Add ability to handle variables in prefixed paths (#266)

Co-authored-by: Mario Micklisch <[email protected]>

Author: ifavo

index.js

@@ -235,7 +235,14 @@ async function httpProxy (fastify, opts) {
   function handler (request, reply) {
     const queryParamIndex = request.raw.url.indexOf('?')
     let dest = request.raw.url.slice(0, queryParamIndex !== -1 ? queryParamIndex : undefined)
-    dest = dest.replace(this.prefix, rewritePrefix)
+
+    if (this.prefix.includes(':')) {
+      const requestedPathElements = request.url.split('/')
+      const prefixPathWithVariables = this.prefix.split('/').map((_, index) => requestedPathElements[index]).join('/')
+      dest = dest.replace(prefixPathWithVariables, rewritePrefix)
+    } else {
+      dest = dest.replace(this.prefix, rewritePrefix)
+    }
     reply.from(dest || '/', replyOpts)
   }
 

test/test.js

@@ -444,6 +444,27 @@ async function run () {
     t.equal(firstProxyPrefix.body, 'this is /api2/a')
   })
 
+  test('rewritePrefix with variables', async t => {
+    const proxyServer = Fastify()
+
+    proxyServer.register(proxy, {
+      upstream: `http://localhost:${origin.server.address().port}`,
+      prefix: '/api/:id/static',
+      rewritePrefix: '/api2'
+    })
+
+    await proxyServer.listen({ port: 0 })
+
+    t.teardown(() => {
+      proxyServer.close()
+    })
+
+    const firstProxyPrefix = await got(
+      `http://localhost:${proxyServer.server.address().port}/api/123/static/a`
+    )
+    t.equal(firstProxyPrefix.body, 'this is /api2/a')
+  })
+
   test('rewrite location headers', async t => {
     const proxyServer = Fastify()