Add Gecko webdriver to linux images

images/linux/scripts/installers/firefox.sh

@@ -23,3 +23,26 @@ echo "Lastly, documenting what we added to the metadata file"
 #           ($HOME is /home/packer which is owned by packer.)
 HOME=/root
 DocumentInstalledItem "Firefox ($(firefox --version))"
+
+# Download and unpack latest release of geckodriver
+URL=https:`curl -s https://api.github.com/repos/mozilla/geckodriver/releases/latest|grep 'browser_download_url.*linux64.tar.gz'|sed -e 's/^.*"https://'|sed -e 's/"//g'`
+echo "Downloading geckodriver $URL..."
+wget "$URL" -O geckodriver.tar.gz
+tar -xzf geckodriver.tar.gz
+rm geckodriver.tar.gz
+
+GECKODRIVER_BIN="/usr/bin/geckodriver"
+mv "geckodriver" $GECKODRIVER_BIN
+chown root:root $GECKODRIVER_BIN
+chmod +x $GECKODRIVER_BIN
+echo "GECKOWEBDRIVER=$GECKODRIVER_BIN" | tee -a /etc/environment
+
+# Run tests to determine that the geckodriver installed as expected
+echo "Testing to make sure that script performed as expected, and basic scenarios work"
+if ! command -v geckodriver; then
+    echo "geckodriver was not installed"
+    exit 1
+fi
+
+echo "Lastly, documenting what we added to the metadata file"
+DocumentInstalledItem "Geckodriver ($(geckodriver --version)); Gecko Driver is available via GECKOWEBDRIVER environment variable"