Use official checksums to verify Tini (#55717)

Firstly, backport the use of tini as the Docker entrypoint. This was supposed
to have been done following #50277, but was missed. It isn't a direct backport
as this branch will continue using root as the initial Docker user.

Secondly, backport #55491 to use the official checksums when downloading tini.

distribution/docker/build.gradle

@@ -28,22 +28,32 @@ dependencies {
 }
 
 ext.expansions = { architecture, oss, local ->
+  String base_image = null
+  String tini_arch = null
+  String classifier = null
   switch (architecture) {
     case "aarch64":
+      base_image = "arm64v8/centos:7"
+      tini_arch = "arm64"
+      classifier = "linux-aarch64"
+      break;
     case "x64":
+      base_image = "amd64/centos:7"
+      tini_arch = "amd64"
+      classifier = "linux-x86_64"
       break;
     default:
       throw new IllegalArgumentException("unrecongized architecture [" + architecture + "], must be one of (aarch64|x64)")
   }
-  final String classifier = "aarch64".equals(architecture) ? "linux-aarch64" : "linux-x86_64"
   final String elasticsearch = oss ? "elasticsearch-oss-${VersionProperties.elasticsearch}-${classifier}.tar.gz" : "elasticsearch-${VersionProperties.elasticsearch}-${classifier}.tar.gz"
   return [
-    'base_image'          : "aarch64".equals(architecture) ? "arm64v8/centos:7" : "centos:7",
+    'base_image'          : base_image,
     'build_date'          : BuildParams.buildDate,
     'elasticsearch'       : elasticsearch,
     'git_revision'        : BuildParams.gitRevision,
     'license'             : oss ? 'Apache-2.0' : 'Elastic-License',
     'source_elasticsearch': local ? "COPY $elasticsearch /opt/" : "RUN cd /opt && curl --retry 8 -s -L -O https://artifacts.elastic.co/downloads/elasticsearch/${elasticsearch} && cd -",
+    'tini_arch'           : tini_arch,
     'version'             : VersionProperties.elasticsearch
   ]
 }
@@ -227,6 +237,7 @@ subprojects { Project subProject ->
     def tarFile = "${parent.projectDir}/build/elasticsearch${"aarch64".equals(architecture) ? '-aarch64' : ''}${oss ? '-oss' : ''}_test.${VersionProperties.elasticsearch}.docker.tar"
 
     final Task exportDockerImageTask = task(exportTaskName, type: LoggedExec) {
+      inputs.file("${parent.projectDir}/build/markers/${buildTaskName}.marker")
       executable 'docker'
       outputs.file(tarFile)
       args "save",

distribution/docker/src/docker/Dockerfile

@@ -14,10 +14,22 @@
 FROM ${base_image} AS builder
 
 RUN for iter in {1..10}; do yum update --setopt=tsflags=nodocs -y && \
-    yum install --setopt=tsflags=nodocs -y gzip shadow-utils tar && \
+    yum install --setopt=tsflags=nodocs -y wget gzip shadow-utils tar && \
     yum clean all && exit_code=0 && break || exit_code=\$? && echo "yum error: retry \$iter in 10s" && sleep 10; done; \
     (exit \$exit_code)
 
+# `tini` is a tiny but valid init for containers. This is used to cleanly
+# control how ES and any child processes are shut down.
+#
+# The tini GitHub page gives instructions for verifying the binary using
+# gpg, but the keyservers are slow to return the key and this can fail the
+# build. Instead, we check the binary against a checksum that they provide.
+RUN wget --no-cookies --quiet https://github.com/krallin/tini/releases/download/v0.19.0/tini-${tini_arch} \
+    && wget --no-cookies --quiet https://github.com/krallin/tini/releases/download/v0.19.0/tini-${tini_arch}.sha256sum \
+    && sha256sum -c tini-${tini_arch}.sha256sum \
+    && mv tini-${tini_arch} /tini \
+    && chmod +x /tini
+
 ENV PATH /usr/share/elasticsearch/bin:\$PATH
 
 RUN groupadd -g 1000 elasticsearch && \
@@ -45,6 +57,8 @@ FROM ${base_image}
 
 ENV ELASTIC_CONTAINER true
 
+COPY --from=builder /tini /tini
+
 RUN for iter in {1..10}; do yum update --setopt=tsflags=nodocs -y && \
     yum install --setopt=tsflags=nodocs -y nc shadow-utils zip unzip && \
     yum clean all && exit_code=0 && break || exit_code=\$? && echo "yum error: retry \$iter in 10s" && sleep 10; done; \
@@ -65,17 +79,14 @@ RUN ln -sf /etc/pki/ca-trust/extracted/java/cacerts /usr/share/elasticsearch/jdk
 
 ENV PATH /usr/share/elasticsearch/bin:\$PATH
 
-COPY --chown=1000:0 bin/docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
+COPY bin/docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
+
+RUN chmod g=u /etc/passwd && \
+    chmod 0775 /usr/local/bin/docker-entrypoint.sh
 
 # Ensure that there are no files with setuid or setgid, in order to mitigate "stackclash" attacks.
 RUN find / -xdev -perm -4000 -exec chmod ug-s {} +
 
-# Openshift overrides USER and uses ones with randomly uid>1024 and gid=0
-# Allow ENTRYPOINT (and ES) to run even with a different user
-RUN chgrp 0 /usr/local/bin/docker-entrypoint.sh && \
-    chmod g=u /etc/passwd && \
-    chmod 0775 /usr/local/bin/docker-entrypoint.sh
-
 EXPOSE 9200 9300
 
 LABEL org.label-schema.build-date="${build_date}" \
@@ -98,7 +109,7 @@ LABEL org.label-schema.build-date="${build_date}" \
   org.opencontainers.image.vendor="Elastic" \
   org.opencontainers.image.version="${version}"
 
-ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
+ENTRYPOINT ["/tini", "--", "/usr/local/bin/docker-entrypoint.sh"]
 # Dummy overridable parameter parsed by entrypoint
 CMD ["eswrapper"]
 

qa/os/src/test/java/org/elasticsearch/packaging/test/DockerTests.java

@@ -68,6 +68,7 @@
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.nullValue;
+import static org.hamcrest.Matchers.startsWith;
 import static org.junit.Assume.assumeFalse;
 import static org.junit.Assume.assumeTrue;
 
@@ -139,7 +140,7 @@ public void test040JavaUsesTheOsProvidedKeystore() {
     /**
      * Checks that there are Amazon trusted certificates in the cacaerts keystore.
      */
-    public void test043AmazonCaCertsAreInTheKeystore() {
+    public void test041AmazonCaCertsAreInTheKeystore() {
         final boolean matches = Arrays.stream(
             sh.run("jdk/bin/keytool -cacerts -storepass changeit -list | grep trustedCertEntry").stdout.split("\n")
         ).anyMatch(line -> line.contains("amazonrootca"));
@@ -251,8 +252,8 @@ public void test080ConfigurePasswordThroughEnvironmentVariableFile() throws Exce
             waitForElasticsearch("green", null, installation, "elastic", "hunter2");
         } catch (Exception e) {
             throw new AssertionError(
-                "Failed to check whether Elasticsearch had started. This could be because authentication isn't working properly. "
-                    + "Check the container logs",
+                "Failed to check whether Elasticsearch had started. This could be because "
+                    + "authentication isn't working properly. Check the container logs",
                 e
             );
         }
@@ -335,8 +336,7 @@ public void test083EnvironmentVariablesUsingFilesHaveCorrectPermissions() throws
 
         Files.write(tempDir.resolve(passwordFilename), "hunter2\n".getBytes(StandardCharsets.UTF_8));
 
-        Map<String, String> envVars = new HashMap<>();
-        envVars.put("ELASTIC_PASSWORD_FILE", "/run/secrets/" + passwordFilename);
+        Map<String, String> envVars = singletonMap("ELASTIC_PASSWORD_FILE", "/run/secrets/" + passwordFilename);
 
         // Set invalid file permissions
         Files.setPosixFilePermissions(tempDir.resolve(passwordFilename), p660);
@@ -484,7 +484,6 @@ public void test101AllFilesAreGroupZero() {
 
     /**
      * Check that the Docker image has the expected "Label Schema" labels.
-     *
      * @see <a href="http://label-schema.org/">Label Schema website</a>
      */
     public void test110OrgLabelSchemaLabels() throws Exception {
@@ -526,7 +525,6 @@ public void test110OrgLabelSchemaLabels() throws Exception {
 
     /**
      * Check that the Docker image has the expected "Open Containers Annotations" labels.
-     *
      * @see <a href="https://github.com/opencontainers/image-spec/blob/master/annotations.md">Open Containers Annotations</a>
      */
     public void test110OrgOpencontainersLabels() throws Exception {
@@ -577,10 +575,10 @@ public void test120DockerLogsIncludeElasticsearchLogs() throws Exception {
     }
 
     /**
-     * Check that the Java process running inside the container has the expect PID, UID and username.
+     * Check that the Java process running inside the container has the expected UID, GID and username.
      */
-    public void test130JavaHasCorrectPidAndOwnership() {
-        final List<String> processes = Arrays.stream(sh.run("ps -o pid,uid,user -C java").stdout.split("\n"))
+    public void test130JavaHasCorrectOwnership() {
+        final List<String> processes = Arrays.stream(sh.run("ps -o uid,gid,user -C java").stdout.split("\n"))
             .skip(1)
             .collect(Collectors.toList());
 
@@ -589,11 +587,34 @@ public void test130JavaHasCorrectPidAndOwnership() {
         final String[] fields = processes.get(0).trim().split("\\s+");
 
         assertThat(fields, arrayWithSize(3));
-        assertThat("Incorrect PID", fields[0], equalTo("1"));
-        assertThat("Incorrect UID", fields[1], equalTo("1000"));
+        assertThat("Incorrect UID", fields[0], equalTo("1000"));
+        assertThat("Incorrect GID", fields[1], equalTo("0"));
         assertThat("Incorrect username", fields[2], equalTo("elasticsearch"));
     }
 
+    /**
+     * Check that the init process running inside the container has the expected PID, UID, GID and user.
+     * The PID is particularly important because PID 1 handles signal forwarding and child reaping.
+     */
+    public void test131InitProcessHasCorrectPID() {
+        final List<String> processes = Arrays.stream(sh.run("ps -o pid,uid,gid,command -p 1").stdout.split("\n"))
+            .skip(1)
+            .collect(Collectors.toList());
+
+        assertThat("Expected a single process", processes, hasSize(1));
+
+        final String[] fields = processes.get(0).trim().split("\\s+", 4);
+
+        assertThat(fields, arrayWithSize(4));
+        assertThat("Incorrect PID", fields[0], equalTo("1"));
+        assertThat("Incorrect UID", fields[1], equalTo("0"));
+        assertThat("Incorrect GID", fields[2], equalTo("0"));
+        assertThat("Incorrect init command", fields[3], startsWith("/tini"));
+    }
+
+    /**
+     * Check that Elasticsearch reports per-node cgroup information.
+     */
     public void test140CgroupOsStatsAreAvailable() throws Exception {
         waitForElasticsearch(installation);