https://github.com/neomantra/srv-plz
SRV record extractor with custom resolver
https://github.com/neomantra/srv-plz
srv
Last synced: 4 months ago
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SRV record extractor with custom resolver
- Host: GitHub
- URL: https://github.com/neomantra/srv-plz
- Owner: neomantra
- License: mit
- Created: 2022-03-02T16:43:38.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2023-04-16T17:30:54.000Z (about 2 years ago)
- Last Synced: 2025-02-01T10:11:31.745Z (4 months ago)
- Topics: srv
- Language: Go
- Homepage:
- Size: 20.5 KB
- Stars: 7
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE.txt
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README
# srv-plz - SRV record extractor
## *Service Please!*
`srv-plz` looks up a [DNS SRV record](https://en.wikipedia.org/wiki/SRV_record) from the specified DNS server
and outputs the result.
```
$ SRV_DNS=127.0.0.1:8600 srv-plz example.service.consul
```
`srv-plz` includes support for injecting SRV records into invoked commands. This is useful for enhancing tools like `curl` which do not support SRV records (it is on curl's [TODO list](https://curl.se/docs/todo.html#SRV_and_URI_DNS_records)). Here we recursively resolve a [Consul](https://consul.io) query and invoke `curl` in a URL with the result:
```
$ SRV_DNS=127.0.0.1:8600 srv-plz example.service.consul -r -c -- curl https://%SRV%/health
```
## Usage
```
$ srv-plz --help
usage: srv-plz [service1 [service2 [...]]] [-- command]
srv-plz resolves DNS SRV records and outputs the result.
The resolver is specified with "--dns " argument or by setting
the SRV_DNS environment variable. If only an IP address is set, port 53 is used.
If no DNS resolver is specified, the system resolver is used.
The default output is "host:port". This may be customized with the --template
argument. Possible fields are Target, Port, Priority, and Weight.
The default template is "{{.Target}}:{{.Port}}\n" for SRV records and "{{.Target}}\n" for A/AAAA records.
If "--command" is flagged, each SRV record will be injected into the command
specified after "--", using "%SRV%" or the "--match" argument as a matcher. Example:
srv-plz webserver.service.consul -r -c -- curl https://%SRV%/health
Arguments:
-a, --a Check A records, not SRV records
-6, --aaaa Check AAAA records, not SRV records
-c, --command for each record, invoke exec.Command on the args after '--', replacing %SRV% with its template
-d, --dns string DNS resolver to use. Must be in form IP (using port 53) or IP:port
-h, --help show help
-l, --limit uint32 only return N records (default 1)
-m, --match string specify forward args after '--' to shell with replaced by the lookup (default "%SRV%")
-r, --recurse recurse with the same resolver
-t, --template string output using template (default "{{.Target}}:{{.Port}}")
```
----
## Installing
Binaries for multiple platforms are [released on GitHub](https://github.com/neomantra/srv-plz/releases) through [GitHub Actions](https://github.com/neomantra/srv-plz/actions).
You can also install for various platforms with [Homebrew](https://brew.sh) from [`neomantra/homebrew-tap`](https://github.com/neomantra/homebrew-tap):
```
brew tap neomantra/homebrew-tap
brew install srv-plz
```
----
## Example Usage
### Lookup with system resolver, without or with recursion:
```
$ srv-plz _http._tcp.mxtoolbox.com
mxtoolbox.com.:80
$ srv-plz -r _http._tcp.mxtoolbox.com
13.225.202.38:80
```
### Lookup with custom resolver, either via CLI or `SRV_DNS` environment variable:
```
$ srv-plz -d 10.4.20.69:8600 -r webserver.service.consul
10.4.20.69:55420
$ SRV_DNS=10.4.20.69:8600 srv-plz -r webserver.service.consul
10.4.20.69:55420
```
### Lookup with a custom output template. Note the shell expression `$'\n'` is used to include a newline at the end.
```
$ srv-plz -d 10.4.20.69:8600 -r webserver.service.consul -t $'t:{{.Target}} p:{{.Port}} w:{{.Weight}} p:{{.Priority}}\n'
t:10.0.10.25 p:26877 w:1 p:1
```
### Check a URL with multiple records of multiple services using curl:
```
$ srv-plz -d consul.example.com:8600 -r -n 10 -c webserver.service.consul other.service.consul -- curl -s http://%SRV%/health
```
----
## Building
Building is performed with [task](https://taskfile.dev/):
```
$ task
task: [build] go build -o srv-plz cmd/srv-plz/main.go
```
----
## Credits and License
Thanks to [github.com/miekg/dns](https://github.com/miekg/dns) for the heavy lifting.
Copyright (c) 2022-2023 Neomantra BV. Authored by Evan Wies.
Released under the [MIT License](https://en.wikipedia.org/wiki/MIT_License), see [LICENSE.txt](./LICENSE.txt).