whatcanGOwrong

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2024-09-19 21:38:24 -04:00
commit d0ae4d841d
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# Cassandra / ScyllaDB
* `Drop()` method will not work on Cassandra 2.X because it rely on
system_schema table which comes with 3.X
* Other methods should work properly but are **not tested**
* The Cassandra driver (gocql) does not natively support executing multiple statements in a single query. To allow for multiple statements in a single migration, you can use the `x-multi-statement` param. There are two important caveats:
* This mode splits the migration text into separately-executed statements by a semi-colon `;`. Thus `x-multi-statement` cannot be used when a statement in the migration contains a string with a semi-colon.
* The queries are not executed in any sort of transaction/batch, meaning you are responsible for fixing partial migrations.
**ScyllaDB**
* No additional configuration is required since it is a drop-in replacement for Cassandra.
* The `Drop()` method` works for ScyllaDB 5.1
## Usage
`cassandra://host:port/keyspace?param1=value&param2=value2`
| URL Query | Default value | Description |
|------------|-------------|-----------|
| `x-migrations-table` | schema_migrations | Name of the migrations table |
| `x-multi-statement` | false | Enable multiple statements to be ran in a single migration (See note above) |
| `port` | 9042 | The port to bind to |
| `consistency` | ALL | Migration consistency
| `protocol` | | Cassandra protocol version (3 or 4)
| `timeout` | 1 minute | Migration timeout
| `connect-timeout` | 600ms | Initial connection timeout to the cluster |
| `username` | nil | Username to use when authenticating. |
| `password` | nil | Password to use when authenticating. |
| `sslcert` | | Cert file location. The file must contain PEM encoded data. |
| `sslkey` | | Key file location. The file must contain PEM encoded data. |
| `sslrootcert` | | The location of the root certificate file. The file must contain PEM encoded data. |
| `sslmode` | | Whether or not to use SSL (disable\|require\|verify-ca\|verify-full) |
| `disable-host-lookup`| false | Disable initial host lookup. |
`timeout` is parsed using [time.ParseDuration(s string)](https://golang.org/pkg/time/#ParseDuration)
## Upgrading from v1
1. Write down the current migration version from schema_migrations
2. `DROP TABLE schema_migrations`
4. Download and install the latest migrate version.
5. Force the current migration version with `migrate force <current_version>`.
@@ -0,0 +1,352 @@
package cassandra
import (
"errors"
"fmt"
"io"
nurl "net/url"
"strconv"
"strings"
"time"
"go.uber.org/atomic"
"github.com/gocql/gocql"
"github.com/golang-migrate/migrate/v4/database"
"github.com/golang-migrate/migrate/v4/database/multistmt"
"github.com/hashicorp/go-multierror"
)
func init() {
db := new(Cassandra)
database.Register("cassandra", db)
}
var (
multiStmtDelimiter = []byte(";")
DefaultMultiStatementMaxSize = 10 * 1 << 20 // 10 MB
)
var DefaultMigrationsTable = "schema_migrations"
var (
ErrNilConfig = errors.New("no config")
ErrNoKeyspace = errors.New("no keyspace provided")
ErrDatabaseDirty = errors.New("database is dirty")
ErrClosedSession = errors.New("session is closed")
)
type Config struct {
MigrationsTable string
KeyspaceName string
MultiStatementEnabled bool
MultiStatementMaxSize int
}
type Cassandra struct {
session *gocql.Session
isLocked atomic.Bool
// Open and WithInstance need to guarantee that config is never nil
config *Config
}
func WithInstance(session *gocql.Session, config *Config) (database.Driver, error) {
if config == nil {
return nil, ErrNilConfig
} else if len(config.KeyspaceName) == 0 {
return nil, ErrNoKeyspace
}
if session.Closed() {
return nil, ErrClosedSession
}
if len(config.MigrationsTable) == 0 {
config.MigrationsTable = DefaultMigrationsTable
}
if config.MultiStatementMaxSize <= 0 {
config.MultiStatementMaxSize = DefaultMultiStatementMaxSize
}
c := &Cassandra{
session: session,
config: config,
}
if err := c.ensureVersionTable(); err != nil {
return nil, err
}
return c, nil
}
func (c *Cassandra) Open(url string) (database.Driver, error) {
u, err := nurl.Parse(url)
if err != nil {
return nil, err
}
// Check for missing mandatory attributes
if len(u.Path) == 0 {
return nil, ErrNoKeyspace
}
cluster := gocql.NewCluster(u.Host)
cluster.Keyspace = strings.TrimPrefix(u.Path, "/")
cluster.Consistency = gocql.All
cluster.Timeout = 1 * time.Minute
if len(u.Query().Get("username")) > 0 && len(u.Query().Get("password")) > 0 {
authenticator := gocql.PasswordAuthenticator{
Username: u.Query().Get("username"),
Password: u.Query().Get("password"),
}
cluster.Authenticator = authenticator
}
// Retrieve query string configuration
if len(u.Query().Get("consistency")) > 0 {
var consistency gocql.Consistency
consistency, err = parseConsistency(u.Query().Get("consistency"))
if err != nil {
return nil, err
}
cluster.Consistency = consistency
}
if len(u.Query().Get("protocol")) > 0 {
var protoversion int
protoversion, err = strconv.Atoi(u.Query().Get("protocol"))
if err != nil {
return nil, err
}
cluster.ProtoVersion = protoversion
}
if len(u.Query().Get("timeout")) > 0 {
var timeout time.Duration
timeout, err = time.ParseDuration(u.Query().Get("timeout"))
if err != nil {
return nil, err
}
cluster.Timeout = timeout
}
if len(u.Query().Get("connect-timeout")) > 0 {
var connectTimeout time.Duration
connectTimeout, err = time.ParseDuration(u.Query().Get("connect-timeout"))
if err != nil {
return nil, err
}
cluster.ConnectTimeout = connectTimeout
}
if len(u.Query().Get("sslmode")) > 0 {
if u.Query().Get("sslmode") != "disable" {
sslOpts := &gocql.SslOptions{}
if len(u.Query().Get("sslrootcert")) > 0 {
sslOpts.CaPath = u.Query().Get("sslrootcert")
}
if len(u.Query().Get("sslcert")) > 0 {
sslOpts.CertPath = u.Query().Get("sslcert")
}
if len(u.Query().Get("sslkey")) > 0 {
sslOpts.KeyPath = u.Query().Get("sslkey")
}
if u.Query().Get("sslmode") == "verify-full" {
sslOpts.EnableHostVerification = true
}
cluster.SslOpts = sslOpts
}
}
if len(u.Query().Get("disable-host-lookup")) > 0 {
if flag, err := strconv.ParseBool(u.Query().Get("disable-host-lookup")); err != nil && flag {
cluster.DisableInitialHostLookup = true
} else if err != nil {
return nil, err
}
}
session, err := cluster.CreateSession()
if err != nil {
return nil, err
}
multiStatementMaxSize := DefaultMultiStatementMaxSize
if s := u.Query().Get("x-multi-statement-max-size"); len(s) > 0 {
multiStatementMaxSize, err = strconv.Atoi(s)
if err != nil {
return nil, err
}
}
return WithInstance(session, &Config{
KeyspaceName: strings.TrimPrefix(u.Path, "/"),
MigrationsTable: u.Query().Get("x-migrations-table"),
MultiStatementEnabled: u.Query().Get("x-multi-statement") == "true",
MultiStatementMaxSize: multiStatementMaxSize,
})
}
func (c *Cassandra) Close() error {
c.session.Close()
return nil
}
func (c *Cassandra) Lock() error {
if !c.isLocked.CAS(false, true) {
return database.ErrLocked
}
return nil
}
func (c *Cassandra) Unlock() error {
if !c.isLocked.CAS(true, false) {
return database.ErrNotLocked
}
return nil
}
func (c *Cassandra) Run(migration io.Reader) error {
if c.config.MultiStatementEnabled {
var err error
if e := multistmt.Parse(migration, multiStmtDelimiter, c.config.MultiStatementMaxSize, func(m []byte) bool {
tq := strings.TrimSpace(string(m))
if tq == "" {
return true
}
if e := c.session.Query(tq).Exec(); e != nil {
err = database.Error{OrigErr: e, Err: "migration failed", Query: m}
return false
}
return true
}); e != nil {
return e
}
return err
}
migr, err := io.ReadAll(migration)
if err != nil {
return err
}
// run migration
if err := c.session.Query(string(migr)).Exec(); err != nil {
// TODO: cast to Cassandra error and get line number
return database.Error{OrigErr: err, Err: "migration failed", Query: migr}
}
return nil
}
func (c *Cassandra) SetVersion(version int, dirty bool) error {
// DELETE instead of TRUNCATE because AWS Keyspaces does not support it
// see: https://docs.aws.amazon.com/keyspaces/latest/devguide/cassandra-apis.html
squery := `SELECT version FROM "` + c.config.MigrationsTable + `"`
dquery := `DELETE FROM "` + c.config.MigrationsTable + `" WHERE version = ?`
iter := c.session.Query(squery).Iter()
var previous int
for iter.Scan(&previous) {
if err := c.session.Query(dquery, previous).Exec(); err != nil {
return &database.Error{OrigErr: err, Query: []byte(dquery)}
}
}
if err := iter.Close(); err != nil {
return &database.Error{OrigErr: err, Query: []byte(squery)}
}
// Also re-write the schema version for nil dirty versions to prevent
// empty schema version for failed down migration on the first migration
// See: https://github.com/golang-migrate/migrate/issues/330
if version >= 0 || (version == database.NilVersion && dirty) {
query := `INSERT INTO "` + c.config.MigrationsTable + `" (version, dirty) VALUES (?, ?)`
if err := c.session.Query(query, version, dirty).Exec(); err != nil {
return &database.Error{OrigErr: err, Query: []byte(query)}
}
}
return nil
}
// Return current keyspace version
func (c *Cassandra) Version() (version int, dirty bool, err error) {
query := `SELECT version, dirty FROM "` + c.config.MigrationsTable + `" LIMIT 1`
err = c.session.Query(query).Scan(&version, &dirty)
switch {
case err == gocql.ErrNotFound:
return database.NilVersion, false, nil
case err != nil:
if _, ok := err.(*gocql.Error); ok {
return database.NilVersion, false, nil
}
return 0, false, &database.Error{OrigErr: err, Query: []byte(query)}
default:
return version, dirty, nil
}
}
func (c *Cassandra) Drop() error {
// select all tables in current schema
query := fmt.Sprintf(`SELECT table_name from system_schema.tables WHERE keyspace_name='%s'`, c.config.KeyspaceName)
iter := c.session.Query(query).Iter()
var tableName string
for iter.Scan(&tableName) {
err := c.session.Query(fmt.Sprintf(`DROP TABLE %s`, tableName)).Exec()
if err != nil {
return err
}
}
return nil
}
// ensureVersionTable checks if versions table exists and, if not, creates it.
// Note that this function locks the database, which deviates from the usual
// convention of "caller locks" in the Cassandra type.
func (c *Cassandra) ensureVersionTable() (err error) {
if err = c.Lock(); err != nil {
return err
}
defer func() {
if e := c.Unlock(); e != nil {
if err == nil {
err = e
} else {
err = multierror.Append(err, e)
}
}
}()
err = c.session.Query(fmt.Sprintf("CREATE TABLE IF NOT EXISTS %s (version bigint, dirty boolean, PRIMARY KEY(version))", c.config.MigrationsTable)).Exec()
if err != nil {
return err
}
if _, _, err = c.Version(); err != nil {
return err
}
return nil
}
// ParseConsistency wraps gocql.ParseConsistency
// to return an error instead of a panicking.
func parseConsistency(consistencyStr string) (consistency gocql.Consistency, err error) {
defer func() {
if r := recover(); r != nil {
var ok bool
err, ok = r.(error)
if !ok {
err = fmt.Errorf("Failed to parse consistency \"%s\": %v", consistencyStr, r)
}
}
}()
consistency = gocql.ParseConsistency(consistencyStr)
return consistency, nil
}
@@ -0,0 +1,122 @@
package cassandra
import (
"context"
"fmt"
"github.com/golang-migrate/migrate/v4"
"strconv"
"testing"
)
import (
"github.com/dhui/dktest"
"github.com/gocql/gocql"
)
import (
dt "github.com/golang-migrate/migrate/v4/database/testing"
"github.com/golang-migrate/migrate/v4/dktesting"
_ "github.com/golang-migrate/migrate/v4/source/file"
)
var (
opts = dktest.Options{PortRequired: true, ReadyFunc: isReady}
// Supported versions: http://cassandra.apache.org/download/
// Although Cassandra 2.x is supported by the Apache Foundation,
// the migrate db driver only supports Cassandra 3.x since it uses
// the system_schema keyspace.
// last ScyllaDB version tested is 5.1.11
specs = []dktesting.ContainerSpec{
{ImageName: "cassandra:3.0", Options: opts},
{ImageName: "cassandra:3.11", Options: opts},
{ImageName: "scylladb/scylla:5.1.11", Options: opts},
}
)
func isReady(ctx context.Context, c dktest.ContainerInfo) bool {
// Cassandra exposes 5 ports (7000, 7001, 7199, 9042 & 9160)
// We only need the port bound to 9042
ip, portStr, err := c.Port(9042)
if err != nil {
return false
}
port, err := strconv.Atoi(portStr)
if err != nil {
return false
}
cluster := gocql.NewCluster(ip)
cluster.Port = port
cluster.Consistency = gocql.All
p, err := cluster.CreateSession()
if err != nil {
return false
}
defer p.Close()
// Create keyspace for tests
if err = p.Query("CREATE KEYSPACE testks WITH REPLICATION = {'class': 'SimpleStrategy', 'replication_factor':1}").Exec(); err != nil {
return false
}
return true
}
func Test(t *testing.T) {
t.Run("test", test)
t.Run("testMigrate", testMigrate)
t.Cleanup(func() {
for _, spec := range specs {
t.Log("Cleaning up ", spec.ImageName)
if err := spec.Cleanup(); err != nil {
t.Error("Error removing ", spec.ImageName, "error:", err)
}
}
})
}
func test(t *testing.T) {
dktesting.ParallelTest(t, specs, func(t *testing.T, c dktest.ContainerInfo) {
ip, port, err := c.Port(9042)
if err != nil {
t.Fatal("Unable to get mapped port:", err)
}
addr := fmt.Sprintf("cassandra://%v:%v/testks", ip, port)
p := &Cassandra{}
d, err := p.Open(addr)
if err != nil {
t.Fatal(err)
}
defer func() {
if err := d.Close(); err != nil {
t.Error(err)
}
}()
dt.Test(t, d, []byte("SELECT table_name from system_schema.tables"))
})
}
func testMigrate(t *testing.T) {
dktesting.ParallelTest(t, specs, func(t *testing.T, c dktest.ContainerInfo) {
ip, port, err := c.Port(9042)
if err != nil {
t.Fatal("Unable to get mapped port:", err)
}
addr := fmt.Sprintf("cassandra://%v:%v/testks", ip, port)
p := &Cassandra{}
d, err := p.Open(addr)
if err != nil {
t.Fatal(err)
}
defer func() {
if err := d.Close(); err != nil {
t.Error(err)
}
}()
m, err := migrate.NewWithDatabaseInstance("file://./examples/migrations", "testks", d)
if err != nil {
t.Fatal(err)
}
dt.TestMigrate(t, m)
})
}
@@ -0,0 +1 @@
SELECT table_name from system_schema.tables
@@ -0,0 +1 @@
SELECT table_name from system_schema.tables