New tool, docs/version-check

Intended to be run from nightly Cirrus cron job.

 1) Queries github for highest-sorting (not necessarily "latest") tag
 2) Checks that the Windows MSI exists, fails if not
 3) Cross-checks markdown files to ensure they have up-to-date links

When run interactively, it will auto-update the .md files
to show and link to the latest version. This makes it easy
for anyone to then submit an update PR.

And, it turns out that MSI is obsolete, the new thing is EXE.
Update the tutorials to reflect that.

Signed-off-by: Ed Santiago <santiago@redhat.com>

contrib/cirrus/runner.sh

@@ -275,6 +275,7 @@ function _run_altbuild() {
         *Windows*)
             make podman-remote-release-windows_amd64.zip
             make podman.msi
+            docs/version-check
             ;;
         *Without*)
             make build-no-cgo

docs/tutorials/mac_win_client.md

@@ -16,7 +16,8 @@ The remote client uses a client-server model. You need Podman installed on a Lin
 
 ### Windows
 
-Installing the Windows Podman client begins by downloading the Podman Windows installer. The Windows installer is built with each Podman release and is downloadable from its [release description page](https://github.com/containers/podman/releases/latest).  The Windows installer file is named `podman-v.#.#.#.msi`, where the `#` symbols represent the version number of Podman.  At the time of this writing, the file name is `podman-v3.4.4.msi`. You can also build the installer from source using the `podman.msi` Makefile endpoint.
+Installing the Windows Podman client begins by downloading the Podman Windows installer. The Windows installer is built with each Podman release and is downloadable from its [release description page](https://github.com/containers/podman/releases/latest).  The Windows installer file is named `podman-#.#.#-setup.exe`, where the `#` symbols represent the version number of Podman.
+As of 2022-11-09 the latest version is [v4.3.0](https://github.com/containers/podman/releases/download/v4.3.0/podman-v4.3.0-setup.exe).
 
 Once you have downloaded the installer to your Windows host, simply double click the installer and Podman will be installed.  The path is also set to put `podman` in the default user path.
 

docs/tutorials/podman-for-windows.md

@@ -41,13 +41,14 @@ Installing the Windows Podman client begins by downloading the Podman Windows
 installer. The Windows installer is built with each Podman release and can be
 downloaded from the official
  [Github release page](https://github.com/containers/podman/releases). The
-Windows installer file is named podman-v.#.#.#.msi, where the # symbols
+Windows installer file is named podman-#.#.#-setup.exe, where the # symbols
 represent the version number of Podman. Be sure to download a 4.1 or later
 release for the capabilities discussed in this guide.
+As of 2022-11-09 the latest version is [v4.3.0](https://github.com/containers/podman/releases/download/v4.3.0/podman-v4.3.0-setup.exe).
 
 ![Installing Podman 4.1.0](podman-win-install.jpg)
 
-Once downloaded, simply run the MSI file, and relaunch a new terminal. After
+Once downloaded, simply run the EXE file, and relaunch a new terminal. After
 this point, podman.exe will be present on your PATH, and you will be able to run
 the `podman machine init` command to create your first machine.
 

docs/version-check

@@ -0,0 +1,115 @@
+#!/bin/bash
+#
+# docs/version-check - cross-check that doc pages link to latest version
+#
+# As of 2022-11-10 this is only useful for Windows, but I think it'd be
+# nice to be able to auto-update more pages with up-to-date links. If
+# we do that, there are some exe assumptions that need to be cleaned up.
+#
+ME=$(basename $0)
+
+URLBASE="https://github.com/containers/podman"
+
+docfiles=(
+    docs/tutorials/mac_win_client.md
+    docs/tutorials/podman-for-windows.md
+)
+
+set -eo pipefail
+
+function warn() {
+    echo "$ME: $*" >&2
+}
+
+# Setup check: exit gracefully unless we're in the desired environment
+if [[ -n "$CIRRUS_PR" ]]; then
+    warn "we don't run on PRs"
+    exit 0
+fi
+
+if [[ -n "$CIRRUS_CRON" ]]; then
+    if [[ "$CIRRUS_CRON" != "nightly" ]]; then
+        warn "Only meaningful when CIRRUS_CRON=nightly (it is '$CIRRUS_CRON')"
+        exit 0
+    fi
+fi
+
+# No sense running on release branches
+current_branch=$(git rev-parse --abbrev-ref HEAD)
+if [[ "$current_branch" != "main" ]]; then
+    warn "only meaningful on 'main' (current branch is '$current_branch')"
+    if [[ ! -t 0 ]]; then
+        exit 0
+    fi
+fi
+
+# Okay. Fetch the highest-sorting tag. THIS MAY NOT BE THE SAME AS THE NEWEST!
+LATEST=$(git ls-remote --tags --refs --sort="v:refname" "${URLBASE}.git" \
+             | sed 's/.*\///' \
+             | grep -E '^v[0-9]+\.[0-9]+\.[0-9]+$' \
+             | tail -n1)
+
+echo LATEST=$LATEST
+
+# The "#v" thing strips leading "v", because filename is numbers only
+exe="${URLBASE}/releases/download/${LATEST}/podman-${LATEST#v}-setup.exe"
+
+# EXE must exist. The convoluted {}||: is to handle errors gracefully
+rc=
+{
+    found=$(curl --head --silent -o /dev/null --write-out '%{http_code}' $exe)
+    rc=$?
+} || :
+
+if [[ $rc -ne 0 ]]; then
+    warn "FATAL: curl failed, rc=$rc, on $exe"
+    exit 1
+fi
+
+if [[ $found = 404 ]]; then
+    warn "FATAL: Windows EXE missing: $exe"
+    exit 1
+fi
+
+# Expect 200 or 3xx; anything else is an error
+if [[ ! $found =~ ^[23] ]]; then
+    warn "FATAL: Windows EXE: HTTP code $found on $exe"
+    exit 1
+fi
+
+# Cross-check all doc files for an up-to-date "latest version is" line.
+fail=0
+as_of='^As of .* the latest version is'
+for md in ${docfiles[*]}; do
+    as_of_match=$(grep -E "$as_of" $md)
+    if [[ -z "$as_of_match" ]]; then
+        warn "$md does not have an 'As of ... the latest version is' line"
+        fail=1
+        continue
+    fi
+
+    md_latest=$(sed -ne 's;^.* version is \[\(.*\)\](.*;\1;' <<<"$as_of_match")
+    if [[ -n "$md_latest" ]]; then
+        warn "$md: No version found in '$as_of_match'"
+        fail=1
+        continue
+    fi
+
+    if [[ "$md_latest" != "$LATEST" ]]; then
+        warn "$md: needs updating."
+        # Running interactively? Do it.
+        if [[ -t 0 ]]; then
+            today=$(date --iso-8601=date)
+            sed -i "s;$as_of.*\$;As of $today the latest version is \[$LATEST\]\($exe\).;" $md
+        else
+            warn "Please run this script in an interactive shell, and I'll fix it."
+            fail=1
+        fi
+    fi
+done
+
+if [[ $fail -ne 0 ]] && [[ -t 0 ]]; then
+    git status --untracked=no
+fi
+
+exit $fail