Add workflow, link checker and modify Readme (#30)

* Add test workflow for dockerfile build
* Add link checker workflow
* Modify Readme to divide input for build strategies

Signed-off-by: divyansh42 <diagrawa@redhat.com>

.github/workflows/scratch_build.yml

@@ -0,0 +1,89 @@
+# This workflow will perform a test whenever there
+# is some change in code done to ensure that the changes
+# are not buggy and we are getting the desired output.
+name: Build
+on: [push, pull_request, workflow_dispatch]
+env:
+  PROJECT_DIR: spring-petclinic
+  IMAGE_NAME: spring-petclinic
+  MVN_REPO_DIR: ~/.m2/repository
+
+jobs:
+  build:
+    name: Build image using Buildah
+    runs-on: ubuntu-20.04
+    steps:
+
+      # Checkout buildah action github repository
+      - name: Checkout Buildah action
+        uses: actions/checkout@v2
+        with:
+          path: "buildah-build"
+
+      # Checkout spring-petclinic github repository
+      - name: Checkout spring-petclinic project
+        uses: actions/checkout@v2
+        with:
+          repository: "spring-projects/spring-petclinic"
+          path: ${{ env.PROJECT_DIR }}
+      
+      # If none of these files has changed, we assume that the contents of
+      # .m2/repository can be fetched from the cache.
+      - name: Hash Maven files
+        working-directory: ${{ env.PROJECT_DIR }}
+        run: |
+          echo "MVN_HASH=${{ hashFiles('**/pom.xml', '.mvn/**/*', 'mvnw*') }}" >> $GITHUB_ENV
+      
+      # Download the m2 repository from the cache to speed up the build.
+      - name: Check for Maven cache
+        id: check-mvn-cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ env.MVN_REPO_DIR }}
+          key: ${{ env.MVN_HASH }}
+
+      # Setup java.
+      - name: Setup Java
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11
+
+      # Run maven to build the project
+      - name: Maven
+        working-directory: ${{ env.PROJECT_DIR }}
+        run: |
+          mvn package -ntp -B 
+
+       # If there was no cache hit above, store the output into the cache now.
+      - name: Save Maven repo into cache
+        if: ${{ steps.check-mvn-cache.outputs.cache-hit }} != 'true'
+        uses: actions/cache@v2
+        with:
+          path: ${{ env.MVN_REPO_DIR }}
+          key: ${{ env.MVN_HASH }}
+      
+      # Build image using Buildah action
+      - name: Build Image
+        id: build_image
+        uses: ./buildah-build/
+        with:
+          image: ${{ env.IMAGE_NAME }}
+          tags: 'latest ${{ github.sha }}'
+          base-image: 'registry.access.redhat.com/openjdk/openjdk-11-rhel7'
+          # To avoid hardcoding a particular version of the binary.
+          content: |
+            ./spring-petclinic/target/spring-petclinic-*.jar
+          entrypoint: |
+            java
+            -jar
+            spring-petclinic-*.jar
+          port: 8080
+      
+      - name: Echo Outputs
+        run: | 
+          echo "Image: ${{ steps.build_image.outputs.image }}"
+          echo "Tags: ${{ steps.build_image.outputs.tags }}"
+
+      # Check if image is build
+      - name: Check images created
+        run: buildah images | grep '${{ env.IMAGE_NAME }}'