add rudimentary release script

Author: dgoffredo

.gitignore

@@ -15,3 +15,6 @@
 
 # file used as part of the build configuration
 /nginx-tag
+
+# scratch directory for preparing releases
+/.release/

bin/docker_build.sh

@@ -67,7 +67,7 @@ ask() {
 
 built_tag="nginx-datadog-build-$nginx_tag"
 if ! ask "Build image compatible with nginx:$nginx_tag and tag as $built_tag?"; then
-    exit
+    exit 1
 fi
 docker build --build-arg "BASE_IMAGE=nginx:$nginx_tag" --tag "$built_tag" "$repo"
 

bin/release.sh

@@ -0,0 +1,50 @@
+#!/bin/sh
+
+# Create a github draft prelease.
+
+set -e
+
+REPO=$(dirname "$(dirname "$(realpath "$0")")")
+cd "$REPO"
+release_tag=$(<release.json jq --raw-output .release_tag)
+
+build_module() {
+    printf '%s' "$nginx_tag" >nginx-tag
+    
+    # `docker build` the build image, if it isn't already built.
+    bin/docker_build.sh --yes
+    # clean slate
+    make clobber
+    # Build the nginx module in the build image created above.
+    make build-in-docker
+    cp .docker-build/libngx_http_datadog_module.so .release/ngx_http_datadog_module.so
+    cd .release
+    tar cvzf "${nginx_tag}-ngx_http_datadog_module.so.tgz" ngx_http_datadog_module.so
+    gpg --armor --detach-sign "${nginx_tag}-ngx_http_datadog_module.so.tgz"
+    rm ngx_http_datadog_module.so
+    cd -
+}
+
+# Build one module per nginx tag listed in $REPO/release.json
+# But first, warn and prompt if there are files in .release/
+mkdir -p .release
+if [ "$(ls .release | wc -l)" -ne 0 ]; then
+    while true; do
+        printf '.release/ is not empty.  Delete contents first?\n'
+        ls .release
+        printf ' [yN] '
+        read response
+        case "$response" in
+          y|Y|yes|YES) rm .release/*; break ;;
+          n|N|no|NO|"") break ;;
+          *) printf "\nI don't understand.\n" ;;
+        esac
+    done
+fi
+
+<release.json jq --raw-output .nginx_tags[] | { while read nginx_tag || [ -n "$nginx_tag" ]; do
+    build_module "$nginx_tag"
+done }
+
+cd .release
+gh release create --prerelease --draft --title "$release_tag" --notes 'TODO' "$release_tag" *.tgz *.asc

release.json

@@ -0,0 +1,7 @@
+{
+    "release_tag": "v0.3.0",
+    "nginx_tags": [
+        "1.18.0-alpine",
+        "1.19.1"
+    ]
+}