docs: README & LICENSE

Author: zeidlitz

LICECNSE

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+MIT License
+
+Copyright (c) 2025 DH Tech
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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-**Observer** is a tool that runs on blackbox probes in our network to e2e test our services.
+# observer
 
+A lightweight network observer written in Go that monitors network interfaces, performs ICMP and DNS health checks, and exposes Prometheus metrics.
 
+## features
+
+- Periodically samples DHCPv4 and DHCPv6 addresses on a specified interface.
+- Performs ICMP pings to one or more target hosts.
+- Performs DNS health checks for specified DNS servers and query names.
+- Dynamically adds and removes IP addresses on the interface during checks.
+- Exposes Prometheus metrics via an HTTP endpoint.
+- Supports toggling IPv4 or IPv6 monitoring independently.
+- Verbose logging for debugging and operational insight.
+
+## installation
+
+```bash
+git clone <repo-url>
+cd observer
+go build .
+./observer
+```
+
+## configuration
+
+| Flag | Default | Description |
+|------|---------|-------------|
+| `-interface` | `""` | Network interface to operate on |
+| `-icmp-targets` | `""` | Comma-separated list of ICMP targets |
+| `-icmp-count` | `3` | Number of ICMP packets to send per target |
+| `-interval` | `5s` | Interval for collecting Prometheus metrics |
+| `-verbose` | `false` | Enable verbose logging |
+| `-disable4` | `false` | Disable all IPv4 client behavior (DHCPv4 & ICMPv4) |
+| `-disable6` | `false` | Disable all IPv6 client behavior (DHCPv6 & ICMPv6) |
+| `-qname` | `healthcheck.event.dreamhack.se.` | DNS health check query name |
+| `-dns` | `""` | Comma-separated DNS servers to probe |
+| `-host-port` | `9023` | HTTP port to serve Prometheus metrics |
+
+example:
+```bash
+./observer \
+  -interface eth0 \
+  -icmp-targets 8.8.8.8,1.1.1.1 \
+  -icmp-count 5 \
+  -dns 8.8.8.8,1.1.1.1 \
+  -interval 10s \
+  -verbose
+```