build_server.go

/*
 * Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package commands

import (
	"errors"
	"fmt"
	"html/template"
	"io/ioutil"
	"os"

	"github.com/fnproject/cli/common"
	"github.com/urfave/cli"
	yaml "gopkg.in/yaml.v2"
)

type BuildServerCmd struct {
	noCache bool
}

// BuildServerCommand returns build server cli.command
func BuildServerCommand() cli.Command {
	cmd := BuildServerCmd{}
	flags := append([]cli.Flag{}, cmd.flags()...)
	return cli.Command{
		Name:        "build-server",
		Usage:       "Build custom Fn server",
		Category:    "SERVER COMMANDS",
		Description: "This command builds a custom Fn server.",
		Flags:       flags,
		Action:      cmd.buildServer,
	}
}

func (b *BuildServerCmd) flags() []cli.Flag {
	return []cli.Flag{
		cli.BoolFlag{
			Name:        "verbose, v",
			Usage:       "verbose mode",
			Destination: &common.CommandVerbose,
		},
		cli.BoolFlag{
			Name:        "no-cache",
			Usage:       "Don't use docker cache",
			Destination: &b.noCache,
		},
		cli.StringFlag{
			Name:  "tag,t",
			Usage: "Image name and optional tag",
		},
	}
}

// steps:
// • Yaml file with extensions listed
// • NO‎TE: All extensions should use env vars for config
// • ‎Generating main.go with extensions
// * Generate a Dockerfile that gets all the extensions (using dep)
// • ‎then generate a main.go with extensions
// • ‎compile, throw in another container like main dockerfile
func (b *BuildServerCmd) buildServer(c *cli.Context) error {

	if c.String("tag") == "" {
		return errors.New("Docker tag required")
	}

	// path, err := os.Getwd()
	// if err != nil {
	// 	return err
	// }
	fpath := "ext.yaml"
	bb, err := ioutil.ReadFile(fpath)
	if err != nil {
		return fmt.Errorf("Could not open %s for parsing. Error: %v", fpath, err)
	}
	ef := &extFile{}
	err = yaml.Unmarshal(bb, ef)
	if err != nil {
		return err
	}

	err = os.MkdirAll("tmp", 0777)
	if err != nil {
		return err
	}
	err = os.Chdir("tmp")
	if err != nil {
		return err
	}
	err = generateMain(ef)
	if err != nil {
		return err
	}
	err = generateDockerfile()
	if err != nil {
		return err
	}
	dir, err := os.Getwd()
	if err != nil {
		return err
	}
	containerEngineType, err := common.GetContainerEngineType()
	if err != nil {
		return err
	}
	err = common.RunBuild(common.IsVerbose(), dir, c.String("tag"), "Dockerfile", nil, b.noCache, containerEngineType, "")
	if err != nil {
		return err
	}
	fmt.Printf("Custom Fn server built successfully.\n")
	return nil
}

func generateMain(ef *extFile) error {
	tmpl, err := template.New("main").Parse(mainTmpl)
	if err != nil {
		return err
	}
	f, err := os.Create("main.go")
	if err != nil {
		return err
	}
	defer f.Close()
	err = tmpl.Execute(f, ef)
	if err != nil {
		return err
	}
	return nil
}

func generateDockerfile() error {
	return ioutil.WriteFile("Dockerfile", []byte(dockerFileTmpl), os.FileMode(0644))
}

type extFile struct {
	Extensions []*extInfo `yaml:"extensions"`
}

type extInfo struct {
	Name string `yaml:"name"`
	// will have version and other things down the road
}

var mainTmpl = `package main

import (
	"context"

	"github.com/fnproject/fn/api/server"
	_ "github.com/fnproject/fn/api/server/defaultexts"

	{{- range .Extensions }}
		_ "{{ .Name }}"
	{{- end}}
)

func main() {
	ctx := context.Background()
	funcServer := server.NewFromEnv(ctx)
	{{- range .Extensions }}
		funcServer.AddExtensionByName("{{ .Name }}")
	{{- end}}
	funcServer.Start(ctx)
}
`

// NOTE: Getting build errors with dep, probably because our vendor dir is wack. Might work again once we switch to dep.
// vendor/github.com/fnproject/fn/api/agent/drivers/docker/registry.go:93: too many arguments in call to client.NewRepository
// have ("context".Context, reference.Named, string, http.RoundTripper) want (reference.Named, string, http.RoundTripper)
// go build github.com/x/y/vendor/github.com/rdallman/migrate/database/mysql: no buildable Go source files in /go/src/github.com/x/y/vendor/github.com/rdallman/migrate/database/mysql
// # github.com/x/y/vendor/github.com/openzipkin/zipkin-go-opentracing/thrift/gen-go/scribe
// vendor/github.com/openzipkin/zipkin-go-opentracing/thrift/gen-go/scribe/scribe.go:210: undefined: thrift.TClient
var dockerFileTmpl = `# build stage
FROM golang:1-alpine AS build-env
RUN apk --no-cache add build-base git bzr mercurial gcc
ENV D=/go/src/github.com/x/y
ADD main.go $D/
RUN cd $D && go get
RUN cd $D && go build -o fnserver && cp fnserver /tmp/

# final stage
FROM fnproject/dind
RUN apk add --no-cache ca-certificates
WORKDIR /app
COPY --from=build-env /tmp/fnserver /app/fnserver
CMD ["./fnserver"]
`