ecrimagefetcher

README

AWS ECR Image Fetcher

This Go script fetches the latest image tags from an AWS ECR repository based on specified criteria such as a grep string and optional semantic version constraints. It sorts and filters the tags and returns a specified number of the latest ones (according to semantic versioning).

Usage

go run main.go <repository_name> <grep_string> <count> [<semver_constraints>]

Example

go run main.go 'my-repo' '^v[0-9]+\.[0-9]+\.[0-9]+$' 5 '>=1.0.0, <2.0.0'

Command Line Arguments

• <repository_name>: The name of the ECR repository.
• <grep_string>: A regex string to filter the tags.
• <count>: The number of latest tags to return.
• [<semver_constraints>]: Optional semantic version constraints to filter tags further.

Output

• The script prints the specified number of latest image tags from the repository that match the given criteria, formatted as repository_name:tag, e.g.hyperledger/besu:24.3,hyperledger/besu:24.2.
• If the number of matching tags is less than the requested count, a warning is printed to stderr, and the available tags are returned.

Error Handling

The script will panic and display error messages in the following scenarios:

• Insufficient command line arguments.
• Empty or invalid repository_name, grep_string, or count.
• Invalid regex for grep_string.
• Invalid integer value for count.
• Invalid semantic version constraints.
• Errors in fetching or parsing the image details from AWS ECR.

Detailed Steps

1. Argument Parsing and Validation:
   • The script checks that at least 4 command line arguments are provided.
   • Validates the format and values of repository_name, grep_string, and count.
   • Optionally validates semantic version constraints if provided.
2. Fetch Image Details:
   • Constructs and executes an AWS CLI command to describe images in the specified ECR repository.
   • Parses the JSON output to extract image tags.
3. Filter and Sort Tags:
   • Filters tags based on the grep_string regex.
   • Optionally filters tags based on semantic version constraints.
   • Sorts the tags in descending order.
4. Return Latest Tags:
   • Constructs the output of the latest tags formatted as repository_name:tag.
   • Prints the result to stdout.

Notes

• Ensure AWS CLI is configured and you have the necessary permissions to access the ECR repository.
• The environment variable AWS_REGION must be set to the appropriate AWS region.
• Semantic version constraints are optional and can be used to further filter the tags.