Dd Apm

# Install Datadog Agent on Linux

> **Before doing anything else:** Fully resolve all variables in `## Context to resolve before acting`. Do not begin Step 1 until every variable has a concrete value.

## Triggers

Invoke this skill when the user expresses intent to:
- Install the Datadog Agent on Linux hosts or VMs
- Set up Datadog monitoring on bare-metal or cloud Linux instances
- Prepare Linux hosts for APM onboarding

Do NOT invoke this skill if:
- The Agent is already installed on all hosts — check with `datadog-agent status` first
- The target is a Kubernetes cluster — use `dd-apm-k8s-agent-install` instead

---

## Phase 0: Load Credentials

```bash
[ -f environment ] && source environment
echo "DD_API_KEY set: $([ -n "${DD_API_KEY:-}" ] && echo yes || echo no)"
echo "DD_SITE: ${DD_SITE:-not set}"
```

**If `DD_API_KEY` is already set** — proceed directly to gathering infrastructure info.

**If `DD_API_KEY` is not set** — tell the user:

> Please run the following in this chat to set your credentials (the `!` prefix executes it in this session):
> ```
> ! export DD_API_KEY=your-api-key-here
> ! export DD_SITE=datadoghq.com
> ```

Wait for the user to run the commands, then re-run the check above before continuing.

---

## Phase 1: Gather Infrastructure Info

Only do this phase if the user hasn't already provided the information. If SSH credentials are known, skip to Phase 2.

Ask the user:
1. **Which hosts** need the agent? Get a list of IPs or hostnames.
2. **How do I SSH to them?** Get the SSH user, key path, and any jump host or bastion configuration.
3. **Do any hosts already have the Datadog Agent installed?** If so, skip install for those hosts and go straight to `verify-ssi`.

### Claude runs

Verify SSH works for each host before proceeding:

```bash
ssh -o StrictHostKeyChecking=no -i <SSH_KEY> <SSH_USER>@<SSH_HOST> "hostname"
```

If it returns a hostname — proceed.
ERROR: Connection refused or timeout — resolve connectivity before continuing.

Once SSH is confirmed, present a plan to the user before proceeding. For example:

```
Here's what I'm going to do:
  1. Install the Datadog Agent with SSI on: <host1>, <host2>, ...
  2. Verify each agent is running and healthy
  3. Discover services on each host that need restarting for SSI to take effect
  4. After you restart services, verify instrumentation is working

Ready to proceed?
```

Wait for user confirmation before starting installs.

---

## Prerequisites

**Per host — check before installing:**

### Claude runs

```bash
ssh -o StrictHostKeyChecking=no -i <SSH_KEY> <SSH_USER>@<SSH_HOST> \
  "uname -m && cat /etc/os-release | grep -E '^(ID|VERSION_ID|PRETTY_NAME)='"
```

If architecture is `x86_64` or `aarch64`, and the OS is a supported distribution (Ubuntu 16.04+, Debian 9+, RHEL/CentOS 6-9, Amazon Linux 2/2023, SUSE 12+) — proceed.

ERROR: Architecture is `armv7l` (32-bit ARM) or unsupported OS — stop. Datadog Agent 7 and SSI do not support this configuration.

---

## Context to resolve before acting

| Variable | How to resolve |
|---|---|
| `DD_API_KEY` | Check `echo $DD_API_KEY` first — if set, use it. Otherwise ask the user for their API key from Datadog UI: Organization Settings → API Keys. Never log or print the key. |
| `DD_SITE` | Check `echo $DD_SITE` first — if set, use it. Otherwise ask the user. Default: `datadoghq.com`. Options: `datadoghq.com`, `us3.datadoghq.com`, `us5.datadoghq.com`, `datadoghq.eu`, `ap1.datadoghq.com` |
| `SSH_KEY` | Ask the user for the path to their SSH private key, or check `CLAUDE.md` |
|