wpa_supplicant/wpa_supplicant.conf"
+EOF
+fi