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fix(ec2): prevent deduplication of init command args (#30821)
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### Issue # (if applicable)

Closes #26221 

### Reason for this change

Previously, using `ec2.InitCommand.argvCommand()` would remove some duplicate strings in the input array. This produces an incorrect command in the template, leading to unexpected behaviour.

### Description of changes

An additional line was added to the `deepMerge` function that is called in the `InitConfig.bindForType()` method, which checks the key of the input array, preventing it from becoming a set (removing duplicates) if it is a list of commands.

### Description of how you validated changes

A unit test was added to generate an `AWS::CloudFormation::Init` resource identical to the one reproduced in the issue. The test was run and failed before the changes were made, and following the changes in `cfn-init.ts`, the test passed.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*
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Leo10Gama authored Aug 8, 2024
1 parent 79b5cd2 commit 1e7c690
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Original file line number Diff line number Diff line change
Expand Up @@ -906,7 +906,7 @@
"Fn::Join": [
"",
[
"#!/bin/bash\n# fingerprint: 8787022e9944cbeb\n(\n set +e\n /opt/aws/bin/cfn-init -v --region ",
"#!/bin/bash\n# fingerprint: 370d9b2dcf8bf44b\n(\n set +e\n /opt/aws/bin/cfn-init -v --region ",
{
"Ref": "AWS::Region"
},
Expand Down Expand Up @@ -955,6 +955,29 @@
"owner": "root",
"group": "root"
}
},
"commands": {
"000": {
"command": [
"useradd",
"-u",
"1001",
"-g",
"1001",
"eguser"
]
},
"001": {
"command": [
"useradd",
"-a",
"-u",
"1001",
"-g",
"1001",
"eguser"
]
}
}
}
},
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,12 @@ class TestStack extends cdk.Stack {
'/target/path/config.json',
path.join(tmpDir, 'testConfigFile2'),
),
ec2.InitCommand.argvCommand([
'useradd', '-u', '1001', '-g', '1001', 'eguser',
]),
ec2.InitCommand.argvCommand([
'useradd', '-a', '-u', '1001', '-g', '1001', 'eguser',
]),
]),
},
}),
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15 changes: 11 additions & 4 deletions packages/aws-cdk-lib/aws-ec2/lib/cfn-init.ts
Original file line number Diff line number Diff line change
Expand Up @@ -311,10 +311,17 @@ function deepMerge(target?: Record<string, any>, src?: Record<string, any>) {
if (target[key] && !Array.isArray(target[key])) {
throw new Error(`Trying to merge array [${value}] into a non-array '${target[key]}'`);
}
target[key] = Array.from(new Set([
...target[key] ?? [],
...value,
]));
if (key === 'command') { // don't deduplicate command arguments
target[key] = new Array(
...target[key] ?? [],
...value,
);
} else {
target[key] = Array.from(new Set([
...target[key] ?? [],
...value,
]));
}
continue;
}
if (typeof value === 'object' && value) {
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62 changes: 62 additions & 0 deletions packages/aws-cdk-lib/aws-ec2/test/cfn-init.test.ts
Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,68 @@ test('empty configs are not rendered', () => {
});
});

test('duplicate config arguments not deduplicated', () => {
//GIVEN
const config = new ec2.InitConfig([
ec2.InitCommand.argvCommand([
'useradd', '-u', '1001', '-g', '1001', 'eguser',
]),
ec2.InitCommand.argvCommand([
'useradd', '-a', '-u', '1001', '-g', '1001', 'eguser',
]),
]);

// WHEN
const init = ec2.CloudFormationInit.fromConfigSets({
configSets: { default: ['config'] },
configs: { config },
});
init.attach(resource, linuxOptions());

// THEN
expectMetadataLike({
'AWS::CloudFormation::Init': {
configSets: {
default: ['config'],
},
config: {
commands: {
'000': {
command: ['useradd', '-u', '1001', '-g', '1001', 'eguser'],
},
'001': {
command: ['useradd', '-a', '-u', '1001', '-g', '1001', 'eguser'],
},
},
},
},
});
});

test('deepMerge properly deduplicates non-command arguments', () => {
// WHEN
const config = new ec2.InitConfig([
ec2.InitSource.fromUrl('/tmp/blinky', 'https://amazon.com/blinky.zip'),
ec2.InitSource.fromUrl('/tmp/blinky', 'https://amazon.com/blinky.zip'),
ec2.InitSource.fromUrl('/tmp/pinky', 'https://amazon.com/pinky.zip'),
ec2.InitSource.fromUrl('/tmp/pinky', 'https://amazon.com/pinky.zip'),
ec2.InitSource.fromUrl('/tmp/inky', 'https://amazon.com/inky.zip'),
ec2.InitSource.fromUrl('/tmp/clyde', 'https://amazon.com/blinky.zip'),
ec2.InitSource.fromUrl('/tmp/clyde', 'https://amazon.com/blinky.zip'),
ec2.InitSource.fromUrl('/tmp/clyde', 'https://amazon.com/blinky.zip'),
]);

// THEN
expect(config._bind(stack, linuxOptions()).config).toEqual(expect.objectContaining({
sources: {
'/tmp/blinky': 'https://amazon.com/blinky.zip',
'/tmp/pinky': 'https://amazon.com/pinky.zip',
'/tmp/inky': 'https://amazon.com/inky.zip',
'/tmp/clyde': 'https://amazon.com/blinky.zip',
},
}));
});

describe('userdata', () => {
let simpleInit: ec2.CloudFormationInit;
beforeEach(() => {
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