Put project modules under pkg directory

Dockerfile

@@ -1,10 +1,10 @@
 FROM golang:1.16-alpine AS builder
 ADD . /src
-RUN cd /src/cmd/link && go build
+RUN cd /src/cmd/cgnolink && go build
 
 FROM alpine
 EXPOSE 8080
 WORKDIR /app
-COPY --from=builder /src/cmd/link/link /app/
+COPY --from=builder /src/cmd/cgnolink/cgnolink /app/
 COPY --from=builder /src/migrations /app/migrations
-ENTRYPOINT ./link
+ENTRYPOINT ./cgnolink

cmd/cgnolink/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"cgnolink/pkg/cgnolink"
+	"cgnolink/pkg/cgnolink/database"
+	appserver "cgnolink/pkg/cgnolink/server"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+	"os"
+)
+
+func main() {
+	configureLogger()
+
+	conf := cgnolink.NewConfig()
+
+	pool := database.InitPool(conf)
+
+	server := appserver.NewServer(conf, pool)
+
+	server.Logger.Fatal(server.Start(":8080"))
+}
+
+func configureLogger() {
+	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr, TimeFormat: "2006-01-02 15:04:05"})
+}

cmd/link/main.go

@@ -1,20 +0,0 @@
-package main
-
-import (
-	"link"
-	"link/database"
-)
-
-func main() {
-	conf := link.NewConfig()
-
-	pool := database.Pool(conf)
-
-	if err := link.Migrate(pool); err != nil {
-		panic(err)
-	}
-
-	server := link.NewServer(conf, pool)
-
-	server.Logger.Fatal(server.Start(":8080"))
-}

go.mod

@@ -1,4 +1,4 @@
-module link
+module cgnolink
 
 go 1.16
 
@@ -13,6 +13,9 @@ require (
 	github.com/knadh/koanf v0.15.0
 	github.com/labstack/echo/v4 v4.2.1
 	github.com/mitchellh/copystructure v1.1.1 // indirect
+	github.com/patrickmn/go-cache v2.1.0+incompatible
+	github.com/rs/zerolog v1.20.0
+	golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83
 	golang.org/x/sys v0.0.0-20210309074719-68d13333faf2 // indirect
 	golang.org/x/text v0.3.5 // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect

go.sum

@@ -212,6 +212,8 @@ github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRW
 github.com/oklog/run v1.0.0/go.mod h1:dlhp/R75TPv97u0XWUtDeV/lRKWPKSdTuV0TZvrmrQA=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/pascaldekloe/goe v0.1.0/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144TG7ZOy1lc=
+github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
+github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pelletier/go-toml v1.7.0 h1:7utD74fnzVc/cpcyy8sjrlFr5vYpypUixARcHIMIGuI=
 github.com/pelletier/go-toml v1.7.0/go.mod h1:vwGMzjaWMwyfHwgIBhI2YUM4fB6nL6lVAvS1LBMMhTE=
@@ -237,6 +239,8 @@ github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFR
 github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
 github.com/rs/zerolog v1.13.0/go.mod h1:YbFCdg8HfsridGWAh22vktObvhZbQsZXe4/zB0OKkWU=
 github.com/rs/zerolog v1.15.0/go.mod h1:xYTKnLHcpfU2225ny5qZjxnj9NvkumZYjJHlAThCjNc=
+github.com/rs/zerolog v1.20.0 h1:38k9hgtUBdxFwE34yS8rTHmHBa4eN16E4DJlv177LNs=
+github.com/rs/zerolog v1.20.0/go.mod h1:IzD0RJ65iWH0w97OQQebJEvTZYvsCUm9WVLWBQrJRjo=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/ryanuber/columnize v2.1.0+incompatible/go.mod h1:sm1tb6uqfes/u+d4ooFouqFdy9/2g9QGwK3SQygK0Ts=
 github.com/ryanuber/go-glob v1.0.0/go.mod h1:807d1WSdnB0XRJzKNil9Om6lcp/3a0v4qIHxIXzX/Yc=
@@ -363,6 +367,7 @@ golang.org/x/tools v0.0.0-20190425163242-31fd60d6bfdc/go.mod h1:RgjU9mgBXZiqYHBn
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/tools v0.0.0-20190621195816-6e04913cbbac/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=
 golang.org/x/tools v0.0.0-20190823170909-c4a336ef6a2f/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20190828213141-aed303cbaa74/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191029041327-9cc4af7d6b2c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/xerrors v0.0.0-20190410155217-1f06c39b4373/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

link/handlers.go

@@ -1,144 +0,0 @@
-package link
-
-import (
-	"encoding/json"
-	"github.com/jackc/pgx/v4/pgxpool"
-	"github.com/labstack/echo/v4"
-	"net/http"
-	"strconv"
-)
-
-func redirectHandler(c echo.Context, pool *pgxpool.Pool) error {
-	linkId := c.Param("id")
-
-	rep := PgRepository{pool: pool}
-
-	link, err := rep.FindById(linkId)
-	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	if link == nil {
-		return echo.NewHTTPError(http.StatusNotFound, "Link with given ID was not found.")
-	}
-
-	return c.Redirect(http.StatusSeeOther, link.RedirectURL.String())
-}
-
-func creationHandler(c echo.Context, pool *pgxpool.Pool) error {
-	var model CreationModel
-	if err := json.NewDecoder(c.Request().Body).Decode(&model); err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid data format.")
-	}
-
-	entity, err := model.MapModelToEntity()
-	if err != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Invalid URL.")
-	}
-
-	rep := PgRepository{pool: pool}
-
-	link, err := rep.FindById(entity.Id)
-	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	if link != nil {
-		return echo.NewHTTPError(http.StatusBadRequest, "Link with given ID already exists.")
-	}
-
-	if err = rep.Save(entity); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	return c.NoContent(http.StatusCreated)
-}
-
-func retrievalByIdHandler(c echo.Context, pool *pgxpool.Pool) error {
-	linkId := c.Param("id")
-
-	rep := PgRepository{pool: pool}
-
-	link, err := rep.FindById(linkId)
-	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	if link == nil {
-		return echo.NewHTTPError(http.StatusNotFound, "Link with given ID was not found.")
-	}
-
-	return c.JSON(http.StatusOK, MapEntityToModel(link))
-}
-
-func allRetrievalHandler(c echo.Context, pool *pgxpool.Pool) error {
-	limit := 20
-	if v := c.QueryParam("limit"); v != "" {
-		num, err := strconv.Atoi(v)
-		if err != nil {
-			return echo.NewHTTPError(http.StatusBadRequest, "Invalid limit value.")
-		}
-
-		limit = num
-	}
-
-	offset := 0
-	if v := c.QueryParam("offset"); v != "" {
-		num, err := strconv.Atoi(v)
-		if err != nil {
-			return echo.NewHTTPError(http.StatusBadRequest, "Invalid offset value.")
-		}
-
-		offset = num
-	}
-
-	rep := PgRepository{pool: pool}
-
-	links, err := rep.FindAll(limit, offset)
-	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	models := make([]ResourceModel, len(links))
-	for i, link := range links {
-		models[i] = MapEntityToModel(&link)
-	}
-
-	return c.JSON(http.StatusOK, models)
-}
-
-func removalHandler(c echo.Context, pool *pgxpool.Pool) error {
-	linkId := c.Param("id")
-
-	rep := PgRepository{pool: pool}
-
-	if err := rep.DeleteById(linkId); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError)
-	}
-
-	return c.NoContent(http.StatusNoContent)
-}
-
-func AddHandlers(s *echo.Echo, pool *pgxpool.Pool) {
-	gr := s.Group("/links")
-
-	gr.POST("", func(ctx echo.Context) error {
-		return creationHandler(ctx, pool)
-	})
-
-	gr.GET("", func(ctx echo.Context) error {
-		return allRetrievalHandler(ctx, pool)
-	})
-
-	gr.GET("/:id", func(ctx echo.Context) error {
-		return retrievalByIdHandler(ctx, pool)
-	})
-
-	gr.DELETE("/:id", func(ctx echo.Context) error {
-		return removalHandler(ctx, pool)
-	})
-
-	s.GET("/:id", func(ctx echo.Context) error {
-		return redirectHandler(ctx, pool)
-	})
-}

link/repository.go

@@ -1,189 +0,0 @@
-package link
-
-import (
-	"context"
-	"errors"
-	"github.com/jackc/pgtype"
-	"github.com/jackc/pgx/v4"
-	"github.com/jackc/pgx/v4/pgxpool"
-	"net/url"
-	"time"
-)
-
-type Repository interface {
-	Save(link *Link) error
-	FindById(id string) (*Link, error)
-	FindAll(limit int, offset int) ([]Link, error)
-	DeleteById(id string) error
-}
-
-type PgRepository struct {
-	pool *pgxpool.Pool
-}
-
-func (r *PgRepository) Save(link *Link) error {
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-
-	tx, err := r.pool.Begin(ctx)
-	if err != nil {
-		return err
-	}
-
-	sql := `
-		INSERT INTO links (id, name, redirect_url, creation_time) 
-		VALUES ($1, $2, $3, $4::timestamp)
-	`
-
-	_, err = tx.Exec(ctx, sql, link.Id, link.Name, link.RedirectURL.String(), link.CreationTime.Format("2006-01-02 15:04:05"))
-	if err != nil {
-		_ = tx.Rollback(ctx)
-		return err
-	}
-
-	if err = tx.Commit(ctx); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (r *PgRepository) FindById(id string) (*Link, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-
-	tx, err := r.pool.Begin(ctx)
-	if err != nil {
-		return nil, err
-	}
-
-	sql := `
-		SELECT id, name, redirect_url, creation_time
-		FROM links
-		WHERE id = $1
-	`
-
-	entity, err := mapRowToEntity(tx.QueryRow(ctx, sql, id))
-	if err != nil {
-		if errors.Is(err, pgx.ErrNoRows) {
-			return nil, nil
-		} else {
-			_ = tx.Rollback(ctx)
-			return nil, err
-		}
-	}
-
-	if err = tx.Commit(ctx); err != nil {
-		return nil, err
-	}
-
-	return entity, nil
-}
-
-func (r *PgRepository) FindAll(limit int, offset int) ([]Link, error) {
-	if limit < 0 {
-		return nil, errors.New("limit can't be negative")
-	}
-	if offset < 0 {
-		return nil, errors.New("offset can't be negative")
-	}
-
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-
-	tx, err := r.pool.Begin(ctx)
-	if err != nil {
-		return nil, err
-	}
-
-	sql := `
-		SELECT id, name, redirect_url, creation_time
-		FROM links
-		LIMIT $1
-		OFFSET $2
-	`
-
-	rows, err := tx.Query(ctx, sql, limit, offset)
-	if err != nil {
-		_ = tx.Rollback(ctx)
-		return nil, err
-	}
-	defer rows.Close()
-
-	links := make([]Link, 0)
-	for rows.Next() {
-		link, err := mapRowToEntity(rows)
-		if err != nil {
-			_ = tx.Rollback(ctx)
-			return nil, err
-		}
-
-		links = append(links, *link)
-	}
-
-	if err = rows.Err(); err != nil {
-		_ = tx.Rollback(ctx)
-		return nil, err
-	}
-
-	if err = tx.Commit(ctx); err != nil {
-		return nil, err
-	}
-
-	return links, nil
-}
-
-func (r *PgRepository) DeleteById(id string) error {
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-
-	tx, err := r.pool.Begin(ctx)
-	if err != nil {
-		return err
-	}
-
-	sql := `
-		DELETE FROM links WHERE id = $1
-	`
-
-	_, err = tx.Exec(ctx, sql, id)
-	if err != nil {
-		_ = tx.Rollback(ctx)
-		return err
-	}
-
-	if err = tx.Commit(ctx); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func mapRowToEntity(r interface{}) (*Link, error) {
-	var entity Link
-	var urlStr string
-	var t pgtype.Timestamp
-
-	switch v := r.(type) {
-	case pgx.Row:
-		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
-			return nil, err
-		}
-	case pgx.Rows:
-		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &t); err != nil {
-			return nil, err
-		}
-	default:
-		return nil, errors.New("unsupported type")
-	}
-
-	u, err := url.Parse(urlStr)
-	if err != nil {
-		return nil, err
-	}
-
-	entity.RedirectURL = *u
-	entity.CreationTime = t.Time
-
-	return &entity, nil
-}

migrate.go

@@ -1,29 +0,0 @@
-package link
-
-import (
-	"context"
-	"github.com/jackc/pgx/v4/pgxpool"
-	"github.com/jackc/tern/migrate"
-)
-
-func Migrate(pool *pgxpool.Pool) error {
-	conn, err := pool.Acquire(context.Background())
-	if err != nil {
-		return err
-	}
-
-	migrator, err := migrate.NewMigrator(context.Background(), conn.Conn(), "schema_version")
-	if err != nil {
-		return err
-	}
-
-	if err = migrator.LoadMigrations("./migrations"); err != nil {
-		return err
-	}
-
-	if err = migrator.Migrate(context.Background()); err != nil {
-		return err
-	}
-
-	return nil
-}

migrations/002_add_password.sql

@@ -0,0 +1,13 @@
+ALTER TABLE links
+ADD COLUMN password varchar;
+
+UPDATE links
+SET password = '';
+
+ALTER TABLE links
+ALTER COLUMN password SET not null;
+
+---- create above / drop below ----
+
+ALTER TABLE links
+DROP COLUMN password;

pkg/cgnolink/config.go

@@ -1,4 +1,4 @@
-package link
+package cgnolink
 
 import (
 	"github.com/knadh/koanf"

pkg/cgnolink/database/database.go

@@ -6,16 +6,34 @@ import (
 	"fmt"
 	"github.com/jackc/pgx/v4/pgxpool"
 	"github.com/knadh/koanf"
+	"github.com/rs/zerolog/log"
+	"time"
 )
 
-func Pool(config *koanf.Koanf) *pgxpool.Pool {
-	connStr, err := getConnectionString(config)
-	if err != nil {
+func InitPool(config *koanf.Koanf) *pgxpool.Pool {
+	pool := NewPool(config)
+
+	if err := runMigrations(pool); err != nil {
+		log.Fatal().Err(err).Msg("Couldn't apply migrations")
 		panic(err)
 	}
 
-	pool, err := pgxpool.Connect(context.Background(), connStr)
+	return pool
+}
+
+func NewPool(config *koanf.Koanf) *pgxpool.Pool {
+	connStr, err := getConnectionString(config)
 	if err != nil {
+		log.Fatal().Err(err).Msg("Couldn't construct DB connection string")
+		panic(err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	pool, err := pgxpool.Connect(ctx, connStr)
+	if err != nil {
+		log.Fatal().Err(err).Msg("Couldn't connect to DB")
 		panic(err)
 	}
 

pkg/cgnolink/database/migrate.go

@@ -0,0 +1,33 @@
+package database
+
+import (
+	"context"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/jackc/tern/migrate"
+	"time"
+)
+
+func runMigrations(pool *pgxpool.Pool) (err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	conn, err := pool.Acquire(ctx)
+	if err != nil {
+		return
+	}
+
+	migrator, err := migrate.NewMigrator(ctx, conn.Conn(), "schema_version")
+	if err != nil {
+		return
+	}
+
+	if err = migrator.LoadMigrations("./migrations"); err != nil {
+		return
+	}
+
+	if err = migrator.Migrate(ctx); err != nil {
+		return
+	}
+
+	return
+}

pkg/cgnolink/database/util.go

@@ -0,0 +1,15 @@
+package database
+
+import (
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/rs/zerolog/log"
+)
+
+func LogPoolState(pool *pgxpool.Pool, message string) {
+	stat := pool.Stat()
+	log.Info().
+		Int32("acquired_conns", stat.AcquiredConns()).
+		Int32("idle_conns", stat.IdleConns()).
+		Int32("total_conns", stat.TotalConns()).
+		Msg(message)
+}

pkg/cgnolink/errors/errors.go

@@ -0,0 +1,29 @@
+package errors
+
+type UnknownError struct {
+	Err error
+}
+
+func (err UnknownError) Error() string {
+	return err.Err.Error()
+}
+
+func (err UnknownError) Unwrap() error {
+	return err.Err
+}
+
+type NotFoundError struct {
+	Message string
+}
+
+func (err NotFoundError) Error() string {
+	return err.Message
+}
+
+type AlreadyExistsError struct {
+	Message string
+}
+
+func (err AlreadyExistsError) Error() string {
+	return err.Message
+}

pkg/cgnolink/link/dto.go

@@ -9,6 +9,7 @@ type CreationModel struct {
 	Id          string `json:"id"`
 	Name        string `json:"name"`
 	RedirectURL string `json:"redirectUrl"`
+	Password    string `json:"password"`
 }
 
 type ResourceModel struct {
@@ -18,6 +19,12 @@ type ResourceModel struct {
 	CreationTime int64  `json:"creationTime"`
 }
 
+type UpdateModel struct {
+	Name        string `json:"name,omitempty"`
+	RedirectURL string `json:"redirectUrl,omitempty"`
+	Password    string `json:"password"`
+}
+
 func (m *CreationModel) MapModelToEntity() (*Link, error) {
 	u, err := url.Parse(m.RedirectURL)
 	if err != nil {
@@ -28,6 +35,7 @@ func (m *CreationModel) MapModelToEntity() (*Link, error) {
 		Id:           m.Id,
 		Name:         m.Name,
 		RedirectURL:  *u,
+		Password:     m.Password,
 		CreationTime: time.Now().UTC(),
 	}, nil
 }

pkg/cgnolink/link/entity.go

@@ -9,5 +9,8 @@ type Link struct {
 	Id           string
 	Name         string
 	RedirectURL  url.URL
+	Password     string
 	CreationTime time.Time
 }
+
+type Links = []*Link

pkg/cgnolink/link/handlers.go

@@ -0,0 +1,151 @@
+package link
+
+import (
+	"encoding/json"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/labstack/echo/v4"
+	"net/http"
+	"net/url"
+	"strconv"
+)
+
+func redirectHandler(ctx echo.Context, serv Service) error {
+	linkId := ctx.Param("id")
+	linkPassword := ctx.QueryParam("password")
+
+	redirectUrl, err := serv.AccessLink(linkId, linkPassword)
+	if err != nil {
+		return err
+	}
+
+	return ctx.Redirect(http.StatusSeeOther, redirectUrl.String())
+}
+
+func creationHandler(ctx echo.Context, serv Service) error {
+	var model CreationModel
+	if err := json.NewDecoder(ctx.Request().Body).Decode(&model); err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid data format.")
+	}
+
+	entity, err := model.MapModelToEntity()
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid URL.")
+	}
+
+	if err = serv.Create(entity); err != nil {
+		return err
+	}
+
+	return ctx.NoContent(http.StatusCreated)
+}
+
+func retrievalByIdHandler(ctx echo.Context, serv Service) error {
+	linkId := ctx.Param("id")
+
+	l, err := serv.GetById(linkId)
+	if err != nil {
+		return err
+	}
+
+	return ctx.JSON(http.StatusOK, MapEntityToModel(l))
+}
+
+func allRetrievalHandler(ctx echo.Context, serv Service) error {
+	limit := 20
+	if v := ctx.QueryParam("limit"); v != "" {
+		num, err := strconv.Atoi(v)
+		if err != nil || num < 0 {
+			return echo.NewHTTPError(http.StatusBadRequest, "Invalid limit value.")
+		}
+
+		limit = num
+	}
+
+	offset := 0
+	if v := ctx.QueryParam("offset"); v != "" {
+		num, err := strconv.Atoi(v)
+		if err != nil || num < 0 {
+			return echo.NewHTTPError(http.StatusBadRequest, "Invalid offset value.")
+		}
+
+		offset = num
+	}
+
+	links, err := serv.GetAll(limit, offset)
+	if err != nil {
+		return err
+	}
+
+	models := make([]ResourceModel, len(links))
+	for i, v := range links {
+		models[i] = MapEntityToModel(v)
+	}
+
+	return ctx.JSON(http.StatusOK, models)
+}
+
+func updateHandler(ctx echo.Context, serv Service) error {
+	linkId := ctx.Param("id")
+
+	var model UpdateModel
+	if err := json.NewDecoder(ctx.Request().Body).Decode(&model); err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid data format.")
+	}
+
+	var parsedUrl *url.URL
+	parsedUrl, err := url.Parse(model.RedirectURL)
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "Invalid URL value.")
+	}
+
+	if err := serv.UpdateById(linkId, struct {
+		Name        string
+		Password    string
+		RedirectURL *url.URL
+	}{Name: model.Name, Password: model.Password, RedirectURL: parsedUrl}); err != nil {
+		return err
+	}
+
+	return ctx.NoContent(http.StatusOK)
+}
+
+func removalHandler(ctx echo.Context, serv Service) error {
+	linkId := ctx.Param("id")
+
+	if err := serv.DeleteById(linkId); err != nil {
+		return err
+	}
+
+	return ctx.NoContent(http.StatusNoContent)
+}
+
+func AddHandlers(server *echo.Echo, pool *pgxpool.Pool) {
+	serv := NewService(NewRepository(pool))
+
+	linksGroup := server.Group("/links")
+	exactLinkGroup := linksGroup.Group("/:id")
+
+	linksGroup.POST("", func(ctx echo.Context) error {
+		return creationHandler(ctx, serv)
+	})
+
+	linksGroup.GET("", func(ctx echo.Context) error {
+		return allRetrievalHandler(ctx, serv)
+	})
+
+	exactLinkGroup.GET("", func(ctx echo.Context) error {
+		return retrievalByIdHandler(ctx, serv)
+	})
+
+	exactLinkGroup.PATCH("", func(ctx echo.Context) error {
+		return updateHandler(ctx, serv)
+	})
+
+	exactLinkGroup.DELETE("", func(ctx echo.Context) error {
+		return removalHandler(ctx, serv)
+	})
+
+	server.GET("/:id", func(ctx echo.Context) error {
+		return redirectHandler(ctx, serv)
+	})
+}

pkg/cgnolink/link/repository.go

@@ -0,0 +1,182 @@
+package link
+
+import (
+	"cgnolink/pkg/cgnolink/database"
+	"context"
+	"errors"
+	"github.com/jackc/pgtype"
+	"github.com/jackc/pgx/v4"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"net/url"
+	"time"
+)
+
+const defaultContextTimeout = 10 * time.Second
+
+type Repository interface {
+	Save(link *Link) error
+	FindById(id string) (*Link, error)
+	GetAll(limit int, offset int) (Links, error)
+	Update(link *Link) error
+	DeleteById(id string) error
+}
+
+type PgRepository struct {
+	pool *pgxpool.Pool
+}
+
+func NewRepository(pool *pgxpool.Pool) Repository {
+	return &PgRepository{pool: pool}
+}
+
+func (r *PgRepository) Save(link *Link) error {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+	defer cancel()
+
+	sql := `
+		INSERT INTO links (id, name, redirect_url, password, creation_time) 
+		VALUES ($1, $2, $3, $4, $5::timestamp)
+	`
+
+	database.LogPoolState(r.pool, "Saving link")
+	_, err := r.pool.Exec(ctx, sql, link.Id, link.Name, link.RedirectURL.String(), link.Password, link.CreationTime.Format("2006-01-02 15:04:05"))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *PgRepository) FindById(id string) (*Link, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+	defer cancel()
+
+	sql := `
+		SELECT id, name, redirect_url, password, creation_time
+		FROM links
+		WHERE id = $1
+	`
+
+	database.LogPoolState(r.pool, "Finding link by ID")
+	entity, err := mapRowToEntity(r.pool.QueryRow(ctx, sql, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil
+		} else {
+			return nil, err
+		}
+	}
+
+	return entity, nil
+}
+
+func (r *PgRepository) GetAll(limit int, offset int) (Links, error) {
+	if limit < 0 {
+		return nil, errors.New("limit can't be negative")
+	}
+	if offset < 0 {
+		return nil, errors.New("offset can't be negative")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+	defer cancel()
+
+	sql := `
+		SELECT id, name, redirect_url, password, creation_time
+		FROM links
+		LIMIT $1
+		OFFSET $2
+	`
+
+	database.LogPoolState(r.pool, "Getting all links")
+	rows, err := r.pool.Query(ctx, sql, limit, offset)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	links := make(Links, 0)
+	for rows.Next() {
+		link, err := mapRowToEntity(rows)
+		if err != nil {
+			return nil, err
+		}
+
+		links = append(links, link)
+	}
+
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return links, nil
+}
+
+func (r *PgRepository) Update(link *Link) error {
+	if link.Id == "" {
+		return errors.New("link ID must not be empty")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+	defer cancel()
+
+	sql := `
+		UPDATE links
+		SET name = $1, redirect_url = $2, password = $3
+		WHERE id = $4
+	`
+
+	database.LogPoolState(r.pool, "Updating link")
+	_, err := r.pool.Exec(ctx, sql, link.Name, link.RedirectURL.String(), link.Password, link.Id)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *PgRepository) DeleteById(id string) error {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
+	defer cancel()
+
+	sql := `
+		DELETE FROM links WHERE id = $1
+	`
+
+	database.LogPoolState(r.pool, "Deleting link")
+	_, err := r.pool.Exec(ctx, sql, id)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func mapRowToEntity(r interface{}) (*Link, error) {
+	var entity Link
+	var urlStr string
+	var t pgtype.Timestamp
+
+	switch v := r.(type) {
+	case pgx.Row:
+		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &entity.Password, &t); err != nil {
+			return nil, err
+		}
+	case pgx.Rows:
+		if err := v.Scan(&entity.Id, &entity.Name, &urlStr, &entity.Password, &t); err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.New("unsupported type")
+	}
+
+	u, err := url.Parse(urlStr)
+	if err != nil {
+		return nil, err
+	}
+
+	entity.RedirectURL = *u
+	entity.CreationTime = t.Time
+
+	return &entity, nil
+}

pkg/cgnolink/link/service.go

@@ -0,0 +1,171 @@
+package link
+
+import (
+	apperrors "cgnolink/pkg/cgnolink/errors"
+	"github.com/patrickmn/go-cache"
+	"golang.org/x/crypto/bcrypt"
+	"net/url"
+)
+
+var linkNotFoundError = apperrors.NotFoundError{Message: "Link with given ID was not found."}
+
+type Service interface {
+	Create(link *Link) error
+	GetById(id string) (*Link, error)
+	AccessLink(id string, password string) (*url.URL, error)
+	GetAll(limit int, offset int) (Links, error)
+	UpdateById(
+		id string,
+		data struct {
+			Name        string
+			Password    string
+			RedirectURL *url.URL
+		},
+	) error
+	DeleteById(id string) error
+}
+
+type PgService struct {
+	rep   Repository
+	cache *cache.Cache
+}
+
+func (service *PgService) AccessLink(id string, password string) (*url.URL, error) {
+	link, err := service.GetById(id)
+	if err != nil {
+		return nil, err
+	}
+
+	if link.Password != "" {
+		if password == "" || bcrypt.CompareHashAndPassword([]byte(link.Password), []byte(password)) != nil {
+			return nil, linkNotFoundError
+		}
+	}
+
+	return &link.RedirectURL, nil
+}
+
+func NewService(rep Repository) Service {
+	return &PgService{
+		rep:   rep,
+		cache: cache.New(cache.NoExpiration, 0),
+	}
+}
+
+func (service *PgService) Create(link *Link) error {
+	existingLink, err := service.rep.FindById(link.Id)
+	if err != nil {
+		return apperrors.UnknownError{Err: err}
+	}
+
+	if existingLink != nil {
+		return apperrors.AlreadyExistsError{Message: "Link with given ID already exists."}
+	}
+
+	if link.Password != "" {
+		hashedPassword, err := HashPassword(link.Password)
+		if err != nil {
+			return err
+		}
+
+		link.Password = hashedPassword
+	}
+
+	if err = service.rep.Save(link); err != nil {
+		return apperrors.UnknownError{Err: err}
+	}
+
+	return nil
+}
+
+func (service *PgService) GetById(id string) (*Link, error) {
+	if v, found := service.cache.Get(id); found {
+		if link, ok := v.(*Link); ok {
+			return link, nil
+		}
+	}
+
+	link, err := service.rep.FindById(id)
+	if err != nil {
+		return nil, apperrors.UnknownError{Err: err}
+	}
+
+	if link == nil {
+		return nil, linkNotFoundError
+	}
+
+	service.cache.Set(id, link, cache.DefaultExpiration)
+
+	return link, nil
+}
+
+func (service *PgService) GetAll(limit int, offset int) (Links, error) {
+	links, err := service.rep.GetAll(limit, offset)
+	if err != nil {
+		return nil, apperrors.UnknownError{Err: err}
+	}
+
+	return links, nil
+}
+
+func (service *PgService) UpdateById(
+	id string,
+	data struct {
+		Name        string
+		Password    string
+		RedirectURL *url.URL
+	},
+) error {
+	link, err := service.GetById(id)
+	if err != nil {
+		return err
+	}
+
+	hasChanges := false
+	switch {
+	case data.Name != "":
+		link.Name = data.Name
+
+		hasChanges = true
+	case data.RedirectURL != nil:
+		link.RedirectURL = *data.RedirectURL
+
+		hasChanges = true
+	case data.Password != "":
+		hashedPw, err := HashPassword(data.Password)
+		if err != nil {
+			return err
+		}
+
+		link.Password = hashedPw
+
+		hasChanges = true
+	}
+
+	if hasChanges {
+		if err := service.rep.Update(link); err != nil {
+			return apperrors.UnknownError{Err: err}
+		}
+		service.cache.Delete(link.Id)
+	}
+
+	return nil
+}
+
+func (service *PgService) DeleteById(id string) error {
+	if err := service.rep.DeleteById(id); err != nil {
+		return apperrors.UnknownError{Err: err}
+	}
+	service.cache.Delete(id)
+
+	return nil
+}
+
+func HashPassword(password string) (string, error) {
+	hashedPw, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return "", apperrors.UnknownError{Err: err}
+	}
+
+	return string(hashedPw), nil
+}

pkg/cgnolink/server/middleware.go

@@ -0,0 +1,34 @@
+package server
+
+import (
+	"github.com/labstack/echo/v4"
+	"github.com/rs/zerolog/log"
+	"time"
+)
+
+func Logger() echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) (err error) {
+			req := c.Request()
+			res := c.Response()
+			start := time.Now()
+			if err = next(c); err != nil {
+				c.Error(err)
+			}
+			stop := time.Now()
+
+			log.Info().
+				Str("remote_ip", c.RealIP()).
+				Str("host", req.Host).
+				Str("uri", req.RequestURI).
+				Str("method", req.Method).
+				Str("path", req.URL.Path).
+				Str("user_agent", req.UserAgent()).
+				Int("status", res.Status).
+				Str("latency", stop.Sub(start).String()).
+				Msg("Request")
+
+			return
+		}
+	}
+}

pkg/cgnolink/server/server.go

@@ -1,17 +1,22 @@
-package link
+package server
 
 import (
+	apperrors "cgnolink/pkg/cgnolink/errors"
+	"cgnolink/pkg/cgnolink/link"
 	"github.com/jackc/pgx/v4/pgxpool"
 	"github.com/knadh/koanf"
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
-	"link/link"
+	"github.com/rs/zerolog/log"
 	"net/http"
+	"regexp"
 )
 
 func NewServer(conf *koanf.Koanf, pool *pgxpool.Pool) *echo.Echo {
 	server := echo.New()
 
+	server.HTTPErrorHandler = errorHandler(server)
+
 	addMiddleware(server, conf)
 	addHandlers(server, pool)
 
@@ -21,9 +26,13 @@ func NewServer(conf *koanf.Koanf, pool *pgxpool.Pool) *echo.Echo {
 func addMiddleware(s *echo.Echo, conf *koanf.Koanf) {
 	s.Use(middleware.CORS())
 
+	s.Use(Logger())
+
 	s.Use(middleware.JWTWithConfig(middleware.JWTConfig{
 		Skipper: func(ctx echo.Context) bool {
-			return ctx.Request().Method == "GET" && ctx.Request().URL.Path != "/links"
+			matchesLinks, _ := regexp.MatchString("^/links", ctx.Request().URL.Path)
+
+			return ctx.Request().Method == "GET" && !matchesLinks
 		},
 		SigningMethod: conf.String("jwt.method"),
 		SigningKey:    conf.Bytes("jwt.key"),
@@ -41,3 +50,21 @@ func addHandlers(s *echo.Echo, pool *pgxpool.Pool) {
 
 	link.AddHandlers(s, pool)
 }
+
+func errorHandler(s *echo.Echo) echo.HTTPErrorHandler {
+	return func(err error, c echo.Context) {
+		mappedErr := err
+
+		switch v := err.(type) {
+		case apperrors.NotFoundError:
+			mappedErr = echo.NewHTTPError(http.StatusNotFound, v.Error())
+		case apperrors.UnknownError:
+			log.Err(v.Err).Send()
+			mappedErr = echo.NewHTTPError(http.StatusInternalServerError)
+		case apperrors.AlreadyExistsError:
+			mappedErr = echo.NewHTTPError(http.StatusBadRequest, v.Error())
+		}
+
+		s.DefaultHTTPErrorHandler(mappedErr, c)
+	}
+}