Abstract regions, account numbers and tags from buildspec (#365)

* Abstract regions, account numbers and tags from buildspec

* Add comment on defaults

.codepipeline/buildspec-govuk-build.yml

@@ -3,18 +3,28 @@ version: 0.2
 phases:
   pre_build:
     commands:
-      - echo Checking out to govuk_${ENVIRONMENT}_latest tag...
-      - git checkout tags/govuk_${ENVIRONMENT}_latest
+      - |
+        if [ -n "$COMMIT_ID" ]; then
+          echo Checking out to govuk_${ENVIRONMENT}_latest tag...
+          git checkout tags/govuk_${ENVIRONMENT}_latest
+        fi
       - echo Logging in to Amazon ECR...
       - aws ecr get-login-password --region $AWS_REGION | docker login --username AWS
         --password-stdin $ACCOUNT_NUMBER.dkr.ecr.$AWS_REGION.amazonaws.com
   build:
     commands:
-      - COMMIT_ID=$(echo $COMMIT_ID | cut -c 1-7)
+      - |
+        TAGS="-t $REPOSITORY_URI:latest -t $REPOSITORY_URI:pipeline_$EXECUTION_ID"
+        if [ -n "$COMMIT_ID" ]; then
+          COMMIT_ID=$(echo $COMMIT_ID | cut -c 1-7)
+          TAGS="$TAGS -t $REPOSITORY_URI:commit_$COMMIT_ID"
+        fi
       - echo Build started on `date`
       - echo Building Docker image...
-      - docker build -t $REPOSITORY_URI:latest -t $REPOSITORY_URI:pipeline_$EXECUTION_ID -t $REPOSITORY_URI:commit_$COMMIT_ID
-        -f Dockerfile.eas-govuk-alerts --build-arg ECS_ACCOUNT_NUMBER=$ACCOUNT_NUMBER --build-arg RESOURCE_PREFIX=${RESOURCE_PREFIX:-eas-app} --no-cache .
+      - docker build $TAGS -f Dockerfile.eas-govuk-alerts
+        --build-arg ECS_ACCOUNT_NUMBER=$ACCOUNT_NUMBER
+        --build-arg AWS_REGION=${AWS_REGION:-eu-west-2}
+        --build-arg RESOURCE_PREFIX=${RESOURCE_PREFIX:-eas-app} --no-cache .
   post_build:
     commands:
       - echo Building complete on `date`

.codepipeline/buildspec-govuk-deploy.yml

@@ -3,8 +3,11 @@ version: 0.2
 phases:
   pre_build:
     commands:
-      - echo Checking out to govuk_${ENVIRONMENT}_latest tag...
-      - git checkout tags/govuk_${ENVIRONMENT}_latest
+      - |
+        if [ -n "$COMMIT_ID" ]; then
+          echo Checking out to govuk_${ENVIRONMENT}_latest tag...
+          git checkout tags/govuk_${ENVIRONMENT}_latest
+        fi
   build:
     commands:
       - echo Deployment started on `date`

Dockerfile.eas-govuk-alerts

@@ -1,7 +1,10 @@
+# Sensible defaults, but they will be explicitly overridden in the context of a buildspec anyway.
+# The only one that needs to be passed in however is the ECS_ACCOUNT_NUMBER, as this changes per environment.
 ARG ECS_ACCOUNT_NUMBER
 ARG RESOURCE_PREFIX=eas-app
+ARG AWS_REGION=eu-west-2
 ARG BASE_VERSION=latest
-FROM ${ECS_ACCOUNT_NUMBER}.dkr.ecr.eu-west-2.amazonaws.com/${RESOURCE_PREFIX}-base:${BASE_VERSION}
+FROM ${ECS_ACCOUNT_NUMBER}.dkr.ecr.${AWS_REGION}.amazonaws.com/${RESOURCE_PREFIX}-base:${BASE_VERSION}
 
 ENV SERVICE=govuk-alerts
 ENV FLASK_APP=app.py