doc: Add developer information

doc/developer_information.rst

@@ -0,0 +1,55 @@
+Developer Information
+#####################
+
+Reproducible Builds
+*******************
+
+This section describes how to reproduce the official released binaries for
+restic for version 0.9.3 and later. The binary produced depends on the
+following things:
+
+ * The source code for the release
+ * The exact version of the official `Go compiler <https://golang.org>`__ used to produce the binaries (running ``restic version`` will print this)
+ * The architecture and operating system the Go compiler runs on (Linux, ``amd64``)
+ * The path where the source code is extracted to (``/restic``)
+ * The path to the Go compiler (``/usr/local/go``)
+ * The build tags (for official binaries, it's the tag ``selfupdate``)
+ * The environment variables (mostly ``$GOOS``, ``$GOARCH``, ``$CGO_ENABLED``)
+
+In addition, The compressed ZIP files for Windows depends on the modification
+timestamp of the binary contained in it. In order to reproduce the exact same
+ZIP file every time, we update the timestamp of the file ``VERSION`` in the
+source code archive and set the timezone to Europe/Berlin.
+
+In the following example, we'll use the file ``restic-0.9.3.tar.gz`` and Go
+1.11.1 to reproduce the released binaries.
+
+1. Download and extract the Go compiler into ``/usr/local/go``:
+
+.. code::
+
+    # cd /usr/local
+    # curl -L https://dl.google.com/go/go1.11.1.linux-amd64.tar.gz | tar xz
+
+2. Extract the restic source code into ``/restic``
+
+.. code::
+
+    # mkdir /restic
+    # cd /restic
+    # TZ=Europe/Berlin curl -L https://github.com/restic/restic/releases/download/v0.9.3/restic-0.9.3.tar.gz | tar xz --strip-components=1
+
+3. Build the binaries for Windows and Linux:
+
+.. code::
+
+    $ export PATH=/usr/local/go/bin:$PATH
+    $ go version
+    go version go1.11.1 linux/amd64
+
+    $ GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -mod=vendor -ldflags "-s -w" -tags selfupdate -o restic_linux_amd64 ./cmd/restic
+    $ bzip2 restic_linux_amd64
+
+    $ GOOS=windows GOARCH=amd64 CGO_ENABLED=0 go build -mod=vendor -ldflags "-s -w" -tags selfupdate -o restic_windows_amd64.exe ./cmd/restic
+    $ touch --reference VERSION restic_windows_amd64.exe
+    $ TZ=Europe/Berlin zip -q -X restic_windows_amd64.zip restic_windows_amd64.exe

doc/index.rst

@@ -19,3 +19,4 @@ Restic Documentation
    110_talks
    faq
    manual_rest
+   developer_information