doc: Readd instructions for downloading releases to getting-starting.md

The simplifications of firecracker-microvm#3484 removed instructions for how to download firecracker releases from the getting started guide, instead only describing how to compiel firecracker from source. This commit re-introduces these instructions due to customer request. Closes firecracker-microvm#3531 Signed-off-by: Patrick Roy <[email protected]>
CuriousGeorgiy · Aug 24, 2023 · 1639a95 · 1639a95
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commit 1639a95
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diff --git a/docs/getting-started.md b/docs/getting-started.md
@@ -66,6 +66,12 @@ an execution jail, set up by the [`jailer`](../src/jailer/) binary. This is how
 our [integration test suite](#running-the-integration-test-suite) does it. This
 guide will not use the [`jailer`](../src/jailer/).
 
+### Getting a rootfs and Guest Kernel Image
+
+To successfully start a microVM with you will need an uncompressed Linux kernel binary,
+and an ext4 file system image (to use as rootfs). This guide uses a 5.10 kernel image
+with a Ubuntu 22.04 rootfs from our CI:
+
 ```bash
 ARCH="$(uname -m)"
 
@@ -80,6 +86,33 @@ wget https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.5/${ARCH}/ubuntu-2
 
 # Set user read permission on the ssh key
 chmod 400 ./ubuntu-22.04.id_rsa
+```
+
+### Getting a Firecracker Binary
+
+There are two options for getting a firecracker binary:
+
+- Downloading an official firecracker release from our
+  [release page](https://github.com/firecracker-microvm/firecracker/releases), or
+- Building firecracker from source.
+
+To download the latest firecracker release, run
+
+```bash
+ARCH="$(uname -m)"
+release_url="https://github.com/firecracker-microvm/firecracker/releases"
+latest=$(basename $(curl -fsSLI -o /dev/null -w  %{url_effective} ${release_url}/latest))
+curl -L ${release_url}/download/${latest}/firecracker-${latest}-${ARCH}.tgz \
+| tar -xz
+
+# Rename the binary to "firecracker"
+mv release-${latest}-$(uname -m)/firecracker-${latest}-${ARCH} firecracker
+```
+
+To instead build firecracker from source, you will need to have `docker` installed:
+
+```bash
+ARCH="$(uname -m)"
 
 # Clone the firecracker repository
 git clone https://github.com/firecracker-microvm/firecracker
@@ -96,6 +129,17 @@ sudo systemctl start docker
 #
 sudo ./firecracker/tools/devtool build
 
+# Rename the binary to "firecracker"
+mv ./firecracker/build/cargo_target/${ARCH}-unknown-linux-musl/debug/firecracker firecracker
+```
+
+### Starting Firecracker
+
+Running firecracker will require two terminals, the first one running the
+firecracker binary, and a second one for communicating with the firecracker
+process via HTTP requests:
+
+```bash
 API_SOCKET="/tmp/firecracker.socket"
 
 # Remove API unix socket