title: Receiving error on building an Alpine image on my M1 Macbook
body: <p>When I build my Dockerfile image on my Macbook M1, I begin to receive errors in regards to <code>syslinux</code> specifically, and if I were to comment this out I continue to receive errors such as this:</p>
  <pre><code>fetch http://dl-cdn.alpinelinux.org/alpine/v3.13/main/x86_64/APKINDEX.tar.gz
  ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.13/main: UNTRUSTED signature
  WARNING: Ignoring http://dl-cdn.alpinelinux.org/alpine/v3.13/main: No such file or directory
  fetch http://dl-cdn.alpinelinux.org/alpine/v3.13/community/x86_64/APKINDEX.tar.gz
  ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.13/community: UNTRUSTED signature
  WARNING: Ignoring http://dl-cdn.alpinelinux.org/alpine/v3.13/community: No such file or directory
  </code></pre>
  <p>So I know the issue revolves around my repositories that I use so this is where I have the <code>ENTRYPOINT</code> say this in my Dockerfile:</p>
  <pre><code>ENTRYPOINT /src/aports/scripts/mkimage.sh \
      --tag v3.13 \
      --outdir /build \
      --arch x86_64 \
      --repository http://dl-cdn.alpinelinux.org/alpine/v3.13/main \
      --extra-repository http://dl-cdn.alpinelinux.org/alpine/v3.13/community \
      --profile iot
  </code></pre>
  <p>I would believe this would work on my M1 but it doesn't! I used other another Macbook and that builds it but why not the M1? I would greatly appreciate any help in this.</p>
  <p>EDIT 2: Adding full Dockerfile:</p>
  <pre><code># This image contains the build environment for edge appliance install ISOs
  FROM alpine:3.13
  
  # Define metadata
  LABEL maintainer=&quot;this_dude@dude.net&quot;
  
  # Configure user
  RUN addgroup root this_build
  
  # Initialize update and upgrade on Alpine AMI
  RUN apk -U upgrade
  
  # Install dependencies
  RUN apk add --no-cache \
      alpine-conf \
      alpine-sdk \
      apk-tools \
      dosfstools \
      grub-efi \
      mtools \
      squashfs-tools \
      syslinux \
      xorriso
  
  WORKDIR /src
  
  # Clone alpine ports repository containing the iso builder
  RUN git clone --depth=1 --branch v3.13.2 git://git.alpinelinux.org/aports
  RUN chmod +x aports/scripts/mkimage.sh
  
  # Include edge appliance image profile
  RUN ln -sf /build/mkimg.run.sh /src/aports/scripts/mkimg.run.sh
  
  WORKDIR /build
  
  # Run ISO build
  ENTRYPOINT /src/aports/scripts/mkimage.sh \
      --tag v3.13 \
      --outdir /build \
      --arch x86_64 \
      --repository http://dl-cdn.alpinelinux.org/alpine/v3.13/main \
      --extra-repository http://dl-cdn.alpinelinux.org/alpine/v3.13/community \
      --profile iot
  </code></pre>