Add a download_manifests tool to our agent harness mcp server #751
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,174 @@ | ||
| package tool | ||
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| import ( | ||
| "context" | ||
| "fmt" | ||
| "os" | ||
| "path/filepath" | ||
| "regexp" | ||
| "strings" | ||
|
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| "github.com/mark3labs/mcp-go/mcp" | ||
| "github.com/mark3labs/mcp-go/server" | ||
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| "github.com/pluralsh/deployment-operator/pkg/agentrun-harness/environment" | ||
| console "github.com/pluralsh/deployment-operator/pkg/client" | ||
| "github.com/pluralsh/deployment-operator/pkg/manifests" | ||
| ) | ||
|
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| // manifestsSubdir is the top-level directory (relative to the agent harness | ||
| // working directory) under which manifests for individual services are | ||
| // extracted. The actual files live in | ||
| // "<workingDir>/<manifestsSubdir>/<handle>-<service>/". | ||
| const manifestsSubdir = "manifests" | ||
|
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| // safeNamePattern matches characters that are safe to use in a directory name | ||
| // derived from a cluster handle / service name. | ||
| var safeNamePattern = regexp.MustCompile(`[^a-zA-Z0-9._-]+`) | ||
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| func (in *DownloadManifests) Install(s *server.MCPServer) { | ||
| s.AddTool( | ||
| mcp.NewTool( | ||
| in.id.String(), | ||
| mcp.WithDescription(in.description), | ||
| mcp.WithString("cluster", | ||
| mcp.Required(), | ||
| mcp.Description("Handle of the Plural cluster the service is deployed to (e.g. 'mgmt' or 'prod-eu-1')"), | ||
| ), | ||
| mcp.WithString("service", | ||
| mcp.Required(), | ||
| mcp.Description("Name of the Plural service whose rendered manifests should be downloaded"), | ||
| ), | ||
| ), | ||
| in.handler, | ||
| ) | ||
| } | ||
|
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||
| func (in *DownloadManifests) handler(_ context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) { | ||
| if err := in.fromRequest(request); err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("could not handle download manifests request: %v", err)), nil | ||
| } | ||
|
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| svc, err := in.client.GetServiceDeploymentByHandle(in.ClusterHandle, in.ServiceName) | ||
| if err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to look up service %q on cluster %q: %v", in.ServiceName, in.ClusterHandle, err)), nil | ||
| } | ||
| if svc.Tarball == nil || *svc.Tarball == "" { | ||
| return mcp.NewToolResultError(fmt.Sprintf("service %q on cluster %q does not yet have a rendered tarball available", in.ServiceName, in.ClusterHandle)), nil | ||
| } | ||
|
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| _, token := in.client.GetCredentials() | ||
| if token == "" { | ||
| return mcp.NewToolResultError("Plural Console credentials are not configured for the MCP server"), nil | ||
| } | ||
|
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| baseDir, err := resolveManifestsBaseDir() | ||
| if err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to resolve manifests base directory: %v", err)), nil | ||
| } | ||
|
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| targetDir := filepath.Join(baseDir, manifestsSubdir, sanitizeSegment(in.ClusterHandle)+"-"+sanitizeSegment(in.ServiceName)) | ||
|
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| if err := os.RemoveAll(targetDir); err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to clear target directory %q: %v", targetDir, err)), nil | ||
| } | ||
| if err := os.MkdirAll(targetDir, 0o755); err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to create target directory %q: %v", targetDir, err)), nil | ||
| } | ||
|
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| reader, _, err := manifests.GetReader(*svc.Tarball, token) | ||
| if err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to download service tarball: %v", err)), nil | ||
| } | ||
| defer reader.Close() | ||
|
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| if err := manifests.Untar(targetDir, reader); err != nil { | ||
| return mcp.NewToolResultError(fmt.Sprintf("failed to extract service tarball into %q: %v", targetDir, err)), nil | ||
| } | ||
|
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| return mcp.NewToolResultJSON(struct { | ||
| Success bool `json:"success"` | ||
| Message string `json:"message"` | ||
| Cluster string `json:"cluster"` | ||
| Service string `json:"service"` | ||
| ServiceID string `json:"serviceId"` | ||
| Directory string `json:"directory"` | ||
| Instructions string `json:"instructions"` | ||
| }{ | ||
| Success: true, | ||
| Message: fmt.Sprintf("downloaded manifests for service %q on cluster %q", in.ServiceName, in.ClusterHandle), | ||
| Cluster: in.ClusterHandle, | ||
| Service: in.ServiceName, | ||
| ServiceID: svc.ID, | ||
| Directory: targetDir, | ||
| Instructions: fmt.Sprintf( | ||
| "The rendered Kubernetes manifests for the service have been written to %q. "+ | ||
| "Use Read/Glob/Grep against this directory to inspect the actual resources Plural is applying "+ | ||
| "(including resources rendered from external Helm charts) instead of guessing via web searches.", | ||
| targetDir, | ||
| ), | ||
| }) | ||
| } | ||
|
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| func (in *DownloadManifests) fromRequest(request mcp.CallToolRequest) (err error) { | ||
| if in.ClusterHandle, err = request.RequireString("cluster"); err != nil { | ||
| return | ||
| } | ||
|
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| if in.ServiceName, err = request.RequireString("service"); err != nil { | ||
| return | ||
| } | ||
|
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| in.ClusterHandle = strings.TrimSpace(in.ClusterHandle) | ||
| in.ServiceName = strings.TrimSpace(in.ServiceName) | ||
|
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| if in.ClusterHandle == "" { | ||
| return fmt.Errorf("cluster handle must not be empty") | ||
| } | ||
| if in.ServiceName == "" { | ||
| return fmt.Errorf("service name must not be empty") | ||
| } | ||
|
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| return nil | ||
| } | ||
|
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| // resolveManifestsBaseDir picks the directory under which the | ||
| // "manifests/<handle>-<service>" tree should live. We prefer the parent of | ||
| // the cloned repository (the agent harness working directory) so that | ||
| // downloaded manifests are kept side-by-side with the repo without polluting | ||
| // the git working tree. | ||
| func resolveManifestsBaseDir() (string, error) { | ||
| if cfg, err := environment.Load(); err == nil && cfg != nil && cfg.Dir != "" { | ||
| return filepath.Dir(cfg.Dir), nil | ||
| } | ||
|
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| return os.Getwd() | ||
| } | ||
|
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| // sanitizeSegment normalises a value coming from outside the harness into | ||
| // something safe to use as a directory name segment. | ||
| func sanitizeSegment(s string) string { | ||
| s = strings.TrimSpace(s) | ||
| s = safeNamePattern.ReplaceAllString(s, "-") | ||
| s = strings.Trim(s, "-") | ||
| if s == "" { | ||
| return "service" | ||
| } | ||
| return s | ||
| } | ||
|
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| func NewDownloadManifests(client console.Client, agentRunID string) Tool { | ||
| return &DownloadManifests{ | ||
| ConsoleTool: ConsoleTool{ | ||
| id: DownloadManifestsTool, | ||
| description: "Downloads the fully rendered Kubernetes manifests for a Plural service " + | ||
| "and writes them to a dedicated '<handle>-<name>' subdirectory under '" + manifestsSubdir + "/' " + | ||
| "next to the cloned repository. Use this whenever you need to understand what Plural " + | ||
| "is actually applying for a service - including resources rendered from external Helm " + | ||
| "charts or the Plural gitops layout - instead of guessing via web searches. After it " + | ||
| "returns, inspect the listed directory with Read/Glob/Grep.", | ||
| client: client, | ||
| agentRunID: agentRunID, | ||
| }, | ||
| } | ||
| } | ||
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fromRequestwritesin.ClusterHandleandin.ServiceNamedirectly onto the*DownloadManifestsreceiver, which is a single instance shared across all concurrent MCP tool calls. Two simultaneous invocations can interleave: Request A setsClusterHandle = "prod", Request B overwrites it withClusterHandle = "dev", then Request A proceeds to callGetServiceDeploymentByHandle("dev", ...)— fetching and extracting the wrong service's manifests, and potentially writing them to the wrongtargetDir.The fix is to keep
clusterHandleandserviceNameas function-local variables inhandlerinstead of struct fields.