Add MediaMetadata model.

Add a model for storing image and video metadata for uploaded files.

Metadata is extracted using ExifTool. You will need to install ExifTool
after this commit. ExifTool 12.22 is the minimum required version
because we use the `--binary` option, which was added in this release.

The MediaMetadata model is separate from the MediaAsset model because
some files contain tons of metadata, and most of it is non-essential.
The MediaAsset model represents an uploaded file and contains essential
metadata, like the file's size and type, while the MediaMetadata model
represents all the other non-essential metadata associated with a file.

Metadata is stored as a JSON column in the database.

ExifTool returns all the file's metadata, not just the EXIF metadata.
EXIF is one of several types of image metadata, hence why we call
it MediaMetadata instead of EXIFMetadata.

config/docker/Dockerfile.danbooru

@@ -2,6 +2,7 @@ ARG RUBY_VERSION=2.7.1
 ARG NODE_VERSION=14.15.5
 ARG VIPS_VERSION=8.10.6
 ARG FFMPEG_VERSION=4.3.2
+ARG EXIFTOOL_VERSION=12.30
 
 
 

config/docker/build-base-image.sh

@@ -5,6 +5,7 @@ set -xeuo pipefail
 RUBY_VERSION="${RUBY_VERSION:-2.7.1}"
 VIPS_VERSION="${VIPS_VERSION:-8.10.6}"
 FFMPEG_VERSION="${FFMPEG_VERSION:-4.3.2}"
+EXIFTOOL_VERSION="${EXIFTOOL_VERSION:-12.30}"
 
 COMMON_BUILD_DEPS="
   curl ca-certificates build-essential pkg-config git
@@ -59,6 +60,17 @@ install_ffmpeg() {
   ffprobe -version
 }
 
+install_exiftool() {
+  EXIFTOOL_URL="https://github.com/exiftool/exiftool/archive/refs/tags/${EXIFTOOL_VERSION}.tar.gz"
+  curl -L "$EXIFTOOL_URL" | tar -C /usr/local/src -xzvf -
+  cd /usr/local/src/exiftool-${EXIFTOOL_VERSION}
+
+  perl Makefile.PL
+  make -j "$(nproc)" install
+
+  exiftool -ver
+}
+
 install_ruby() {
   apt_install $RUBY_BUILD_DEPS
 
@@ -73,7 +85,7 @@ cleanup() {
   apt-get purge -y $RUBY_BUILD_DEPS $VIPS_BUILD_DEPS $FFMPEG_BUILD_DEPS
   apt-get purge -y --allow-remove-essential \
     build-essential pkg-config e2fsprogs git libglib2.0-bin libglib2.0-doc \
-    mount perl-modules-5.30 procps python3 readline-common shared-mime-info tzdata
+    mount procps python3 readline-common shared-mime-info tzdata
   apt-get autoremove -y
 
   rm -rf \
@@ -91,6 +103,7 @@ cleanup() {
 apt-get update
 apt_install $COMMON_BUILD_DEPS $DANBOORU_RUNTIME_DEPS
 install_asdf
+install_exiftool
 install_ffmpeg
 install_vips
 install_ruby