如何让Nginx根据静态JSON内容返回对应状态码？

Got it, let's solve this. Right now your Nginx config serves a static /etc/health.json file at /health with a default 200 OK status, but you want to map the status value in that JSON to a matching HTTP status code. Below are two practical solutions depending on your setup:

Option 1: Use Nginx's Native JS Module (ngx_http_js_module) #

This works if your Nginx version is 1.15.8 or newer and was compiled with the --with-http_js_module flag (verify with nginx -V). No extra dependencies needed.

Step 1: Update Your Nginx Config #

Replace your existing /health location block with this:

location /health {
    default_type "application/json";
    js_content health_check;
}

# Point to our custom JS script
js_include health.js;

Step 2: Create the Health Check Script #

In your Nginx config directory (usually /etc/nginx/), create a file named health.js with this code:

function health_check(r) {
    // Read the static JSON file
    const fs = require('fs');
    const healthContent = fs.readFileSync('/etc/health.json', 'utf8');
    const healthData = JSON.parse(healthContent);

    // Map JSON status to HTTP status codes
    switch (healthData.status) {
        case 'up':
            r.status = 200; // OK
            break;
        case 'down':
            r.status = 503; // Service Unavailable
            break;
        case 'maintenance':
            r.status = 503; // Add custom mappings here as needed
            break;
        default:
            r.status = 400; // Bad Request for unknown statuses
    }

    // Send the JSON content to the client
    r.sendHeader();
    r.send(healthContent);
    r.finish();
}

Step 3: Reload Nginx #

Make the changes take effect with:

sudo nginx -s reload

Option 2: Use OpenResty's Lua Module (ngx_http_lua_module) #

If you're already using OpenResty (a Nginx distribution with Lua support), this is a lightweight, flexible option.

Update Your Nginx Config #

Replace your /health location block with this:

location /health {
    default_type "application/json";
    content_by_lua_block {
        -- Read the static JSON file
        local file_handle = io.open("/etc/health.json", "r")
        local json_content = file_handle:read("*a")
        file_handle:close()

        -- Parse JSON using OpenResty's built-in cjson
        local health_status = require("cjson").decode(json_content)

        -- Set HTTP status based on JSON value
        if health_status.status == "up" then
            ngx.status = ngx.HTTP_OK
        elseif health_status.status == "down" then
            ngx.status = ngx.HTTP_SERVICE_UNAVAILABLE
        else
            ngx.status = ngx.HTTP_BAD_REQUEST
        end

        -- Send the original JSON content
        ngx.say(json_content)
    }
}

Reload OpenResty #

Apply the config change:

sudo openresty -s reload

Quick Notes #

• If your health.json content never changes, you can skip scripting entirely: just add return 200; to your original location block if it's always up. Use the script solutions only if the JSON content might dynamically switch between statuses.
• Make sure the Nginx/OpenResty process has read permissions for /etc/health.json (run sudo chmod 644 /etc/health.json if needed).
• Feel free to adjust the status code mappings to fit your use case (e.g., return 206 for a degraded status).

内容的提问来源于stack exchange，提问作者Bara' ayyash