Switch hack to use the new envtest tool

We can now drop the `setup-envtest.sh` script, and instead just use
`source <(setup-envtest fetch -k ${version} -p env)` (plus a couple
lines to install setup-envtest ;-)).

hack/check-everything.sh

@@ -20,16 +20,27 @@ set -o pipefail
 
 hack_dir=$(dirname ${BASH_SOURCE})
 source ${hack_dir}/common.sh
-source ${hack_dir}/setup-envtest.sh
 
 tmp_root=/tmp
 kb_root_dir=$tmp_root/kubebuilder
 
 ENVTEST_K8S_VERSION=${ENVTEST_K8S_VERSION:-"1.19.2"}
 
-fetch_envtest_tools "$kb_root_dir"
-fetch_envtest_tools "${hack_dir}/../pkg/internal/testing/integration/assets"
-setup_envtest_env "$kb_root_dir"
+# set up envtest tools if necessary
+
+header_text "installing envtest tools@${ENVTEST_K8S_VERSION} with setup-envtest if necessary"
+tmp_bin=/tmp/cr-tests-bin
+(
+    # don't presume to install for the user
+    cd ${hack_dir}/../tools/setup-envtest
+    GOBIN=${tmp_bin} go install .
+)
+source <(${tmp_bin}/setup-envtest use --use-env -p env ${ENVTEST_K8S_VERSION})
+
+# link the assets into integration
+for tool in kube-apiserver etcd kubectl; do
+    ln -f -s "${KUBEBUILDER_ASSETS:?unable find envtest assets}/${tool}" "${hack_dir}/../pkg/internal/testing/integration/assets/bin/${tool}"
+done
 
 ${hack_dir}/verify.sh
 ${hack_dir}/test-all.sh

tools/setup-envtest/README.md

@@ -32,23 +32,23 @@ setup-envtest cleanup <1.16
 
 # use the value from $KUBEBUILDER_ASSETS if set, otherwise follow the normal
 # logic for 'use'
-setup-envtest --use-env=always
+setup-envtest --use-env
 
 # use the value from $KUBEBUILDER_ASSETS if set, otherwise use the latest
 # installed version
-setup-envtest use -i --use-env=always
+setup-envtest use -i --use-env
 
 # sideload a pre-downloaded tarball as Kubernetes 1.16.2 into our store
 setup-envtest sideload 1.16.2 < downloaded-envtest.tar.gz
 ```
 
 ## Where does it put all those binaries?
 
-By default, binaries are stored in an OS-specific cache directory, as per
-the OS's conventions (see Go's `os.UserCacheDir`).
+By default, binaries are stored in a subdirectory of an OS-specific data
+directory, as per the OS's conventions. 
 
-For example, on Linux this is `$XDG_CACHE_DIR`, or just `~/.config` if
-that's unset.
+On Linux, this is `$XDG_DATA_HOME`; on Windows, `%LocalAppData`; and on
+OSX, `~/Library/Application Support`.
 
 There's an overall folder that holds all files, and inside that is
 a folder for each version/platform pair.  The exact directory structure is
@@ -57,6 +57,19 @@ expected by envtest.  You should always use `setup-envtest fetch` or
 `setup-envtest switch` (generally with the `-p path` or `-p env` flags) to
 get the directory that you should use.
 
+## Why do I have to do that `source <(blah blah blah)` thing
+
+This is a normal binary, not a shell script, so we can't set the parent
+process's environment variables.  If you use this by hand a lot and want
+to save the typing, you could put something like the following in your
+`~/.bashrc` (or similar):
+
+```shell
+function setup-envtest() {
+    export KUBEBUILDER_ASSETS=$(GOPATH/bin/setup-envtest -p path $@)
+}
+```
+
 ## What if I don't want to talk to the internet?
 
 There are a few options.
@@ -69,16 +82,16 @@ Then, you have a few options for managing your binaries:
 
 - If you don't *really* want to manage with this tool, or you want to
   respect the $KUBEBUILDER_ASSETS variable if it's set to something
-  outside the store, use the `use --use-env=always -i` command.
+  outside the store, use the `use --use-env -i` command.
 
-  `--use-env=always` makes the command unconditionally use the value of
+  `--use-env` makes the command unconditionally use the value of
   KUBEBUILDER_ASSETS as long as it contains the required binaries, and
   `-i` indicates that we only ever want to work with installed binaries
   (no reaching out the the remote GCS storage).
 
   As noted about, you can use `ENVTEST_INSTALLED_ONLY=true` to switch `-i`
-  on by default, and you can use `ENVTEST_USE_ENV=always` to switch
-  `--use-env=always` on by default.
+  on by default, and you can use `ENVTEST_USE_ENV=true` to switch
+  `--use-env` on by default.
 
 - If you want to use this tool, but download your gziped tarballs
   separately, you can use the `sideload` command.  You'll need to use the