Install latest firefox and geckodriver in Docker Alpine. Headless Firefox works for both AMD64 and ARM64.

firefox-geckodriver-alpine-amd64-arm64.Dockerfile

# ================== Install Firefox & Driver ==================
RUN apk add --no-cache firefox-esr

# Install Geckodriver
SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
RUN apk add --no-cache --virtual .build-deps wget \
    && GECKODRIVER_VERSION=$(wget -qO- https://api.github.com/repos/mozilla/geckodriver/releases/latest \
    | grep "tag_name" | sed -E 's/.*"([^"]+)".*/\1/') \
    && wget -qO /tmp/geckodriver.tar.gz \
    "https://github.com/mozilla/geckodriver/releases/download/$GECKODRIVER_VERSION/geckodriver-$GECKODRIVER_VERSION-linux64.tar.gz" \
    && tar -xzf /tmp/geckodriver.tar.gz -C /usr/local/bin/ \
    && rm /tmp/geckodriver.tar.gz \
    && apk del .build-deps