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71 lines
2.0 KiB
71 lines
2.0 KiB
package run
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import (
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"fmt"
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"math/rand"
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"strings"
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"time"
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)
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const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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const (
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letterIdxBits = 6 // 6 bits to represent a letter index
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letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
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letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
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)
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var src = rand.NewSource(time.Now().UnixNano())
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// GenerateRandomString thanks to https://stackoverflow.com/a/31832326/6450189
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// GenerateRandomString is used to generate a random string that is used as a cluster secret
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func GenerateRandomString(n int) string {
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sb := strings.Builder{}
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sb.Grow(n)
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// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
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for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = src.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
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sb.WriteByte(letterBytes[idx])
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i--
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}
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cache >>= letterIdxBits
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remain--
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}
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return sb.String()
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}
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/*** Cluster Name Validation ***/
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const clusterNameMaxSize int = 35
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// CheckClusterName ensures that a cluster name is also a valid host name according to RFC 1123.
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// We further restrict the length of the cluster name to maximum 'clusterNameMaxSize'
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// so that we can construct the host names based on the cluster name, and still stay
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// within the 64 characters limit.
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func CheckClusterName(name string) error {
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if len(name) > clusterNameMaxSize {
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return fmt.Errorf("[ERROR] Cluster name is too long")
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}
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if name[0] == '-' || name[len(name)-1] == '-' {
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return fmt.Errorf("[ERROR] Cluster name can not start or end with - (dash)")
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}
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for _, c := range name {
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switch {
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case '0' <= c && c <= '9':
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case 'a' <= c && c <= 'z':
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case 'A' <= c && c <= 'Z':
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case c == '-':
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break
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default:
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return fmt.Errorf("[ERROR] Cluster name contains characters other than 'Aa-Zz', '0-9' or '-'")
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}
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}
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return nil
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}
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