Files
coder/agent/api.go
T
Kyle Carberry ee855f9618 feat: make agent context paths configurable via env vars (#23878)
Replace hardcoded paths for instruction files, skills, and MCP config
with
values read from `CODER_AGENT_EXP_*` environment variables. Template
authors
configure paths via the existing `coder_agent` `env` block. The agent
resolves `~`, relative, and absolute paths locally, then serves the
resolved config over `GET /api/v0/context-config`. `chatd` fetches this
once per workspace attach and falls back to today's defaults for older
agents.

All path env vars are comma-separated, allowing multiple directories:

| Env Var | Default | Controls |
|---|---|---|
| `CODER_AGENT_EXP_INSTRUCTIONS_DIRS` | `~/.coder` | Dirs containing the
instruction file |
| `CODER_AGENT_EXP_INSTRUCTIONS_FILE` | `AGENTS.md` | Instruction file
name |
| `CODER_AGENT_EXP_SKILLS_DIRS` | `.agents/skills` | Skills directories
|
| `CODER_AGENT_EXP_SKILL_META_FILE` | `SKILL.md` | Skill metadata file
name |
| `CODER_AGENT_EXP_MCP_CONFIG_FILES` | `.mcp.json` | MCP config files |

### Example

```hcl
resource "coder_agent" "main" {
  os   = "linux"
  arch = "amd64"
  env = {
    CODER_AGENT_EXP_INSTRUCTIONS_DIRS  = "/opt/company/agent-config,~/.coder"
    CODER_AGENT_EXP_INSTRUCTIONS_FILE  = "CLAUDE.md"
    CODER_AGENT_EXP_SKILLS_DIRS        = "/opt/company/ai-skills,.agents/skills"
    CODER_AGENT_EXP_MCP_CONFIG_FILES   = "/opt/company/mcp.json,.mcp.json"
  }
}
```

<details>
<summary>Implementation Details</summary>

### Architecture

Follows the same pattern as MCP tool discovery:
agent resolves locally → exposes via HTTP → chatd consumes.

**Agent-side** (`agent/agentcontextconfig/`):
- `ResolvePath` / `ResolvePaths` handle `~`, relative, and absolute path
forms; returns `""` for relative paths when baseDir is empty
- `Config` reads env vars, falls back to defaults, resolves all paths
- `GET /api/v0/context-config` serves the resolved config as JSON

**chatd-side** (`coderd/x/chatd/`):
- Calls `conn.ContextConfig()` once on first workspace attach
- Falls back to hardcoded defaults on 404 (older agents)
- Iterates instruction dirs, skills dirs using resolved absolute paths
- `LSRelativityRoot` everywhere — no more home/root juggling

### Key design decisions

- **`EXP_` prefix**: env vars use `CODER_AGENT_EXP_*` to indicate
experimental status
- **Plural names**: comma-separated vars use plural names (`DIRS`,
`FILES`); single-value vars use singular (`FILE`)
- **Defaults in `workspacesdk`**: default constants live in
`codersdk/workspacesdk/` so both agent and server reference them without
cross-layer imports
- **`skillMetaFile` persistence**: stored on context-file parts via
`ContextFileSkillMetaFile` and restored on subsequent chat turns so
custom values survive across turns
- **Working dir dedup**: `slices.Contains` guard prevents reading the
same instruction file from both `InstructionsDirs` and the working
directory
- **MCP server dedup**: first-occurrence-wins dedup prevents leaking
duplicate connections from overlapping config files
- **ResolvePath safety**: returns `""` for relative paths when `baseDir`
is empty, so `ResolvePaths` filters them out

### Files changed

| File | Change |
|---|---|
| `agent/agentcontextconfig/` | New package — path resolution + HTTP
endpoint |
| `codersdk/workspacesdk/agentconn.go` | `ContextConfigResponse` type,
default constants, client method |
| `agent/agent.go` + `agent/api.go` | Wire up endpoint, pass config to
MCP |
| `agent/x/agentmcp/manager.go` | Accept `[]string` MCP config paths,
dedup by name |
| `coderd/x/chatd/chatd.go` | Fetch config, thread through, named
returns |
| `coderd/x/chatd/instruction.go` | Accept configurable dir + file name,
`skillMetaFileFromParts` |
| `coderd/x/chatd/chattool/skill.go` | Accept configurable dirs + meta
file |
| `codersdk/chats.go` | `ContextFileSkillMetaFile` field for persistence
|

### Test coverage

- `TestConfig` (4 cases): defaults, custom env vars, whitespace
trimming, comma-separated dirs
- `TestResolvePath` / `TestResolvePaths`: including empty baseDir edge
case
- `TestPersistInstructionFilesFallbackOnOlderAgent`: backward-compat
path when `ContextConfig` returns 404
- `TestChatMessagePartVariantTags`: updated exclusion list for new
internal field

### Backward compatibility

Older agents return 404 for the new endpoint. `chatd` catches this and
falls back to today's defaults via `readHomeInstructionFile` (using
`LSRelativityHome`). Existing workspaces work with no changes.

</details>
2026-04-01 12:28:47 -04:00

108 lines
3.5 KiB
Go

package agent
import (
"net/http"
"github.com/go-chi/chi/v5"
"github.com/google/uuid"
"github.com/coder/coder/v2/coderd/httpapi"
"github.com/coder/coder/v2/coderd/httpmw/loggermw"
"github.com/coder/coder/v2/coderd/tracing"
"github.com/coder/coder/v2/codersdk"
"github.com/coder/coder/v2/codersdk/workspacesdk"
"github.com/coder/coder/v2/httpmw"
)
func (a *agent) apiHandler() http.Handler {
r := chi.NewRouter()
r.Use(
httpmw.Recover(a.logger),
tracing.StatusWriterMiddleware,
loggermw.Logger(a.logger),
)
r.Get("/", func(rw http.ResponseWriter, r *http.Request) {
httpapi.Write(r.Context(), rw, http.StatusOK, codersdk.Response{
Message: "Hello from the agent!",
})
})
r.Mount("/api/v0", a.filesAPI.Routes())
r.Mount("/api/v0/git", a.gitAPI.Routes())
r.Mount("/api/v0/processes", a.processAPI.Routes())
r.Mount("/api/v0/desktop", a.desktopAPI.Routes())
r.Mount("/api/v0/mcp", a.mcpAPI.Routes())
r.Mount("/api/v0/context-config", a.contextConfigAPI.Routes())
if a.devcontainers {
r.Mount("/api/v0/containers", a.containerAPI.Routes())
} else if manifest := a.manifest.Load(); manifest != nil && manifest.ParentID != uuid.Nil {
r.HandleFunc("/api/v0/containers", func(w http.ResponseWriter, r *http.Request) {
httpapi.Write(r.Context(), w, http.StatusForbidden, codersdk.Response{
Message: "Dev Container feature not supported.",
Detail: "Dev Container integration inside other Dev Containers is explicitly not supported.",
})
})
} else {
r.HandleFunc("/api/v0/containers", func(w http.ResponseWriter, r *http.Request) {
httpapi.Write(r.Context(), w, http.StatusForbidden, codersdk.Response{
Message: "Dev Container feature not enabled.",
Detail: "To enable this feature, set CODER_AGENT_DEVCONTAINERS_ENABLE=true in your template.",
})
})
}
promHandler := PrometheusMetricsHandler(a.prometheusRegistry, a.logger)
r.Get("/api/v0/listening-ports", a.listeningPortsHandler.handler)
r.Get("/api/v0/netcheck", a.HandleNetcheck)
r.Get("/debug/logs", a.HandleHTTPDebugLogs)
r.Get("/debug/magicsock", a.HandleHTTPDebugMagicsock)
r.Get("/debug/magicsock/debug-logging/{state}", a.HandleHTTPMagicsockDebugLoggingState)
r.Get("/debug/manifest", a.HandleHTTPDebugManifest)
r.Get("/debug/prometheus", promHandler.ServeHTTP)
return r
}
type ListeningPortsGetter interface {
GetListeningPorts() ([]codersdk.WorkspaceAgentListeningPort, error)
}
type listeningPortsHandler struct {
// In production code, this is set to an osListeningPortsGetter, but it can be overridden for
// testing.
getter ListeningPortsGetter
ignorePorts map[int]string
}
// handler returns a list of listening ports. This is tested by coderd's
// TestWorkspaceAgentListeningPorts test.
func (lp *listeningPortsHandler) handler(rw http.ResponseWriter, r *http.Request) {
ports, err := lp.getter.GetListeningPorts()
if err != nil {
httpapi.Write(r.Context(), rw, http.StatusInternalServerError, codersdk.Response{
Message: "Could not scan for listening ports.",
Detail: err.Error(),
})
return
}
filteredPorts := make([]codersdk.WorkspaceAgentListeningPort, 0, len(ports))
for _, port := range ports {
if port.Port < workspacesdk.AgentMinimumListeningPort {
continue
}
// Ignore ports that we've been told to ignore.
if _, ok := lp.ignorePorts[int(port.Port)]; ok {
continue
}
filteredPorts = append(filteredPorts, port)
}
httpapi.Write(r.Context(), rw, http.StatusOK, codersdk.WorkspaceAgentListeningPortsResponse{
Ports: filteredPorts,
})
}