WebAssembly WASI Integration

Makefile

@@ -3,13 +3,13 @@ BIN=bin
 all: serverledge executor serverledge-cli lb
 
 serverledge:
-	CGO_ENABLED=0 GOOS=linux go build -o $(BIN)/$@ cmd/$@/main.go
+	GOOS=linux go build -o $(BIN)/$@ cmd/$@/main.go
 
 lb:
-	CGO_ENABLED=0 GOOS=linux go build -o $(BIN)/$@ cmd/$@/main.go
+	GOOS=linux go build -o $(BIN)/$@ cmd/$@/main.go
 
 serverledge-cli:
-	CGO_ENABLED=0 GOOS=linux go build -o $(BIN)/$@ cmd/cli/main.go
+	GOOS=linux go build -o $(BIN)/$@ cmd/cli/main.go
 
 executor:
 	CGO_ENABLED=0 GOOS=linux go build -o $(BIN)/$@ cmd/$@/executor.go

docs/writing-functions.md

@@ -28,6 +28,60 @@ Available runtime: `nodejs17` (NodeJS 17)
 Specify the handler as `<script_file_name>.js` (e.g., `myfile.js`).
 An example is given in `examples/sieve.js`.
 
+## WebAssembly/WASI
+
+Serverledge supports the execution of WebAssembly modules through WASI using
+[wasmtime-go](https://github.com/bytecodealliance/wasmtime-go).
+
+A WebAssembly function can be defined in Serverledge by specifying the following
+arguments to `serverledge-cli`:
+
+- `runtime`: `wasi`
+- `src`: the path of the `.wasm` file. If the file is larger than 2MB (`etcd`
+  message size limit), it has to point to a URL of a `.tar` containing the
+  `.wasm` file
+- `custom_image`: the name of the `.wasm` file inside the `.tar` file
+
+When running a function written in Python, the `handler` argument is **required**
+and it has to point to the `.py` file inside the `.tar` passed in `src`.
+
+NOTE: if the WebAssembly module is a component, the execution of the function
+will be handled by the `wasmtime` CLI which has to be installed and its 
+installation path added to the `PATH` environment variable.
+
+### Examples
+
+**Wasm file smaller than 2MB**: assuming we have a `hello.wasm` file inside the
+`/home/user/code/` directory
+
+A function can be created using this command:
+
+	serverledge-cli create -f func-name \
+		--runtime wasi \
+		--src /home/user/code/hello.wasm \
+		--custom_image hello
+
+**Python** (using the official build): assuming the `.tar` is hosted on
+`localhost:8000/python.tar` and inside the `.tar` file there is a `func.py`
+
+At the time of writing, the official build is provided by the maintainer of the
+WASI platform in Python at the following [link](https://github.com/brettcannon/cpython-wasi-build/releases/tag/v3.13.0)
+
+Serverledge assumes the structure of the `python.tar` file to be the following:
+
+- `func.py`: this can also be in a sub-directory and is specified in the
+  `handler` argument of the function creation
+- `python.wasm`
+- `lib/`
+
+A function can be created using this command:
+
+	serverledge-cli create -f func-name \
+		--runtime wasi \
+		--src http://localhost:8000/python.tar \
+		--custom_image python \
+		--handler func.py
+
 ## Custom function runtimes
 
 Follow [these instructions](./custom_runtime.md).

go.mod

@@ -6,6 +6,7 @@ toolchain go1.22.5
 
 require (
 	github.com/LK4D4/trylock v0.0.0-20191027065348-ff7e133a5c54
+	github.com/bytecodealliance/wasmtime-go/v25 v25.0.0
 	github.com/docker/docker v20.10.12+incompatible
 	github.com/hexablock/vivaldi v0.0.0-20180727225019-07adad3f2b5f
 	github.com/labstack/echo/v4 v4.6.1
@@ -17,7 +18,9 @@ require (
 	go.opentelemetry.io/otel v1.28.0
 	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.28.0
 	go.opentelemetry.io/otel/sdk v1.28.0
+	go.opentelemetry.io/otel/trace v1.28.0
 	golang.org/x/net v0.0.0-20220225172249-27dd8689420f
+	golang.org/x/sys v0.21.0
 )
 
 require (
@@ -65,12 +68,10 @@ require (
 	go.etcd.io/etcd/api/v3 v3.5.1 // indirect
 	go.etcd.io/etcd/client/pkg/v3 v3.5.1 // indirect
 	go.opentelemetry.io/otel/metric v1.28.0 // indirect
-	go.opentelemetry.io/otel/trace v1.28.0 // indirect
 	go.uber.org/atomic v1.7.0 // indirect
 	go.uber.org/multierr v1.6.0 // indirect
 	go.uber.org/zap v1.17.0 // indirect
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5 // indirect
-	golang.org/x/sys v0.21.0 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/time v0.0.0-20201208040808-7e3f01d25324 // indirect
 	google.golang.org/genproto v0.0.0-20210602131652-f16073e35f0c // indirect

go.sum

@@ -100,6 +100,8 @@ github.com/buger/jsonparser v0.0.0-20180808090653-f4dd9f5a6b44/go.mod h1:bbYlZJ7
 github.com/bugsnag/bugsnag-go v0.0.0-20141110184014-b1d153021fcd/go.mod h1:2oa8nejYd4cQ/b0hMIopN0lCRxU0bueqREvZLWFrtK8=
 github.com/bugsnag/osext v0.0.0-20130617224835-0dd3f918b21b/go.mod h1:obH5gd0BsqsP2LwDJ9aOkm/6J86V6lyAXCoQWGw3K50=
 github.com/bugsnag/panicwrap v0.0.0-20151223152923-e2c28503fcd0/go.mod h1:D/8v3kj0zr8ZAKg1AQ6crr+5VwKN5eIywRkfhyM/+dE=
+github.com/bytecodealliance/wasmtime-go/v25 v25.0.0 h1:ZTn4Ho+srrk0466ugqPfTDCITczsWdT48A0ZMA/TpRU=
+github.com/bytecodealliance/wasmtime-go/v25 v25.0.0/go.mod h1:8mMIYQ92CpVDwXPIb6udnhtFGI3vDZ/937cGeQr5I68=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
@@ -446,7 +448,6 @@ github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxv
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
-github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/pty v1.1.5/go.mod h1:9r2w37qlBe7rQ6e1fg1S/9xpWHSnaqNdHD3WcMdbPDA=
@@ -506,6 +507,8 @@ github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRW
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f/go.mod h1:ZdcZmHo+o7JKHSa8/e818NopupXU1YMK5fe1lsApnBw=
 github.com/ncw/swift v1.0.47/go.mod h1:23YIA4yWVnGwv2dQlN4bB7egfYX6YLn0Yo/S6zZO/ZM=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/nxadm/tail v1.4.4/go.mod h1:kenIhsEOeOJmVchQTgglprH7qJGnHDVpk1VPCcaMI8A=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5/go.mod h1:vsDQFd/mU46D+Z4whnwzcISnGGzXWMclvtLoiIKAKIo=
@@ -1093,8 +1096,9 @@ gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLks
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20141024133853-64131543e789/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b h1:QRR6H1YWRnHb4Y/HeNFCTJLFVxaq6wH4YuVdsUOr75U=
+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/cheggaaa/pb.v1 v1.0.25/go.mod h1:V/YB90LKu/1FcN3WVnfiiE5oMCibMjukxqG/qStrOgw=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=

internal/api/api.go

@@ -142,8 +142,13 @@ func CreateFunction(c echo.Context) error {
 
 	log.Printf("New request: creation of %s\n", f.Name)
 
+	if f.Runtime == container.WASI_RUNTIME {
+		// Dropping memory requirements because it cannot be enforced in Wasi
+		f.MemoryMB = 0
+	}
+
 	// Check that the selected runtime exists
-	if f.Runtime != container.CUSTOM_RUNTIME {
+	if f.Runtime != container.CUSTOM_RUNTIME && f.Runtime != container.WASI_RUNTIME {
 		_, ok := container.RuntimeToInfo[f.Runtime]
 		if !ok {
 			return c.JSON(http.StatusNotFound, "Invalid runtime.")

internal/cli/cli.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"os"
 	"strings"
 
@@ -195,10 +196,18 @@ func create(cmd *cobra.Command, args []string) {
 
 	var encoded string
 	if runtime != "custom" {
-		srcContent, err := readSourcesAsTar(src)
-		if err != nil {
-			fmt.Printf("%v\n", err)
-			os.Exit(3)
+		var srcContent []byte
+		u, err := url.ParseRequestURI(src)
+		if err == nil && u.Scheme != "" && u.Host != "" {
+			// src is a URL
+			srcContent = []byte(src)
+		} else {
+			// src is a folder; a tar has to be created to be uploaded to etcd
+			srcContent, err = readSourcesAsTar(src)
+			if err != nil {
+				fmt.Printf("%v\n", err)
+				os.Exit(3)
+			}
 		}
 		encoded = base64.StdEncoding.EncodeToString(srcContent)
 	} else {

internal/container/container.go

@@ -8,22 +8,44 @@ import (
 	"io"
 	"log"
 	"net/http"
+	"net/url"
+	"os/exec"
+	"strings"
 	"time"
 
 	"github.com/grussorusso/serverledge/internal/executor"
+	"github.com/grussorusso/serverledge/internal/function"
 )
 
 // NewContainer creates and starts a new container.
-func NewContainer(image, codeTar string, opts *ContainerOptions) (ContainerID, error) {
+func NewContainer(image, codeTar string, opts *ContainerOptions, f *function.Function) (ContainerID, error) {
+	cf := GetFactoryFromFunction(f)
 	contID, err := cf.Create(image, opts)
 	if err != nil {
 		log.Printf("Failed container creation\n")
 		return "", err
 	}
 
 	if len(codeTar) > 0 {
+		var r io.Reader
+		// Decoding codeTar
 		decodedCode, _ := base64.StdEncoding.DecodeString(codeTar)
-		err = cf.CopyToContainer(contID, bytes.NewReader(decodedCode), "/app/")
+		// Check if decoded src is a url
+		u, err := url.ParseRequestURI(string(decodedCode))
+		if err == nil && u.Scheme != "" && u.Host != "" {
+			// codeTar is an URL; it has to be downloaded
+			resp, err := http.Get(string(decodedCode))
+			if err != nil {
+				log.Printf("Failed to download code %s", decodedCode)
+				return "", err
+			}
+			defer resp.Body.Close()
+			r = resp.Body
+		} else {
+			// assuming decodedCode is base64 encoded tar
+			r = bytes.NewReader(decodedCode)
+		}
+		err = cf.CopyToContainer(contID, r, "/app/")
 		if err != nil {
 			log.Printf("Failed code copy\n")
 			return "", err
@@ -38,10 +60,128 @@ func NewContainer(image, codeTar string, opts *ContainerOptions) (ContainerID, e
 	return contID, nil
 }
 
+func Execute(contID ContainerID, req *executor.InvocationRequest, f *function.Function) (*executor.InvocationResult, time.Duration, error) {
+	if f.Runtime == WASI_RUNTIME {
+		return wasiExecute(contID, req)
+	} else {
+		return dockerExecute(contID, req)
+	}
+}
+
+func wasiExecute(contID ContainerID, req *executor.InvocationRequest) (*executor.InvocationResult, time.Duration, error) {
+	wf := factories[WASI_FACTORY_KEY].(*WasiFactory)
+	wrValue, _ := wf.runners.Load(contID)
+	wr := wrValue.(*wasiRunner)
+
+	if wr.wasiType == WASI_TYPE_UNDEFINED {
+		return nil, 0, fmt.Errorf("Unrecognized WASI Type")
+	}
+
+	var paramsBytes []byte
+	if req.Params != nil {
+		var err error
+		paramsBytes, err = json.Marshal(req.Params)
+		if err != nil {
+			return nil, 0, fmt.Errorf("Failed to convert params to JSON: %v", err)
+		}
+	}
+
+	res := &executor.InvocationResult{Success: false}
+	t0 := time.Now()
+	var invocationWait time.Duration
+	if wr.wasiType == WASI_TYPE_MODULE {
+		// Create a new Wasi Configuration
+		wcc, err := wr.BuildStore(contID, wf.engine, req.Handler, string(paramsBytes))
+		if err != nil {
+			return nil, time.Now().Sub(t0), err
+		}
+		defer wcc.Close()
+
+		// Create an instance of the module
+		instance, err := wr.linker.Instantiate(wcc.store, wr.module)
+		if err != nil {
+			return nil, time.Now().Sub(t0), fmt.Errorf("Failed to instantiate WASI module: %v", err)
+		}
+
+		// Get the _start function (entrypoint of any wasm module)
+		start := instance.GetFunc(wcc.store, "_start")
+		if start == nil {
+			return nil, time.Now().Sub(t0), fmt.Errorf("WASI Module does not have a _start function")
+		}
+
+		invocationWait = time.Now().Sub(t0)
+		// Call the _start function
+		if _, err := start.Call(wcc.store); err != nil &&
+			!strings.Contains(err.Error(), "exit status 0") {
+			return nil, invocationWait, fmt.Errorf("Failed to run WASI module: %v", err)
+		}
+
+		// Read stdout from the temp file
+		stdout, err := io.ReadAll(wcc.stdout)
+		if err != nil {
+			return nil, invocationWait, fmt.Errorf("Failed to read stdout for WASI: %v", err)
+		}
+
+		// Read stderr from the temp file
+		stderr, err := io.ReadAll(wcc.stderr)
+		if err != nil {
+			return nil, invocationWait, fmt.Errorf("Failed to read stderr for WASI: %v", err)
+		}
+
+		// Populate result
+		res.Success = true
+		res.Result = string(stdout)
+		if req.ReturnOutput {
+			res.Output = fmt.Sprintf("%s\n%s", string(stdout), string(stderr))
+		}
+	} else if wr.wasiType == WASI_TYPE_COMPONENT {
+		// Create wasmtime CLI command
+		args := append(wr.cliArgs, wr.mount+req.Handler)
+		if len(paramsBytes) > 0 {
+			args = append(args, string(paramsBytes))
+		}
+		execCmd := exec.Command("wasmtime", args...)
+
+		// Save stdout and stderr to another buffer
+		var stdoutBuffer, stderrBuffer bytes.Buffer
+		execCmd.Stdout = &stdoutBuffer
+		execCmd.Stderr = &stderrBuffer
+
+		invocationWait = time.Now().Sub(t0)
+
+		// Execute wasmtime CLI
+		err := execCmd.Run()
+		if err != nil {
+			log.Printf("wasmtime failed with %v\n", err)
+		}
+
+		// Read stdout from temporary buffer
+		stdout, err := io.ReadAll(&stdoutBuffer)
+		if err != nil {
+			log.Printf("Failed to read stdout: %v", err)
+		}
+
+		// Read stderr from temporary buffer
+		stderr, err := io.ReadAll(&stderrBuffer)
+		if err != nil {
+			log.Printf("Failed to read stderr: %v", err)
+		}
+
+		// Create response
+		res.Success = err == nil
+		res.Result = string(stdout)
+		if req.ReturnOutput {
+			res.Output = fmt.Sprintf("%s\n%s", string(stdout), string(stderr))
+		}
+	}
+
+	return res, invocationWait, nil
+}
+
 // Execute interacts with the Executor running in the container to invoke the
 // function through a HTTP request.
-func Execute(contID ContainerID, req *executor.InvocationRequest) (*executor.InvocationResult, time.Duration, error) {
-	ipAddr, err := cf.GetIPAddress(contID)
+func dockerExecute(contID ContainerID, req *executor.InvocationRequest) (*executor.InvocationResult, time.Duration, error) {
+	ipAddr, err := factories[DOCKER_FACTORY_KEY].GetIPAddress(contID)
 	if err != nil {
 		return nil, 0, fmt.Errorf("Failed to retrieve IP address for container: %v", err)
 	}
@@ -70,12 +210,12 @@ func Execute(contID ContainerID, req *executor.InvocationRequest) (*executor.Inv
 	return response, waitDuration, nil
 }
 
-func GetMemoryMB(id ContainerID) (int64, error) {
-	return cf.GetMemoryMB(id)
+func GetMemoryMB(id ContainerID, f *function.Function) (int64, error) {
+	return GetFactoryFromFunction(f).GetMemoryMB(id)
 }
 
-func Destroy(id ContainerID) error {
-	return cf.Destroy(id)
+func Destroy(id ContainerID, f *function.Function) error {
+	return GetFactoryFromFunction(f).Destroy(id)
 }
 
 func sendPostRequestWithRetries(url string, body *bytes.Buffer) (*http.Response, time.Duration, error) {

internal/container/docker.go

@@ -27,7 +27,10 @@ func InitDockerContainerFactory() *DockerFactory {
 	}
 
 	dockerFact := &DockerFactory{cli, ctx}
-	cf = dockerFact
+	if factories == nil {
+		factories = make(map[string]Factory)
+	}
+	factories[DOCKER_FACTORY_KEY] = dockerFact
 	return dockerFact
 }