Elastic Package Registry (EPR)

API

Endpoints:

• /: Info about the registry
• /search: Search for packages. By default returns all the most recent packages available.
• /categories: List of the existing package categories and how many packages are in each category.
• /package/{name}/{version}: Info about a package
• /epr/{name}/{name}-{version}.zip: Download a package

/search

The /search API endpoint has few additional query parameters. More might be added in the future, but for now these are:

• kibana.version: Filters out all the packages which are not compatible with the given Kibana version. If it is set to 7.3.1 and a package requires 7.4, the package will not be returned or an older compatible package will be shown. By default this endpoint always returns only the newest compatible package.
• category: Filters the package by the given category. Available categories can be seend when going to /categories endpoint.
• package: Filters by a specific package name, for example mysql. Returns the most recent version.
• all: This can be set to true to list all package versions. This is set to false by default.
• prerelease: This can be set to true to list prerelease versions of packages. Versions are considered prereleases if they are not stable according to sematic versioning, that is, if they are 0.x versions, or if they contain a prerelease tag. This is set to false by default.
• experimental (deprecated): This can be set to true to list packages considered to be experimental. This is set to false by default.

The different query parameters above can be combined, so ?package=mysql&kibana.version=7.3.0 will return all mysql package versions which are compatible with 7.3.0.

/categories

The /categories API endpoint has two additional query parameters.

• prerelease: This can be set to true to list prerelease versions of packages. Versions are considered prereleases if they are not stable according to sematic versioning, that is, if they are 0.x versions, or if they contain a prerelease tag. This is set to false by default.
• experimental (deprecated): This can be set to true to list categories from experimental packages. This is set to false by default.
• include_policy_templates: This can be set to true to include categories from policy templates. This is set to false by default.

Package structure

The package structure has been formalized and described using package specification. If you need to modify the structure and corresponding implementation of the Package Registry, remember to adjust the spec first.

Architecture

There are 2 main parts to the package registry:

• Generation of package and content
• Serving content through a simple http endpoint

As much of the endpoints as possible is generated in advance. All package data is pregenerate and is statically served. The only exceptions here are the /categories and /search endpoint as they allow query parameters which leads to many variations and will also get more complex over time.

mage build takes all the packages and generates the content under public. The generated content itself is not checked in.

Directories

• build/packages: Contains all the example packages. These are only example packages used for development. Run mage build to generate these.
• testdata/package: Contains the package for testing. This also serves as an example for a package.

Running

There are several options to run this for development purposes.

Go command

To use the correct golang version, run:

gvm use $(cat .go-version)

When using the go command, first the example packages must be built:

mage build

Afterwards the service can be started:

go run .

Docker

Deployment

The following active endpoints exist:

• prod, CDN: https://epr.elastic.co
• staging, CDN: https://epr-staging.elastic.co
• snapshot, CDN: https://epr-snapshot.elastic.co/

Additionally, the following frozen endpoints exist and are no longer updated:

• experimental, CDN: https://epr-experimental.elastic.co
• 7.9, CDN: https://epr-7-9.elastic.co

An dev registry is running on https://epr-staging.elastic.co/. This is updated from time to time to be in sync with main.

The deployment runs on an Elastic internal k8s cluster. To get all the deployments for the registry use the following command:

kubectl get deployment -n package-registry

This will output the list of available deployments. To do a rolling restart of the staging deployment run:

kubectl rollout restart deployment package-registry-staging-vanilla -n package-registry

General

docker build .
docker run -p 8080:8080 {image id from prior step}

Commands ready to cut-and-paste

docker build --rm -t docker.elastic.co/package-registry/package-registry:main .
docker run -it -p 8080:8080 $(docker images -q docker.elastic.co/package-registry/package-registry:main)

Listening on HTTPS

docker run -it -p 8443:8443 \
  -v /etc/ssl/package-registry.key:/etc/ssl/package-registry.key:ro \
  -v /etc/ssl/package-registry.crt:/etc/ssl/package-registry.crt:ro \
  -e EPR_ADDRESS=0.0.0.0:8443
  -e EPR_TLS_KEY=/etc/ssl/package-registry.key \
  -e EPR_TLS_CERT=/etc/ssl/package-registry.crt \
  docker.elastic.co/package-registry/package-registry:main

Docker images published

We publish a Docker image with each successful build commit on branches, tags, or PR. For each commit we have two docker image tags, one with the commit as tag

docker.elastic.co/package-registry/package-registry:f999b7a84d977cd19a379f0cec802aa1ef7ca379

Another Docker tag with the git branch or tag name

• docker.elastic.co/package-registry/package-registry:main
• docker.elastic.co/package-registry/package-registry:pr-111
• docker.elastic.co/package-registry/package-registry:v0.2.0

If you want to run the most recent registry for development, run the main tag.

These images contain only the package registry, they don't contain any package.

Testing with Kibana

The Docker image of Package Registry is just an empty distribution without any packages. To test it with Kibana using elastic-package, you need to rebuild the snapshot distribution first:

0. Make sure you've built the Docker image for Package Registry:

docker build --rm -t docker.elastic.co/package-registry/package-registry:main .

1. Git clone latest distribution:snapshot from Git:

git clone --branch snapshot https://github.com/elastic/package-storage.git

2. Open Dockerfile and change the base image for the Package Registry (use main instead of v0.19.0):

FROM docker.elastic.co/package-registry/package-registry:main

(Docker builder will use the custom image you've built in step 0.)

3. Rebuild the distribution:snapshot:

docker build --rm -t docker.elastic.co/package-registry/distribution:snapshot .

4. Now you're able to start the stack using Elastic Package (Elasticsearch, Kibana, Agent, Fleet Server, Package Registry):

elastic-package stack up -v -d

(Elastic Package uses the distribution:snapshot by default)

Healthcheck

For Docker / Kubernetes the /health endpoint can be queried. As soon as /health returns a 200, the service is ready.

Configuration

Package Registry needs to be configured with the source of packages. This configuration is loaded by default from the config.yml file. An example file is provided with the distribution.

Cache headers can also be configured in the configuration file. They are used to inform clients about the amount of time a resource is considered fresh. Check the reference configuration file for the available settings.

Additional runtime settings can be provided using flags, for more information about the available flags, use package-registry -help. Flags can be provided also as environment variables, in their uppercased form, for example the following commands are equivalent:

EPR_DRY_RUN=true package-registry

package-registry -dry-run

Performance monitoring

Package Registry is instrumented with the Elastic APM Go Agent. This Agent collects some system and runtime metrics, and detailed information about every request handled by the service. You can read more about the kind of information collected for requests in the APM Guide.

You can configure the agent to send the data to any APM Server using the following environment variables:

• ELASTIC_APM_SERVER_URL: Address of the APM Server. Instrumentation is disabled in Package Registry if this variable is not set.
• ELASTIC_APM_API_KEY: API key to use to authenticate with the APM Server, if needed.
• ELASTIC_APM_SECRET_TOKEN: If configured in the APM Server, this token has to be the same in the agents sending data.
• ELASTIC_APM_TRANSACTION_SAMPLE_RATE: Sample rate for transaction collection, it can be a value from 0.0 to 1.0. 1.0 is the default value, that collects all transactions.

You can find a full reference of these and other options in the Elastic APM Go Agent configuration guide.

Performance profiling

You can enable the HTTP profiler in Package Registry starting it with the -httpprof <address> flag. It will be listening in the given address.

You can read more about this profiler and the available endpoints in the pprof documentation.

Metrics

Package registry can be instrumented to expose Prometheus metrics under /metrics endpoint. By default this endpoint is disabled.

To enable this instrumentation, the required address (host and port) where this endpoint needs to run must be set using the parameter metrics-address (or the EPR_METRICS_ADDRESS environment variable). For example:

package-registry --metrics-address 0.0.0.0:9000

Release

New versions of the package registry need to be released from time to time. The following steps should be followed to create a new release:

1. Create a new branch with the changes to be done for the release
2. Update the changelog by putting in a line for the release, remove all not needed section and put in a new Unreleased section. Don't forget to update the links to the diffs.
3. Update the registry version in the main.go file to be the same version as the release is planned and update the generated files with go test . -generate.
4. Open a pull request and get it merged
5. Tag the new release by creating a new release in Github, put in the changelog in the release
6. Update the main.go to increase the version number to the version of the potential next release version.

CI automatically creates a new Docker image which will be available under docker.elastic.co/package-registry/package-registry:vA.B.C a few minutes after creating the tag.

After the new registry Docker image is available, update the following projects that consume it:

• Integrations: Update the version of the Package Registry Docker image as shown in this sample PR.
• Package Storage: Follow the documentation on how to update the distributions.
• Kibana: Do this only after all Package Storage distributions have been updated and released as new Docker images. Update the version of the Package Registry Distribution Docker image as shown in this sample PR.