From fcc67da9f42928a8cd8e18b76a6f1cf702ca555a Mon Sep 17 00:00:00 2001
From: Erik Arvstedt <erik.arvstedt@gmail.com>
Date: Sun, 27 Sep 2020 12:43:28 +0200
Subject: [PATCH] test: add container support

---
 test/lib/make-container.sh | 89 ++++++++++++++++++++++++++++++++++++++
 test/lib/make-test.nix     | 10 +++++
 test/lib/test-lib.nix      | 11 ++++-
 test/run-tests.sh          | 12 +++++
 test/tests.nix             |  8 ++++
 5 files changed, 129 insertions(+), 1 deletion(-)
 create mode 100755 test/lib/make-container.sh

diff --git a/test/lib/make-container.sh b/test/lib/make-container.sh
new file mode 100755
index 0000000..327f13d
--- /dev/null
+++ b/test/lib/make-container.sh
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+
+# Usage:
+#
+#   run-tests.sh [--scenario|-s <scenario>] container
+#
+#     Start container and start a shell session with helper commands
+#     for accessing the container.
+#     A short command documentation is printed at the start of the session.
+#     The container is destroyed after exiting the shell.
+#     An existing container is destroyed before starting.
+#
+#     Supported arguments:
+#
+#       --destroy|-d to destroy
+#
+#         When `run-tests.sh container` from inside an existing shell session,
+#         the current container is updated without restarting by switching
+#         its NixOS configuration.
+#         Use this arg to destroy and restart the container instead.
+#
+#       --no-destroy|-n
+#
+#         By default, all commands destroy an existing container before starting and,
+#         when appropriate, before exiting.
+#         This ensures that containers start with no leftover filesystem state from
+#         previous runs and that containers don't consume system resources after use.
+#         This args disables auto-destructing containers.
+#
+#
+#   run-tests.sh container --run|-r c systemctl status bitcoind
+#
+#     Run a command in the shell session environmentand exit.
+#     Destroy the container afterwards.
+#     All arguments following `--run` are used as a command.
+#     Supports argument '--no-destroy|-n' (see above for an explanation).
+#
+#     Example: Start shell inside container
+#     run-tests.sh container --run c
+#
+#
+#   run-tests.sh [--scenario|-s <scenario>] container --command|--c
+#
+#     Provide a custom extra-container command.
+#
+#     Example:
+#       run-tests.sh container --command create -s
+#       Create and start a container without a shell.
+#
+#
+#   All extra args are passed to extra-container (unless --command is used):
+#   run-tests.sh container --build-args --builders 'ssh://worker - - 8'
+
+set -euo pipefail
+
+if [[ $EUID != 0 ]]; then
+    # NixOS containers require root permissions.
+    # By using sudo here and not at the user's call-site extra-container can detect if it is running
+    # inside an existing shell session (by checking an internal environment variable).
+    exec sudo scenario="$scenario" testDir="$testDir" NIX_PATH="$NIX_PATH" PATH="$PATH" \
+         scenarioOverridesFile="${scenarioOverridesFile:-}" "$testDir/lib/make-container.sh" "$@"
+fi
+
+export containerName=nb-test
+containerCommand=shell
+
+while [[ $# > 0 ]]; do
+    case $1 in
+        --command|-c)
+            shift
+            containerCommand=$1
+            shift
+            ;;
+        *)
+            break
+    esac
+done
+
+containerBin=$(type -P extra-container) || true
+if [[ ! ($containerBin && $(realpath $containerBin) == *extra-container-0.5*) ]]; then
+    echo "Building extra-container. Skip this step by adding extra-container 0.5 to PATH."
+    nix-build --out-link /tmp/extra-container "$testDir"/../pkgs -A extra-container >/dev/null
+    export PATH="/tmp/extra-container/bin${PATH:+:}$PATH"
+fi
+
+read -d '' src <<EOF || true
+(import "$testDir/tests.nix" { scenario = "$scenario"; }).container
+EOF
+exec extra-container $containerCommand -E "$src" "$@"
diff --git a/test/lib/make-test.nix b/test/lib/make-test.nix
index c3b5edc..9deb067 100644
--- a/test/lib/make-test.nix
+++ b/test/lib/make-test.nix
@@ -38,4 +38,14 @@ scenario: testConfig:
         ''
       ];
   };
+
+  container = {
+    # The container name has a 11 char length limit
+    containers.nb-test = { config, ...}: {
+      config = {
+        extra = config.config.test.container;
+        config = testConfig;
+      };
+    };
+  };
 }
diff --git a/test/lib/test-lib.nix b/test/lib/test-lib.nix
index 5490643..f34c5d9 100644
--- a/test/lib/test-lib.nix
+++ b/test/lib/test-lib.nix
@@ -5,7 +5,7 @@ with lib;
     test = {
       noConnections = mkOption {
         type = types.bool;
-        default = true;
+        default = !config.test.container.enableWAN;
         description = ''
           Whether services should be configured to not connect to external hosts.
           This can silence some warnings while running the test in an offline environment.
@@ -19,6 +19,15 @@ with lib;
           dictionary variable 'test_data'. The data is exported via JSON.
         '';
       };
+
+      container = {
+        # Forwarded to extra-container. For descriptions, see
+        # https://github.com/erikarvstedt/extra-container/blob/master/eval-config.nix
+        addressPrefix = mkOption { default = "10.225.255"; };
+        enableWAN = mkOption { default = false; };
+        firewallAllowHost = mkOption { default = true; };
+        exposeLocalhost = mkOption { default = false; };
+      };
     };
 
     tests = mkOption {
diff --git a/test/run-tests.sh b/test/run-tests.sh
index 24ef18d..d360419 100755
--- a/test/run-tests.sh
+++ b/test/run-tests.sh
@@ -25,6 +25,14 @@
 #     This starts the testing VM and drops you into a Python REPL where you can
 #     manually execute the tests from ./tests.py
 #
+#   Run a test scenario in a container
+#   sudo ./run-tests.sh [--scenario <scenario>] container
+#
+#     This is useful for quick experiments; containers start much faster than VMs.
+#     Running the Python test suite in containers is not yet supported.
+#     For now, creating NixOS containers requires root permissions.
+#     See ./lib/make-container.sh for a complete documentation.
+#
 #   To add custom scenarios, set the environment variable `scenarioOverridesFile`.
 
 set -eo pipefail
@@ -108,6 +116,10 @@ debug() {
     run --interactive
 }
 
+container() {
+  . "$testDir/lib/make-container.sh" "$@"
+}
+
 # Run the test by building the test derivation
 buildTest() {
     if [[ $outLinkPrefix ]]; then
diff --git a/test/tests.nix b/test/tests.nix
index cb8aa4e..db073a1 100644
--- a/test/tests.nix
+++ b/test/tests.nix
@@ -115,6 +115,14 @@ let testEnv = rec {
       };
     };
 
+    # Container-specific features
+    containerFeatures = {
+      # Container has WAN access and bitcoind connects to external nodes
+      test.container.enableWAN = true;
+      # See ./lib/test-lib.nix for a description
+      test.container.exposeLocalhost = true;
+    };
+
     adhoc = {
       # <Add your config here>
       # You can also set the env var `scenarioOverridesFile` (used below) to define custom scenarios.