chore: makes docker build produce a runnable wait-for image (#2) Than…

…ks to @gesellix

This change alters the Dockerfile used in this project. Now, it is a multi-stage Dockerfile with one stage which can be used to run the tests and one stage which is a runnable image including the wait-for script.

In this way, we run the tests in a similar-ish* environment as what the script runs in when distributed as a container image.

*The tests are setup and ran using Node and npm. The final image doesn't include those two dependencies to create a more slim image.

Co-authored-by: Adriaan Knapen <[email protected]>

.github/workflows/ci.yml

@@ -11,12 +11,12 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-      
+
     - name: Build the test Docker image
-      run: docker build --tag wait-for .
-      
+      run: docker build --no-cache --target test-env --tag wait-for-test .
+
     - name: Run the tests
-      run: docker run --tty wait-for
+      run: docker run wait-for-test
 
   release:
     name: Release

.gitignore

@@ -3,3 +3,5 @@
 
 # Node
 node_modules
+
+delay

Dockerfile

@@ -1,20 +1,38 @@
-FROM node:16-alpine@sha256:a9b9cb880fa429b0bea899cd3b1bc081ab7277cc97e6d2dcd84bd9753b2027e1
+#################
+#  Base layer   #
+#################
+FROM alpine:edge as runtime-base
 
-# Install bash
-RUN apk add --no-cache bash
+# Install all dependencies
+RUN apk add --no-cache bash nmap-ncat wget
 
-# Create working directory
-RUN mkdir -p /app
 WORKDIR /app
 
+#################
+#  Test image   #
+#################
+FROM runtime-base as test-env
+
+# Install Node.js
+RUN apk add --no-cache nodejs npm
+
 # Install all Node dependencies
 COPY package.json /app/
 COPY package-lock.json /app/
-
 RUN npm ci
 
 # Copy source code
 COPY . /app/
 
-# Define default command
+# Perform tests when running this test-env container
 CMD npm test
+
+#################
+# Runtime image #
+#################
+FROM runtime-base as runtime
+
+COPY ./wait-for .
+
+ENTRYPOINT ["./wait-for"]
+CMD ["--help"]

README.md

@@ -123,10 +123,10 @@ services:
 
 Testing is done using [bats](https://github.com/bats-core/bats-core), which we install using [npm](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm). 
 
-For reproducability, we run our tests inside Docker, such that we have control over the version of [bash](<https://en.wikipedia.org/wiki/Bash_(Unix_shell)>) we're testing against.
+For reproducibility, we run our tests inside Docker, such that we have control over the version of [bash](<https://en.wikipedia.org/wiki/Bash_(Unix_shell)>) we're testing against.
 
 ```bash
-docker build -t wait-for .
+docker build --target test-env --tag wait-for .
 docker run --rm -t wait-for
 ```