Add install from source instructions to README

README.md

@@ -118,6 +118,134 @@ Installing on Windows is as simple as pasting the above snippet into PowerShell.
 iwr https://windows.spacetimedb.com -useb | iex
 ```
 
+#### Installing from Source
+
+A quick note on installing from source: we recommend that you don't install from source unless there is a feature that is available in `master` that hasn't been released yet, otherwise follow the official installation instructions.
+
+##### MacOS + Linux
+
+Installing on macOS + Linux is pretty straightforward. First we are going to build all of the binaries that we need:
+
+```bash
+# Install rustup, you can skip this step if you have cargo and the wasm32-unknown-unknown target already installed.
+curl https://sh.rustup.rs -sSf | sh
+# Clone SpacetimeDB
+git clone https://github.com/clockworklabs/SpacetimeDB
+# Build and install the CLI
+cd SpacetimeDB
+cargo build --locked --release -p spacetimedb-standalone -p spacetimedb-update -p spacetimedb-cli
+
+# Create directories
+mkdir -p ~/.local/bin
+export STDB_VERSION="$(./target/release/spacetimedb-cli --version | sed -n 's/.*spacetimedb tool version \([0-9.]*\);.*/\1/p')"
+mkdir -p ~/.local/share/spacetime/bin/$STDB_VERSION
+
+# Install the update binary
+cp target/release/spacetimedb-update ~/.local/bin/spacetime
+cp target/release/spacetimedb-cli ~/.local/share/spacetime/bin/$STDB_VERSION
+cp target/release/spacetimedb-standalone ~/.local/share/spacetime/bin/$STDB_VERSION
+```
+
+At this stage you'll need to add ~/.local/bin to your path if you haven't already.
+
+```
+# Please add the following line to your shell configuration and open a new shell session:
+export PATH="$HOME/.local/bin:$PATH"
+
+```
+
+Then finally set your SpacetimeDB version:
+```
+
+# Then, in a new shell, set the current version:
+spacetime version use $STDB_VERSION
+
+# If STDB_VERSION is not set anymore then you can use the following command to list your versions:
+spacetime version list
+```
+
+You can verify that the correct version has been installed via `spacetime --version`.
+
+##### Windows
+
+Building on windows is a bit more complicated. You'll need a slightly different version of perl compared to what comes pre-bundled in most Windows terminals. We recommend [Strawberry Perl](https://strawberryperl.com/). You may also need access to an `openssl` binary which actually comes pre-installed with [Git for Windows](https://git-scm.com/downloads/win). Also, you'll need to install [rustup](https://rustup.rs/) for Windows.
+
+In a Git for Windows shell you should have something that looks like this:
+```
+$ which perl
+/c/Strawberry/perl/bin/perl
+$ which openssl
+/mingw64/bin/openssl
+$ which cargo 
+/c/Users/<user>/.cargo/bin/cargo
+```
+
+If that looks correct then you're ready to proceed!
+
+```powershell
+# Clone SpacetimeDB
+git clone https://github.com/clockworklabs/SpacetimeDB
+
+# Build and install the CLI
+cd SpacetimeDB
+cargo build --locked --release -p spacetimedb-standalone -p spacetimedb-update -p spacetimedb-cli
+
+# Create directories
+$stdbDir = "$HOME\AppData\Local\SpacetimeDB"
+$stdbVersion = & ".\target\release\spacetimedb-cli" --version | Select-String -Pattern 'spacetimedb tool version ([0-9.]+);' | ForEach-Object { $_.Matches.Groups[1].Value }
+New-Item -ItemType Directory -Path "$stdbDir\bin\$stdbVersion" -Force | Out-Null
+
+# Install the update binary
+Copy-Item "target\release\spacetimedb-update.exe" "$stdbDir\spacetime.exe"
+Copy-Item "target\release\spacetimedb-cli.exe" "$stdbDir\bin\$stdbVersion\"
+Copy-Item "target\release\spacetimedb-standalone.exe" "$stdbDir\bin\$stdbVersion\"
+
+```
+
+Now add the directory we just created to your path. We recommend adding it to the system path because then it will be available to all of your applications (including Unity3D). After you do this, restart your shell!
+
+```
+%USERPROFILE%\AppData\Local\SpacetimeDB
+```
+
+Then finally, open a new shell and use the installed SpacetimeDB version:
+```
+spacetime version use $stdbVersion
+
+# If stdbVersion is no longer set, list versions using the following command:
+spacetime version list
+```
+
+You can verify that the correct version has been installed via `spacetime --version`.
+
+If you're using Git for Windows you can follow these instructions instead:
+
+```bash
+# Clone SpacetimeDB
+git clone https://github.com/clockworklabs/SpacetimeDB
+# Build and install the CLI
+cd SpacetimeDB
+# Build the CLI binaries - this takes a while on windows so go grab a coffee :)
+cargo build --locked --release -p spacetimedb-standalone -p spacetimedb-update -p spacetimedb-cli
+
+# Create directories
+export STDB_VERSION="$(./target/release/spacetimedb-cli --version | sed -n 's/.*spacetimedb tool version \([0-9.]*\);.*/\1/p')"
+mkdir -p ~/AppData/Local/SpacetimeDB/bin/$STDB_VERSION
+
+# Install the update binary
+cp target/release/spacetimedb-update ~/AppData/Local/SpacetimeDB/spacetime
+cp target/release/spacetimedb-cli ~/AppData/Local/SpacetimeDB/bin/$STDB_VERSION
+cp target/release/spacetimedb-standalone ~/AppData/Local/SpacetimeDB/bin/$STDB_VERSION
+
+# Now add the directory we just created to your path. We recommend adding it to the system path because then it will be available to all of your applications (including Unity3D). After you do this, restart your shell!
+# %USERPROFILE%\AppData\Local\SpacetimeDB
+
+# Set the current version
+spacetime version use $STDB_VERSION
+```
+
+You can verify that the correct version has been installed via `spacetime --version`.
+
 #### Running with Docker
 
 If you prefer to run Spacetime in a container, you can use the following command to start a new instance.