refactor(api): restructured API for type safety, maintainability and docs generation

- These changes makes the API incombatible with previous versions
- Added new types for error handling, success responses, and health checks.
- Updated health check logic to utilize the new types for better clarity and structure.
- Refactored existing handlers to improve response consistency and error handling.
- Updated Makefile to include a new target for generating API types from Swagger.
- Updated "new agent" API to respond an encrypted cert pair

internal/api/v1/agent/common.go

@@ -0,0 +1,67 @@
+package agentapi
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"sync/atomic"
+	"time"
+
+	"github.com/rs/zerolog/log"
+	"github.com/yusing/go-proxy/agent/pkg/agent"
+)
+
+type PEMPairResponse struct {
+	Cert string `json:"cert" format:"base64"`
+	Key  string `json:"key" format:"base64"`
+} // @name PEMPairResponse
+
+var encryptionKey atomic.Value
+
+const rotateKeyInterval = 15 * time.Minute
+
+func init() {
+	if err := rotateKey(); err != nil {
+		log.Panic().Err(err).Msg("failed to generate encryption key")
+	}
+	go func() {
+		for range time.Tick(rotateKeyInterval) {
+			if err := rotateKey(); err != nil {
+				log.Error().Err(err).Msg("failed to rotate encryption key")
+			}
+		}
+	}()
+}
+
+func getEncryptionKey() []byte {
+	return encryptionKey.Load().([]byte)
+}
+
+func rotateKey() error {
+	// generate a random 32 bytes key
+	key := make([]byte, 32)
+	if _, err := rand.Read(key); err != nil {
+		return err
+	}
+	encryptionKey.Store(key)
+	return nil
+}
+
+func toPEMPairResponse(encPEMPair agent.PEMPair) PEMPairResponse {
+	return PEMPairResponse{
+		Cert: base64.StdEncoding.EncodeToString(encPEMPair.Cert),
+		Key:  base64.StdEncoding.EncodeToString(encPEMPair.Key),
+	}
+}
+
+func fromEncryptedPEMPairResponse(pemPair PEMPairResponse) (agent.PEMPair, error) {
+	encCert, err := base64.StdEncoding.DecodeString(pemPair.Cert)
+	if err != nil {
+		return agent.PEMPair{}, err
+	}
+	encKey, err := base64.StdEncoding.DecodeString(pemPair.Key)
+	if err != nil {
+		return agent.PEMPair{}, err
+	}
+	pair := agent.PEMPair{Cert: encCert, Key: encKey}
+	return pair.Decrypt(getEncryptionKey())
+}

internal/api/v1/agent/create.go

@@ -0,0 +1,103 @@
+package agentapi
+
+import (
+	"fmt"
+	"net/http"
+
+	_ "embed"
+
+	"github.com/gin-gonic/gin"
+	"github.com/yusing/go-proxy/agent/pkg/agent"
+	apitypes "github.com/yusing/go-proxy/internal/api/types"
+)
+
+type NewAgentRequest struct {
+	Name    string `form:"name" validate:"required"`
+	Host    string `form:"host" validate:"required"`
+	Port    int    `form:"port" validate:"required,min=1,max=65535"`
+	Type    string `form:"type" validate:"required,oneof=docker system"`
+	Nightly bool   `form:"nightly" validate:"omitempty"`
+} // @name NewAgentRequest
+
+type NewAgentResponse struct {
+	Compose string          `json:"compose"`
+	CA      PEMPairResponse `json:"ca"`
+	Client  PEMPairResponse `json:"client"`
+} // @name NewAgentResponse
+
+// @x-id				"create"
+// @BasePath		/api/v1
+// @Summary		Create a new agent
+// @Description	Create a new agent and return the docker compose file, encrypted CA and client PEMs
+// @Description	The returned PEMs are encrypted with a random key and will be used for verification when adding a new agent
+// @Tags			agent
+// @Accept			json
+// @Produce		json
+// @Param			request	body		NewAgentRequest	true	"Request"
+// @Success		200		{object}	NewAgentResponse
+// @Failure		400		{object}	apitypes.ErrorResponse
+// @Failure		403		{object}	apitypes.ErrorResponse
+// @Failure		409		{object}	apitypes.ErrorResponse
+// @Failure		500		{object}	apitypes.ErrorResponse
+// @Router			/agent/create [post]
+func Create(c *gin.Context) {
+	var request NewAgentRequest
+	if err := c.ShouldBindQuery(&request); err != nil {
+		c.JSON(http.StatusBadRequest, apitypes.Error("invalid request", err))
+		return
+	}
+	hostport := fmt.Sprintf("%s:%d", request.Host, request.Port)
+	if _, ok := agent.GetAgent(hostport); ok {
+		c.JSON(http.StatusConflict, apitypes.Error("agent already exists"))
+		return
+	}
+
+	var image string
+	if request.Nightly {
+		image = agent.DockerImageNightly
+	} else {
+		image = agent.DockerImageProduction
+	}
+
+	ca, srv, client, err := agent.NewAgent()
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to create agent"))
+		return
+	}
+
+	var cfg agent.Generator = &agent.AgentEnvConfig{
+		Name:    request.Name,
+		Port:    request.Port,
+		CACert:  ca.String(),
+		SSLCert: srv.String(),
+	}
+	if request.Type == "docker" {
+		cfg = &agent.AgentComposeConfig{
+			Image:          image,
+			AgentEnvConfig: cfg.(*agent.AgentEnvConfig),
+		}
+	}
+	template, err := cfg.Generate()
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to generate agent config"))
+		return
+	}
+
+	key := getEncryptionKey()
+	encCA, err := ca.Encrypt(key)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to encrypt CA PEMs"))
+		return
+	}
+	encClient, err := client.Encrypt(key)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to encrypt client PEMs"))
+		return
+	}
+
+	c.JSON(http.StatusOK, NewAgentResponse{
+		Compose: template,
+		CA:      toPEMPairResponse(encCA),
+		Client:  toPEMPairResponse(encClient),
+	})
+}

internal/api/v1/agent/list.go

@@ -0,0 +1,32 @@
+package agentapi
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/yusing/go-proxy/agent/pkg/agent"
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/gphttp/websocket"
+)
+
+// @x-id				"list"
+// @BasePath		/api/v1
+// @Summary		List agents
+// @Description	List agents
+// @Tags			agent,websocket
+// @Accept			json
+// @Produce		json
+// @Success		200	{array}		Agent
+// @Failure		403	{object}	apitypes.ErrorResponse
+// @Failure		500	{object}	apitypes.ErrorResponse
+// @Router			/agent/list [get]
+func List(c *gin.Context) {
+	if httpheaders.IsWebsocket(c.Request.Header) {
+		websocket.PeriodicWrite(c, 10*time.Second, func() (any, error) {
+			return agent.ListAgents(), nil
+		})
+	} else {
+		c.JSON(http.StatusOK, agent.ListAgents())
+	}
+}

internal/api/v1/agent/verify.go

@@ -0,0 +1,76 @@
+package agentapi
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/gin-gonic/gin"
+	"github.com/yusing/go-proxy/agent/pkg/certs"
+	. "github.com/yusing/go-proxy/internal/api/types"
+	config "github.com/yusing/go-proxy/internal/config/types"
+)
+
+type VerifyNewAgentRequest struct {
+	Host   string          `json:"host"`
+	CA     PEMPairResponse `json:"ca"`
+	Client PEMPairResponse `json:"client"`
+} // @name VerifyNewAgentRequest
+
+// @x-id          "verify"
+// @BasePath		/api/v1
+// @Summary		Verify a new agent
+// @Description	Verify a new agent and return the number of routes added
+// @Tags			agent
+// @Accept			json
+// @Produce		json
+// @Param			request	body		VerifyNewAgentRequest	true	"Request"
+// @Success		200		{object}	SuccessResponse
+// @Failure		400		{object}	ErrorResponse
+// @Failure		403		{object}	ErrorResponse
+// @Failure		500		{object}	ErrorResponse
+// @Router			/agent/verify [post]
+func Verify(c *gin.Context) {
+	var request VerifyNewAgentRequest
+	if err := c.ShouldBindJSON(&request); err != nil {
+		c.JSON(http.StatusBadRequest, Error("invalid request", err))
+		return
+	}
+
+	filename, ok := certs.AgentCertsFilepath(request.Host)
+	if !ok {
+		c.JSON(http.StatusBadRequest, Error("invalid host", nil))
+		return
+	}
+
+	ca, err := fromEncryptedPEMPairResponse(request.CA)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, Error("invalid CA", err))
+		return
+	}
+
+	client, err := fromEncryptedPEMPairResponse(request.Client)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, Error("invalid client", err))
+		return
+	}
+
+	nRoutesAdded, err := config.GetInstance().VerifyNewAgent(request.Host, ca, client)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, Error("invalid request", err))
+		return
+	}
+
+	zip, err := certs.ZipCert(ca.Cert, client.Cert, client.Key)
+	if err != nil {
+		c.Error(InternalServerError(err, "failed to zip certs"))
+		return
+	}
+
+	if err := os.WriteFile(filename, zip, 0o600); err != nil {
+		c.Error(InternalServerError(err, "failed to write certs"))
+		return
+	}
+
+	c.JSON(http.StatusOK, Success(fmt.Sprintf("Added %d routes", nRoutesAdded)))
+}