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dsyer/spring-boot-thin-launcher#25 Generate Docker build #26

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11 changes: 11 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -248,6 +248,7 @@ You can set a variety of options on the command line with system properties (`-D
| Option | Default | Description |
|--------|---------|-------------|
| `thin.main` | Start-Class in MANIFEST.MF| The main class to launch (for a Spring Boot app, usually the one with `@SpringBootApplication`)|
| `thin.docker` | false | Prepare a Docker build by creating a Dockerfile in the local directory and including all dependencies as separate Docker layers. |
| `thin.dryrun` | false | Only resolve and download the dependencies. Don't run any main class. N.B. any value other than "false" (even empty) is true. |
| `thin.offline` | false | Switch to "offline" mode. All dependencies must be avalailable locally (e.g. via a previous dry run) or there will be an exception. |
| `thin.classpath` | false | Only print the classpath. Don't run and main class. N.B. any value other than "false" (even empty) is true. |
Expand Down Expand Up @@ -292,6 +293,16 @@ ENTRYPOINT [ "sh", "-c", "java -Djava.security.egd=file:/dev/./urandom -jar app.
EXPOSE 8080
```

### How to Create a complete Docker build

Creates Dockerfile and `.m2/` directory with all runtime dependencies in current directory.
Dockerfile will contain all dependencies and application jar as separate layers (will improve build and shipment)

```
$ java -jar app.jar --thin.docker
$ docker build -t myname/myapp:myversion .
```

## Building

To build this project locally, use the maven wrapper in the top level
Expand Down
135 changes: 125 additions & 10 deletions launcher/src/main/java/org/springframework/boot/loader/thin/ThinJarLauncher.java
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Expand Up @@ -17,6 +17,7 @@
package org.springframework.boot.loader.thin;

import java.io.File;
import java.io.FileOutputStream;
import java.net.URL;
import java.security.AccessControlException;
import java.util.ArrayList;
Expand All @@ -35,6 +36,7 @@
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.SimpleCommandLinePropertySource;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.StringUtils;

import ch.qos.logback.classic.Level;
Expand Down Expand Up @@ -131,8 +133,15 @@ public class ThinJarLauncher extends ExecutableArchiveLauncher {
*/
public static final String THIN_PARENT_BOOT = "thin.parent.boot";

/**
* Flag to say that a Docker build should be created, i.e., .m2 with repository and appropriate Dockerfile.
* Default false.
*/
public static final String THIN_DOCKER = "thin.docker";

private StandardEnvironment environment = new StandardEnvironment();
private boolean debug;
private String root = "";

public static void main(String[] args) throws Exception {
LogUtils.setLogLevel(Level.OFF);
Expand All @@ -147,7 +156,7 @@ protected ThinJarLauncher(String[] args) throws Exception {
protected void launch(String[] args) throws Exception {
addCommandLineProperties(args);
args = removeThinArgs(args);
String root = environment.resolvePlaceholders("${" + THIN_ROOT + ":}");
root = environment.resolvePlaceholders("${" + THIN_ROOT + ":}");
boolean classpath = !"false".equals(
environment.resolvePlaceholders("${" + THIN_CLASSPATH + ":false}"));
boolean compute = !"false"
Expand Down Expand Up @@ -181,6 +190,13 @@ protected void launch(String[] args) throws Exception {
return;
}
log.info("Version: " + getVersion());
if (!"false".equals(
environment.resolvePlaceholders("${" + THIN_DOCKER + ":false}"))) {

createDockerBuild();

return;
}
if (!"false".equals(
environment.resolvePlaceholders("${" + THIN_DRYRUN + ":false}"))) {
List<Archive> archives = getClassPathArchives();
Expand Down Expand Up @@ -245,19 +261,115 @@ private String classpath(List<Archive> archives) throws Exception {
builder.append(separator);
}
log.info("Archive: {}", archive);
String uri = archive.getUrl().toURI().toString();
uri = cutFileAndInternalJarRootFromUri(uri);
builder.append(new File(uri).getCanonicalPath());
}
return builder.toString();
}

private String cutFileAndInternalJarRootFromUri(String uri) {
if (uri.startsWith("jar:")) {
uri = uri.substring("jar:".length());
}
if (uri.startsWith("file:")) {
uri = uri.substring("file:".length());
}
if (uri.endsWith("!/")) {
uri = uri.substring(0, uri.length() - "!/".length());
}
return uri;
}

// TODO: Add some more options, e.g.,
// thin.docker.file for the path to the docker file
// thin.docker.base for the base image,
// ...
private void createDockerBuild() throws Exception {
// FIXME Find a better name for the root since it not (only) contains a Maven kind of repository
final String dockerM2 = ".m2";
if (StringUtils.hasText(root)) {
log.warn ("Overriding current 'thin.root' ('{}') by Docker Maven root '{}' for Dockerfile", root, dockerM2);
} else {
log.info ("Using '{}' as Docker Maven root", dockerM2);
}
root = dockerM2;

List<Archive> archives = getClassPathArchives();

StringBuilder builder = new StringBuilder();

// TODO: Make the base image configurable
builder.append ("FROM openjdk:8-alpine\n" +
"\n" +
"# The dependencies\n");

File rootDir = new File (root);
int rootDirPathlen = rootDir.getAbsolutePath().length();
String mainJar = null;
String separator = System.getProperty("path.separator");
StringBuilder classpath = new StringBuilder();
for (Archive archive : archives) {
String uri = archive.getUrl().toURI().toString();
if (uri.startsWith("jar:")) {
uri = uri.substring("jar:".length());
}
if (uri.startsWith("file:")) {
uri = uri.substring("file:".length());
if (null != mainJar) {
log.warn("Cannot ADD another main JAR '{}' to Dockerfile (already have '{}')", uri, mainJar);
} else {
uri = cutFileAndInternalJarRootFromUri(uri);
mainJar = uri;
}
}
if (uri.endsWith("!/")) {
uri = uri.substring(0, uri.length() - "!/".length());
else {
uri = cutFileAndInternalJarRootFromUri(uri);
uri = uri.substring(rootDirPathlen);
String fullUri = root + uri;
builder.append ("ADD " + fullUri + " /" + fullUri + "\n");
if (classpath.length() != 0) {
classpath.append(separator);
}
classpath.append("/" + fullUri);
}
builder.append(new File(uri).getCanonicalPath());
}
return builder.toString();

if (null == mainJar) {
throw new RuntimeException ("There is no main jar defined");
}

String mainJarBasename = new File (mainJar).getName();
String mainJarTarget = root + "/" + mainJarBasename;

// This is a hack to get the Jar file into the Docker build (can we do it better?)
log.debug ("Copying application Jar '{}' to '{}'", mainJar, mainJarTarget);
File mainJarIn = new File(mainJar);
File mainJarOut = new File (mainJarTarget);
FileCopyUtils.copy(mainJarIn, mainJarOut);

builder.append ("\n" +
"EXPOSE 8080" +
"\n" +
"ENV CLASSPATH=/" +mainJarTarget + separator + classpath.toString() +
"\n\n" +
// Let the Application be the latest Docker layer
"# The Spring Boot Application\n" +
"ADD " + mainJarTarget + " /" + mainJarTarget + "\n" +
"\n" +
// TODO: Set Spring/Thin profile(s) as provided by THIN_PROFILE property
// "CMD [ \"sh\", \"-c\", \"java -Djava.security.egd=file:/dev/./urandom ${JAVA_OPTS} -jar "
// + mainJarBasename + " --thin.root=/" + root + "\" ${MAIN_ARGS} ]\n"
"\n"+
"CMD [ \"sh\", \"-c\", \"java -Djava.security.egd=file:/dev/./urandom ${JAVA_OPTS} " +
getMainClass() + " ${MAIN_ARGS}\" ]\n"
);
File dockerfile = new File ("Dockerfile");
if (dockerfile.exists()) {
log.warn ("Overriding existing Dockerfile");
dockerfile.delete();
} else {
log.info ("Creating Dockerfile");
}
FileOutputStream dockerstream = new FileOutputStream(dockerfile);
dockerstream.write(builder.toString().getBytes());
dockerstream.close();
}

private void addCommandLineProperties(String[] args) {
Expand Down Expand Up @@ -339,7 +451,10 @@ protected List<Dependency> getDependencies() throws Exception {
private PathResolver getResolver() {
String locations = environment
.resolvePlaceholders("${" + ThinJarLauncher.THIN_LOCATION + ":}");
String root = environment.resolvePlaceholders("${" + THIN_ROOT + ":}");
if (!StringUtils.hasText(root)) {
// root might already be set, e.g., by overriding it for Docker build generator
root = environment.resolvePlaceholders("${" + THIN_ROOT + ":}");
}
String offline = environment.resolvePlaceholders("${" + THIN_OFFLINE + ":false}");
PathResolver resolver = new PathResolver(DependencyResolver.instance());
if (StringUtils.hasText(locations)) {
Expand Down