Set docker daemon log-level to warn by default (#98)

And remove deprecated fix-attrs.

rootfs/etc/docker/daemon.json

@@ -1,7 +1,4 @@
 {
-    "data-root": "/home/jenkins/agent/docker",
-    "features": {
-        "buildkit": true
-    },
-    "mtu": 1400
+  "data-root": "/home/jenkins/agent/docker",
+  "log-level": "warn"
 }

rootfs/etc/optional-services.d/sshd/check_readiness.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-exec ssh -q -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null jenkins@127.0.0.1 true &>/dev/null
+exec ssh -q -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "${NON_ROOT_USER?}@127.0.0.1" true &>/dev/null

scripts/prepare_image.sh

@@ -32,8 +32,8 @@ sudo -u "${NON_ROOT_USER}" true
 
 # ensure jenkins-agent directory exists
 mkdir -p "${AGENT_WORKDIR}"
-# and is owned by the jenkins user
 chown -R "${NON_ROOT_USER}:${NON_ROOT_USER}" "${AGENT_WORKDIR}"
+chmod 755 "${AGENT_WORKDIR}"
 
 ## apt repositories
 ${APT_GET_INSTALL} \
@@ -143,7 +143,7 @@ chmod +x /usr/local/bin/dind
 docker_agent_version=$(basename "$(${CURL} -o /dev/null -w "%{url_effective}" https://github.com/jenkinsci/docker-agent/releases/latest)")
 version=$(echo "${docker_agent_version}" | cut -d'-' -f1)
 mkdir -p /usr/share/jenkins
-chmod 0755 /usr/share/jenkins
+chmod 755 /usr/share/jenkins
 ${CURL} -o /usr/share/jenkins/agent.jar "https://repo.jenkins-ci.org/public/org/jenkins-ci/main/remoting/${version}/remoting-${version}.jar"
 chmod +x /usr/share/jenkins/agent.jar
 ln -sf /usr/share/jenkins/agent.jar /usr/share/jenkins/slave.jar