Whats the way around aliases with .local/.dev?

[abbeymaniak]

my organisation requires us to use uses .local / .dev and the flyenv docs says to avoid both, is there a way forward?

[xpf0000]

This content was generated by Google Gemini 2.5Pro, for reference only. Actual implementation may vary depending on your development environment.

Can .local and .dev Domain Suffixes Be Used for Local Web Development?

When performing local web development on Windows, macOS, and Linux, choosing an appropriate local domain suffix is crucial. While .local and .dev are popular due to their intuitiveness, using them may introduce technical issues and specific requirements. Overall, it is recommended to avoid using .local, while .dev can be used under certain conditions.

.local: Potential Conflict Risks

The .local suffix is officially reserved for use by multicast DNS (mDNS) in the Zeroconf (Zero Configuration Networking) protocol suite. This means that in many operating systems, .local is used for device discovery and resolution within local networks, rather than traditional DNS queries.

• macOS: macOS deeply integrates Bonjour (Apple's implementation of mDNS). Any address ending in .local is prioritized as a Bonjour service and attempts to resolve via mDNS, preventing it from correctly pointing to the IP address (e.g., 127.0.0.1) set in your hosts file or local DNS service. This will directly cause your local development site to be inaccessible.

• Linux: Most modern Linux distributions provide mDNS functionality through the Avahi service, which behaves similarly to macOS's Bonjour. Therefore, using .local on Linux can also cause domain resolution conflicts, leading to an unstable development environment.

• Windows: Although Windows handles .local more leniently and may not immediately cause issues under certain network configurations, it also supports mDNS. In mixed network environments that include Apple or Linux devices (such as printers, NAS, etc.), using .local can easily lead to difficult-to-troubleshoot resolution problems.

Conclusion: Given the official status of .local as a special-use top-level domain and its widespread use in mDNS, it is strongly recommended not to use it for local web development on any operating system to avoid potential domain resolution conflicts.

.dev: HTTPS Is Mandatory

.dev is a generic top-level domain (gTLD) owned by Google. To enhance network security, Google has added the entire .dev TLD to the HSTS (HTTP Strict Transport Security) preload list.

This means all modern browsers (Chrome, Firefox, Safari, Edge, etc.) will enforce the use of the https:// protocol for any domain ending in .dev. If you attempt to access it via http://, the browser will automatically redirect to https://. If your local development server is not configured with an SSL/TLS certificate, the access will fail.

To use .dev domains for local development, you must:

1. Configure a local HTTPS environment: You need to generate an SSL/TLS certificate for your local development site.
2. Establish local trust: Since this certificate is self-signed and not issued by a browser-trusted certificate authority (CA), you need to add your own local CA to the operating system's trust store.

Fortunately, tools like mkcert can greatly simplify this process. With simple commands, mkcert can create a private certificate authority (CA) on your local machine and use it to issue trusted certificates for your local sites (e.g., myproject.dev).

Conclusion: You can use the .dev suffix on Windows, macOS, and Linux, but only if you have configured HTTPS for your local development environment.

Recommended Alternatives

To avoid the issues mentioned above, it is recommended to choose safer, conflict-free domain suffixes for local development. Here are some excellent options:

• .test: This suffix is explicitly reserved by the IETF (Internet Engineering Task Force) for testing purposes, ensuring it will never be registered as a public TLD. It is currently the most recommended suffix for local development.
• .localhost: Also reserved by the IETF, .localhost always points to the loopback address 127.0.0.1. Although its behavior is similar to directly using localhost, it allows you to create multiple subdomains (e.g., project1.localhost, project2.localhost), which is very useful in certain development scenarios.
• Other custom suffixes: You can also choose descriptive suffixes that are not yet generic top-level domains, such as .wip (work in progress) or .app (note that .app is also a gTLD that requires HTTPS, so caution is needed when using it).

Summary Table

Domain Suffix	Platforms	Advantages	Disadvantages & Requirements	Recommendation
.local	Windows, macOS, Linux	Intuitive	Conflicts with mDNS (Bonjour/Avahi), highly prone to resolution failures	Not Recommended
.dev	Windows, macOS, Linux	Concise, modern feel	Enforces HTTPS, requires local SSL certificate configuration	Recommended (with HTTPS configured)
.test	Windows, macOS, Linux	Officially reserved for testing, no conflict risks	None	Highly Recommended
.localhost	Windows, macOS, Linux	Officially reserved, always points to local, supports subdomains	None	Highly Recommended