Create data volume with configuration seed data (#196)

* Adds a seed container that we copy the default configurations onto. Then we mount a volume (data) onto the path where the seed data has been copied on this image. When the volume is created, this mount configuration will copy the contents from the seed container into the volume. On subsequent start ups it will be a no-op, which is exactly what we want.

.env

@@ -4,6 +4,6 @@ DATABASE_USER=docker
 DATABASE_PASSWORD=docker
 DATABASE_DB=dataline
 DATABASE_URL=jdbc:postgresql://db:5432/dataline
-CONFIG_ROOT=data/config
+CONFIG_ROOT=/data
 WORKSPACE_ROOT=/tmp/workspace
 WORKSPACE_DOCKER_MOUNT=workspace

Dockerfile.build

@@ -50,6 +50,17 @@ EXPOSE 80
 
 COPY --from=build /code/dataline-webapp/build /usr/share/nginx/html
 
+####################
+# Build seed image #
+####################
+FROM alpine:3.4 AS seed
+
+WORKDIR /app
+
+# the sole purpose of this image is to seed the data volume with the default data
+# that the app should have when it is first installed.
+COPY --from=build /code/dataline-config/init/src/main/resources/config seed/config
+
 ######################
 # Build server image #
 ######################
@@ -66,7 +77,6 @@ WORKDIR /app
 ADD https://github.com/ufoscout/docker-compose-wait/releases/download/${WAIT_VERSION}/wait wait
 RUN chmod +x wait
 
-COPY --from=build /code/dataline-config/init/src/main/resources/config data/config
 COPY --from=build /code/${APPLICATION}/build/distributions/${APPLICATION}*.tar ${APPLICATION}.tar
 
 RUN tar xf ${APPLICATION}.tar --strip-components=1
@@ -88,7 +98,6 @@ WORKDIR /app
 ADD https://github.com/ufoscout/docker-compose-wait/releases/download/${WAIT_VERSION}/wait wait
 RUN chmod +x wait
 
-COPY --from=build /code/dataline-config/init/src/main/resources/config data/config
 COPY --from=build /code/${APPLICATION}/build/distributions/${APPLICATION}*.tar ${APPLICATION}.tar
 
 RUN tar xf ${APPLICATION}.tar --strip-components=1

dataline-config/persistence/src/main/java/io/dataline/config/persistence/DefaultConfigPersistence.java

@@ -41,6 +41,8 @@
 // we force all interaction with disk storage to be effectively single threaded.
 public class DefaultConfigPersistence implements ConfigPersistence {
 
+  private static final String CONFIG_DIR = "config";
+
   private static final Object lock = new Object();
 
   private final JsonSchemaValidator jsonSchemaValidator;
@@ -51,7 +53,7 @@ public DefaultConfigPersistence(final Path storageRoot) {
   }
 
   public DefaultConfigPersistence(final Path storageRoot, final JsonSchemaValidator schemaValidator) {
-    this.storageRoot = storageRoot;
+    this.storageRoot = storageRoot.resolve(CONFIG_DIR);
     jsonSchemaValidator = schemaValidator;
   }
 

docker-compose.build.yaml

@@ -6,6 +6,12 @@ services:
     build:
       dockerfile: Dockerfile.database
       context: .
+  seed:
+    image: dataline/seed:dev
+    build:
+      dockerfile: Dockerfile.build
+      target: seed
+      context: .
   scheduler:
     image: dataline/scheduler:dev
     build:
@@ -25,9 +31,6 @@ services:
       target: webapp
       context: .
 
-volumes:
-  workspace:
-
 networks:
   dataline:
     driver: "bridge"

docker-compose.yaml

@@ -8,6 +8,23 @@ services:
       - POSTGRES_USER=${DATABASE_USER}
       - POSTGRES_PASSWORD=${DATABASE_PASSWORD}
       - POSTGRES_DB=db-${DATABASE_DB}
+  seed:
+    image: dataline/seed:${VERSION}
+    container_name: dataline-data-seed
+    environment:
+      - ENV=${ENV}
+    # When the volume is created for the first time it will be populated with the contents of /app/seed,
+    # which is prepopulated with the configs that we want config persistence to have access to upon
+    # installation. On subsequent compose up / down, this will get mounted, but not copy any data.
+    # Effectively it'll be a no-op on subsequent runs, though we may be able to use it to add new data
+    # to the volume if we need to as we release updates.
+    # reference:
+    # https://docs.docker.com/storage/volumes/#populate-a-volume-using-a-container
+    # https://docs.docker.com/compose/compose-file/#long-syntax-3
+    volumes:
+      - type: volume
+        source: data
+        target: /app/seed
   scheduler:
     image: dataline/scheduler:${VERSION}
     container_name: dataline-scheduler
@@ -24,8 +41,10 @@ services:
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - "${WORKSPACE_DOCKER_MOUNT}:${WORKSPACE_ROOT}"
+      - "data:${CONFIG_ROOT}"
     depends_on:
       - db
+      - seed
   server:
     image: dataline/server:${VERSION}
     container_name: dataline-server
@@ -39,6 +58,8 @@ services:
       - CONFIG_ROOT=${CONFIG_ROOT}
     ports:
       - 8001:8001
+    volumes:
+      - "data:${CONFIG_ROOT}"
     depends_on:
       - db
   webapp:
@@ -52,3 +73,5 @@ services:
 volumes:
   workspace:
     name: ${WORKSPACE_DOCKER_MOUNT}
+  data:
+    name: data