diff --git a/Dockerfile b/Dockerfile
index 61f1816ad7c808be6c5211afb5ae033381d211e9..8ee65ebdb2ae4f0cedc830a9e842148529abab39 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -20,13 +20,14 @@ ARG wp_version=latest
 WORKDIR /app
 ENV WORDPRESS_ROOT=/app
 
-COPY scripts/wp.sh /usr/local/bin/wp
 COPY --from=compile /usr/local/etc/php /usr/local/etc/php
 COPY --from=compile /usr/local/lib/php /usr/local/lib/php
+COPY scripts/wp.sh /usr/local/bin/wp
+COPY data/composer.json /app/composer.json
 RUN --mount=type=bind,source=scripts/install-wp.sh,target=/stage \
     /stage ${wp_version}
 
-COPY plugins/probe.php wp-content/mu-plugins/
+COPY plugins/* wp-content/mu-plugins/
 COPY data/fpm.conf /usr/local/etc/php-fpm.d/image.conf
 COPY data/opcache.ini /usr/local/etc/php/conf.d/opcache-recommended.ini
 COPY data/wp-config.php /usr/share/wordpress/wp-config.php
diff --git a/data/composer.json b/data/composer.json
new file mode 100644
index 0000000000000000000000000000000000000000..c028f78b051f0f31074739ee76689ab6e3514fbd
--- /dev/null
+++ b/data/composer.json
@@ -0,0 +1,21 @@
+{
+	"type": "project",
+	"license": "MPL-2.0",
+	"repositories": [
+		{
+			"type": "gitlab",
+			"url": "https://code.kodo.org.uk/singing-chimes.co.uk/s3-uploads"
+		}
+	],
+	"require": {
+		"humanmade/s3-uploads": "dev-develop"
+	},
+	"config": {
+		"gitlab-domains": [ "code.kodo.org.uk" ]
+	},
+	"extra": {
+		"installer-paths": {
+			"wp-content/mu-plugins/{$name}/": [ "type:wordpress-plugin" ]
+		}
+	}
+}
diff --git a/data/wp-config.php b/data/wp-config.php
index 78063c294ec38bbcb32a6a03434f031e5a70a670..b05132f7b3d42c3aec4b0e817e5707a4a5c1ad41 100644
--- a/data/wp-config.php
+++ b/data/wp-config.php
@@ -22,3 +22,10 @@ define('DISABLE_WP_CRON', true);
  * installation.
  **/
 define('UPLOADS', 'media');
+
+/**
+ * Run the Composer autoloader, if available
+ * Assume the CWD is always /app and vendor is always in it.
+ **/
+if ( is_file(ABSPATH . 'vendor/autoload.php') )
+	require_once ABSPATH . 'vendor/autoload.php';
diff --git a/plugins/media-url.php b/plugins/media-url.php
index d1b1171bb6f986110dd50ee51323ba4faecbc1fb..955cc97efdfeb5932785cb6b042e549ef08c74b3 100644
--- a/plugins/media-url.php
+++ b/plugins/media-url.php
@@ -30,7 +30,7 @@ function unparse_url( array $parts ) {
 		(isset($parts['scheme'])   ?  "{$parts['scheme']}://" : '') .
 		(isset($parts['user'])     ?    $parts['user']        : '') .
 		(isset($parts['pass'])     ? ":{$parts['pass']}"      : '') .
-		(isset($parts['user'] || isset($parts['pass'])) ? '@' : '') .
+		(isset($parts['user']) || isset($parts['pass']) ? '@' : '') .
 		(isset($parts['host'])     ?    $parts['host']        : '') .
 		(isset($parts['port'])     ? ":{$parts['port']}"      : '') .
 		(isset($parts['path'])     ?    $parts['path']        : '') .
diff --git a/plugins/s3-uploads.php b/plugins/s3-uploads.php
new file mode 100644
index 0000000000000000000000000000000000000000..727db18f1550cb45e83a06a128c11ec273ab1109
--- /dev/null
+++ b/plugins/s3-uploads.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * Plugin Name: S3-Uploads
+ * Plugin URI: https://github.com/humanmade/S3-Uploads
+ * Description: S3-Uploads with custom endpoint configuration
+ * Licence: GPL-2.0+
+ * Licence URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
+ * Author: Human Made Limited
+ * Author URI: http://hmn.md/
+ **/
+
+if ( defined( 'S3_UPLOADS_ENTRYPOINT_URL' ) || defined( 'WP_CLI' ) ):
+
+add_filter( 's3_uploads_s3_client_params', function ( $params ) {
+	$params['endpoint'] = S3_UPLOADS_ENDPOINT_URL;
+	$params['bucket_endpoint'] = true;
+	$params['disable_host_prefix_injection'] = true;
+	$params['use_path_style_endpoint'] = true;
+	$params['debug'] = WP_DEBUG && WP_DEBUG_DISPLAY;
+	$params['region'] = '';
+	return $params;
+} );
+
+require WPMU_PLUGIN_DIR . '/s3-uploads/s3-uploads.php';
+
+endif;
diff --git a/scripts/entrypoint.sh b/scripts/entrypoint.sh
index c2965f621bdae94df9e9985ea57b274169b3d62d..3a7779bd60436e22b35b63760ac5462a712373dd 100755
--- a/scripts/entrypoint.sh
+++ b/scripts/entrypoint.sh
@@ -32,6 +32,7 @@ declare -a STATIC_PATTERNS=(
 	"LICEN[CS]E"
 	"README"
 	"readme.html"
+	"composer.*"
 )
 declare -a PHP_DIRECTIVES=(
 	${PHP_DIRECTIVES-}
@@ -94,6 +95,46 @@ setup_database() {
 	wp rewrite structure /posts/%postname%
 }
 
+setup_s3() {
+	# https://github.com/humanmade/S3-Uploads
+
+	declare -a configs=( "${!S3_ENDPOINT_@}" )
+	[[ ${#configs[*]} -gt 0 ]] || return 0
+
+	[[ -v S3_UPLOADS_ENDPOINT_URL ]] &&
+	[[ -v S3_ENDPOINT_KEY ]] &&
+	[[ -v S3_ENDPOINT_SECRET ]] ||
+		return 0
+
+	composer update --prefer-dist --no-dev --with-dependencies \
+		humanmade/s3-uploads
+
+	[[ -v S3_UPLOADS_USE_LOCAL ]] &&
+		wp config set S3_UPLOADS_USE_LOCAL true --raw
+
+	if [[ -v S3_UPLOADS_REWRITE_URL ]]; then
+		wp config set S3_UPLOADS_BUCKET_URL "${S3_UPLOADS_REWRITE_URL}"
+	else
+		wp config set S3_UPLOADS_BUCKET_URL "${S3_UPLOADS_ENDPOINT_URL}"
+	fi
+
+	wp config set S3_UPLOADS_ENDPOINT_URL "${S3_UPLOADS_ENDPOINT_URL}"
+	wp config set S3_UPLOADS_KEY ${S3_ENDPOINT_KEY}
+	wp config set S3_UPLOADS_SECRET ${S3_ENDPOINT_SECRET} --quiet
+
+	# Plugin requires something here, it's not used
+	wp config set S3_UPLOADS_REGION ''
+
+	# Due to what appears to be a bug in the plugin, this MUST be a non-empty
+	# string; mostly it just affects the log output
+	wp config set S3_UPLOADS_BUCKET "CONFIGURED-BUCKET"
+
+	# If there is anything in ./media, upload it
+	local contents=( media/* )
+	[[ ${#contents[*]} -gt 0 ]] &&
+		wp s3-uploads upload-directory media
+}
+
 setup_components() {
 	setup_database
 
@@ -119,6 +160,8 @@ setup_components() {
 	[[ $(wp theme list --status=active --format=count) -eq 0 ]] &&
 		wp theme activate $(wp theme list --field=name | head -n1)
 
+	setup_s3
+
 	return 0
 }
 
@@ -154,8 +197,9 @@ collect_static()
 		--delete-delay \
 		--exclude-from=- \
 		--exclude='*.php' \
-		--exclude=static/ \
 		--exclude="${MEDIA}" \
+		--exclude=/static/ \
+		--exclude=/vendor/ \
 		--force \
 		--info="${flags[*]}" \
 		--times \
diff --git a/scripts/install-wp.sh b/scripts/install-wp.sh
index bf3a8186ad59dfa88edf07142e78b679c6bad2e4..55d1fb70ba91aae2680df75e8666d5708d081310 100755
--- a/scripts/install-wp.sh
+++ b/scripts/install-wp.sh
@@ -1,9 +1,15 @@
 #!/bin/bash
 set -eux
 
+COMPOSER_INSTALLER_URL=https://getcomposer.org/installer
 WP_CLI_URL=https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar
 WP_PASSWORD_HASH=https://raw.githubusercontent.com/Ayesh/WordPress-Password-Hash/1.5.1
 
+# Install Composer
+curl -sSL ${COMPOSER_INSTALLER_URL} |
+	php -- --install-dir=/usr/local/lib --filename=composer.phar
+ln -s ../lib/composer.phar /usr/local/bin/composer
+
 # Install WP-CLI
 curl -sSL ${WP_CLI_URL} \
     >/usr/local/lib/wp-cli.phar
@@ -21,3 +27,7 @@ mkdir -p wp-content/mu-plugins
 # Install non-optional plugins
 curl ${WP_PASSWORD_HASH}/wp-php-password-hash.php \
 	>wp-content/mu-plugins/password-hash.php
+
+# Install composer managed dependencies
+export COMPOSER_ALLOW_SUPERUSER=1
+composer install --prefer-dist