Registry Cache
Jessica Wade
If you have multiple instances of Docker running in your environment, such asmultiple physical or virtual machines all running Docker, each daemon goes outto the internet and fetches an image it doesn't have locally, from the Dockerrepository. You can run a local registry mirror and point all your daemonsthere, to avoid this extra internet traffic.
The first time you request an image from your local registry mirror, it pullsthe image from the public Docker registry and stores it locally before handingit back to you. On subsequent requests, the local registry mirror is able toserve the image from its own storage.
In environments with high churn rates, stale data can build up in the cache.When running as a pull through cache the Registry periodically removes oldcontent to save disk space. Subsequent requests for removed content causes aremote fetch and local re-caching.
The easiest way to run a registry as a pull through cache is to run the officialRegistry image.At least, you need to specify proxy.remoteurl within /etc/docker/registry/config.ymlas described in the following subsection.
Multiple registry caches can be deployed over the same back-end. A singleregistry cache ensures that concurrent requests do not pull duplicate data,but this property does not hold true for a registry cache cluster.
When using Docker Hub, all paid Docker subscriptions are limited to 5000 pulls per day. If you require a higher number of pulls, you can purchase an Enhanced Service Account add-on. SeeService Accounts for more details.
If you specify a username and password, it's very important to understand thatprivate resources that this user has access to Docker Hub is made available onyour mirror. You must secure your mirror by implementing authentication ifyou expect these resources to stay private!
The registry cache storage can be thought of as an extension to the inlinecache. Unlike the inline cache, the registry cache is entirely separate fromthe image, which allows for more flexible usage - registry-backed cache can doeverything that the inline cache can do, and more:
You can choose any valid value for ref, as long as it's not the same as thetarget location that you push your image to. You might choose different tags(e.g. foo/bar:latest and foo/bar:build-cache), separate image names (e.g.foo/bar and foo/bar-cache), or even different repositories (e.g.docker.io/foo/bar and ghcr.io/foo/bar). It's up to you to decide thestrategy that you want to use for separating your image from your cache images.
Artifact cache offers faster and more reliable pull operations through Azure Container Registry (ACR), utilizing features like Geo-Replication and Availability Zone support for higher availability and speed image pulls.
Artifact cache addresses the challenge of pull limits imposed by public registries. We recommend users authenticate their cache rules with their upstream source credentials. Then pull images from the local ACR, to help mitigate rate limits.
Cache will only occur after at least one image pull is complete on the available container image. For every new image available, a new image pull must be complete. Artifact cache doesn't automatically pull new tags of images when a new tag is available. It is on the roadmap but not supported in this release.
Wildcard cache rules use asterisks (*) to match multiple paths within the container image registry. These rules can't overlap with other wildcard cache rules. In other words, if you have a wildcard cache rule for a certain registry path, you cannot add another wildcard rule that overlaps with it.
Static or fixed cache rules are more specific and do not use wildcards. They can overlap with wildcard-based cache rules. If a cache rule specifies a fixed repository path, then it allows overlapping with a wildcard-based cache rule.
Before configuring the Credentials, you have to create and store secrets in the Azure KeyVault and retrieve the secrets from the Key Vault. Learn more about creating and storing credentials in a Key Vault. And to set and retrieve a secret from Key Vault..
Before configuring the Credentials, you require to create and store secrets in the Azure KeyVault and retrieve the secrets from the Key Vault. Learn more about creating and storing credentials in a Key Vault. And to set and retrieve a secret from Key Vault..
Solution: use JDK8 on windows.I installed AdoptOpenJDK 8 and configured it in JAVA_HOME environment variable.For some reason if I set JAVA_HOME in windows terminal it was not picking up.Had to explicitly add it via Control panel -> System properties -> Advanced -> Environment variables.
FYI: the error I saw in nifi registry logs when using java 11 was:Caused by: java.lang.RuntimeException: Unable to create JAXBContext.at org.apache.nifi.registry.provider.StandardProviderFactory.initializeJaxbContext(StandardProviderFactory.java:73)at org.apache.nifi.registry.provider.StandardProviderFactory.(StandardProviderFactory.java:64)... 54 common frames omittedCaused by: javax.xml.bind.JAXBException: Implementation of JAXB-API has not been found on module path or classpath.
In our last blog post, Peter talked about how to Simulate A Docker Hub Outage, where he gave some context on what a pull-through cache (aka registry mirror) is and why Shipyard needs to mirror parts of Docker Hub.
Docker allows you to pass the registry-mirrors as a flag when starting the docker daemon or as a key/value on the daemon JSON config file. I added the flag to our terraform since we use that to deploy to whichever cloud our customers might be on.
Most of our customers use private registries (DockerHub, Quay, ECR, GCR, etc.) to store, well, their private images. Security is a first class citizen at Shipyard so obviously we had some questions and concerns to test / figure out:
Artifact Registry caches frequently-accessed public Docker Hub images onmirror.gcr.io. You can configure the Docker daemon to use a cached publicimage if one is available, or pull the image from Docker Hub if a cached copyis unavailable.
Pulling cached images does not count against Docker Hub rate limits. However,there is no guarantee that a particular image will remain cached for an extendedperiod of time. Only obtain cached images on mirror.gcr.io byconfiguring the Docker daemon.
To authenticate to Docker Hub for images that aren't cached on mirror.gcr.io,use Artifact Registry remote repositories. Remoterepositories support authentication to Docker Hub. We recommend authenticatingto Docker Hub even if you are only using public images, as it will increase yourdownload rate limit. For more information on Docker Hub download rate limits,see Docker Hub rate limit.
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When running Talos locally, pulling images from container registries might take a significant amount of time.We spin up local caching pass-through registries to cache images and configure a local Talos cluster to use those proxies.A similar approach might be used to run Talos in production in air-gapped environments.It can be also used to verify that all the images are available in local registries.
The Talos local cluster should now start pulling via caching registries.This can be verified via registry logs, e.g. docker logs -f registry-docker.io.The first time cluster boots, images are pulled and cached, so next cluster boot should be much faster.
Harbor is an open source container registry that can be used as a caching proxy.Harbor supports configuring multiple upstream registries, so it can be used to cache multiple registries at once behind a single endpoint.
You can use a proxy cache to pull images from a target Harbor or non-Harbor registry in an environment with limited or no access to the internet. You can also use a proxy cache to limit the amount of requests made to a public registry, avoiding consuming too much bandwidth or being throttled by the registry server.
A Harbor system administrator configures a proxy cache by creating a proxy cache project, which connects to a target registry using a registry endpoint you have configured. A proxy cache project works similarly to a normal Harbor project, except that you are not able to push images to a proxy cache project.
When a pull request comes to a proxy cache project, if the image is not cached, Harbor pulls the image from the target registry and serves the pull command as if it is a local image from the proxy cache project. The proxy cache project then caches the image for a future request.
As of Harbor v2.1.1, Harbor proxy cache fires a HEAD request to determine whether any layer of a cached image has been updated in the Docker Hub registry. Using this method to check the target registry will not trigger the Docker Hub rate limiter. If any image layer was updated, the proxy cache will pull the new image, which will count towards the Docker Hub rate limiter.
A proxy cache project is able to use the same features available to a normal Harbor project, except that you are not able to push images to a proxy cache project. For more information on projects, see the Working with Projects documentation.
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This directory planned and applied with this lockfile before so this seems strange. However, I tried something by locking down the provider versions with required_providers to exactly what is in the lockfile and ran an init -upgrade. The lockfile came back with a diff. Both the confluent and aws provider changed the h1 has at the top of the hashes list:
You are right that this is odd behavior. If you are running just terraform init (without -upgrade) then Terraform can potentially add new checksums, but should not remove any that are already present.
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