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Expand build argument from environment when no value specified #993

Merged
merged 1 commit into from
Jan 31, 2020
Merged

Expand build argument from environment when no value specified #993

merged 1 commit into from
Jan 31, 2020

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antechrestos
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@antechrestos antechrestos commented Jan 23, 2020

Fixes #713

Description

This change adds the feature of getting value of build argument from environment when build argument is specified as follows

/kaniko/executor .... --build-arg MY_ARGUMENT ...

Submitter Checklist

  • Includes unit tests
  • Adds integration tests if needed.

Reviewer Notes

  • The code flow looks good.
  • Unit tests and or integration tests added.

Release Notes

Allow user to provide build argument from environment variable as follows:
$> export MY_ARGUMENT="the value"
$> /kaniko/executor ... --build-arg MY_ARGUMENT ...
Or
$> docker run -e MY_ARGUMENT="the value" gcr.io/kaniko-project/executor ... --build-arg MY_ARGUMENT ...

@googlebot googlebot added the cla: yes CLA signed by all commit authors label Jan 23, 2020
@antechrestos
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@cvgw As promised... Do I need to add integration test?

@tejal29
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tejal29 commented Jan 24, 2020

Thank you so much for your contribution!

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@cvgw cvgw left a comment

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I'm not sure this addresses the primary use case which is secrets

won't docker -e SOME_SECRET=secret-value run .... output the value of the secret to the log/shell history?

I think we need a solution that won't be logged out. We also need to audit the logs in kaniko and make sure this value will never be logged. Infact, we should probably write an integration tests that checks the logs to make sure a known secret value is never logged

@stewi2
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stewi2 commented Jan 25, 2020

won't docker -e SOME_SECRET=secret-value run .... output the value of the secret to the log/shell history?

At least that part can be solved via a .env file. I.e.

docker --env-file .secrets run ....

with .secrets containing this:

SOME_SECRET=secret-value

Granted, that file would need to be written to disk first, but this is a common way to pass along environment variables without exposing them via the command line.

@antechrestos antechrestos requested a review from cvgw January 25, 2020 22:04
@antechrestos
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@tejal29 you're welcome
@cvgw I added it. To do so I added a new dedicated dockerfile. I also added a way to pass environment variable to build (with cmd.Env for docker build and -e for kaniko build as kaniko build is done inside docker) and also tested the expansion of docker variable.
For this test a check of output is provided te do a research on argument value and ensure that it is not printed.

@@ -206,6 +207,17 @@ func resolveDockerfilePath() error {
return errors.New("please provide a valid path to a Dockerfile within the build context with --dockerfile")
}

// resolveEnvironmentBuildArgs replace build args without value by the same named environment variable
func resolveEnvironmentBuildArgs(arguments []string, resolver func(string) string) {
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@cvgw cvgw Jan 27, 2020

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So this will take an argument like FOO and replace it with FOO=FOO ?

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@cvgw this will take the argument array such as [ "foo=bar", "EnvVariable" ] crawl through it and replace any argument without = with "EnvVariable=EnvValue" if a value was returned by resolver function (os.Getenv in prod code, mocked function in tests). If zero length value returned, it will be replaced with "EnvVariable="

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Thanks for explaining, cheers


// Checks if argument are not printed in output.
// Argument may be passed through --build-arg key=value manner or --build-arg key with key in environment
func checkArgsNotPrinted(dockerfile string, out []byte) error {
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So this checks to make sure the value of none of the build args are logged? It makes no distinction between whether they were added as literals or expanded from the env?

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@cvgw I could have make the distinction in the test, however I could not find any way to make the distinction in the code as env like variable (env, arg and meta arg ) are used everywhere as a mere string key=value and could not make the distinction without breaking everything.
Do you want I change the test? Or everything?

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No changes needed. Was just clarifying for my owner understanding. I think it's reasonable to not log any ARG values.

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This looks really nice, just a couple questions

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@cvgw Thank you for the feed back. I answered .

@@ -206,6 +207,17 @@ func resolveDockerfilePath() error {
return errors.New("please provide a valid path to a Dockerfile within the build context with --dockerfile")
}

// resolveEnvironmentBuildArgs replace build args without value by the same named environment variable
func resolveEnvironmentBuildArgs(arguments []string, resolver func(string) string) {
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@cvgw this will take the argument array such as [ "foo=bar", "EnvVariable" ] crawl through it and replace any argument without = with "EnvVariable=EnvValue" if a value was returned by resolver function (os.Getenv in prod code, mocked function in tests). If zero length value returned, it will be replaced with "EnvVariable="

@@ -206,6 +207,17 @@ func resolveDockerfilePath() error {
return errors.New("please provide a valid path to a Dockerfile within the build context with --dockerfile")
}

// resolveEnvironmentBuildArgs replace build args without value by the same named environment variable
func resolveEnvironmentBuildArgs(arguments []string, resolver func(string) string) {
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Thanks for explaining, cheers

@antechrestos
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antechrestos commented Jan 28, 2020

@cvgw something went wrong with kaniko. However, things went well in Travis 🤔... What went wrong?

@tejal29
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tejal29 commented Jan 28, 2020

@antechrestos i triggered a rebuilt. Previous failure was a flake.

@antechrestos
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@tejal29 thanks

@antechrestos
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@tejal29 I have rebased my branch. I am not sure it might change anything 🤔

@antechrestos
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@cvgw @tejal29 may I have another try with kokoro? 🙏

@tejal29
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tejal29 commented Jan 31, 2020

@antechrestos The travis test passed, so i am going to merge this in!

@tejal29 tejal29 merged commit de4b734 into GoogleContainerTools:master Jan 31, 2020
@antechrestos
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@tejal29 at our own risk 😊

@antechrestos antechrestos deleted the feature/expand_build_args_with_environment_variable branch January 31, 2020 20:04
@sourcec0de
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THANK YOU! ❤️

@nhed
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nhed commented Feb 9, 2023

Thanks this is so helpful (albeit undocumented) feature

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Kaniko's --build-arg accepts only literal values
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