Issue Converting to PDF Using LibreOffice Command in Terminal

I'm using the following Dockerfile:

# Install OpenJDK, LibreOffice, and Xorg ServerRUN apk add openjdk11-jreRUN apk add libreofficeRUN apk add libreoffice-writerRUN apk add ttf-freefontRUN apk add libreoffice-commonRUN apk add --no-cache msttcorefonts-installer fontconfig && \    update-ms-fonts && \    fc-cache -f

When I try to run this command:

export HOME=/app/www/protocolo-online/public && libreoffice --headless --nologo --convert-to pdf /app/www/protocolo-online/storage/desenvolvimento/titulo-legitimacao-775/titulo-legitimacao-individual-1233.docx --outdir /app/www/protocolo-online/storage/desenvolvimento/titulo-legitimacao-775

I get the following error:

usr/lib/libreoffice/program/soffice.bin X11 error: Can't open display:    Set DISPLAY environment variable, use -display option   or check permissions of your X-Server   (See "man X" resp. "man xhost" for details)

Can anyone help me?