Container images

kogut records a deploy when a container of a service starts from a different image, such as after docker compose pull && docker compose up -d, an automatic image update, or a platform’s redeploy button. It needs only the agent on the host.

What counts as a deploy

When a container runs an image id it did not run in the previous sample, kogut records a deploy of the container’s service. Compose containers are followed by Compose project and service, so a container recreated under a new name is the same one, and replicas of one Compose service make one deploy.

The deploy belongs to the service whose name is part of the container name, or to the only service on the host. A container without a service, a restart, or a container recreated from the same image records nothing. An image that changed while kogut was stopped is not recorded.

Version

The version is the image tag as written and the first 12 hex digits of the image digest, such as 1.4.2@3f9c2e1aa0b1, or latest@3f9c2e1aa0b1 without a tag. The timeline shows the deploy with source agent and the host it happened on.

Deploys from CI

When CI announced a deploy of the service through the API or GitHub in the 10 min before the agent sees the new image, kogut records nothing more. When the announcement comes up to 10 min after, both deploys stay on the timeline and only the announced one gets a report.

The same image change seen on several hosts within 10 min is one deploy.

Rollback hint

A deploy noticed from an image change is a likely cause like any other. Its evidence names the previous image:

Deploy of api 1.4.3@4d2b9e81c0aa at 14:02, 5 min before the first failure
Previous image: ghcr.io/acme/api@sha256:3f9c2e1aa0b1…

To roll back, pin that reference in your Compose file or docker run command. An image built on the host has no registry digest, so the line shows the image id.

The digest comes from GET /images/{id}/json, so a socket proxy needs IMAGES=1. Without it, the hint shows the image id.