Ewan Valentine’s 2018 tutorial shows how to run Go microservices and their datastores together locally with Docker Compose, using MongoDB for consignment and vessel examples and Postgres for a user service. Its architectural lessons remain useful, but its commands and Go Micro APIs are historical; treat the code as a guide to the design decisions, not as a current copy-and-paste setup.
What this part of the series demonstrates
The tutorial addresses two related problems: service data held only in memory disappears when a container restarts, and launching several services separately can make a local development stack cumbersome. Valentine adds persistent datastores and uses Compose to describe services and a database in one configuration. The examples are for local development; they do not establish a production-ready deployment.
The central architectural idea is that each service can choose storage suited to its data. That flexibility has a cost: every additional database technology adds operational work and knowledge the team must maintain. The tutorial does not identify one database as universally best.
How to think about database choice
Valentine’s examples use MongoDB for consignment and vessel data and Postgres for user data. They illustrate different storage approaches rather than prescribe a database for every service. Before choosing, consider the shape of the data, how the service reads and writes it, and the complexity of its queries.
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- Data structure: Is the information naturally represented as flexible documents, or does it have a more strictly defined relational structure?
- Read and write patterns: Does the service mostly read, mostly write, or need a balanced workload? The tutorial raises this as a consideration but does not supply workload measurements.
- Query needs: How complex are the queries the service must perform?
- Operational overhead: Does the benefit of a distinct datastore justify supporting another technology across development and operations?
The tutorial also mentions managed database services as an alternative to running database software yourself, naming Amazon RDS and DynamoDB and Google Cloud examples. Those are examples cited in a 2018 article, not current product recommendations or a comparison of their suitability.
What the Compose configuration contributes
Instead of starting services through separate commands and Makefiles, the tutorial describes their build paths, ports, and environment variables together in a Compose YAML file. It adds a MongoDB service named datastore and configures an application with DB_HOST=datastore:27017. The hostname works because services on a Compose network can reach one another using their service names.
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For current Docker Compose, use the Compose v2 command form, such as docker compose up, rather than assuming the 2018 docker-compose command is still the recommended interface. Docker’s official Compose project and its Compose documentation describe the current project and usage. Docker says Compose v1 has been superseded by Compose v2 and is no longer maintained in its retired-products documentation. Check the installed Compose version and current file guidance before adapting old examples.
Persistence models and repository boundaries
The MongoDB portion moves repository-related code out of main.go into handler, datastore, and repository files. It uses the mgo driver, a master session, and cloned sessions for repository work; the accompanying discussion describes closing request-level sessions. These implementation details explain the tutorial’s structure, but do not establish that mgo is maintained or appropriate for a new project. Verify the selected driver, its version, and its lifecycle guidance independently.
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A further design choice is whether generated protobuf structs should also serve as persistence models. Reusing them can avoid conversion code, but it ties storage representation to API or wire definitions. Separate persistence models add mapping work while allowing the two representations to evolve independently. The tutorial presents both as viable options; the right trade-off depends on how much separation the service needs.
From a vessel operation to a user service
The tutorial adds a vessel Create RPC and a repository insert operation, then introduces a user service with protobuf messages and RPCs. Its example persists users in Postgres through GORM and demonstrates a GORM hook that assigns a UUID before creation. It also shows command-line examples for creating and listing a user.
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The example stores passwords in plaintext. The tutorial explicitly identifies this as insecure and defers authentication and JWT work to a later installment. Do not use that password handling in a real service: the sample is a demonstration of service and persistence structure, not a safe authentication implementation.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What must be checked before adapting the code today
The tutorial appeared on DZone on June 20, 2018. Its Go Micro imports and APIs represent the framework’s 2018 surface and should not be assumed to compile with current releases. The project’s repository and release page show newer v6 material, including the go-micro.dev/v6 import path. Confirm API and dependency compatibility for the versions you choose; the historical snippets have not been established as compatible with them.
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- Update the Compose invocation and check current Compose documentation.
- Choose and verify current database drivers, framework APIs, and dependency versions rather than relying on the article’s 2018 stack.
- Treat the Compose example as a local stack demonstration. It does not specify production resilience, authentication, secrets management, persistent-volume strategy, health checks, backups, or production service discovery.
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