TLS and mTLS v3.8.1

GripMock supports native TLS for gRPC and optional mTLS (client certificate authentication).

How TLS is enabled

gRPC TLS is enabled only when both variables are set:

• GRPC_TLS_CERT_FILE
• GRPC_TLS_KEY_FILE

If one of them is missing, gRPC starts without TLS.

gRPC TLS environment variables

Variable	Purpose	Required
GRPC_TLS_CERT_FILE	Server certificate file (PEM)	Yes, for TLS
GRPC_TLS_KEY_FILE	Server private key file (PEM)	Yes, for TLS
GRPC_TLS_CLIENT_AUTH	Enable mTLS (true/false)	No (default: false)
GRPC_TLS_CA_FILE	CA bundle used to verify client certificates	Required when GRPC_TLS_CLIENT_AUTH=true
GRPC_TLS_MIN_VERSION	Minimal TLS version (1.2 or 1.3)	No (default: 1.2)

HTTP TLS environment variables

The HTTP API can also run with TLS:

Variable	Purpose
HTTP_TLS_CERT_FILE	HTTP server certificate file
HTTP_TLS_KEY_FILE	HTTP server private key file
HTTP_TLS_CLIENT_AUTH	Enable mTLS for HTTP clients
HTTP_TLS_CA_FILE	CA bundle for HTTP client certificate verification

Examples

gRPC TLS (server auth only)

GRPC_TLS_CERT_FILE=./third_party/tls/tls12/server.crt \
GRPC_TLS_KEY_FILE=./third_party/tls/tls12/server.key \
GRPC_TLS_CA_FILE=./third_party/tls/tls12/ca.crt \
GRPC_TLS_MIN_VERSION=1.2 \
gripmock --stub=examples examples

gRPC mTLS

GRPC_TLS_CERT_FILE=./third_party/tls/mtls/server.crt \
GRPC_TLS_KEY_FILE=./third_party/tls/mtls/server.key \
GRPC_TLS_CA_FILE=./third_party/tls/mtls/ca.crt \
GRPC_TLS_CLIENT_AUTH=true \
GRPC_TLS_MIN_VERSION=1.3 \
gripmock --stub=examples examples

gripmock check with TLS

gripmock check uses the same GRPC_TLS_* environment variables as the server.

For TLS-enabled gRPC, check must trust the server certificate chain.

Minimal env for TLS (server auth only)

GRPC_TLS_CA_FILE=./third_party/tls/tls13/ca.crt \
GRPC_TLS_MIN_VERSION=1.3 \
gripmock check --timeout=60s --silent

Env for mTLS

GRPC_TLS_CA_FILE=./third_party/tls/mtls/ca.crt \
GRPC_TLS_CERT_FILE=./third_party/tls/mtls/client.crt \
GRPC_TLS_KEY_FILE=./third_party/tls/mtls/client.key \
GRPC_TLS_MIN_VERSION=1.3 \
gripmock check --timeout=60s --silent

Notes:

• GRPC_TLS_CA_FILE is required in practice for self-signed/local CA certs.
• GRPC_TLS_CERT_FILE + GRPC_TLS_KEY_FILE are required only when server enforces mTLS.
• GRPC_TLS_CLIENT_AUTH affects server behavior and is not required for check itself.

Client-side test env (grpctestify)

When running grpctestify, set these vars for TLS calls:

GRPCTESTIFY_TLS_CA_FILE=./third_party/tls/tls13/ca.crt
GRPCTESTIFY_TLS_SERVER_NAME=localhost
GRPCTESTIFY_TLS_CERT_FILE=./third_party/tls/mtls/client.crt
GRPCTESTIFY_TLS_KEY_FILE=./third_party/tls/mtls/client.key

For plain TLS (no mTLS), GRPCTESTIFY_TLS_CERT_FILE and GRPCTESTIFY_TLS_KEY_FILE can be empty.

Reverse proxy TLS termination

If you prefer terminating TLS on a proxy, keep GripMock on an internal port and route traffic through Caddy/Nginx.

Self-signed certificate setup

mkdir certs && openssl req \
  -x509 -newkey rsa:2048 \
  -keyout certs/key.pem -out certs/cert.pem \
  -days 365 -nodes \
  -subj "/CN=localhost"

Caddy

services:
  gripmock:
    # ... existing configuration ...

  caddy:
    image: caddy:latest
    ports:
      - "443:443"
    volumes:
      - ./Caddyfile:/etc/caddy/Caddyfile
      - ./certs:/certs
    depends_on:
      - gripmock
    # ... other configuration ...

localhost:443 {
  tls /certs/cert.pem /certs/key.pem
  reverse_proxy gripmock:4770 {
    transport http {
      tls_insecure_skip_verify
    }
  }
}

Nginx

server {
  listen 443 ssl http2;
  ssl_certificate /etc/nginx/certs/cert.pem;
  ssl_certificate_key /etc/nginx/certs/key.pem;

  location / {
    grpc_pass grpc://gripmock:4770;
    grpc_ssl_verify off;
  }
}

Verification

grpcurl -proto helloworld.proto \
  -cacert certs/cert.pem \
  -d '{"name": "TLS Test"}' \
  localhost:443 \
  helloworld.Greeter/SayHello