Add support for environment variable substition for ADD and COPY resources

mocleiri · mocleiri · commit 11c0554daeea · 2014-07-07T13:53:30.000-04:00
Supports the case where the name of the file is supposed to be resolved using an
environment variable.

ENV VAR sub

ADD files/$VAR.dat /$VAR.dat
ADD files/${VAR}.dat /${VAR}.dat

In both cases the VAR is substituted for sub.

This allows the tar file creation process to capture the real source file.
diff --git a/src/main/java/com/github/dockerjava/client/command/BuildImgCmd.java b/src/main/java/com/github/dockerjava/client/command/BuildImgCmd.java
@@ -6,7 +6,9 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -35,7 +37,9 @@ public class BuildImgCmd extends AbstrDockerCmd<BuildImgCmd, ClientResponse>  {
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(BuildImgCmd.class);
 	
-	private static final Pattern ADD_PATTERN = Pattern.compile("^ADD\\s+(.*)\\s+(.*)$");
+	private static final Pattern ADD_OR_COPY_PATTERN = Pattern.compile("^(ADD|COPY)\\s+(.*)\\s+(.*)$");
+	
+	private static final Pattern ENV_PATTERN = Pattern.compile("^ENV\\s+(.*)\\s+(.*)$");
 	
 	private File dockerFolder = null;
 	private InputStream tarInputStream = null;
@@ -133,14 +137,40 @@ protected File buildDockerFolderTar() {
 			List<File> filesToAdd = new ArrayList<File>();
 			filesToAdd.add(dockerFile);
 
+			Map<String, String>environmentMap = new HashMap<String, String>();
+			
+			int lineNumber = 0;
+			
 			for (String cmd : dockerFileContent) {
-				final Matcher matcher = ADD_PATTERN.matcher(cmd.trim());
+				
+				lineNumber++;
+				
+				if (cmd.trim().isEmpty() || cmd.startsWith("#"))
+					continue; // skip emtpy and commend lines
+				
+				final Matcher envMatcher = ENV_PATTERN.matcher(cmd.trim());
+				
+				if (envMatcher.find()) {
+					if (envMatcher.groupCount() != 2)
+						throw new DockerException(String.format("Wrong ENV format on line [%d]", lineNumber));
+					
+					String variable = envMatcher.group(1).trim();
+					
+					String value = envMatcher.group(2).trim();
+					
+					environmentMap.put(variable, value);
+				}
+				
+				
+				final Matcher matcher = ADD_OR_COPY_PATTERN.matcher(cmd.trim());
 				if (matcher.find()) {
-					if (matcher.groupCount() != 2) {
-						throw new DockerException(String.format("Wrong format on line [%s]", cmd));
+					if (matcher.groupCount() != 3) {
+						throw new DockerException(String.format("Wrong ADD or COPY format on line [%d]", lineNumber));
 					}
 
-					String resource = matcher.group(1).trim();
+					String extractedResource = matcher.group(2);
+					
+					String resource = filterForEnvironmentVars(extractedResource, environmentMap);
 					
 					if(isFileResource(resource)) {
 						File src = new File(resource);
@@ -170,6 +200,33 @@ protected File buildDockerFolderTar() {
 		}
 	}
 	
+	private String filterForEnvironmentVars(String extractedResource,
+			Map<String, String> environmentMap) {
+		
+		if (environmentMap.size() > 0) {
+			
+			String currentResourceContent = extractedResource;
+			
+			for (Map.Entry<String, String> entry : environmentMap.entrySet()) {
+				
+				String variable = entry.getKey();
+				
+				String replacementValue = entry.getValue();
+				
+				// handle: $VARIABLE case
+				currentResourceContent = currentResourceContent.replaceAll("\\$" + variable, replacementValue);
+				
+				// handle ${VARIABLE} case
+				currentResourceContent = currentResourceContent.replaceAll("\\$\\{" + variable + "\\}", replacementValue);
+				
+			}
+			
+			return currentResourceContent;
+		}
+		else 
+			return extractedResource;
+	}
+
 	private static boolean isFileResource(String resource)  {
         URI uri;
 		try {
