Show useful 502 message for not running/existent sandbox

[0div]

Description

[re-using previous work from @dobrac in #224]

To return a meaningful error during the DNS resolution in API from client-proxy we route the traffic to a "dummy" server that serves the exception if the sandbox cannot be found.
Per feedback, also split the DNS package between api/ and orchestrator/ , with only the latter having the special "sandbox not found" routing.

Test

• deploy
• test ✅

✨

Description by Callstackai

This PR introduces a new DNS handling feature that provides a meaningful 502 error message when a sandbox is not running or does not exist. It also refactors the DNS package structure and updates the configuration for the client proxy.

Diagrams of code changes

sequenceDiagram
    participant Client
    participant DNS Server
    participant Records Map
    
    Note over DNS Server: Initialized with empty records map
    
    alt Add Sandbox Record
        Client->>DNS Server: Add(sandboxID, ip)
        DNS Server->>Records Map: Insert(hostname, ip)
    end

    alt DNS Request
        Client->>DNS Server: DNS Query
        DNS Server->>Records Map: Get(sandboxID)
        alt Record Found
            Records Map-->>DNS Server: Return IP
            DNS Server-->>Client: Response with Sandbox IP
        else Record Not Found
            Records Map-->>DNS Server: Not Found
            DNS Server-->>Client: Response with 127.0.0.1
        end
    end

    alt Remove Sandbox Record
        Client->>DNS Server: Remove(sandboxID, ip)
        DNS Server->>Records Map: Remove Entry
    end

Loading

Files Changed

File	Summary
packages/api/internal/dns/server.go	Added a new DNS server implementation that handles sandbox requests and returns appropriate IP addresses or a default routing IP.
packages/api/internal/orchestrator/orchestrator.go	Updated import path for the DNS package to reflect the new structure.
packages/nomad/proxies/client.conf	Modified the Nginx configuration to return a 404 error with a message for invalid sandbox URLs and added a mock server for handling non-existent sandboxes.
packages/orchestrator/cmd/mock-sandbox/mock.go	Updated import path for the DNS package to reflect the new structure.
packages/orchestrator/cmd/mock-snapshot/mock.go	Updated import path for the DNS package to reflect the new structure.
packages/orchestrator/internal/sandbox/sandbox.go	Updated import path for the DNS package to reflect the new structure.
packages/orchestrator/internal/server/main.go	Updated import path for the DNS package to reflect the new structure.

This PR includes files in programming languages that we currently do not support. We have not reviewed files with the extensions .conf. See list of supported languages.

[linear]

E2B-1327 Return error indicating that the sandbox is not running when making requests from SDK

[jakubno]

the DNS is now shared for API and orchestrator. I think it will behave the same, because there's nothing running on 3003 port, but it would be better and cleaner to split it

[0div]

@jakubno split the DNS package between api/ and orchestrator/ , with only the latter having the special "sandbox not found" routing

[callstackai]

Key Issues

Setting a TTL of 0 can lead to performance issues due to excessive DNS queries; consider using a positive TTL value for caching. The code lacks validation for empty DNS questions, which could result in undefined behavior. Assumptions about the format of q.Name may cause errors if the expected '-' character is missing; implement validation or safer parsing.

[callstackai]

Key Issues

The code fails to handle cases where a sandbox is not found, potentially leading to empty DNS responses and unexpected client behavior, unlike the original code which returned a default IP.