vercel.json #1695
vercel.json #1695
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WalkthroughAdds a Vercel deployment configuration file for a Go app, specifying build/runtime settings and a catch-all route directing all requests to main.go. Changes
Sequence Diagram(s)sequenceDiagram
autonumber
participant U as User
participant V as Vercel Edge
participant G as main.go (Go Runtime)
rect rgba(200,220,255,0.3)
note over V: New routing config (catch-all)
U->>V: HTTP request to /
V->>G: Forward request to /main.go
G-->>V: Response
V-->>U: HTTP response
end
Estimated code review effort🎯 1 (Trivial) | ⏱️ ~3 minutes Poem
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Actionable comments posted: 2
🧹 Nitpick comments (2)
vercel.json (2)
3-8: Consider using the api/ directory (file‑based functions) instead of legacy builds.Vercel’s Go functions conventionally live under api/*.go. That avoids custom routing to a root-level file and aligns with platform defaults.
If you choose to follow the convention, move main.go to api/index.go and simplify routes:
"builds": [ - { - "src": "main.go", - "use": "@vercel/go" - } + { "src": "api/**/*.go", "use": "@vercel/go" } ], - "routes": [ - { "src": "/(.*)", "dest": "/main.go" } - ] + "routes": [ + { "handle": "filesystem" }, + { "src": "/(.*)", "dest": "/api/index.go" } + ]I can also propose a version that drops "builds" entirely and relies on auto-detection if desired.
2-2: Keep “version”: 2 but note it’s the legacy schema; prefer rewrites/redirects/headers blocks where possible.No change required now, but if you expand config (redirects, headers), consider the newer “rewrites/redirects/headers” keys for clarity.
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📒 Files selected for processing (1)
vercel.json(1 hunks)
| "src": "main.go", | ||
| "use": "@vercel/go" |
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💡 Verification agent
🧩 Analysis chain
Verify handler shape and Go runtime expectations.
Ensure main.go exposes a Vercel-compatible handler (and uses package main). Mismatch here results in 500s at runtime.
Run this to sanity-check the PR branch:
🏁 Script executed:
#!/bin/bash
set -euo pipefail
# 1) Confirm file exists at expected path
test -f main.go || { echo "main.go not found at repo root"; exit 1; }
# 2) Check it’s a main package
rg -nP '^\s*package\s+main\b' main.go || { echo "package main not declared"; exit 1; }
# 3) Look for an http handler signature commonly used with Vercel Go runtimes
rg -nP '\bfunc\s+(Handler|Handle|handler)\s*\(\s*w\s+http\.ResponseWriter\s*,\s*r\s+\*http\.Request\s*\)' main.go || {
echo "No obvious http handler function found (Handler/Handle/handler)"; exit 1;
}
echo "Basic checks passed."Length of output: 354
Add missing Vercel-compatible HTTP handler in main.go
main.go declares package main but lacks an exported function matching Vercel’s Go runtime entrypoint (func Handler(w http.ResponseWriter, r *http.Request)). Add this handler signature (or update vercel.json to point at your custom entry) to avoid 500 errors at runtime.
🤖 Prompt for AI Agents
In vercel.json around lines 5 to 6, Vercel is configured to use the Go runtime
but main.go currently lacks the exported HTTP entrypoint expected by that
runtime; add an exported function with the exact signature func Handler(w
http.ResponseWriter, r *http.Request) in main.go that forwards to your existing
router/logic (or alternatively update vercel.json to reference a custom
entrypoint if you intend a different export), ensure the package is main and the
function is exported so Vercel can invoke it, and wire any context/response
handling to return appropriate status and body to avoid 500s.
| "src": "/(.*)", | ||
| "dest": "/main.go" | ||
| } | ||
| ] |
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🛠️ Refactor suggestion
Catch‑all route can shadow static assets and may self-match; add filesystem handle and exclude the function path.
As written, every request (including to /main.go) routes to /main.go. This can 1) bypass any static files you might add later and 2) ambiguously self-match the function path. Safer to handle existing files first and exclude the function file from the catch-all.
Apply:
"routes": [
- {
- "src": "/(.*)",
- "dest": "/main.go"
- }
+ { "handle": "filesystem" },
+ {
+ "src": "/(?!main\\.go$)(.*)",
+ "dest": "/main.go"
+ }
]📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| "src": "/(.*)", | |
| "dest": "/main.go" | |
| } | |
| ] | |
| "routes": [ | |
| { "handle": "filesystem" }, | |
| { | |
| "src": "/(?!main\\.go$)(.*)", | |
| "dest": "/main.go" | |
| } | |
| ] |
🤖 Prompt for AI Agents
In vercel.json around lines 11 to 14, the catch‑all route currently matches
every request (including /main.go) which can shadow static assets and
self‑match; add a filesystem handle entry before the catch‑all and change the
catch‑all src to exclude the function file (e.g. use a negative lookahead for
main.go) so existing files are served first and requests to /main.go aren’t
routed into the function.
Summary by CodeRabbit