> ## Documentation Index > Fetch the complete documentation index at: https://docs.formal.ai/llms.txt > Use this file to discover all available pages before exploring further. # ClickHouse > Manage ClickHouse Cloud services, backups, ClickPipes, and costs. Data Publisher: ClickHouse Route ClickHouse MCP traffic through Formal to control and log what AI agents do in ClickHouse: * **Block** tools you don't want agents to call, such as `get_organization_details`. * **Mask** sensitive data in tool results, such as emails in `get_organizations` responses. * **Keep credentials at the Connector**, so users and agents never see ClickHouse tokens. * **Log** every tool call with the user, the MCP client and its parameters. Cloud agents Laptop / VM Endpoint [https://mcp.clickhouse.cloud/mcp](https://mcp.clickhouse.cloud/mcp) Connector ![](https://docs.formal.ai/static/brands/mcp/clickhouse.svg) ## 0. Prepare your Connector The Connector needs an MCP listener and a hostname with wildcard DNS and TLS. Set them up once by following [Deploy the Connector](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#deploy-the-connector). Every MCP server reuses them. ## 1. Add ClickHouse MCP server to your Resources > [tab] UI > > 1. Open the [Admin Catalog](https://app.formal.ai/catalog) and click **Add MCP**. > 2. Select the **ClickHouse** template. > 3. Enter a DNS-label **Name**, such as `clickhouse`. > 4. Choose the **Space** containing your Connector, such as `default`. > 5. Configure upstream authentication as described below, then save. > > If no Connector is in the selected Space, the **Configuration** tab shows **MCP clients can't connect directly yet**. > The reason reads: `No Connector is in this server's Space.` > > Adding ClickHouse to the Admin Catalog > [tab] Terraform > > Set `space_id` to the ID of the Space containing your Connector. > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > resource "formal_resource" "clickhouse" { > name = "clickhouse" > technology = "mcp" > hostname = "mcp.clickhouse.cloud" > space_id = "" > native_users_v3_enabled = true > port = 443 > tags = { > "mcp-endpoint" = "/mcp" > } > } > > resource "formal_resource_oauth_settings" "clickhouse" { > resource_id = formal_resource.clickhouse.id > } > ``` > [tab] Pulumi > > Set `spaceId` to the ID of the Space containing your Connector. > > ```ts theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > import * as formal from "@formalco/pulumi"; > > const resource = new formal.Resource("mcp", { > name: "clickhouse", > technology: "mcp", > hostname: "mcp.clickhouse.cloud", > port: 443, > spaceId: "", > tags: { "mcp-endpoint": "/mcp" }, > nativeUsersV3Enabled: true, > }); > > new formal.ResourceOauthSettings("mcpOAuth", { > resourceId: resource.id, > }); > ``` > [tab] API > > Create a Resource with the MCP endpoint and its Space ID. > > ```bash theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > export FORMAL_API_KEY="" > RESOURCE_RESPONSE=$(curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.ResourceService/CreateResource \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- < { > "name": "clickhouse", > "hostname": "mcp.clickhouse.cloud", > "port": 443, > "technology": "mcp", > "spaceId": "", > "tags": [ > { > "key": "mcp-endpoint", > "value": "/mcp" > } > ] > } > JSON > ) > RESOURCE_ID=$(printf '%s' "${RESOURCE_RESPONSE}" | jq -r '.resource.id') > curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.ResourceService/CreateResourceOAuthSettings \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- < { > "resourceId": "${RESOURCE_ID}" > } > JSON > ``` ## 2. Setup Authentication > [tab] Linked Accounts (Recommended) > > Each user links their own ClickHouse account once in the Employee Catalog, and the Connector sends that user's token to ClickHouse. > > ![Linked Accounts selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/vzPMpIcsF4BYmdx8/assets/images/mcp-servers/auth-linked-accounts.png?fit=max\&auto=format\&n=vzPMpIcsF4BYmdx8\&q=85\&s=dc448db2a373faa6e1bf49fd5ffaf7c4) > > Under **OAuth app**, keep **Formal's App**. > > #### Formal's App (default) > > Formal has a registered OAuth app with ClickHouse, so you register nothing. > Users see Formal on ClickHouse's consent screen. > [tab] Shared Credentials > > An administrator stores one ClickHouse token in Formal, and the Connector sends it on every user's requests without showing it to them. > > ![Shared Credentials selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/R-3CwVgs8IU6liji/assets/images/mcp-servers/auth-shared-credentials.png?fit=max\&auto=format\&n=R-3CwVgs8IU6liji\&q=85\&s=91032e202518088292ee1cf39451b9ef) > > ClickHouse's MCP endpoint accepts a [ClickHouse Cloud API key](https://clickhouse.com/docs/products/cloud/features/ai-ml/mcp/remote-mcp) with HTTP Basic authentication. > Create one at [console.clickhouse.cloud](https://console.clickhouse.cloud/). > Grant only the organization and service roles required, and restrict the key's IP allowlist to the MCP host. > > 1. Open this server from the [Admin Catalog](https://app.formal.ai/catalog). > 2. Select **Configuration**, then **Authentication**. > 3. Choose **Shared Credentials**, then select **Add credential**. > 4. Enter the credential, make it the default, and select **Save authentication**. > > See [Native Users](https://docs.formal.ai/docs/guides/core-concepts/resources/native-users.md). > > Choose **HTTP Basic** and set **Header Name** to `Authorization`. > Enter the API key ID under **Username** and the API key secret under **Password**. > The Connector builds the Basic value. > > In the Terraform tab, set `native_users_v3_enabled = true` on the Resource and `upstream_oauth_mode = "none"` on its OAuth settings. > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > variable "mcp_shared_credential_username" { > type = string > sensitive = true > } > > variable "mcp_shared_credential_password" { > type = string > sensitive = true > } > > resource "formal_native_user_v3" "mcp_shared_credential" { > resource_id = formal_resource.clickhouse.id > label = "shared-credential" > > http_basic { > header = "Authorization" > username = var.mcp_shared_credential_username > password { > literal_wo = var.mcp_shared_credential_password > literal_wo_version = 1 > } > } > } > > resource "formal_resource_native_user_selection" "mcp_shared_credential" { > resource_id = formal_resource.clickhouse.id > cel = "\"${formal_native_user_v3.mcp_shared_credential.id}\"" > } > ``` > [tab] Pass Through > > Each user sends their own ClickHouse sign-in or token from their MCP client, and Formal forwards it unchanged without storing it. > > ![Pass Through selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/R-3CwVgs8IU6liji/assets/images/mcp-servers/auth-pass-through.png?fit=max\&auto=format\&n=R-3CwVgs8IU6liji\&q=85\&s=c14ae61de2dba8b567626cba03aae2cf) > > Nothing in the request identifies the Formal user. Formal attributes these requests only when they come through the [Formal Endpoint](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#identity-headers). Pass-through servers have no Connector address, so cloud agents can't use them. > > For OAuth, each MCP client signs in to ClickHouse itself. ## 3. Route Endpoint traffic Auth is managed at the Connector level when you use Linked Accounts or Shared Credentials, so the Endpoint needs to forward the MCP traffic to it. Laptops and VMs with the Formal Endpoint keep using `https://mcp.clickhouse.cloud/mcp`, and a network rule sends that traffic to the Connector. > [tab] UI > > 1. Go to [Network Rules](https://app.formal.ai/network-rules) and create a rule named `clickhouse-mcp`. > 2. Paste this expression, set the rule to **Active**, then save: > > ```javascript theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > { > "condition": { > "pre_tcp": process.is_agent, > // Every MCP server added to Formal: process.is_agent && resource.technology == "mcp" > "pre_tls": process.is_agent && hostname == "mcp.clickhouse.cloud", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > ``` > [tab] Terraform > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > resource "formal_network_rule" "clickhouse_mcp" { > name = "clickhouse-mcp" > description = "Forward ClickHouse MCP traffic from agents to the Connector" > status = "active" > > # Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > cel_expression = <<-EOT > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.clickhouse.cloud", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > EOT > } > ``` > [tab] Pulumi > > ```ts theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > import * as formal from "@formalco/pulumi"; > > new formal.NetworkRule("clickhouseMcp", { > name: "clickhouse-mcp", > description: "Forward ClickHouse MCP traffic from agents to the Connector", > status: "active", > // Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > celExpression: ` > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.clickhouse.cloud", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > `, > }); > ``` > [tab] API > > ```bash theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > export FORMAL_API_KEY="" > # Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > CEL_EXPRESSION=$(cat <<'CEL' > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.clickhouse.cloud", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > CEL > ) > jq -n --arg cel "${CEL_EXPRESSION}" '{ > name: "clickhouse-mcp", > description: "Forward ClickHouse MCP traffic from agents to the Connector", > status: "active", > celExpression: $cel > }' | curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.DesktopService/CreateDesktopRoutingRule \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- > ``` The rule matches [known agents](https://docs.formal.ai/docs/guides/network-rules.md#known-agent-identities) only. See [Identity headers](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#identity-headers). Cloud agents such as Claude, ChatGPT and Cursor Cloud Agents don't run the Endpoint. Point them at this server's Connector address, `https://clickhouse./mcp`. Find it in the [Admin Catalog](https://app.formal.ai/catalog): open ClickHouse, then copy **Connector address** on the **Configuration** tab. ## 4. Create policies ### Tools The Admin Catalog lists these tools for ClickHouse: | Tool | Description | | - | - | | `get_organizations` | List the ClickHouse Cloud organizations you can access. | | `get_organization_details` | Get details of an organization. | | `get_services_list` | List the services in an organization. | | `get_service_details` | Get details of a service. | | `list_service_backups` | List a service's backups, most recent first. | | `get_service_backup_configuration` | Get a service's backup schedule and retention. | | `list_clickpipes` | List the ClickPipes configured for a service. | | `get_clickpipe` | Get details of a ClickPipe. | | `get_organization_cost` | Get billing and usage costs for an organization. | ## 5. Check the logs Open [Logs](https://app.formal.ai/logs) and search for `resource.name:clickhouse`. Each ClickHouse tool call is one `request` log with the user, the MCP client and the tool. Open a log to see its tool parameters and the policies it triggered. ClickHouse tool calls in Logs, including a masked response and a blocked write See [Logs](https://docs.formal.ai/docs/guides/observability/logs.md) for search syntax and filters. ## Troubleshooting > [accordion] The agent says Formal has no current sign-in > > The agent relays: `Formal has no current clickhouse sign-in for you. Link or re-link your clickhouse account in Formal…` > > **Cause:** The user never linked ClickHouse, or the token expired and couldn't be refreshed. > > **Fix:** Open the server in the [Employee Catalog](https://catalog.formal.ai) and link ClickHouse again. > [accordion] The agent says ClickHouse rejected your credentials > > The agent relays: `clickhouse rejected your credentials. Link or re-link your clickhouse account in Formal…` > > **Cause:** ClickHouse no longer accepts the linked token, for example after the user revoked access in ClickHouse. > > **Fix:** Link ClickHouse again from the [Employee Catalog](https://catalog.formal.ai). > > With Shared Credentials, the message asks the user to contact an administrator. Replace the token in the server's **Shared Credentials**. > [accordion] Laptop traffic doesn't appear in Logs > > **Cause:** The Endpoint isn't running, or the network rule doesn't match the client. > > **Fix:** Check the Endpoint is connected. The rule above only matches [known agents](https://docs.formal.ai/docs/guides/network-rules.md#known-agent-identities). Other clients, such as a browser, reach ClickHouse directly unless the rule also matches them. See [Network rules](https://docs.formal.ai/docs/guides/network-rules.md). > [accordion] MCP clients can't connect directly yet > > **Cause:** The **Configuration** tab lists the reason, most often `No Connector is in this server's Space.` > > **Fix:** Edit the server and choose the Space containing its Connector. ## Next Steps > [card] [MCP Gateway](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md) > > Configure Connector routing and downstream access > [card] [All MCP servers](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-servers/index.md) > > Browse every MCP server template This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.