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Version: 1.x

Go HTTP Server

This example is a WebAssembly Component compiled using TinyGo, which:

Dependencies

Before starting, ensure that you have the following installed in addition to the Go toolchain:

Quickstart​

To get started developing this repository quickly, clone the repo and run wash dev:

console
wash dev

wash dev does many things for you:

  • Starts the wasmCloud host that can run your WebAssembly component
  • Builds this project
  • Builds a declarative WADM manifest consisting of:
    • Your locally built component
    • A HTTP server provider which will receive requests from the outside world (on port 8000 by default)
    • Necessary links between providers and your component so your component can handle web traffic
  • Deploys the built manifest (i.e all dependencies to run this application) locally
  • Watches your code for changes and re-deploys when necessary.

Send a request to the running component​

Once wash dev is serving your component, to send a request to the running component (via the HTTP server provider)

Available Endpoints​

GET /​

Returns a list of available endpoints and their descriptions.

console
curl http://localhost:8000/
  /error - return a 500 error
  /form - echo the fields of a POST request
  /headers - echo your user agent back as a server side header
  /post - echo the body of a POST request

GET /error​

Returns a 500 Internal Server Error.

console
curl -v http://localhost:8000/error
* Host localhost:8000 was resolved.
* IPv6: ::1
* IPv4: 127.0.0.1
*   Trying [::1]:8000...
* connect to ::1 port 8000 from ::1 port 51390 failed: Connection refused
*   Trying 127.0.0.1:8000...
* Connected to localhost (127.0.0.1) port 8000
> GET /error HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/8.7.1
> Accept: */*
> 
* Request completely sent off
< HTTP/1.1 500 Internal Server Error
< content-type: text/plain; charset=utf-8
< x-content-type-options: nosniff
< vary: origin, access-control-request-method, access-control-request-headers
< access-control-allow-origin: *
< access-control-expose-headers: *
< connection: close
< transfer-encoding: chunked
< date: Thu, 19 Dec 2024 23:52:34 GMT
< 
Something went wrong
* Closing connection

GET /headers​

Returns your User-Agent in the response headers.

console
curl -v http://localhost:8000/headers
* Host localhost:8000 was resolved.
* IPv6: ::1
* IPv4: 127.0.0.1
*   Trying [::1]:8000...
* connect to ::1 port 8000 from ::1 port 51499 failed: Connection refused
*   Trying 127.0.0.1:8000...
* Connected to localhost (127.0.0.1) port 8000
> GET /headers HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/8.7.1
> Accept: */*
> 
* Request completely sent off
< HTTP/1.1 200 OK
< x-your-user-agent: curl/8.7.1
< vary: origin, access-control-request-method, access-control-request-headers
< access-control-allow-origin: *
< access-control-expose-headers: *
< connection: close
< transfer-encoding: chunked
< date: Thu, 19 Dec 2024 23:53:49 GMT
< 
* Closing connection
Check headers!

POST /form​

Echoes back form data from a POST request.

console
curl -X POST -d "field1=value1&field2=value2" http://localhost:8000/form
field2: value2
field1: value1

POST /post​

Echoes back the entire body of a POST request.

console
curl -X POST -d "Hello World" http://localhost:8000/post
Hello World

Adding Capabilities​

To learn how to extend this example with additional capabilities, see the Adding Capabilities section of the wasmCloud documentation.

Issues/ FAQ

curl produces a "failed to invoke" error​

If curling produces

➜ curl localhost:8000
failed to invoke `wrpc:http/incoming-handler.handle`: failed to invoke `wrpc:http/incoming-handler@0.1.0.handle`: failed to shutdown synchronous parameter channel: not connected%

You may need to just wait a little bit -- the HTTP server takes a second or two to start up.

If the issue persists, you may have a lingering HTTP server provider running on your system. You can use pgrep to find it:

console
❯ pgrep -la ghcr_io
4007604 /tmp/wasmcloudcache/NBCBQOZPJXTJEZDV2VNY32KGEMTLFVP2XJRZJ5FWEJJOXESJXXR2RO46/ghcr_io_wasmcloud_http_server_0_23_1