Create rmfakecloud-proxy package (#448)

This PR provides a new package intended to ease the setup of rmfakecloud on a device. [rmfakecloud](https://github.com/ddvk/rmfakecloud) is an alternative Xochitl sync server developed by ddvk that anyone can self-host. With this package, connecting to an rmfakecloud server only takes a few steps:

* `opkg install rmfakecloud-proxy`
* `rmfakecloudctl set-upstream https://...` (define the server to use)
* `rmfakecloudctl enable`

One can then run `rmfakecloudctl disable` (or uninstall the package) to revert back to the default reMarkable servers.

Co-authored-by: Nathaniel van Diepen <[email protected]>

Author: matteodelabre

package/rmfakecloud-proxy/package

@@ -0,0 +1,82 @@
+#!/usr/bin/env bash
+# Copyright (c) 2021 The Toltec Contributors
+# SPDX-License-Identifier: MIT
+
+pkgnames=(rmfakecloud-proxy)
+pkgdesc="Connect Xochitl to a rmfakecloud server"
+_url=https://github.com/ddvk/rmfakecloud-proxy
+url="$_url"
+_upver=0.0.3
+pkgver="$_upver-1"
+timestamp=2021-09-26T20:38:44Z
+section="utils"
+maintainer="Mattéo Delabre <[email protected]>"
+license=MIT
+installdepends=(procps-ng-pgrep findutils)
+
+image=golang:v2.2
+source=(
+    "https://github.com/ddvk/rmfakecloud-proxy/archive/v$_upver.zip"
+    rmfakecloudctl
+    rmfakecloud-proxy.service
+)
+sha256sums=(
+    eaa3fdcce250e23f368a4c9ddcfb99ff178decf31b2a7f84501dfc6fdb2e6d8f
+    SKIP
+    SKIP
+)
+
+build() {
+    eval "$(go env)"
+    cat > version.go << GO
+package main
+const Version = "rmfakecloud-proxy ${_upver%-*} ($GOOS-$GOARCH) $GOVERSION\n$_url"
+GO
+
+    GOARCH=arm GOARM=7 go build -ldflags="-w -s" -o dist/rmfakecloud-proxy
+}
+
+package() {
+    install -D -m 755 -t "$pkgdir"/opt/bin "$srcdir"/dist/rmfakecloud-proxy
+    install -D -m 755 -t "$pkgdir"/opt/bin "$srcdir"/rmfakecloudctl
+    install -D -m 644 -t "$pkgdir"/lib/systemd/system "$srcdir"/rmfakecloud-proxy.service
+}
+
+configure() {
+    # shellcheck source=rmfakecloudctl
+    source /opt/bin/rmfakecloudctl
+    systemctl daemon-reload
+
+    # Sync the proxy state to the value of its configuration flag
+    if is-enabled; then
+        # This branch is reached when upgrading the package
+        install-certificates
+        systemctl enable --now rmfakecloud-proxy
+        install-hosts
+    else
+        uninstall-certificates
+        systemctl disable --now rmfakecloud-proxy
+        uninstall-hosts
+    fi
+
+    if ! is-enabled; then
+        cat << MSG
+
+Run the following commands to use rmfakecloud-proxy:
+
+$ rmfakecloudctl set-upstream https://your-server.example.org
+$ rmfakecloudctl enable
+
+Replace your-server.example.org with the address of the server you want to use.
+
+MSG
+    fi
+}
+
+preremove() {
+    rmfakecloudctl disable
+}
+
+postremove() {
+    systemctl daemon-reload
+}

package/rmfakecloud-proxy/rmfakecloud-proxy.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=rmfakecloud reverse proxy
+Documentation=https://github.com/ddvk/rmfakecloud-proxy
+After=home.mount network.target
+Before=xochitl.service launcher.service
+ConditionPathExists=/opt/etc/rmfakecloud-proxy/enabled
+ConditionPathExists=/opt/etc/rmfakecloud-proxy/config
+
+[Service]
+Environment=HOME=/home/root
+ExecStart=/opt/bin/rmfakecloud-proxy -c /opt/etc/rmfakecloud-proxy/config
+Restart=on-failure
+
+[Install]
+WantedBy=multi-user.target