Use the source version of drake's install_prereqs for external examples

Previously, the binary version of the script was called in addition to
replicating much of the source version. With this change, the
copy-and-paste is removed.

drake_bazel_external/.github/setup

@@ -4,8 +4,18 @@
 set -euxo pipefail
 
 cd $(dirname "${BASH_SOURCE}")
+
 sudo ./ubuntu_setup
 
+# Download the drake source
+wget -O drake.tar.gz \
+  https://github.com/RobotLocomotion/drake/archive/master.tar.gz
+trap 'rm -f drake.tar.gz' EXIT
+tar -xf drake.tar.gz
+
+# Install the source prereqs
+sudo ./drake-master/setup/ubuntu/install_prereqs.sh
+
 cat > "${HOME}/.bazelrc" << EOF
 startup --output_user_root=${WORKSPACE}/_bazel_${USER}
 test --color=yes

drake_bazel_external/.github/ubuntu_setup

@@ -3,10 +3,25 @@
 
 set -euxo pipefail
 
+if [[ "${EUID:-}" -ne 0 ]]; then
+  echo 'This script must be run as root' >&2
+  exit 2
+fi
+
 echo 'APT::Acquire::Retries "4";' > /etc/apt/apt.conf.d/80-acquire-retries
 echo 'APT::Get::Assume-Yes "true";' > /etc/apt/apt.conf.d/90-get-assume-yes
 
 export DEBIAN_FRONTEND='noninteractive'
 
-cd $(dirname "${BASH_SOURCE}")/..
-setup/install_prereqs
+apt-get update
+apt-get install --no-install-recommends lsb-release
+
+if [[ "$(lsb_release -sc)" != 'jammy' ]]; then
+  echo 'This script requires Ubuntu 22.04 (Jammy)' >&2
+  exit 3
+fi
+
+apt-get install --no-install-recommends $(cat <<EOF
+  wget
+EOF
+)

drake_bazel_external/README.md

@@ -7,10 +7,14 @@ For an introduction to Bazel, refer to
 
 ## Instructions
 
-First, install the required Ubuntu packages:
+First, download the drake source and run the source setup script to install
+the required Ubuntu packages:
 
 ```
-sudo setup/install_prereqs
+wget -O drake.tar.gz \
+  https://github.com/RobotLocomotion/drake/archive/master.tar.gz
+tar -xf drake.tar.gz
+sudo ./drake-master/setup/ubuntu/install_prereqs.sh
 ```
 
 Then, to build and test all apps:

drake_cmake_external/.github/ci_build_test

@@ -13,7 +13,7 @@ pushd build
 export LD_LIBRARY_PATH="${PWD}/install/lib${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}"
 
 cmake ..
-make
+cmake --build .
 
 cd drake_external_examples
 ctest -V .

drake_cmake_external/.github/setup

@@ -4,8 +4,18 @@
 set -euxo pipefail
 
 cd $(dirname "${BASH_SOURCE}")
+
 sudo ./ubuntu_setup
 
+# Download the drake source
+wget -O drake.tar.gz \
+  https://github.com/RobotLocomotion/drake/archive/master.tar.gz
+trap 'rm -f drake.tar.gz' EXIT
+tar -xf drake.tar.gz
+
+# Install the source prereqs
+sudo ./drake-master/setup/ubuntu/install_prereqs.sh
+
 cat > "${HOME}/.bazelrc" << EOF
 startup --output_user_root=${WORKSPACE}/_bazel_${USER}
 test --color=yes

drake_cmake_external/README.md

@@ -2,14 +2,32 @@
 
 This pulls in Drake using the CMake `ExternalProject_Add(drake)` mechanism.
 
-To build all apps using CMake and Make:
+## Instructions
+
+First, download the drake source and run the source setup script to install
+the required Ubuntu packages:
+
+```
+wget -O drake.tar.gz \
+  https://github.com/RobotLocomotion/drake/archive/master.tar.gz
+tar -xf drake.tar.gz
+sudo ./drake-master/setup/ubuntu/install_prereqs.sh
+```
+
+Keep in mind that within the top-level CMakeLists, the drake source is once
+again downloaded as an external project. If the CMakeLists is modified to use
+a specific version of drake other than master, and any dependencies have
+changed within that version, then the same version must also be used above.
+
+Once all necessary dependencies have been installed, build and run tests
+using CMake:
 
 ```
 mkdir build
 cd build
 cmake ..
-make
-```
-
-**Under Construction**
+cmake --build .
 
+cd drake_external_examples
+ctest -V .
+```