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resource_id.go
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resource_id.go
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// Copyright 2016-2018, Pulumi Corporation.
//
// 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 resource
import (
"crypto"
cryptorand "crypto/rand"
"encoding/binary"
"encoding/hex"
"github.com/pkg/errors"
"lukechampine.com/frand"
"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
)
// ID is a unique resource identifier; it is managed by the provider and is mostly opaque.
type ID string
// String converts a resource ID into a string.
func (id ID) String() string {
return string(id)
}
// StringPtr converts an optional ID into an optional string.
func (id *ID) StringPtr() *string {
if id == nil {
return nil
}
ids := (*id).String()
return &ids
}
// IDStrings turns an array of resource IDs into an array of strings.
func IDStrings(ids []ID) []string {
ss := make([]string, len(ids))
for i, id := range ids {
ss[i] = id.String()
}
return ss
}
// MaybeID turns an optional string into an optional resource ID.
func MaybeID(s *string) *ID {
var ret *ID
if s != nil {
id := ID(*s)
ret = &id
}
return ret
}
// NewUniqueHex generates a new "random" hex string for use by resource providers. It will take the optional prefix
// and append randlen random characters (defaulting to 8 if not > 0). The result must not exceed maxlen total
// characterss (if > 0). Note that capping to maxlen necessarily increases the risk of collisions.
func NewUniqueHex(prefix string, randlen, maxlen int) (string, error) {
if randlen <= 0 {
randlen = 8
}
if maxlen > 0 && len(prefix)+randlen > maxlen {
return "", errors.Errorf(
"name '%s' plus %d random chars is longer than maximum length %d", prefix, randlen, maxlen)
}
bs := make([]byte, (randlen+1)/2)
n, err := cryptorand.Read(bs)
contract.AssertNoError(err)
contract.Assert(n == len(bs))
return prefix + hex.EncodeToString(bs)[:randlen], nil
}
// NewUniqueHexID generates a new "random" hex string for use by resource providers. It will take the optional prefix
// and append randlen random characters (defaulting to 8 if not > 0). The result must not exceed maxlen total
// characterss (if > 0). Note that capping to maxlen necessarily increases the risk of collisions.
func NewUniqueHexID(prefix string, randlen, maxlen int) (ID, error) {
u, err := NewUniqueHex(prefix, randlen, maxlen)
return ID(u), err
}
// NewUniqueHexV2 generates a new "random" hex string for use by resource providers. It will take the optional prefix
// and append randLen random characters (defaulting to 8 if not > 0). The result must not exceed maxLen total
// characters (if > 0). Note that capping to maxLen necessarily increases the risk of collisions.
// The randomness for this method is a function of urn and sequenceNumber iff sequenceNUmber > 0, else it falls back to
// a non-deterministic source of randomness.
func NewUniqueHexV2(urn URN, sequenceNumber int, prefix string, randLen, maxLen int) (string, error) {
if randLen <= 0 {
randLen = 8
}
if maxLen > 0 && len(prefix)+randLen > maxLen {
return "", errors.Errorf(
"name '%s' plus %d random chars is longer than maximum length %d", prefix, randLen, maxLen)
}
if sequenceNumber == 0 {
// No sequence number fallback to old logic
return NewUniqueHex(prefix, randLen, maxLen)
}
if randLen > 32 {
return "", errors.Errorf("randLen is longer than 32, %d", randLen)
}
// TODO(seqnum) This is seeded by urn and sequence number, and urn has the stack and project names in it.
// But do we care about org name as well?
// Do we need a config source of randomness so if users hit a collision they can set a config value to get out of it?
hasher := crypto.SHA512.New()
_, err := hasher.Write([]byte(urn))
contract.AssertNoError(err)
err = binary.Write(hasher, binary.LittleEndian, uint32(sequenceNumber))
contract.AssertNoError(err)
bs := hasher.Sum(nil)
contract.Assert(len(bs) == 64)
return prefix + hex.EncodeToString(bs)[:randLen], nil
}
// NewUniqueName generates a new "random" string primarily intended for use by resource providers for
// autonames. It will take the optional prefix and append randlen random characters (defaulting to 8 if not >
// 0). The result must not exceed maxlen total characters (if > 0). The characters that make up the random
// suffix can be set via charset, and will default to [a-f0-9]. Note that capping to maxlen necessarily
// increases the risk of collisions. The randomness for this method is a function of randomSeed if given, else
// it falls back to a non-deterministic source of randomness.
func NewUniqueName(randomSeed []byte, prefix string, randlen, maxlen int, charset []rune) (string, error) {
if randlen <= 0 {
randlen = 8
}
if maxlen > 0 && len(prefix)+randlen > maxlen {
return "", errors.Errorf(
"name '%s' plus %d random chars is longer than maximum length %d", prefix, randlen, maxlen)
}
if charset == nil {
charset = []rune("0123456789abcdef")
}
var random *frand.RNG
if len(randomSeed) == 0 {
random = frand.New()
} else {
// frand.NewCustom needs a 32 byte seed. Take the SHA256 hash of whatever bytes we've been given as a
// seed and pass the 32 byte result of that to frand.
hash := crypto.SHA256.New()
hash.Write(randomSeed)
seed := hash.Sum(nil)
bufsize := 1024 // Same bufsize as used by frand.New.
rounds := 12 // Same rounds as used by frand.New.
random = frand.NewCustom(seed, bufsize, rounds)
}
randomSuffix := make([]rune, randlen)
for i := range randomSuffix {
randomSuffix[i] = charset[random.Intn(len(charset))]
}
return prefix + string(randomSuffix), nil
}