Add script to run tests inside a docker container easily

.github/workflows/run_tests.yml

@@ -4,11 +4,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           submodules: true
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.2
+          ruby-version: '3.2'
       - run: gem install jls-grok minitest
       - run: ruby test/test.rb

README.md

@@ -36,7 +36,7 @@ Tests
 
 In the `test/` directory, there is a test suite that tries to make sure that no previously supported log line will break because of changing common patterns and such. It also returns results a lot faster than doing `sudo service logstash restart` :-).
 
-The test suite needs the patterns provided by Logstash, you can easily pull these from github by running `git submodule update --init`. To run the test suite, you also need `ruby 2.2` or higher, and the `jls-grok` and `minitest` gems. Then simply execute `ruby test/test.rb`.
+The test suite needs the patterns provided by Logstash, you can easily pull these from github by running `git submodule update --init`. To run the test suite, you also need `ruby 2.2` or higher, and the `jls-grok` and `minitest` gems. Then simply execute `ruby test/test.rb`. NOTE: The whole test process can now be executed inside a docker container, simply by running the `runtests.sh` script.
 
 Adding new test cases can easily be done by creating new yaml files in the test directory. Each file specifies a grok pattern to validate, a sample log line, and a list of expected results.
 

runtests.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+set -eux
+
+git submodule update --init
+
+docker build -t postfix-grok-patterns-runtests - <<EOF
+FROM ruby:slim
+RUN gem install jls-grok minitest
+EOF
+
+TESTPATH=/runtests
+docker run -v $(pwd):"${TESTPATH}" postfix-grok-patterns-runtests sh -c "cd ${TESTPATH} && ruby test/test.rb"