(core) updates from grist-core

sandbox/docker_entrypoint.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+# Runs the command provided as arguments, but attempts to configure permissions first.
+
+important_read_dirs=("/grist" "/persist")
+write_dir="/persist"
+current_user_id=$(id -u)
+
+# We want to avoid running Grist as root if possible.
+# Try to setup permissions and de-elevate to a normal user.
+if [[ $current_user_id == 0 ]]; then
+  target_user=${GRIST_DOCKER_USER:-grist}
+  target_group=${GRIST_DOCKER_GROUP:-grist}
+
+  # Make sure the target user owns everything that Grist needs write access to.
+  find $write_dir ! -user "$target_user" -exec chown "$target_user" "{}" +
+
+  # Restart as the target user, replacing the current process (replacement is needed for security).
+  # Alternative tools to setpriv are: chroot, gosu.
+  # Need to use `exec` to close the parent shell, to avoid vulnerabilities: https://github.com/tianon/gosu/issues/37
+  exec setpriv --reuid "$target_user" --regid "$target_group" --init-groups /usr/bin/env bash "$0" "$@"
+fi
+
+# Validate that this user has access to the top level of each important directory.
+# There might be a benefit to testing individual files, but this is simpler as the dir may start empty.
+for dir in "${important_read_dirs[@]}"; do
+  if ! { test -r "$dir" ;} ; then
+    echo "Invalid permissions, cannot read '$dir'. Aborting." >&2
+    exit 1
+  fi
+done
+for dir in "${important_write_dirs[@]}"; do
+  if ! { test -r "$dir" && test -w "$dir" ;} ; then
+    echo "Invalid permissions, cannot write '$dir'. Aborting." >&2
+    exit 1
+  fi
+done
+
+exec /usr/bin/tini -s -- "$@"

sandbox/supervisor.mjs

@@ -0,0 +1,35 @@
+import {spawn} from 'child_process';
+
+let grist;
+
+function startGrist(newConfig={}) {
+  saveNewConfig(newConfig);
+  // H/T https://stackoverflow.com/a/36995148/11352427
+  grist = spawn('./sandbox/run.sh', {
+    stdio: ['inherit', 'inherit', 'inherit', 'ipc']
+  });
+  grist.on('message', function(data) {
+    if (data.action === 'restart') {
+      console.log('Restarting Grist with new environment');
+
+      // Note that we only set this event handler here, after we have
+      // a new environment to reload with. Small chance of a race here
+      // in case something else sends a SIGINT before we do it
+      // ourselves further below.
+      grist.on('exit', () => {
+        grist = startGrist(data.newConfig);
+      });
+
+      grist.kill('SIGINT');
+    }
+  });
+  return grist;
+}
+
+// Stub function
+function saveNewConfig(newConfig) {
+  // TODO: something here to actually persist the new config before
+  // restarting Grist.
+}
+
+startGrist();