Infracost LSP

Warning

This repository is in early alpha. Features may change and rough edges are expected. Open a discussion thread to report bugs or share feedback — it is genuinely appreciated.

A Language Server Protocol (LSP) server that shows cloud cost estimates inline while editing Terraform and CloudFormation files. It talks directly to the Infracost parser and provider gRPC plugins to analyze IaC and return costs.

Features

• Code Lenses — $X.XX/mo shown above each resource block
• Inlay Hints — inline cost display for editors without code lens support
• Hover — markdown table with cost component breakdown
• Diagnostics — FinOps policy violations as warnings, parse errors as errors
• Code Actions — quick fixes for policy violations (attribute replacements, dismiss)
• Dismiss / Ignore — suppress violations per-resource or globally, persisted locally

Prerequisites

• Go 1.25+
• Infracost parser and provider plugins (gRPC binaries)

Editor Extensions

Note

These extensions are in beta. Formal marketplace releases are coming soon.

• VS Code: vscode-infracost v0.3.0-beta.2
• JetBrains: jetbrains-infracost v2.0.0-beta.1

Quickstart

Important

You need to have done a login with the new cli - this will create your token file that the LSP currently piggy backs on. Without this, a lot of functionality won't work because it can't get your org, talk to the pricing server, talk to the dashboard, or anything.

1. Install one of the editor extensions above.
2. Open a directory containing .tf, .yaml, or .json IaC files. Cost lenses should appear above resource blocks.

Configuration

The LSP server is configured via environment variables. Most are optional — the server discovers plugins from PATH by default.

Variable	Description	Default
INFRACOST_CLI_CURRENCY	Currency for cost estimates	USD
INFRACOST_LOG_LEVEL	Log level (debug for verbose)	warn
INFRACOST_DEBUG_UI	Port for debug UI (development only)	(disabled)

Workspace configuration

The server discovers projects from an infracost.yml file in the workspace root. This file defines project paths and settings used during scanning.

Ignore file

Dismissed violations are stored in a local JSON file at $XDG_CONFIG_HOME/infracost/ignores.json (falls back to ~/.infracost/ignores.json). Override the path with INFRACOST_IGNORES_FILE.

Architecture

sequenceDiagram
    participant Editor as Editor (VS Code / Neovim / JetBrains)
    participant LSP as infracost-ls
    participant Parser as Parser Plugin (gRPC)
    participant Provider as Provider Plugin (gRPC)

    Editor->>LSP: initialize (workspace root)
    LSP->>Parser: Parse project HCL
    Parser-->>LSP: Resources + source locations
    LSP->>Provider: Price resources
    Provider-->>LSP: Costs + FinOps violations
    LSP-->>Editor: Code lenses, diagnostics

    Note over Editor,LSP: On file save (debounced per project)
    Editor->>LSP: didSave
    LSP->>LSP: Debounce (300ms), cancel in-flight scan
    LSP->>Parser: Re-parse project
    Parser-->>LSP: Updated resources
    LSP->>Provider: Re-price
    Provider-->>LSP: Updated costs + violations
    LSP-->>Editor: Refresh code lenses, diagnostics, hover

Loading

The server re-scans the affected project on file open or save. Rapid saves are debounced per project — only one scan runs at a time, and a new save cancels any in-flight scan. Results are cached per project and used to serve code lens and hover requests.

Vim / Neovim

The LSP server communicates over stdio and follows the LSP 3.16 spec, so it works with any editor that has LSP support.

For Neovim, add the following to your config (or adapt it for your plugin manager):

vim.api.nvim_create_autocmd("FileType", {
  pattern = "terraform",
  callback = function()
    local root = vim.fs.dirname(vim.fs.find("infracost.yml", { upward = true })[1])
      or vim.fn.fnamemodify(vim.api.nvim_buf_get_name(0), ":p:h")
    vim.lsp.start({
      name = "infracost",
      cmd = { "infracost-ls" },
      root_dir = root,
      capabilities = vim.lsp.protocol.make_client_capabilities(),
    })
  end,
})

This starts the LSP client automatically when opening .tf files. Make sure infracost-ls is on your PATH (see Development below).

Development

Information about developing the LSP

Environment variables

These override the plugin binaries the server launches. You only need them if the plugins aren't on your PATH or you want to test local builds.

Variable	Description	Default
INFRACOST_CLI_PARSER_PLUGIN	Path to the parser plugin binary	infracost-parser-plugin (from PATH)
INFRACOST_CLI_PROVIDER_PLUGIN_AWS	Path to the AWS provider plugin	infracost-provider-plugin-aws (from PATH)
INFRACOST_CLI_PROVIDER_PLUGIN_GOOGLE	Path to the GCP provider plugin	infracost-provider-plugin-google (from PATH)
INFRACOST_CLI_PROVIDER_PLUGIN_AZURERM	Path to the Azure provider plugin	infracost-provider-plugin-azurerm (from PATH)
INFRACOST_CLI_PARSER_PLUGIN_VERSION	Parser plugin version override	(latest)
INFRACOST_CLI_PROVIDER_PLUGIN_AWS_VERSION	AWS provider plugin version override	(latest)
INFRACOST_CLI_PROVIDER_PLUGIN_GOOGLE_VERSION	GCP provider plugin version override	(latest)
INFRACOST_CLI_PROVIDER_PLUGIN_AZURE_VERSION	Azure provider plugin version override	(latest)
INFRACOST_CLI_PLUGIN_MANIFEST_URL	URL for the plugin manifest	https://releases.infracost.io/plugins/manifest.json

Building

make build      # build to bin/infracost-ls
make install    # build and copy to ~/go/bin/

Testing with Neovim

A minimal Neovim plugin is included for quick iteration:

make nvim-run DIR=~/my-terraform-project

Testing with VS Code

1. Install the VS Code extension.
2. In VS Code settings, set infracost.serverPath to your local build (e.g. ~/go/bin/infracost-ls).
3. Reload the window. The extension will use your local LSP binary.

Testing with JetBrains

1. Install the JetBrains plugin.
2. Configure the plugin to point to your local infracost-ls binary.
3. Restart the IDE.