entrypoint for docker image, apply migration on start up

Dockerfile

@@ -9,12 +9,23 @@ ADD . /go/src/github.com/vulcanize/tracing-api
 WORKDIR /go/src/github.com/vulcanize/tracing-api
 RUN make linux
 
+# Build migration tool
+WORKDIR /
+RUN go get -u -d github.com/pressly/goose/cmd/goose
+WORKDIR /go/src/github.com/pressly/goose/cmd/goose
+RUN GCO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -ldflags '-extldflags "-static"' -tags='no_mysql no_sqlite' -o goose .
+
 # app container
 FROM alpine
 
+WORKDIR /app
+
 # keep binaries immutable
 COPY --from=builder /go/src/github.com/vulcanize/tracing-api/build/tracer-linux /usr/local/bin/tracer
+COPY --from=builder /go/src/github.com/pressly/goose/cmd/goose/goose /usr/local/bin/goose
+COPY --from=builder /go/src/github.com/vulcanize/tracing-api/startup_script.sh .
+COPY --from=builder /go/src/github.com/vulcanize/tracing-api/db/migrations migrations
 
 EXPOSE 8080
 
-ENTRYPOINT ["tracer"]
+ENTRYPOINT ["/app/startup_script.sh"]

startup_script.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# Runs the db migrations and starts the service
+
+set +x
+
+# Construct the connection string for postgres
+VDB_PG_CONNECT=postgresql://$CACHE_DATABASE_USER:$CACHE_DATABASE_PASSWORD@$CACHE_DATABASE_HOSTNAME:$CACHE_DATABASE_PORT/$CACHE_DATABASE_NAME?sslmode=disable
+
+# Run the DB migrations
+echo "Connecting with: $VDB_PG_CONNECT"
+echo "Running database migrations"
+goose -table goose_db_version_trace -dir migrations postgres "$VDB_PG_CONNECT" up
+
+# If the db migrations ran without err
+if [[ $? -ne 0 ]]; then
+    echo "Could not run migrations. Are the database details correct?"
+    exit 1
+fi
+
+echo "Running the Tracing-API process"
+exec tracer "$@"