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Posted to commits@camel.apache.org by "gnodet (via GitHub)" <gi...@apache.org> on 2026/03/23 15:16:41 UTC
[PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
gnodet opened a new pull request, #22200:
URL: https://github.com/apache/camel/pull/22200
## Summary
- Add FreeMarker 2.3.34 as a template engine dependency to camel-jbang-core
- Create `TemplateHelper` utility using FreeMarker's square bracket syntax (`[=var]`, `[#if]...[/#if]`) to avoid conflicts with `${...}` (Maven/Camel expressions) and `<...>` (XML tags) in generated content
- Convert all 23 `.tmpl` template files to `.ftl` FreeMarker templates with proper directives for conditionals and loops
- Refactor `ExportCamelMain`, `ExportSpringBoot`, `ExportQuarkus`, `Export`, `Run`, and `Init` commands to use `TemplateHelper` instead of manual `StringBuilder`/`replaceAll`/`replaceFirst` code generation
- Extract shared helpers (`buildRepositoryList`, `buildDependencyList`, `formatBuildProperties`, `mavenGavComparator`) into `ExportBaseCommand` to eliminate duplication
- Maintain backward compatibility for catalog-provided templates in `ExportSpringBoot` (legacy regex processing path)
- Remove 4 unreferenced templates (`main-docker-*.tmpl`, `main-jkube-pom.tmpl`)
- Keep deprecated bind templates (`.tmpl`) used by `TemplateProvider`
## Motivation
The existing code generation approach used raw string manipulation (`replaceFirst`, `replaceAll`, `StringBuilder.append`) to produce POM files, Dockerfiles, README files, and source code. This was:
- Error-prone (regex escaping issues, ordering dependencies between replacements)
- Hard to read and maintain (XML structure buried in Java string concatenation)
- Difficult to extend (adding new conditional sections required careful regex surgery)
FreeMarker templates make the generated output structure visible and maintainable, with proper control flow (`[#if]`, `[#list]`) replacing ad-hoc string manipulation.
## Test plan
- [x] All 311 camel-jbang-core tests pass
- [x] All 128 camel-jbang-plugin-kubernetes tests pass
- [ ] CI build passes
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4111629678
<!-- ci-tested-modules -->
:test_tube: **CI tested the following changed modules:**
- `dsl/camel-jbang/camel-jbang-core`
- `dsl/camel-jbang/camel-jbang-plugin-kubernetes`
<details><summary>All tested modules (26 modules)</summary>
- Camel :: Coverage
- Camel :: Coverage [pom]
- Camel :: JBang :: Core
- Camel :: JBang :: Core [jar]
- Camel :: JBang :: Integration tests
- Camel :: JBang :: Integration tests [jar]
- Camel :: JBang :: MCP
- Camel :: JBang :: MCP [jar]
- Camel :: JBang :: Main
- Camel :: JBang :: Main [jar]
- Camel :: JBang :: Plugin :: Edit
- Camel :: JBang :: Plugin :: Edit [jar]
- Camel :: JBang :: Plugin :: Generate
- Camel :: JBang :: Plugin :: Generate [jar]
- Camel :: JBang :: Plugin :: Kubernetes
- Camel :: JBang :: Plugin :: Kubernetes [jar]
- Camel :: JBang :: Plugin :: Route Parser
- Camel :: JBang :: Plugin :: Route Parser [jar]
- Camel :: JBang :: Plugin :: Testing
- Camel :: JBang :: Plugin :: Testing [jar]
- Camel :: JBang :: Plugin :: Validate
- Camel :: JBang :: Plugin :: Validate [jar]
- Camel :: Launcher
- Camel :: Launcher [jar]
- Camel :: Launcher :: Container
- Camel :: Launcher :: Container [pom]
</details>
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "Croway (via GitHub)" <gi...@apache.org>.
Croway commented on code in PR #22200:
URL: https://github.com/apache/camel/pull/22200#discussion_r2975896093
##########
dsl/camel-jbang/camel-jbang-core/src/main/java/org/apache/camel/dsl/jbang/core/commands/Export.java:
##########
@@ -370,33 +304,36 @@ protected void copyDockerFiles(String buildDir) throws Exception {
Path docker = Path.of(buildDir).resolve("src/main/docker");
Files.createDirectories(docker);
String[] ids = gav.split(":");
- String templateName = "templates/Dockerfile" + javaVersion + ".tmpl";
- InputStream is = ExportCamelMain.class.getClassLoader().getResourceAsStream(templateName);
- if (is == null) {
+
+ String ftlName = "Dockerfile" + javaVersion + ".ftl";
+ String context;
+ try {
+ Map<String, Object> model = new HashMap<>();
Review Comment:
can this be extracted to avoid code duplication?
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "gnodet (via GitHub)" <gi...@apache.org>.
gnodet commented on code in PR #22200:
URL: https://github.com/apache/camel/pull/22200#discussion_r3000832433
##########
dsl/camel-jbang/camel-jbang-core/src/main/java/org/apache/camel/dsl/jbang/core/common/TemplateHelper.java:
##########
@@ -0,0 +1,76 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.dsl.jbang.core.common;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import freemarker.cache.ClassTemplateLoader;
+import freemarker.template.Configuration;
+import freemarker.template.Template;
+import freemarker.template.TemplateException;
+import freemarker.template.TemplateExceptionHandler;
+
+/**
+ * Utility for processing FreeMarker templates used in code generation.
+ * <p>
+ * Uses square bracket syntax for both interpolation ([=name]) and directives ([#if]...[/#if]) to avoid conflicts with
+ * ${...} (Maven/Camel expressions) and <...> (XML tags) in generated content.
+ */
+public final class TemplateHelper {
+
+ // Matches <#-- ... --> comment blocks that appear as literal text in square bracket tag syntax mode
+ private static final Pattern ANGLE_BRACKET_COMMENT = Pattern.compile("\\A<#--.*?-->\\s*", Pattern.DOTALL);
+
+ private static final Configuration CFG;
+
+ static {
+ CFG = new Configuration(Configuration.VERSION_2_3_34);
+ CFG.setTemplateLoader(new ClassTemplateLoader(TemplateHelper.class, "/templates"));
+ CFG.setDefaultEncoding("UTF-8");
+ CFG.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
+ CFG.setLogTemplateExceptions(false);
+ // Use square bracket syntax to avoid conflicts with ${...} and <...> in templates
+ CFG.setInterpolationSyntax(Configuration.SQUARE_BRACKET_INTERPOLATION_SYNTAX);
+ CFG.setTagSyntax(Configuration.SQUARE_BRACKET_TAG_SYNTAX);
+ }
+
+ private TemplateHelper() {
+ }
+
+ /**
+ * Process a FreeMarker template from classpath resources/templates/ directory.
+ *
+ * @param templateName the template file name (e.g. "main-pom.ftl")
+ * @param model the data model
+ * @return the processed template output
+ */
+ public static String processTemplate(String templateName, Map<String, Object> model) throws IOException {
Review Comment:
Added `TemplateHelperTest` with 6 tests covering: simple interpolation, license header stripping, conditional rendering (`[#if]`), list rendering (`[#list]`), Maven expression pass-through (`${...}`), and missing template error handling.
_Claude Code on behalf of Guillaume Nodet_
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "orpiske (via GitHub)" <gi...@apache.org>.
orpiske commented on code in PR #22200:
URL: https://github.com/apache/camel/pull/22200#discussion_r3000800913
##########
dsl/camel-jbang/camel-jbang-core/src/main/java/org/apache/camel/dsl/jbang/core/common/TemplateHelper.java:
##########
@@ -0,0 +1,76 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.dsl.jbang.core.common;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import freemarker.cache.ClassTemplateLoader;
+import freemarker.template.Configuration;
+import freemarker.template.Template;
+import freemarker.template.TemplateException;
+import freemarker.template.TemplateExceptionHandler;
+
+/**
+ * Utility for processing FreeMarker templates used in code generation.
+ * <p>
+ * Uses square bracket syntax for both interpolation ([=name]) and directives ([#if]...[/#if]) to avoid conflicts with
+ * ${...} (Maven/Camel expressions) and <...> (XML tags) in generated content.
+ */
+public final class TemplateHelper {
+
+ // Matches <#-- ... --> comment blocks that appear as literal text in square bracket tag syntax mode
+ private static final Pattern ANGLE_BRACKET_COMMENT = Pattern.compile("\\A<#--.*?-->\\s*", Pattern.DOTALL);
+
+ private static final Configuration CFG;
+
+ static {
+ CFG = new Configuration(Configuration.VERSION_2_3_34);
+ CFG.setTemplateLoader(new ClassTemplateLoader(TemplateHelper.class, "/templates"));
+ CFG.setDefaultEncoding("UTF-8");
+ CFG.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
+ CFG.setLogTemplateExceptions(false);
+ // Use square bracket syntax to avoid conflicts with ${...} and <...> in templates
+ CFG.setInterpolationSyntax(Configuration.SQUARE_BRACKET_INTERPOLATION_SYNTAX);
+ CFG.setTagSyntax(Configuration.SQUARE_BRACKET_TAG_SYNTAX);
+ }
+
+ private TemplateHelper() {
+ }
+
+ /**
+ * Process a FreeMarker template from classpath resources/templates/ directory.
+ *
+ * @param templateName the template file name (e.g. "main-pom.ftl")
+ * @param model the data model
+ * @return the processed template output
+ */
+ public static String processTemplate(String templateName, Map<String, Object> model) throws IOException {
Review Comment:
Maybe cover this one with a brief test to ensure future work doesn't break it?
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4111417293
:star2: Thank you for your contribution to the Apache Camel project! :star2:
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "davsclaus (via GitHub)" <gi...@apache.org>.
davsclaus commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4326044565
LGTM
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "apupier (via GitHub)" <gi...@apache.org>.
apupier commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4281773421
curretn test failure seems unrelated:
```
[ERROR] [ERROR] Could not find the selected project in the reactor: :camel-allcomponents @
[INFO] 0 goals, 0 executed
[WARNING] Adding build scan buildFinished actions is not allowed once their invocation has started. Newly added action will be ignored.
[ERROR] Could not find the selected project in the reactor: :camel-allcomponents -> [Help 1]
org.apache.maven.MavenExecutionException: Could not find the selected project in the reactor: :camel-allcomponents
at org.apache.maven.graph.DefaultGraphBuilder.trimExcludedProjects (DefaultGraphBuilder.java:219)
at org.apache.maven.graph.DefaultGraphBuilder.reactorDependencyGraph (DefaultGraphBuilder.java:113)
at org.apache.maven.graph.DefaultGraphBuilder.build (DefaultGraphBuilder.java:78)
at org.apache.maven.DefaultMaven.buildGraph (DefaultMaven.java:448)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:197)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
at org.apache.maven.cli.DaemonMavenCli.execute (DaemonMavenCli.java:849)
at org.apache.maven.cli.DaemonMavenCli.doMain (DaemonMavenCli.java:235)
at org.apache.maven.cli.DaemonMavenCli.main (DaemonMavenCli.java:210)
at org.mvndaemon.mvnd.daemon.Server.handle (Server.java:619)
at org.mvndaemon.mvnd.daemon.Server.client (Server.java:293)
at org.mvndaemon.mvnd.daemon.Server.lambda$accept$2 (Server.java:250)
at java.lang.Thread.run (Thread.java:1583)
```
I suppose fixed by https://github.com/apache/camel/pull/22657 , a rebase shoudl do the trick then
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "apupier (via GitHub)" <gi...@apache.org>.
apupier commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4124911777
Hey AI agent, please rebase and resolve the conflict
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "gnodet (via GitHub)" <gi...@apache.org>.
gnodet commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4182080323
> What's the status? Is it ready for another review round? If yes, you should re-request a review from Croway so that he can be aware of it
Yes it is.
@Croway
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "Croway (via GitHub)" <gi...@apache.org>.
Croway commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4182785756
@gnodet I just did a rerun of all the jobs, by any chance did you run [dsl/camel-jbang/camel-jbang-it](https://github.com/apache/camel/tree/main/dsl/camel-jbang/camel-jbang-it) tests? otherwise we can go YOLO and test on the Jenkins CI directly
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "gnodet (via GitHub)" <gi...@apache.org>.
gnodet commented on code in PR #22200:
URL: https://github.com/apache/camel/pull/22200#discussion_r2979583729
##########
dsl/camel-jbang/camel-jbang-core/src/main/java/org/apache/camel/dsl/jbang/core/commands/Export.java:
##########
@@ -370,33 +304,36 @@ protected void copyDockerFiles(String buildDir) throws Exception {
Path docker = Path.of(buildDir).resolve("src/main/docker");
Files.createDirectories(docker);
String[] ids = gav.split(":");
- String templateName = "templates/Dockerfile" + javaVersion + ".tmpl";
- InputStream is = ExportCamelMain.class.getClassLoader().getResourceAsStream(templateName);
- if (is == null) {
+
+ String ftlName = "Dockerfile" + javaVersion + ".ftl";
+ String context;
+ try {
+ Map<String, Object> model = new HashMap<>();
Review Comment:
_Claude Code on behalf of Guillaume Nodet_
Good catch. Looking at this more carefully — the Dockerfile template rendering now uses FreeMarker through the base class, and the Quarkus override handles the fast-jar vs uber-jar distinction which genuinely needs different logic. So the apparent duplication in Export.java line 311 is the shared base implementation. Will add a clarifying comment.
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "gnodet (via GitHub)" <gi...@apache.org>.
gnodet commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4215141841
_Claude Code on behalf of Guillaume Nodet_
@Croway Yes, I ran the `dsl/camel-jbang/camel-jbang-it` tests locally with:
```
mvn verify -B -Djbang-it-test -Dcamel-cli.instance.type=local-camel-cli-process -Dit.test=ExportITCase
```
**ExportITCase results: 11 tests run, 0 failures, 0 errors, 2 skipped** (the skipped tests require custom Quarkus system properties or container-only tags).
All export scenarios pass — Spring Boot, Quarkus, Camel Main, export with files, export with agent, export with JMX management, export with CLI connector, and export with Camel config.
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "gnodet (via GitHub)" <gi...@apache.org>.
gnodet commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4216755762
_Claude Code on behalf of Guillaume Nodet_
CI failures are unrelated to this PR — `camel-langchain4j-embeddings` `LangChain4jEmbeddingsComponentInfinispanTargetIT` fails with Infinispan `SocketTimeoutException` (flaky infra test). The `camel-jbang-core` module was never reached due to the early failure. Needs a rerun.
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "davsclaus (via GitHub)" <gi...@apache.org>.
davsclaus merged PR #22200:
URL: https://github.com/apache/camel/pull/22200
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Re: [PR] CAMEL-21208: Replace manual string-based code generation with FreeMarker templates [camel]
Posted by "apupier (via GitHub)" <gi...@apache.org>.
apupier commented on PR #22200:
URL: https://github.com/apache/camel/pull/22200#issuecomment-4175417368
What's the status? Is it ready for another review round? If yes, you should re-request a review from Croway so that he can be aware of it
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