Add NO_CLUSTER variable

Prevents `pg-start` from initializing and starting a cluster. Add docs
to describe it and a use case.

Also fix some shell issues reported by shellcheck.

.github/workflows/cicd.yml

@@ -32,6 +32,15 @@ jobs:
         run: "docker run -w /repo --rm --volume \"$(pwd)/test:/repo\" -e AS_USER=worker pgxn-tools-test ./runtest.sh ${{ matrix.pg }} zip"
       - name: Test Zip with zip excluded file
         run: "docker run -w /repo --rm --volume \"$(pwd)/test:/repo\" pgxn-tools-test ./runtest.sh ${{ matrix.pg }} zip yes"
+      # Test NO_CLUSTER
+      - name: Test NO_CLUSTER
+        env: { NO_CLUSTER: true }
+        run: |-
+          docker run -w /repo --rm pgxn-tools-test pg-start ${{ matrix.pg }}
+          if [ -d /var/lib/postgresql/16/test ]; then
+            echo "ERROR: /var/lib/postgresql/16/test should not exist!"
+            exit 1;
+          fi
 
   publish:
     # Publish for a tag starting with v.

README.md

@@ -197,6 +197,31 @@ modified the `postgresql.conf` file), use `pg_ctlcluster` like so:
 pg_ctlcluster 12 test restart
 ```
 
+For finer control over running the PostgreSQL cluster, set the `NO_CLUSTER`
+environment variable to prevent `pg-start` from creating and starting a cluster:
+
+```sh
+env NO_CLUSTER=1 pg-start 14
+```
+
+This will simply install Postgres 14; to start it, use the [`pg_createcluster`]
+command, like so:
+
+```sh
+pg_createcluster --start 14 my14 -p 5414 -- -A trust
+```
+
+This starts a cluster named "my14" on port 5414. This technique is useful to run
+multiple clusters, even different versions at once; just given them unique names and
+ports to run on:
+
+```sh
+env NO_CLUSTER=1 pg-start 15
+pg_createcluster --start 15 my15 -p 5415 -- -A trust
+env NO_CLUSTER=1 pg-start 16
+pg_createcluster --start 16 my16 -p 5416 -- -A trust
+```
+
 ### [`pg-build-test`]
 
 ``` sh
@@ -411,6 +436,7 @@ Copyright (c) 2020-2024 The PGXN Maintainers. Distributed under the
   [upload-release-asset]: https://github.com/actions/upload-release-asset
   [git-archive-all]: https://github.com/Kentzo/git-archive-all
   [PGXN]: https://pgxn.org/ "The PostgreSQL Extension Network"
+  [`pg_createcluster`]: https://manpages.debian.org/buster/postgresql-common/pg_createcluster.1.en.html
   [David E. Wheeler]: https://justatheory.com/
   [PostgreSQL License]: https://opensource.org/licenses/PostgreSQL
   [LICENSE]: LICENSE

bin/entrypoint.sh

@@ -6,7 +6,6 @@ set -e
 [ -z "$AS_USER" ] && exec "$@"
 
 USER_ID=${LOCAL_UID:-1001}
-USERNAME=worker
 
 echo "Starting with UID $USER_ID"
 useradd --system --create-home --shell /bin/bash -g root -G sudo -u $USER_ID "$AS_USER"

bin/pg-start

@@ -19,4 +19,4 @@ if [ $# -gt 1 ]; then
     sudo apt-get -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install -y "${@:2}"
 fi
 
-sudo pg_createcluster --start $PGVERSION test -p "${PGPORT:-5432}" -- -A trust
+[ -z ${NO_CLUSTER+x} ] && sudo pg_createcluster --start "$PGVERSION" test -p "${PGPORT:-5432}" -- -A trust

test/runtest.sh

@@ -10,7 +10,7 @@ prefix=widget-1.0.0
 zipfile="${prefix}.zip"
 extrafile=extra.txt
 
-cd $(dirname "$0")
+cd "$(dirname "$0")"
 
 if [ -n "$testopts" ]; then
     # Use GIT_BUNDLE_OPTS to add an untracked file to the Git archive or
@@ -39,6 +39,7 @@ if [ "$expectutil" = "git" ]; then
     # Make sure runtest.sh was omitted thanks to .gitattributes.
     if [ -f "$prefix/runtests.sh" ]; then
         echo 'ERROR:  Zip file contains runtests.sh and should not'
+        # shellcheck disable=SC2016
         echo '        Did pgxn-bundle use `zip` instead of `git archive`?'
         exit 2
     fi
@@ -51,6 +52,7 @@ else
     # Make sure runtest.sh is included in the zip file.
     if [ ! -f "$prefix/runtest.sh" ]; then
         echo 'ERROR:  Zip file contains runtests.sh and should not'
+        # shellcheck disable=SC2016
         echo '        Did pgxn-bundle use `git archive` instead of `zip`?'
         exit 2
     fi