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feat: add experimental multihost mode
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@Zebradil
Zebradil committed Jan 7, 2024
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60 changes: 46 additions & 14 deletions README.md
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Original file line number Diff line number Diff line change
@@ -1,34 +1,58 @@
# Dynamic DNS client for Cloudflare

A small tool for updating IPv6 address at Cloudflare DNS with the currently detected address of the specified network interface.
A small tool for updating the IPv6 address at Cloudflare DNS with the currently detected address of the specified network interface.

It is provided with systemd service and timer files for automation.

```text
Selects an IPv6 address from the specified network interface and updates
AAAA records at Cloudflare for configured domains.
Selects an IPv6 address from the specified network interface and updates AAAA
records at Cloudflare for the configured domains.
Requires a network interface name for a IPv6 address lookup, domain name[s]
and Cloudflare API token with edit access rights to corresponding DNS zone.
=== Required configuration options ===
When multiple IPv6 addresses are found on the interface, the following rules
are used to select the one to use:
--iface: network interface name to look up for an IPv6 address
--domains: one or more domain names to assign the IPv6 address to
--token: Cloudflare API token with edit access rights to the DNS zone
=== IPv6 address selection ===
When multiple IPv6 addresses are found on the interface, the following rules are
used to select the one to use:
1. Only global unicast addresses (GUA) and unique local addresses (ULA) are
considered.
2. GUA addresses are preferred over ULA addresses.
3. If priority subnets are specified, addresses from the subnet with the
highest priority are selected. The priority is determined by the order
of subnets specified on the command line or in the config file.
3. Unique EUI-64 addresses are preferred over randomly generated addresses.
4. If priority subnets are specified, addresses from the subnet with the
highest priority are selected. The priority is determined by the order of
subnets specified on the command line or in the config file.
The program can be run in systemd mode, in which case the previously used
IPv6 address is preserved between runs to avoid unnecessary calls to Cloudflare
=== Daemon/systemd mode ===
The program can be run in systemd mode, in which case the previously used IPv6
address is preserved between runs to avoid unnecessary calls to the Cloudflare
API. This mode is enabled by passing --systemd flag. The state file is stored
in the directory specified by the STATE_DIRECTORY environment variable.
=== Multihost mode (EXPERIMENTAL) ===
In this mode it is possible to assign multiple IPv6 addresses to a single or
multiple domains. For correct operation, this mode must be enabled on all hosts
participating in the same domain and different host-ids must be specified for
each host (see --host-id option). This mode is enabled by passing --multihost
flag.
In the multihost mode, the program will manage only the DNS records that have
the same host-id as the one specified on the command line or in the config file.
Any other records will be ignored. This allows multiple hosts to share the same
domain without interfering with each other. The host-id is stored in the
Cloudflare DNS comments field (see https://developers.cloudflare.com/dns/manage-dns-records/reference/record-attributes/).
=== Persistent configuration ===
The program can be configured using a config file. The default location is
$HOME/.cloudflare-dynamic-dns.yaml. The config file location can be overridden
using --config flag. The config file format is YAML. The following options are
supported (with example values):
using the --config flag. The config file format is YAML. The following options
are supported (with example values):
iface: eth0
token: cloudflare-api-token
Expand All @@ -41,6 +65,8 @@ supported (with example values):
- 2001:db8:1::/48
ttl: 180
systemd: false
multihost: true
hostId: homelab-node-1
Usage:
cloudflare-dynamic-dns [flags]
Expand All @@ -49,14 +75,20 @@ Flags:
--config string config file (default is $HOME/.cloudflare-dynamic-dns.yaml)
--domains strings Domain names to assign the IPv6 address to.
-h, --help help for cloudflare-dynamic-dns
--host-id string Unique host identifier. Must be specified in multihost mode.
--iface string Network interface to look up for a IPv6 address.
--log-level string Sets logging level: trace, debug, info, warning, error, fatal, panic. (default "info")
--multihost Enable multihost mode.
In this mode it is possible to assign multiple IPv6 addresses to a single domain.
For correct operation, this mode must be enabled on all participating hosts and
different host-ids must be specified for each host (see --host-id option).
--priority-subnets strings IPv6 subnets to prefer over others.
If multiple IPv6 addresses are found on the interface, the one from the subnet with the highest priority is used.
--systemd Switch operation mode for running in systemd.
In this mode previously used ipv6 address is preserved between runs to avoid unnecessary calls to CloudFlare API.
--token string Cloudflare API token with DNS edit access rights.
--ttl int Time to live, in seconds, of the DNS record. Must be between 60 and 86400, or 1 for 'automatic'. (default 1)
-v, --version version for cloudflare-dynamic-dns
```

## Installation
Expand Down
74 changes: 60 additions & 14 deletions cmd/root.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,31 +17,54 @@ import (
)

const longDescription = `
Selects an IPv6 address from the specified network interface and updates
AAAA records at Cloudflare for configured domains.
Selects an IPv6 address from the specified network interface and updates AAAA
records at Cloudflare for the configured domains.
Requires a network interface name for a IPv6 address lookup, domain name[s]
and Cloudflare API token with edit access rights to corresponding DNS zone.
=== Required configuration options ===
When multiple IPv6 addresses are found on the interface, the following rules
are used to select the one to use:
--iface: network interface name to look up for an IPv6 address
--domains: one or more domain names to assign the IPv6 address to
--token: Cloudflare API token with edit access rights to the DNS zone
=== IPv6 address selection ===
When multiple IPv6 addresses are found on the interface, the following rules are
used to select the one to use:
1. Only global unicast addresses (GUA) and unique local addresses (ULA) are
considered.
2. GUA addresses are preferred over ULA addresses.
3. Unique EUI-64 addresses are preferred over randomly generated addresses.
4. If priority subnets are specified, addresses from the subnet with the
highest priority are selected. The priority is determined by the order
of subnets specified on the command line or in the config file.
highest priority are selected. The priority is determined by the order of
subnets specified on the command line or in the config file.
=== Daemon/systemd mode ===
The program can be run in systemd mode, in which case the previously used
IPv6 address is preserved between runs to avoid unnecessary calls to Cloudflare
The program can be run in systemd mode, in which case the previously used IPv6
address is preserved between runs to avoid unnecessary calls to the Cloudflare
API. This mode is enabled by passing --systemd flag. The state file is stored
in the directory specified by the STATE_DIRECTORY environment variable.
=== Multihost mode (EXPERIMENTAL) ===
In this mode it is possible to assign multiple IPv6 addresses to a single or
multiple domains. For correct operation, this mode must be enabled on all hosts
participating in the same domain and different host-ids must be specified for
each host (see --host-id option). This mode is enabled by passing --multihost
flag.
In the multihost mode, the program will manage only the DNS records that have
the same host-id as the one specified on the command line or in the config file.
Any other records will be ignored. This allows multiple hosts to share the same
domain without interfering with each other. The host-id is stored in the
Cloudflare DNS comments field (see https://developers.cloudflare.com/dns/manage-dns-records/reference/record-attributes/).
=== Persistent configuration ===
The program can be configured using a config file. The default location is
$HOME/.cloudflare-dynamic-dns.yaml. The config file location can be overridden
using --config flag. The config file format is YAML. The following options are
supported (with example values):
using the --config flag. The config file format is YAML. The following options
are supported (with example values):
iface: eth0
token: cloudflare-api-token
Expand All @@ -54,6 +77,8 @@ supported (with example values):
- 2001:db8:1::/48
ttl: 180
systemd: false
multihost: true
hostId: homelab-node-1
`

var cfgFile string
Expand Down Expand Up @@ -110,6 +135,11 @@ func NewRootCmd(version, commit, date string) *cobra.Command {

rootCmd.Flags().Bool("systemd", false, `Switch operation mode for running in systemd.
In this mode previously used ipv6 address is preserved between runs to avoid unnecessary calls to CloudFlare API.`)
rootCmd.Flags().Bool("multihost", false, `Enable multihost mode.
In this mode it is possible to assign multiple IPv6 addresses to a single domain.
For correct operation, this mode must be enabled on all participating hosts and
different host-ids must be specified for each host (see --host-id option).`)
rootCmd.Flags().String("host-id", "", "Unique host identifier. Must be specified in multihost mode.")
rootCmd.Flags().Int("ttl", 1, "Time to live, in seconds, of the DNS record. Must be between 60 and 86400, or 1 for 'automatic'.")
rootCmd.Flags().StringSlice("domains", []string{}, "Domain names to assign the IPv6 address to.")
rootCmd.Flags().StringSlice("priority-subnets", []string{}, `IPv6 subnets to prefer over others.
Expand All @@ -136,7 +166,9 @@ func rootCmdRun(cmd *cobra.Command, args []string) {

var (
domains = viper.GetStringSlice("domains")
hostId = viper.GetString("host-id")
iface = viper.GetString("iface")
multihost = viper.GetBool("multihost")
prioritySubnets = viper.GetStringSlice("prioritySubnets")
stateFilepath = ""
systemd = viper.GetBool("systemd")
Expand All @@ -158,7 +190,9 @@ func rootCmdRun(cmd *cobra.Command, args []string) {

log.WithFields(log.Fields{
"domains": domains,
"hostId": hostId,
"iface": iface,
"multihost": multihost,
"prioritySubnets": prioritySubnets,
"stateFilepath": stateFilepath,
"systemd": systemd,
Expand All @@ -170,6 +204,10 @@ func rootCmdRun(cmd *cobra.Command, args []string) {
log.Fatal("No domains specified")
}

if multihost && hostId == "" {
log.Fatal("Multihost mode requires host-id to be specified")
}

addr := getIpv6Address(iface, prioritySubnets)

if systemd && addr == getOldIpv6Address(stateFilepath) {
Expand All @@ -185,15 +223,15 @@ func rootCmdRun(cmd *cobra.Command, args []string) {

for _, domain := range domains {
log.Info("Processing domain: ", domain)
processDomain(api, domain, addr, ttl)
processDomain(api, domain, addr, ttl, multihost, hostId)
}

if systemd {
setOldIpv6Address(stateFilepath, addr)
}
}

func processDomain(api *cloudflare.API, domain string, addr string, ttl int) {
func processDomain(api *cloudflare.API, domain string, addr string, ttl int, multihost bool, hostId string) {
ctx := context.Background()

zoneID, err := api.ZoneIDByName(getZoneFromDomain(domain))
Expand All @@ -202,13 +240,19 @@ func processDomain(api *cloudflare.API, domain string, addr string, ttl int) {
}

dnsRecordFilter := cloudflare.ListDNSRecordsParams{Type: "AAAA", Name: domain}
if multihost {
dnsRecordFilter.Comment = hostId
}
existingDNSRecords, _, err := api.ListDNSRecords(ctx, cloudflare.ZoneIdentifier(zoneID), dnsRecordFilter)
if err != nil {
log.WithError(err).WithField("filter", dnsRecordFilter).Fatal("Couldn't get DNS records")
}
log.WithField("records", existingDNSRecords).Debug("Found DNS records")

desiredDNSRecord := cloudflare.DNSRecord{Type: "AAAA", Name: domain, Content: addr, TTL: ttl}
if multihost {
desiredDNSRecord.Comment = hostId
}

if len(existingDNSRecords) == 0 {
createNewDNSRecord(api, zoneID, desiredDNSRecord)
Expand Down Expand Up @@ -237,6 +281,7 @@ func createNewDNSRecord(api *cloudflare.API, zoneID string, desiredDNSRecord clo
Type: desiredDNSRecord.Type,
Name: desiredDNSRecord.Name,
Content: desiredDNSRecord.Content,
Comment: desiredDNSRecord.Comment,
TTL: desiredDNSRecord.TTL,
})
if err != nil {
Expand All @@ -261,6 +306,7 @@ func updateDNSRecord(api *cloudflare.API, zoneID string, oldRecord cloudflare.DN
Type: newRecord.Type,
Name: newRecord.Name,
Content: newRecord.Content,
Comment: &newRecord.Comment,
TTL: newRecord.TTL,
})
if err != nil {
Expand Down

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