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clair/database/pgsql/pgsql.go

354 lines
9.8 KiB

// Copyright 2017 clair authors
//
// 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 pgsql implements database.Datastore with PostgreSQL.
package pgsql
import (
"database/sql"
"fmt"
"io/ioutil"
"net/url"
"strings"
"time"
"gopkg.in/yaml.v2"
"github.com/hashicorp/golang-lru"
"github.com/lib/pq"
"github.com/prometheus/client_golang/prometheus"
"github.com/remind101/migrate"
log "github.com/sirupsen/logrus"
"github.com/coreos/clair/database"
"github.com/coreos/clair/database/pgsql/migrations"
"github.com/coreos/clair/pkg/commonerr"
"github.com/coreos/clair/pkg/pagination"
)
var (
promErrorsTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "clair_pgsql_errors_total",
Help: "Number of errors that PostgreSQL requests generated.",
}, []string{"request"})
promCacheHitsTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "clair_pgsql_cache_hits_total",
Help: "Number of cache hits that the PostgreSQL backend did.",
}, []string{"object"})
promCacheQueriesTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
Name: "clair_pgsql_cache_queries_total",
Help: "Number of cache queries that the PostgreSQL backend did.",
}, []string{"object"})
promQueryDurationMilliseconds = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Name: "clair_pgsql_query_duration_milliseconds",
Help: "Time it takes to execute the database query.",
}, []string{"query", "subquery"})
promConcurrentLockVAFV = prometheus.NewGauge(prometheus.GaugeOpts{
Name: "clair_pgsql_concurrent_lock_vafv_total",
Help: "Number of transactions trying to hold the exclusive Vulnerability_Affects_Feature lock.",
})
)
func init() {
prometheus.MustRegister(promErrorsTotal)
prometheus.MustRegister(promCacheHitsTotal)
prometheus.MustRegister(promCacheQueriesTotal)
prometheus.MustRegister(promQueryDurationMilliseconds)
prometheus.MustRegister(promConcurrentLockVAFV)
database.Register("pgsql", openDatabase)
}
// pgSessionCache is the session's cache, which holds the pgSQL's cache and the
// individual session's cache. Only when session.Commit is called, all the
// changes to pgSQL cache will be applied.
type pgSessionCache struct {
c *lru.ARCCache
}
type pgSQL struct {
*sql.DB
cache *lru.ARCCache
config Config
}
type pgSession struct {
*sql.Tx
key pagination.Key
}
// Begin initiates a transaction to database.
//
// The expected transaction isolation level in this implementation is "Read
// Committed".
func (pgSQL *pgSQL) Begin() (database.Session, error) {
tx, err := pgSQL.DB.Begin()
if err != nil {
return nil, err
}
return &pgSession{
Tx: tx,
key: pagination.Must(pagination.KeyFromString(pgSQL.config.PaginationKey)),
}, nil
}
func (tx *pgSession) Commit() error {
return tx.Tx.Commit()
}
// Close closes the database and destroys if ManageDatabaseLifecycle has been specified in
// the configuration.
func (pgSQL *pgSQL) Close() {
if pgSQL.DB != nil {
pgSQL.DB.Close()
}
if pgSQL.config.ManageDatabaseLifecycle {
dbName, pgSourceURL, _ := parseConnectionString(pgSQL.config.Source)
dropDatabase(pgSourceURL, dbName)
}
}
// Ping verifies that the database is accessible.
func (pgSQL *pgSQL) Ping() bool {
return pgSQL.DB.Ping() == nil
}
// Page is the representation of a page for the Postgres schema.
type Page struct {
// StartID is the ID being used as the basis for pagination across database
// results. It is used to search for an ancestry with ID >= StartID.
//
// StartID is required to be unique to every ancestry and always increasing.
StartID int64
}
// Config is the configuration that is used by openDatabase.
type Config struct {
Source string
CacheSize int
ManageDatabaseLifecycle bool
FixturePath string
PaginationKey string
}
// openDatabase opens a PostgresSQL-backed Datastore using the given
// configuration.
//
// It immediately runs all necessary migrations. If ManageDatabaseLifecycle is
// specified, the database will be created first. If FixturePath is specified,
// every SQL queries that are present insides will be executed.
func openDatabase(registrableComponentConfig database.RegistrableComponentConfig) (database.Datastore, error) {
var pg pgSQL
var err error
// Parse configuration.
pg.config = Config{
CacheSize: 16384,
}
bytes, err := yaml.Marshal(registrableComponentConfig.Options)
if err != nil {
return nil, fmt.Errorf("pgsql: could not load configuration: %v", err)
}
err = yaml.Unmarshal(bytes, &pg.config)
if err != nil {
return nil, fmt.Errorf("pgsql: could not load configuration: %v", err)
}
if pg.config.PaginationKey == "" {
panic("pagination key should be given")
}
dbName, pgSourceURL, err := parseConnectionString(pg.config.Source)
if err != nil {
return nil, err
}
// Create database.
if pg.config.ManageDatabaseLifecycle {
log.Info("pgsql: creating database")
if err = createDatabase(pgSourceURL, dbName); err != nil {
return nil, err
}
}
// Open database.
pg.DB, err = sql.Open("postgres", pg.config.Source)
if err != nil {
pg.Close()
return nil, fmt.Errorf("pgsql: could not open database: %v", err)
}
// Verify database state.
if err = pg.DB.Ping(); err != nil {
pg.Close()
return nil, fmt.Errorf("pgsql: could not open database: %v", err)
}
// Run migrations.
if err = migrateDatabase(pg.DB); err != nil {
pg.Close()
return nil, err
}
// Load fixture data.
if pg.config.FixturePath != "" {
log.Info("pgsql: loading fixtures")
d, err := ioutil.ReadFile(pg.config.FixturePath)
if err != nil {
pg.Close()
return nil, fmt.Errorf("pgsql: could not open fixture file: %v", err)
}
_, err = pg.DB.Exec(string(d))
if err != nil {
pg.Close()
return nil, fmt.Errorf("pgsql: an error occurred while importing fixtures: %v", err)
}
}
// Initialize cache.
// TODO(Quentin-M): Benchmark with a simple LRU Cache.
if pg.config.CacheSize > 0 {
pg.cache, _ = lru.NewARC(pg.config.CacheSize)
}
return &pg, nil
}
func parseConnectionString(source string) (dbName string, pgSourceURL string, err error) {
if source == "" {
return "", "", commonerr.NewBadRequestError("pgsql: no database connection string specified")
}
sourceURL, err := url.Parse(source)
if err != nil {
return "", "", commonerr.NewBadRequestError("pgsql: database connection string is not a valid URL")
}
dbName = strings.TrimPrefix(sourceURL.Path, "/")
pgSource := *sourceURL
pgSource.Path = "/postgres"
pgSourceURL = pgSource.String()
return
}
// migrate runs all available migrations on a pgSQL database.
func migrateDatabase(db *sql.DB) error {
log.Info("running database migrations")
err := migrate.NewPostgresMigrator(db).Exec(migrate.Up, migrations.Migrations...)
if err != nil {
return fmt.Errorf("pgsql: an error occurred while running migrations: %v", err)
}
log.Info("database migration ran successfully")
return nil
}
// createDatabase creates a new database.
// The source parameter should not contain a dbname.
func createDatabase(source, dbName string) error {
// Open database.
db, err := sql.Open("postgres", source)
if err != nil {
return fmt.Errorf("pgsql: could not open 'postgres' database for creation: %v", err)
}
defer db.Close()
// Create database.
_, err = db.Exec("CREATE DATABASE " + dbName)
if err != nil {
return fmt.Errorf("pgsql: could not create database: %v", err)
}
return nil
}
// dropDatabase drops an existing database.
// The source parameter should not contain a dbname.
func dropDatabase(source, dbName string) error {
// Open database.
db, err := sql.Open("postgres", source)
if err != nil {
return fmt.Errorf("could not open database (DropDatabase): %v", err)
}
defer db.Close()
// Kill any opened connection.
if _, err = db.Exec(`
SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE pg_stat_activity.datname = $1
AND pid <> pg_backend_pid()`, dbName); err != nil {
return fmt.Errorf("could not drop database: %v", err)
}
// Drop database.
if _, err = db.Exec("DROP DATABASE " + dbName); err != nil {
return fmt.Errorf("could not drop database: %v", err)
}
return nil
}
// handleError logs an error with an extra description and masks the error if it's an SQL one.
// The function ensures we never return plain SQL errors and leak anything.
// The function should be used for every database query error.
func handleError(desc string, err error) error {
if err == nil {
return nil
}
if err == sql.ErrNoRows {
return commonerr.ErrNotFound
}
log.WithError(err).WithField("Description", desc).Error("Handled Database Error")
promErrorsTotal.WithLabelValues(desc).Inc()
if _, o := err.(*pq.Error); o || err == sql.ErrTxDone || strings.HasPrefix(err.Error(), "sql:") {
return database.ErrBackendException
}
return err
}
// isErrUniqueViolation determines is the given error is a unique contraint violation.
func isErrUniqueViolation(err error) bool {
pqErr, ok := err.(*pq.Error)
return ok && pqErr.Code == "23505"
}
// observeQueryTime computes the time elapsed since `start` to represent the
// query time.
// 1. `query` is a pgSession function name.
// 2. `subquery` is a specific query or a batched query.
// 3. `start` is the time right before query is executed.
func observeQueryTime(query, subquery string, start time.Time) {
promQueryDurationMilliseconds.
WithLabelValues(query, subquery).
Observe(float64(time.Since(start).Nanoseconds()) / float64(time.Millisecond))
}